Patent Publication Number: US-11380154-B2

Title: Coin ejection apparatus capable of preventing incorrect ejection

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a coin ejection apparatus having one or more coin ejection units which is/are switchable between a driving state and a non-driving state in response to instructions. More particularly, the present invention relates to a coin ejection apparatus capable of surely preventing incorrect coin ejection to result in incorrect dispensing from one or more coin ejection units in a non-driving state. 
     In this specification, the term “coin” has a wide meaning that includes not only coins as currency but also coin equivalents such as tokens and medals other than coins as currency, in which the shape of a “coin” is not limited to a circular one and may be a polygonal or any other one. 
     2. Description of the Related Art 
     Conventionally, multi-unit coin ejection apparatuses having a plurality of coin ejection units have been known. For example, Japanese Examined Patent Publication No. 6182787 issued on Aug. 4, 2017 discloses a multi-unit coin ejection apparatus, which comprises a plurality of coin ejection units and a plurality of coin storing containers respectively placed on the coin ejection units. Each of the coin ejection units is configured in such a way that coins stored in a corresponding one of the coin storing containers are ejected by a rotating disk placed just below the said container through a corresponding coin outlet. The coin ejection units, which are assigned to the respective denominations of coins, are driven in synchronization with each other by a single motor. When a dispensing instruction is received, coins of one or more necessary denominations for the instruction are ejected from one or more of the coin ejection unit. In each of the coin ejection units, the control for selectively ejecting one or more coins of the assigned denomination in response to a dispensing instruction is realized by a shutter provided near the coin outlet. The shutter is formed by a passage preventing member provided movably in a through hole of the disk. The passage preventing member is configured in such a way as to protrude from the surface of the disk and to sink below the same. When preventing the coin ejection, the passage preventing member is moved to protrude from the surface of the disk. When permitting the coin ejection, the passage preventing member is moved to sink below the surface of the disk. In this way, the control for selectively ejecting one or more coins of the assigned denomination in each of the coin ejection units in response to a dispensing instruction is realized using the corresponding shutter. 
     The coin ejection units are arranged along a straight line on the mounting surface of a chassis provided in a base section. The coin ejection units are selectively driven by transmitting the rotational driving force of a single motor to a desired one of the coin ejection units in response to an instruction by way of a driving mechanism which is provided in the chassis. 
     Japanese Examined Patent Publication No. 4005869 issued on Aug. 31, 2007 discloses a game machine having a hopper unit (which is equivalent to a coin ejection unit) in which a rotatable disk is provided. A lock pin is provided in such a way as to be movable by a magnetic force of a solenoid and to be engageable with an engagement part (e.g., a hole or depression) of the disk. The rotation of the disk is stopped by engaging the lock pin with the engagement part, thereby preventing incorrect dispensing of medals or coins. 
     Japanese Examined Patent Publication No. 5265046 issued on May 10, 2013 discloses a hopper-type medal ejection apparatus having a rotary disk for ejecting medals and a medal ejection runner for guiding medals in a predetermined direction and counting the medals thus ejected. The medal ejection runner comprises a cylindrical shaft having elongated protrusions on its outer surface (which are similar to gear teeth), and a claw member which are engageable with the elongated protrusions. The combination of the elongated protrusions and the claw member constitutes a ratchet mechanism that prevents the reverse rotation of the cylindrical shaft. 
     With the aforementioned multi-unit coin ejection apparatus disclosed in Publication No. 6182787, since the coin ejection units, which are assigned to the respective denominations of coins, are driven by a single motor in synchronization with each other, there is an advantage that the cost for the motor can be reduced compared with the case where each of the coin ejection units is driven by its own motor. However, in the one or more coin ejection units which is/are not driven by the driving mechanism formed in the chassis, the disk(s) provided in the one or more coin eject ion units is/are separated from the driving mechanism and is/are rotatable freely. Thus, there are a possibility that unintentional normal rotation of the rotary disk(s) usually occurs due to vibration or the like which is induced by a coin ejection operation in the coin ejection unit which is being driven by the driving mechanism and/or vibration or the like applied from the outside of the said coin ejection unit. If such the unintentional normal rotation occurs, one or more coins stored in the one or more coin ejection units in the non-driving state is/are ejected incorrectly (i.e., incorrect ejection) to result in incorrect dispensing. 
     The aforementioned problem of incorrect coin ejection and incorrect dispensing in the one or more coin ejection units in the non-driving state which is likely to occur in the multi-unit coin ejection apparatus of Publication No. 6182787 will occur in any multi-unit coin ejection apparatus also including the apparatus of Publication No. 6182787, if it has a mechanism or structure that the coin ejection units are selectively driven using a single motor in response to instructions and that only desired one of the coin ejection units is connected to the driving mechanism for selectively driving the same. 
     The aforementioned problem of incorrect coin ejection and incorrect dispensing in the one or more non-driven coin ejection units can be solved by using the mechanism of Publication No. 4005869 that stops the rotation of the disk by engaging the lock pin with the engagement part of the disk using the magnetic force, thereby preventing incorrect dispensing of medals or coins. However, with this mechanism, an actuator such as a solenoid needs to be provided only for moving the lock pin and therefore, there arises a disadvantage that the means for solving the said problem is complicated and as a result, the production cost for this means is high. 
     With the ratchet mechanism of Publication No. 5265046 that prevents the reverse rotation of the cylindrical shaft using the elongated protrusions and the claw member, there is no need to provide an actuator such as a solenoid necessitated in the mechanism of Publication No. 4005869. For this reason, the aforementioned problem of incorrect coin ejection and incorrect dispensing in the one or more non-driven coin ejection units can be solved with a comparatively simple structure. However, with a multi-unit coin ejection apparatus having the mechanism or structure that the coin ejection units are selectively driven using a single motor in response to instructions and that only desired one of the coin ejection units is connected the driving mechanism for selectively driving the same, it is essential that the normal rotation of the disk(s) in the one or more coin ejection units in the non-driving state is/are stopped to prevent the incorrect coin ejection and incorrect dispensing, and that when one of the one or more non-driven coin ejection units is shifted to the driving state, both of the normal rotations of the disk for ejecting coins and the reverse rotation thereof for eliminating malfunction such as coin jam are possible. However, it is apparent that the ratchet mechanism of Publication No. 5265046 is unable to realize such the different operations as described here in the driving state and the non-driving state. 
     SUMMARY OF THE INVENTION 
     The present invention was created while taking the aforementioned circumstances into consideration. 
     Accordingly, an object of the present invention is to provide a coin ejection apparatus having one or more coin ejection units that enables one or more coin ejection units in a driving state to perform both of normal rotation of its rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction, and that enables the one or more coin ejection units in a non-driving state to surely prevent undesired normal rotation of its/their rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing, in the case where the one or more coin ejection units is/are selectively driven using a single motor in response to an instruction. 
     Another object of the present invention is to provide a coin ejection apparatus having one or more coin ejection units that can be switched between a state where both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction are possible and a state where undesired normal rotation of a rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing is prevented by simply shifting one or more coin ejection units between a driving state and a non-driving state. 
     Still another object of the present invention is to provide a coin ejection apparatus having one or more coin ejection units that makes it possible to realize the function that both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction are possible in a driving state and undesired normal rotation of a rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing is prevented in a non-driving state using only a mechanical structure. 
     A further object of the present invention is to provide a coin ejection apparatus having one or more coin ejection units that has the function that both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction are possible in a driving state and undesired normal rotation of a rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing is prevented in a non-driving state is realized using only a mechanical structure which is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     The above objects together with others not specifically mentioned here will become clear to those skilled in the art from the following description. 
     According to a first aspect of the present invention, a multi-unit coin ejection apparatus is provided, which comprises: 
     a base having a mounting surface; 
     coin ejection units mounted on the mounting surface, each of the coin ejection units having a rotary disk; 
     a first motor commonly used for driving the coin ejection units; 
     a driving mechanism that is configured to drive the coin ejection units by transmitting a driving force of the first motor using gears; 
     a switching unit that is configured to switch a destination of the driving force of the first motor, thereby selectively driving a desired one of the rotary disks of the coin ejection units; and 
     an unnecessary rotation prevention mechanism, provided in each of the coin ejection units, that is configured to prevent unnecessary normal rotation of a corresponding one of the rotary disks of the coin ejection units; 
     wherein the switching unit comprises (i) first coupling gears which are respectively provided for the coin ejection units, (ii) second coupling gears which are engageable with the corresponding first coupling gears and which are provided for the driving mechanism, and (iii) a coupling gear displacement mechanism that is configured to displace the second coupling gears between a coupling position and a non-coupling position; 
     the coupling gear displacement mechanism is operated in response to an instruction in such a way that a designated one of the coin ejection units is placed in a driving state where a designated one of the second coupling gears is disposed at the coupling position and that a remainder of the coin ejection units is/are placed in a non-driving state where a remainder of the second coupling gears is/are disposed at the non-coupling position; 
     the unnecessary rotation prevention mechanism comprises an unnecessary rotation prevention member that is formed to prevent the relevant rotary disk from normally rotating to result in incorrect coin ejection when the relevant coin ejection unit is placed in the non-driving state; 
     the unnecessary rotation prevention member is structured in such a way as to be engaged with the relevant first coupling gear or disengaged therefrom in response to displacement of the relevant second coupling gear between the coupling position and the non-coupling position; 
     when the relevant coin ejection unit is placed in the non-driving state, an engaging or engaged part (e.g., an engaging part  117   b ) of the unnecessary rotation prevention member is engaged with one or more engaged or engaging parts (e.g., an engagement hole  114   d ) of the relevant first coupling gear, thereby preventing normal rotation of the relevant rotary disk; and when the relevant coin ejection unit is placed in the driving state, the engaging or engaged part (e.g., the engaging part  117   b ) of the unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts (e.g., the engagement hole  114   d ) of the relevant first coupling gear, thereby permuting normal rotation and reverse rotation of the relevant rotary disk. 
     With the multi-unit coin ejection apparatus according to the first aspect of the present invention, as explained above, the coin ejection units, which are mounted on the mounting surface of the base, are structured in such a way that one of the coin ejection units is selectively driven by switching the transmission destination of the driving force of the commonly used first motor using the switching unit. The designated one of the coin ejection units thus driven by the transmitted driving force of the first motor ejects one or more coins of a corresponding denomination to the instruction using a corresponding one of the rotary disks. In this way, it is possible for the designated one of the coin ejection units to eject one or more coins of the desired denomination by selectively transmitting the driving force of the first motor to the desired one of the coin ejection units. 
     Moreover, the unnecessary rotation prevention mechanism, which is provided in each of the coin ejection units, comprises the unnecessary rotation prevention member that is formed to prevent the normal rotation of the relevant rotary disk to result in incorrect coin ejection when the relevant coin ejection unit is placed in the non-driving state. The unnecessary rotation prevention member is structured in such a way as to be engaged with the relevant first coupling gear or disengaged therefrom in response to displacement of the relevant second coupling gear between the coupling position and the non-coupling position. Thus, the unnecessary rotation prevention mechanism can be enabled or disabled by simply moving the relevant coin ejection unit between the driving state and the non-driving state, in other words, by simply moving the relevant second coupling gear between the coupling position and the non-coupling position, using the coupling gear displacement mechanism of the switching unit. Accordingly, the state where both of normal rotation and reverse rotation of the relevant rotary disk are possible (i.e., where the unnecessary rotation prevention mechanism is disabled) and the state where normal rotation of the relevant rotary disk is prevented (i.e., where the unnecessary rotation prevention mechanism is enabled) can be switched by simply moving the relevant second coupling gear between the coupling position and the non-coupling position. 
     Furthermore, when the relevant coin ejection unit is placed in the non-driving state where the relevant second coupling gear is disposed at the non-coupling position, the engaging or engaged part of the unnecessary rotation prevention member is engaged with the one or more engaged or engaging parts of the relevant first coupling gear, thereby preventing normal rotation of the relevant rotary disk. This means that the undesired normal rotation of the relevant rotary disk is surely prevented when the relevant coin ejection unit is placed in the non-driving state. Accordingly, undesired normal rotation of a relevant rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing, which is likely to be caused by vibration from the coin ejection unit placed in the driving state and/or that from outside of the said coin ejection unit, can be surely prevented when a remainder of the coin ejection units is/are in the non-driving state. 
     On the other hand, when the relevant coin ejection unit is placed in the driving state where the relevant second coupling gear is disposed at the coupling position, the engaging or engaged part of the unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the relevant first coupling gear, thereby permitting both of normal rotation and reverse rotation of the relevant rotary disk. This means that both of the normal and reverse rotations of the relevant rotary disk are permitted when the relevant coin ejection unit is placed in the driving state. Accordingly, both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction are possible when a designated one of the coin ejection units is in the driving state. 
     As described above, with the multi-unit coin ejection apparatus according to the first aspect of the present invention which is structured in such a way that the coin ejection units are selectively driven using a single motor in response to an instruction, both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed in a designated one of the coin ejection units which is in a driving state and at the same time, undesired normal rotation of a rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing can be surely prevented in a remainder of the coin ejection units which is/are in a non-driving state. 
     In addition, with the multi-unit coin ejection apparatus according to the first aspect of the present invention, the function that both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed in a designated one of the coin ejection units placed in a driving state while surely preventing undesired normal rotation of a rotary disk or disks for incorrectly ejecting coins to result in incorrect dispensing in a remainder of the coin ejection units which is/are in a non-driving state is realized by switching the engagement/disengagement between the engaging or engaged part of the unnecessary rotation prevention member and the one or more engaged or engaging parts of the relevant first coupling gear. Moreover, since the state where both of normal rotation and reverse rotation of the relevant rotary disk are possible (i.e., the unnecessary rotation prevention mechanism is disabled) and the state where normal rotation of the relevant rotary disk is prevented (i.e., the unnecessary rotation prevention mechanism is enabled) can be switched by simply moving the relevant coin ejection unit between the driving state and the non-driving state using the switching unit, there is no need to provide a dedicated mechanism or device for switching these two states. Accordingly, the aforementioned function can be realized using only a mechanical structure. 
     Further in addition, it is sufficient for the aforementioned mechanical structure for realizing the aforementioned function to include the engaging or engaged part of the unnecessary rotation prevention member and the one or more engaged or engaging parts of the relevant first coupling gear. Moreover, it is unnecessary to provide a dedicated mechanism or device for switching between the state where both of normal rotation of a rotary disk for ejecting coins and reverse rotation thereof for eliminating malfunction can be performed and the state where the undesired normal rotation of the relevant rotary disk can be surely prevented. Accordingly, the aforementioned mechanical structure is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     In a preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, each of the first coupling gears is formed by a first gear which has teeth and grooves formed on one side face thereof and which is fixed to a rotation shaft for the rotary disk of the relevant coin ejection unit, and each of the second coupling gears is formed by a second gear which has grooves and teeth formed on one side face thereof to be engageable respectively with the teeth and the grooves of the first gear and which is fixed to a relevant linking gear (e.g., a driven gear) of the driving mechanism. 
     In another preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, each of the first coupling gears comprises teeth and grooves formed on one side face thereof and is fixed to a rotation shaft for the rotary disk of the relevant coin ejection unit; 
     the relevant first coupling gear comprises an engagement face on or in which the engaged or engaging parts are arranged annularly along a rotation direction of the relevant first coupling gear; and 
     the engaging or engaged part of the unnecessary rotation prevention member is structured in such a way as to be engaged with any one of the engaged or engaging parts of the relevant first coupling gear when the relevant coin ejection unit is placed in the non-driving state. 
     In still another preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, a function of a one-way clutch that permits only normal rotation of the relevant rotary disk is generated by engaging the engaging or engaged part of the unnecessary rotation prevention member with the one or more engaged or engaging parts which is/are formed on or in an engagement face of the relevant first coupling gear. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, in each of the coin ejection units placed in the non-driving state, a function of a one-way clutch that prevents only normal rotation of the relevant rotary disk is generated by engaging the engaging or engaged part of the relevant unnecessary rotation prevention member with the one or more engaged or engaging parts which is/are formed on or in an engagement face of the relevant first coupling gear; and 
     when the relevant coin ejection unit is moved to the driving state from the non-driving state by the switching unit, the relevant unnecessary rotation prevention member is moved in such a way that the engaging or engaged part of the relevant unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the relevant first coupling gear due to displacement of the relevant second coupling gear to the coupling position from the non-coupling position; resulting in loss of the function of the one-way clutch; 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, the relevant unnecessary rotation prevention member comprises a roller which is contactable with the relevant second coupling gear and rotatable thereon; 
     when one of the coin ejection units is moved to the driving state from the non-driving state by the switching unit, the relevant unnecessary rotation prevention member is moved by displacement of the relevant second coupling gear to the coupling position from the non-coupling position in such a way that the engaging or engaged part of the relevant unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the relevant first coupling gear, thereby permitting both of normal rotation and reverse rotation of the relevant rotary disk; and 
     the roller which is in contact with the relevant second coupling gear is rolled with rotation of the relevant second coupling gear while permitting both of normal rotation and reverse rotation of the relevant rotary disk. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, the relevant unnecessary rotation prevention member comprises a spring having an elastic force that urges the engaging or engaged part of the relevant unnecessary rotation prevention member toward the relevant first coupling gear; 
     when the relevant coin ejection unit is placed in the non-driving state, the engaging or engaged part of the relevant unnecessary rotation prevention member is engaged with the one or more engaged or engaging parts of the relevant first coupling gear by the elastic force of the spring; and 
     when the relevant coin ejection units is placed in the driving state, the engaging or engaged part of the relevant unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the relevant first coupling gear by displacement of the relevant second coupling gear to the coupling position from the non-coupling position against the elastic force of the spring, resulting in permission of both of normal rotation and reverse rotation of the relevant rotary disk. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention; the coupling gear displacement mechanism comprises a camshaft which is rotationally driven by a second motor; wherein the camshaft has cams which are respectively assigned to the coin ejection units; and 
     cam followers which are respectively engaged with the second coupling gears and which are displaceable by the corresponding cams; 
     wherein the second coupling gears are structured in such a way as to be displaced between the coupling position and the non-coupling position according to displacements of the corresponding cam followers which are respectively caused by rotations of the corresponding cams. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, there are provided with sensors that detect respectively rotational positions (or rotational angles) of the cams; and 
     which one of the second coupling gears is disposed at the coupling position is judged based on the detected rotational positions (or rotational angles) of the cams using the sensors. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, detection members are fixed to the camshaft in a one-by-one correspondence to the cams; 
     sensors that detect respectively rotational positions of the detection members are provided at corresponding positions to the detection members; and 
     which one of the second coupling gears is disposed at the coupling position is judged based on detection of the detection members by the corresponding sensors. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, there is provided with a switching unit displacement mechanism that is configured to displace the switching unit between a connection position where the driving force of the first motor is selectively transmittable to a designated one of the coin ejection units and a separation position where the driving force of the first motor is transmittable to none of the coin ejection units; 
     the switching unit displacement mechanism comprises an operating member (e.g., a lever  52 ) mounted on the base, and a moving member (e.g., a combination of an operating part  53  and a frame rocking member  54 ) that displaces mechanically the switching unit between the connection position and the separation position in response to a predetermined action applied to the operating member; and 
     when a predetermined action is applied to the operating member in the state where the switching unit is disposed at the connection position, the switching unit is displaced to the separation position. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, when the switching unit is displaced to the separation position from the connection position using the switching unit displacement mechanism, the said apparatus is shifted to a non-operable mode where the driving force of the first motor is transmitted to none of the coin ejection units, wherein a desired one of the coin ejection units can be removed from the base; and 
     when the switching unit is returned to the connection position from the separation position using the switching unit displacement mechanism, the said apparatus is shifted to an operable mode where the driving force of the first motor is selectively transmitted to a desired one of the coin ejection units. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, the operating member of the switching unit displacement mechanism comprises a manually operable lever which is mounted on the base; 
     the moving member of the switching unit displacement mechanism is structured in such a way as to be mechanically connected to the switching unit and to be moved by a manual operation applied to the lever; and 
     when a predetermined manual operation is applied to the lever, the switching unit is displaced mechanically between the connection position and the separation position in response to the applied manual operation. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, the coupling gear displacement mechanism is structured in such a way as to be rockable around a shaft which is supported by the base; and 
     an operable mode where the driving force of the first motor is selectively transmitted to a desired one of the coin ejection units and a non-operable mode where the driving force of the first motor is transmitted to none of the coin ejection units are switched by rocking the coupling gear displacement mechanism around the shaft. 
     In a further preferred embodiment of the multi-unit coin ejection apparatus according to the first aspect of the present invention, a non-operable mode where the driving force of the first motor is transmitted to none of the coin ejection units is provided in addition to an operable mode where the driving force of the first motor is selectively transmitted to a desired one of the coin ejection units are provided; and the coin ejection units are configured to be detachable from the base by sliding a desired one or ones of the coin ejection units along the mounting surface in the separation mode. 
     According to a second aspect of the present invention; a coin ejection apparatus is provided, which comprises: 
     a base having a mounting surface; 
     a coin ejection unit mounted on the mounting surface, the coin ejection unit having a rotary disk; 
     a first motor for driving the coin ejection unit; 
     a driving mechanism that is configured to drive the coin ejection unit by transmitting a driving force of the first motor using gears; 
     a switching unit that is configured to switch between a driving state where the driving force of the first motor is transmitted to the coin ejection unit and a non-driving state where the driving force of the first motor is not transmitted to the coin ejection unit, thereby selectively driving the coin ejection unit; and 
     an unnecessary rotation prevention mechanism, provided in the coin ejection unit, that is configured to prevent unnecessary normal rotation of the rotary disk; 
     wherein the switching unit comprises (i) a first coupling gear which is provided for the coin ejection unit, (ii) a second coupling gear which is engageable with the first coupling gear and which is provided for the driving mechanism, and (iii) a coupling gear displacement mechanism that is configured to displace the second coupling gear between a coupling position and a non-coupling position; 
     the coupling gear displacement mechanism is operated in response to an instruction in such a way that the coin ejection unit is placed in the driving state where the second coupling gear is disposed at the coupling position or in the non-driving state where the second coupling gear is disposed at the non-coupling position; and 
     the unnecessary rotation prevention mechanism comprises an unnecessary rotation prevention member that is formed to prevent the rotary disk from normally rotating to result in incorrect coin ejection when the coin ejection unit is placed in the non-driving state; 
     the unnecessary rotation prevention member is structured in such a way as to be engaged with the first coupling gear or disengaged therefrom in response to displacement of the second coupling gear between the coupling position and the non-coupling position; 
     when the coin ejection unit is placed in the non-driving state, an engaging or engaged part (e.g., an engaging part  117   b ) of the unnecessary rotation prevention member is engaged with one or more engaged or engaging parts (e.g., an engagement hole  114   d ) of the first coupling gear, thereby preventing normal rotation of the rotary disk; and 
     when the coin ejection unit is placed in the driving state, the engaging or engaged part (e.g., the engaging part  117   b ) of the unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts (e.g., the engagement hole  114   d ) of the first coupling gear, thereby permitting normal rotation and reverse rotation of the rotary disk. 
     With the coin ejection apparatus according to the second aspect of the present invention, as explained above, the coin ejection unit, which is mounted on the mounting surface of the base, is structured in such a way that the coin ejection unit is selectively driven by transmitting the driving force of the first motor or not using the switching unit. The coin ejection unit thus driven by the transmitted driving force of the first motor ejects one or more coins of a denomination corresponding to an instruction using the rotary disk. In this way, it is possible for the coin ejection unit to eject one or more coins of the desired denomination by transmitting the driving force of the first motor to the coin ejection unit or not. 
     Moreover, the unnecessary rotation prevention mechanism, which is provided in the coin ejection unit, comprises the unnecessary rotation prevention member that is formed to prevent the normal rotation of the rotary disk to result in incorrect coin ejection when the coin ejection unit is placed in the non-driving state. The unnecessary rotation prevention member is structured in such a way as to be engaged with the first coupling gear or disengaged therefrom in response to displacement of the second coupling gear between the coupling position and the non-coupling position. Thus, the unnecessary rotation prevention mechanism can be enabled or disabled by simply moving the coin ejection unit between the driving state and the non-driving state, in other words, by simply moving the second coupling gear between the coupling position and the non-coupling position, using the coupling gear displacement mechanism of the switching unit. Accordingly, the state where both of normal rotation and reverse rotation of the rotary disk are possible (i.e., where the unnecessary rotation prevention mechanism is disabled) and the state where normal rotation of the rotary disk is prevented (i.e., where the unnecessary rotation prevention mechanism is enabled) can be switched by simply moving the second coupling gear between the coupling position and the non-coupling position. 
     Furthermore, when the coin ejection unit is placed in the non-driving state where the second coupling gear is disposed at the non-coupling position, the engaging or engaged part of the unnecessary rotation prevention member is engaged with the engaged or engaging parts of the first coupling gear, thereby preventing normal rotation of the rotary disk. This means that the undesired normal rotation of the rotary disk is surely prevented when the coin ejection unit is placed in the non-driving state. Accordingly, undesired normal rotation of a rotary disk for incorrectly ejecting coins to result in incorrect dispensing, which is likely to be caused by vibration from outside of the said coin ejection unit, can be surely prevented when the coin ejection unit is in the non-driving state. 
     On the other hand, when the coin ejection unit is placed in the driving state where the second coupling gear is disposed at the coupling position, the engaging or engaged part of the unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the first coupling gear, thereby permitting both of normal rotation and reverse rotation of the rotary disk. This means that both of the normal and reverse rotations of the rotary disk can be performed when the coin ejection unit is placed in the driving state. Accordingly, both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction are possible when the coin ejection unit is in the driving state. 
     As described above, with the coin ejection apparatus according to the second aspect of the present invention, both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed when the coin ejection unit is in a driving state, and undesired normal rotation of a rotary disk for incorrectly ejecting coins to result in incorrect dispensing can be surely prevented when the coin ejection unit is in a non-driving state. 
     In addition, with the coin ejection apparatus according to the second aspect of the present invention, the function that both of normal rotation of a rotary disk for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed when the coin ejection unit is in a driving state while surely preventing undesired normal rotation of a rotary disk for incorrectly ejecting coins to result in incorrect dispensing when the coin ejection units is in a non-driving state is realized by switching the engagement/disengagement between the engaging or engaged part of the unnecessary rotation prevention member and the one or more engaged or engaging parts of the first coupling gear. Moreover, since the state where both of normal rotation and reverse rotation of the rotary disk are possible (i.e., the unnecessary rotation prevention mechanism is disabled) and the state where normal rotation of the rotary disk is prevented (i.e., the unnecessary rotation prevention mechanism is enabled) can be switched by simply moving the coin ejection unit between the driving state and the non-driving state using the switching unit, there is no need to provide a dedicated mechanism or device for switching these two states. Accordingly, the aforementioned function can be realized using only a mechanical structure. 
     Further in addition, it is sufficient for the aforementioned mechanical structure for realizing the aforementioned function to include the engaging or engaged part of the unnecessary rotation prevention member and the one or more engaged or engaging parts of the first coupling gear. Moreover, it is unnecessary to provide a dedicated mechanism or device for switching between the state where both of normal rotation of a rotary disk for ejecting coins and reverse rotation thereof for eliminating malfunction can be performed and the state where the undesired normal rotation of the rotary disk can be surely prevented. Accordingly, the aforementioned mechanical structure is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     In a preferred embodiment of the coin ejection apparatus according to the second aspect of the present invention, the first coupling gear is formed by a first gear which has teeth and grooves formed on one side face thereof and which is fixed to a rotation shaft for the rotary disk of the coin ejection unit, and 
     the second coupling gear is formed by a second gear which has grooves and teeth formed on one side face thereof to be engageable respectively with the teeth and the grooves of the first gear and which is fixed to a linking gear (e.g., a driven gear) of the driving mechanism. 
     In another preferred embodiment of the coin ejection apparatus according to the second aspect of the present invention, the first coupling gear comprises teeth and grooves formed on one side face thereof and is fixed to a rotation shaft for the rotary disk; 
     the first coupling gear comprises an engagement face on or in which the engaged or engaging parts are arranged annularly along a rotation direction of the first coupling gear; and 
     the engaging or engaged part of the unnecessary rotation prevention member is structured in such a way as to be engaged with any one of the engaged or engaging parts of the first coupling gear when the coin ejection unit is placed in the non-driving state. 
     In still another preferred embodiment of the coin ejection apparatus according to the second aspect of the present invention, a function of a one-way clutch that permits only normal rotation of the rotary disk is generated by engaging the engaging or engaged part of the unnecessary rotation prevention member with the one or more engaged or engaging parts which is/are formed on or in the engagement face of the first coupling gear. 
     In a further preferred embodiment of the coin ejection apparatus according to the second aspect of the present invention, when the coin ejection unit is placed in the non-driving state, a function of a one-way clutch that prevents only normal rotation of the rotary disk is generated by engaging the engaging or engaged part of the relevant unnecessary rotation prevention member with the one or more engaged or engaging parts which is/are formed on or in an engagement face of the relevant first coupling gear; and 
     when the coin ejection unit is moved to the driving state from the non-driving state by the switching unit, the unnecessary rotation prevention member is moved in such a way that the engaging or engaged part of the relevant unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the first coupling gear due to displacement of the second coupling gear to the coupling position from the non-coupling position, resulting in loss of the function of the one-way clutch. 
     In a further preferred embodiment of the coin ejection apparatus according to the second aspect of the present invention, the unnecessary rotation prevention member comprises a roller which is contactable with the second coupling gear and rotatable thereon; 
     when the coin ejection unit is moved to the driving state from the non-driving state by the switching unit, the roller of the unnecessary rotation prevention member is moved by displacement of the second coupling gear to the coupling position from the non-coupling position in such a way that the engaging or engaged part of the relevant unnecessary rotation prevention member is disengaged from the one or more engaged or engaging parts of the first coupling gear, thereby permitting both of normal rotation and reverse rotation of the rotary disk; and 
     the roller which is in contact with the second coupling gear is rolled with rotation of the second coupling gear while permitting both of normal rotation and reverse rotation of the rotary disk. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the present invention may be readily carried into effect, it will now be described in detail with reference to the accompanying drawings. 
         FIG. 1  is a perspective view showing the overall structure of a multi-unit coin ejection apparatus according to a first embodiment of the present invention, in which the state where lids of four coin storing containers are removed is shown. 
         FIG. 2  is a perspective view showing the state where four coin storing containers are detached from the multi-unit coin ejection apparatus of  FIG. 1 , 
         FIG. 3  is a bottom view showing the structure of a driving mechanism and a switching unit, both of which are provided in a chassis or base of the multi-unit coin ejection apparatus of  FIG. 1 . 
         FIG. 4  is a bottom view showing the structure of four coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 . 
         FIG. 5  is a perspective view showing the state where the four coin storing containers and the chassis or base are detached from the multi-unit coin ejection apparatus of  FIG. 1 . 
         FIG. 6  is a perspective view showing the structure of the driving mechanism and the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely downward from the upper right front. 
         FIG. 7  is a perspective view showing the structure of the driving mechanism and the switching unit of the mufti-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely upward from the lower left front. 
         FIG. 8  is a perspective view showing the structure of the driving mechanism and the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely upward from the lower left rear. 
         FIG. 9  is a perspective view showing the structure of the driving mechanism and the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely downward from the upper right rear. 
         FIG. 10A  is a perspective view showing an example of the structure of a cam follower used for the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely downward from the upper right front. 
         FIG. 10B  is a perspective view showing the example of the structure of the cam follower of  FIG. 10A , which is seen obliquely downward from the upper right rear. 
         FIG. 11A  is a front view showing an example of the structure of a coupling gear (which corresponds to a second coupling gear) used for the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which shows the state where the coupling gear is fixed to an upper surface (upper side face) of a corresponding driven gear. 
         FIG. 11B  is a perspective view showing the example of the structure of the coupling gear of  FIG. 11A , which is seen obliquely downward from an upper position. 
         FIG. 11C  is a perspective view showing the example of the structure of the driven gear of  FIG. 11A , which is seen obliquely upward from a lower position. 
         FIG. 12A  is a front view showing an example of the engagement structure of the cam follower with the corresponding driven gear, which is used for the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 . 
         FIG. 12B  is a rear view showing the example of the engagement structure of the cam follower of  FIG. 12A  with the corresponding driven gear. 
         FIG. 13A  is a perspective view showing an example of the structure of a coupling gear (which corresponds to a first coupling gear) used for the switching unit of the multi-unit coin ejection apparatus of  FIG. 1 , which is seen obliquely downward from an upper position. 
         FIG. 13B  is a plan view showing the example of the structure of the coupling gear of  FIG. 13A . 
         FIG. 14  is an explanatory view showing the switching operation of the multi-unit coin ejection apparatus of  FIG. 1  between an operable mode and a non-operable mode by a rocking motion of the switching unit around a support shaft, in which the upper part shows the state of the said apparatus in the operable mode and the lower part shows the state thereof in the non-operable mode. 
         FIG. 15A  is a cross-sectional view showing the switching operation of a fourth coin ejection unit of the multi-unit coin ejection apparatus of  FIG. 1  between a driving state and a non-driving state according to a rotation position (or a rotation angle) of cams included in the switching unit, in which the cam end is directed diagonally downward right and the fourth coin ejection unit is in the non-driving state. 
         FIG. 15B  is a cross-sectional view showing the switching operation of the fourth coin ejection unit of the multi-unit coin ejection apparatus of  FIG. 1  between the driving state and the non-driving state, in which the cam end is directed diagonally upward right and the fourth coin ejection unit is in the non-driving state. 
         FIG. 15C  is a cross-sectional view showing the switching operation of the fourth coin ejection unit of the multi-unit coin ejection apparatus of  FIG. 1  between the driving state and the non-driving state, in which the cam end is directed diagonally upward left and the fourth coin ejection unit is in the non-driving state. 
         FIG. 15D  is a cross-sectional view showing the switching operation of the fourth coin ejection unit of the multi-unit coin ejection apparatus of  FIG. 1  between the driving state and the non-driving state, in which the cam end is directed diagonally downward left and the fourth coin ejection unit is in the driving state. 
         FIG. 16  is an explanatory view showing the driving/non-driving state of the first to fourth coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 , in which only the fourth coin ejection unit is in the driving state and the first to third coin ejection units are in the non-driving state. 
         FIG. 17  is an explanatory view showing the driving/non-driving state of the first to fourth coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 , in which only the third coin ejection unit is in the driving state and the first, second, and fourth coin ejection units are in the non-driving state. 
         FIG. 18  is an explanatory view showing the driving/non-driving state of the first to fourth coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 , in which only the second coin ejection unit is in the driving state and the first, and third to fourth coin ejection units are in the non-driving state. 
         FIG. 19  is an explanatory view showing the driving/non-driving state of the first to fourth coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 , in which only the first coin ejection unit is in the driving state and the second to fourth coin ejection units are in the non-driving state. 
         FIG. 20A  is an explanatory view showing the relative positions of the coupling gear in the first coin ejection unit and the corresponding coupling gear fixed to the underlying driven gear, in which the relative positions in the driving (connected) state is shown. 
         FIG. 20B  is an explanatory view showing the relative positions of the coupling gear in the first coin ejection unit and the corresponding coupling gear on the driven gear, in which the relative positions in the non-driving (non-connected) state is shown. 
         FIG. 21  is an explanatory view showing the driving/non-driving state of the first to fourth coin ejection units of the multi-unit coin ejection apparatus of  FIG. 1 , in which all of the first coin ejection units are in the non-driving state (i.e., the multi-unit coin ejection apparatus of  FIG. 1  is in the non-operable mode). 
         FIG. 22  is a perspective view showing the situation where the fourth coin ejection unit is detached from the chassis or base by sliding the same along the mounting surface after entering the non-operable mode in the multi-unit coin ejection apparatus of  FIG. 1 . 
         FIG. 23A  is a perspective view showing the structure of an unnecessary rotation prevention mechanism of the multi-unit coin ejection apparatus of  FIG. 1 , which shows the positional relationship between a rotary disk which is fixed to a rotation shaft of the coin ejection unit and the unnecessary rotation prevention mechanism in the non-driving state. 
         FIG. 23B  is a perspective view showing the structure of the unnecessary rotation prevention mechanism of  FIG. 23A , which shows the engagement state of an engaging part and a roller of an unnecessary rotation prevention member with corresponding two coupling gears in the non-driving state. 
         FIG. 24A  is a perspective view showing an example of the structure of the unnecessary rotation prevention member of  FIG. 23B , which is seen obliquely downward from the upper rear. 
         FIG. 24B  is a side view showing the example of the structure of the unnecessary rotation prevention member of  FIG. 23B . 
         FIG. 24C  is a rear view showing the example of the structure of the unnecessary rotation prevention member of  FIG. 23B . 
         FIG. 25A  is a side view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the non-driving state. 
         FIG. 25B  is a plan view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the non-driving state. 
         FIG. 26A  is a side view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the driving state. 
         FIG. 26B  is a plan view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the driving state. 
         FIG. 27A  is a front view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the non-driving state. 
         FIG. 27B  is a cross-sectional view along the line XXVIIB-XXVIIB in  FIG. 27A . 
         FIG. 28A  is a front view showing the engagement state of the engaging part and the roller of the unnecessary rotation prevention member with the corresponding two coupling gears in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the driving state. 
         FIG. 28B  is a cross-sectional view along the line XXVIIIB-XXVIIIB in  FIG. 28A . 
         FIG. 29  is an explanatory plan view showing the change of the engagement state of the engaging part of the unnecessary rotation prevention member with an engagement hole of the corresponding coupling gear along with the rotation of the said coupling gear for realizing the function of a one-way clutch in the multi-unit coin ejection apparatus of  FIG. 1 , where the relevant coin ejection unit is in the non-driving state. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention will be described in detail below while referring to the drawings attached. 
     First Embodiment 
     A multi-unit coin ejection apparatus  1  having four coin ejection units  110  according to a first embodiment of the present invention is shown in  FIGS. 1 to 9 . 
     Structure of Multi-Unit Coin Ejection Apparatus  1   
     The overall schematic structure of the multi-unit coin ejection apparatus  1  according to the first embodiment of the present invention is shown in  FIG. 1 . Moreover, the state where four coin storing containers  120  are detached from the multi-unit coin ejection apparatus  1  is shown in  FIG. 2 , the schematic structures of a driving mechanism  20  and a switching unit  40  both of which are provided in a chassis or base  11  of the apparatus  1  are shown in  FIG. 3 , and the structure of the first to fourth coin ejection units  110  is shown in  FIG. 4 . 
     As shown in  FIG. 1 , the multi-unit coin ejection apparatus  1  according to the first embodiment is mainly formed by a base section  10  and a coin ejection section  100 . The base section  10  comprises the chassis or base  11  which has a shape like a rectangular parallelepiped, and the approximately rectangular upper surface of the chassis  11  is formed as a mounting surface  11   a . The multi-unit coin ejection apparatus  1  is placed in such a way that the mounting surface  11   a  is approximately parallel to the horizontal plane. 
     The coin ejection section  100  comprises the first to fourth coin ejection units  110 , each of which has a corresponding one of the four coin storing containers  120  and a lid (not shown) that covers the upper opening of the said container  120 . The first to fourth coin ejection units  110  are arranged on the mounting surface  11   a  to be adjacently to each other along a straight line parallel to the long sides of the mounting surface  11   a  and are disengageably engaged with the mounting surface  11   a , A first motor M 1  for conducting the coin ejection operation by driving the respective coin ejection units  110  is fixed to one end of the chassis  11 . The rotational shaft (not shown) of the first motor M 1  is disposed so as to be perpendicular to the mounting surface  11   a . The control of the first motor M 1 , i.e., the start and stop of rotation and the switching of the rotation direction between the normal and reverse directions, is performed by a control device (not shown). 
     As the first motor M 1 , any known motor can be used if it has a rotational driving force sufficient for driving (the rotating disk of) each of the first to fourth coin ejection units  110  to conduct the predetermined coin ejection operation. 
     In the following explanation, the unit  110  disposed at the nearest position to the first motor M 1  is termed the “first coin ejection unit”, and the remaining three units  110  arranged in this order in a direction away from the first coin ejection unit  110  along the long sides of the mounting surface  11   a  are respectively termed the “second coin ejection unit”, the “third coin ejection unit”, and the “fourth coin ejection unit”. 
     The first to fourth coin ejection units  110  are respectively assigned to predetermined four denominations (for example, in the case of Japanese Yen, four denominations of 500 Yen, 100 Yen, 50 Yen, and 10 Yen). Thus, these four coin ejection units  110  are configured in such a way that coins of a relevant denomination are stored in the coin storing container  120  of a corresponding one of the units  110 . Each of the coin ejection units  110  ejects the coins of the relevant denomination stored in the corresponding coin storing container  120  to the outside one by one in response to a dispensing instruction which is sent from an upper-level device (for example, a coin depositing/dispensing apparatus). 
     The first to fourth coin ejection units  110  have the same structure. As shown in  FIGS. 2 and 5 , each of the four units  110  comprises a plate-shaped body  111 , and a rotary disk  112  which has four through holes and which is mounted so as to be rotatable in the body  111 . Since the mounting surface  11   a  is approximately horizontal, the disk  112  is rotatable in an approximately horizontal plane. If a coin of a relevant denomination which has been dropped from the corresponding coin storing container  120  is fitted into one of the through holes of the disk  112  during rotation, the said coin is thrown out of the hole by an inertial force caused by the rotation of the disk  112  and as a result, the said coin is ejected to the outside through an ejection outlet  113  provided at the rear end of the body  111 . In addition, at the time of coin ejection, the said coin thus thrown out of the corresponding hole is controlled so as to abut on a coin guide  116  provided near the ejection outlet  113 ; as a result, the ejection direction of the said coin is always controlled in a predetermined direction. 
     Needless to say, the count of the through holes of the rotary disk  112  is not limited to four and it may be set as any number other than four. Moreover, it is needless to say that the rotary disks  112  provided for all the denominations to be ejected need not have the same structure (i.e. which have an equal count of the holes) and that the disks  112  may have different structures (i.e. which have different counts of the holes) according to the assigned denominations. 
     In each of the first to fourth coin ejection units  110 , a rotational shaft  115  that extends approximately vertically and that is rotatably supported is provided in the body  111 . The rotary disk  112  is engaged with the top end of the shaft  115 . As shown in  FIG. 4 , a coupling gear  114  is fixed to the lower end of the shaft  115  and thus, the coupling gear  114  and the disk  112  are rotated integrally along with the rotation of the shaft  115 . This means that the coupling gear  114  also is rotated in the approximately horizontal plane similar to the disk  112 . 
     As shown in  FIG. 3 , in the chassis  11 , there are provided with a driving mechanism  20  that selectively drives rotationally one of the rotary disks  112  in the first to fourth coin ejection units  110  by transmitting the driving force of the first motor M 1 , and a switching unit  40  that switches the transmission destination of the rotational driving force of the first motor M 1  to selectively drive one of the first to fourth coin ejection units  110 . 
     The structure of the driving mechanism  20  is shown in  FIG. 3  and  FIGS. 6 to 9 . Specifically, the driving mechanism  20  comprises a plurality of gears that are arranged approximately linearly along the long sides of the chassis  11 . More specifically, the driving mechanism  20  comprises (i) a driving gear  21  fixed to the rotational shaft of the first motor M 1 ; (ii) four driven gears  23 ,  25 ,  27 , and  29  that are respectively fixed to the lower ends of the rotational shafts  115  of the first to fourth coin ejection units  110 ; (iii) an intermediate gear  22  rotatably placed between the driving gear  21  and the driven gear  23  for the first coin ejection unit  110 ; (iv) an intermediate gear  24  rotatably placed between the driven gear  23  for the first coin ejection unit  110  and the driven gear  25  for the second coin ejection unit  110 ; (v) an intermediate gear  26  rotatably placed between the driven gear  25  for the second coin ejection unit  110  and the driven gear  27  for the third coin ejection unit  110 ; (vi) and an intermediate gear  28  rotatably placed between the driven gear  27  for the third coin ejection unit  110  and the driven gear  29  for the fourth coin ejection unit  110 . 
     All of the driven gears  23 ,  25 ,  27 , and  29  and the intermediate gears  22 ,  24 ,  26 , and  28  are located in a plane parallel to the mounting surface  11   a  (i.e., an approximately horizontal plane) and are arranged along the straight line parallel to the long sides of the mounting surface  11   a  (along which the first to fourth coin ejection units  110  are arranged). The driven gears  23 ,  25 ,  27 , and  29  and the intermediate gears  22 ,  24 ,  26 , and  28  are rotatable integrally along with the corresponding eight rotational shafts (not shown) which are rotatably supported in the chassis  11 , respectively. As easily understood from the structure of the driving mechanism  20 , all of the driven gears  23 ,  25 ,  27 , and  29  prepared respectively for the first, second, third, and fourth coin ejection units  110  are rotated in the same direction as the driving gear  21 . 
     As shown in  FIGS. 6 to 9 , coupling gears  30 ,  31 ,  32 , and  33  (which correspond to the second coupling gears) are respectively fixed onto the upper surfaces (upper side faces) of the driven gears  23 ,  25 ,  27 , and  29  of the first to fourth coin ejection units  110 . These coupling gears  30 ,  31 ,  32 , and  33  are rotated integrally along with the corresponding driven gears  23 ,  25 ,  27 , and  29 , respectively. Moreover, the coupling gears  30 ,  31 ,  32 , and  33  are disengageably engaged with corresponding four coupling gears  114  (see  FIG. 4  and  FIGS. 13A and 13B ) (which correspond to the first coupling gears) fixed to the corresponding rotational shafts  115  of the first; second, third, and fourth units  110 ; respectively. These four coupling gears  30 ,  31 ,  32 , and  33  are selectively engaged with the corresponding four coupling gears  114  or disengaged from the same by the switching unit  40 . Due to this selective engagement or disengagement, the first to fourth coin ejection units  110  as the transmission destination of the driving force of the first motor M 1  is switched or selectively selected. 
     The switching unit  40  has the structure shown in  FIGS. 6 to 9 . Specifically, the switching unit  40  comprises an approximately bar-shaped frame  42  formed by combining a plurality of thin plates; a camshaft  43  rotatably supported by the frame  42 , and a second motor M 2  supported by the frame  42 . Four cams  44  and four detection members  45  are fixed to the camshaft  43 . The second motor M 2  is used for rotationally driving the camshaft  43 . The frame  42  and the camshaft  43  are parallel to each other and are extended along the aforementioned straight line (along which the first to fourth coin ejection units  110  are arranged), The total length of the frame  42  and that of the camshaft  43  are approximately the same as that of the space that encloses the driven gears  23 ,  25 ,  27 , and  29  and the intermediate gears  22 ,  24 ,  26 , and  28 . The second motor M 2  has a driving gear  50  which is fixed to a rotational shaft (not shown) of the motor M 2  (see  FIG. 8 ). The driving gear  50  is rotatably engaged with the driven gear  51  which is fixed to the camshaft  43  at the position opposing to the driving gear  50 . The camshaft  43  is rotationally driven by the rotational driving force of the second motor M 2 . 
     The frame  42  comprises a belt-shaped frame body  42   a  and four supporting parts  42   b . The frame body  42   a  is extended over the whole length of the frame  42 . All of the four supporting parts  42   b  are formed to protrude perpendicularly from the frame body  42   a  in the same direction. Two of the supporting parts  42   b  are disposed at a predetermined distance near the middle position of the frame body  42   a . The remaining two supporting parts  42   b  are disposed at the two end positions of the frame body  42   a , respectively. Two supporting shafts  41  are fixed to the two supporting parts  42   b  disposed at the end positions in the outside of the frame  42 , respectively. These two supporting shafts  41  are protruded in opposite directions from the corresponding supporting parts  42   b  along the extending direction of the frame  42  and the camshaft  43 , and rotatably supported by two supporting members (not shown) fixed in the chassis  11 , respectively. For this reason, the entire frame  42  can be rocked or rotated around the two supporting shafts  41  disposed at the two ends of the frame  42 . Due to this rocking or rotation motion of the frame  42 , the camshaft  43  also is rocked or rotated around the two supporting shafts  41  to be displaced. The second motor M 2 , which is disposed between the camshaft  43  and the frame body  42   a  at the position approximately opposite to the intermediate gear  24 , is fixed to the inner surface of the frame body  42   a.    
     In this first embodiment, the camshaft  43  is formed by coupling two shaft members  43   a  with a joint or connector  43   b , One of the shaft members  43   a  is rotatably supported by the two supporting parts  42   b  disposed at the right side half of the frame body  42   a , and the other of the shaft members  43   a  is rotatably supported by the two supporting parts  42   b  disposed at the left side half of the frame body  42   a . However, this structure is used for facilitating the assembly. Thus, it is needless to say that the camshaft  43  may be formed by a single shaft member. 
     As the second motor M 2 , a known servo motor or stepping motor may be used. However, the present invention is not limited to these motors. It is needless to say that any motor may be used for the second motor M 2  if it can control precisely the rotational position or rotational angle of the camshaft  43 . 
     The start and stop of the rotation of the second motor M 2  and the switching of the rotation direction thereof between the normal and reverse directions, which are performed by an unillustrated control device, can be appropriately adjusted according to the arrangement of the four cams  44  on the camshaft  43 . For example, the second motor M 2  is usually configured to be rotated in the normal and reverse directions; however, the second motor M 2  may be configured to be rotated only in one direction (i.e., only the normal or reverse direction). 
     The four cams  44  fixed to the camshaft  43  are respectively prepared for the first to fourth coin ejection units  110 . These cams  44  are the same in shape and size as each other. Each of the cams  4  is formed by a member with a predetermined thickness which has a shape like an isosceles triangle whose three corners are rounded. As seen from  FIG. 6 , these four cams  44  are fixed to the camshaft  43  in such a way as to shift sequentially at a phase difference of 90°. This is to make it possible to selectively switch the transmission destination of the driving force of the first motor M 1  among the first to fourth coin ejection units  110  by changing the rotational position or angle of the camshaft  43 . 
     The four cams  44  are configured to cooperate with the four cam followers  48  (see  FIGS. 7 and 8 ) which are respectively engaged with the corresponding driven gears  23 ,  25 ,  27 , and  29  provided respectively for the first to fourth coin ejection units  110 . 
     The four cam followers  48  have the function of displacing the corresponding driven gears  23 ,  25 ,  27 , and  29  in upper and lower directions. These four cam followers  48  are the same in shape and size, each of which has the structure shown in  FIGS. 10A and 10B . Specifically, each of the cam followers  48 , the entire shape of which is like a Y character, comprises a cam receiving part  48   a  and a branching part  48   b . The cam receiving part  48   a  is a part for receiving the corresponding cam  44 . The branching part  48   b  is a part that is engaged with an engagement member (e.g., an engagement member  23   a  shown in  FIGS. 12A and 12B ) mounted on a corresponding one of the driven gears  23 ,  25 ,  27 , and  29 , A shaft hole  48   c  is formed near the boundary between the cam receiving part  48   a  and the branching part  48   b . When the cam reeving part  48   a  is pressed downward by the protruding part (which may be termed the cam end also) of the corresponding cam  44 , the cam follower  48  is rotated around a support shaft  48   f  (see  FIG. 12A ) which is fit in the shaft hole  48   c  and as a result, the branching part  48   b  is pressed upward. When the downward pressing force applied to the cam reeving part  48   a  by the protruding part of the corresponding cam  44  is lost, the cam follower  48  is returned to its initial position by the elastic force of a corresponding spring  47  (see  FIGS. 7 and 8 ) disposed right below the cam reeving part  48   a . This means that the cam follower  48  is rocked upward and downward around the support shaft  48   f  (or the shaft hole  48   c ) like a seesaw in response to the presence or absence of the downward pressing force applied to the cam reeving part  48   a.    
     Two pins  48   d  are respectively fixed inwardly to the ends of two arms that forms the branching part  48   b  of the cam follower  48 . Two rollers  48   e  are rotatably engaged with these two pins  48   d , respectively. The reason why the rollers  48   e  are provided is to realize the smooth engagement operation of the cam follower  48  with the engagement member (e.g., the engagement member  23   a ) mounted on the corresponding one of the driven gears  23 ,  25 ,  27 , and  29 . 
       FIGS. 11A, 11B, and 11C  show an example of the structure of the engagement member  23   a  mounted on the driven gear  23  for the first coin ejection unit  110 , in which the coupling gear  30  is fixed to the driven gear  23 . 
     As seen from  FIGS. 11A, 11B, and 11C , the coupling gear  30 , the diameter of which is slightly smaller than the driven gear  23 , is fixed to the upper side face (upper surface) of the driven gear  23  in such a way as to be coaxial with the same gear  23 . The engagement member  23   a  having an approximately cylindrical shape is fixed to the lower side face (lower surface) of the driven gear  23  in such a way as to protrude downward. The engagement member  23   a , which is fixed to be coaxial with the driven gear  23 , has a flange part  23   aa  that protrudes laterally at the lower end thereof. The flange part  23   aa  forms one of the engagement faces for the branching part  48   b . The lower side face of the driven gear  23  forms the other of the engagement faces for the branching part  48   b . The branching part  48   b  is inserted into between the flange part  23   aa  and the lower surface of the driven gear  23  to be engaged with the same. The engagement member  23   a  has a shaft hole  23   b  which is coaxial with the corresponding driven gear  23  and the corresponding coupling gear  30 . The two rollers  48   e , which are attached to the two ends of the branching part  48   b  of the cam follower  48 , are engaged with the part which is sandwiched by the flange part  23   aa  and the lower surface of the driven gear  23 . While the branching part  48   b  of the cam follower  48  is rocked upward or downward around the support shaft  48   f , the rollers  48   e  are rolled, thereby realizing smooth movement of the driven gear  23  and the coupling gear  30  between the coupling position and the non-coupling position. 
     The aforementioned explanation about the driven gear  23  is applicable to the driven gears  25 ,  27 , and  29 . As shown in  FIG. 7 , engagement members  25   a ,  27   a , and  29   a  each having an approximately cylindrical shape are respectively mounted on the driven gears  25 ,  27 , and  29  for the second to fourth coin ejection units  110 . The engagement members  25   a ,  27   a , and  29   a  are respectively fixed to the lower side faces (lower surfaces) of the driven gears  25 ,  27 , and  29  in such a way as to protrude downward. 
     In this embodiment, as shown in  FIG. 11 , the coupling gear  30  fixed to the upper side face (upper surface) of the driven gear  23  has the structure that gear teeth  30   a  are formed in the upper side face thereof along its circular rim at equal intervals. A gear groove  30   b  is formed between each of the two adjoining gear teeth  30   a . This means that the gear teeth  30   a  of the coupling gear  30  are formed to protrude upward while the gear teeth of the driven gear  23  are formed to protrude laterally and radially. A shaft hole  30   c  is formed at the center of the coupling gear  30  to be coaxial with the shaft hole of the driven gear  23 . 
     The engagement state of the cam follower  48  with the corresponding engagement member  23   a  is shown in  FIGS. 12A and 12B . The cam follower  48  is rockable around the support shaft  48   f  which is fit in the shaft hole  48   c . Due to the rocking motion of the cam follower  48 , the coupling gear  30  (one of the second coupling gears) can be switched between the coupling position and the non-coupling position. In  FIG. 12A , the protruding part of the cam  44  (i.e., the part of the cam  44  that protrudes most from the cam shaft  43 ) lowers slightly the cam receiving part  48   a  and at the same time, the branching part  48   b  is slightly raised due to the lowering of the cam receiving part  48   a , resulting in a slight rising operation of the driven gear  23  and the coupling gear  30 . In this state, the coupling gear  30  is engaged or meshed with the corresponding coupling gear  114  (one of the first coupling gears), which means that the coupling gears  30  and  114  are coupled. On the other hand, when the cam  44  is moved and the protruding end thereof is disengaged from the cam receiving part  48   a , the cam receiving part  48   a  is slightly displaced upward (i.e., returned to the initial position) due to the elastic force of the spring  47  (see  FIG. 7 , for example) placed just below the cam receiving part  48   a , as shown in  FIG. 12B , resulting in a slight lowering operation of the driven gear  23  and the coupling gear  30  (i.e., returned to the initial position). In this state, the coupling gear  30  is not engaged or meshed with the corresponding coupling gear  114 , which means that the coupling gears  30  and  114  are not coupled. 
     The end of the aforementioned spring  47  opposite to the cam receiving part  48   a  is supported by a supporting structure (not shown) provided just below the spring  47  in the chassis  11 . For this reason, the elastic force of the spring  47  is always applied to the cam receiving part  48   a  and as a result, the cam receiving part  48   a  is kept at a predetermined upper position and the branching part  48   b  is kept at a predetermined lower position. Accordingly, the coupling gear  30  is located at the aforementioned lower position, i.e., the “non-coupling position”, except for the time when the cam receiving part  48   a  is pressed downward by the protruding part of the cam  44 . On the other hand, when the cam receiving part  48   a  is pressed downward by the protruding part of the cam  44 , the coupling gear  30  is moved to the aforementioned upper position, i.e., the “coupling position”. When the downward pressing action by the protruding part of the cam  44  is lost, the coupling gear  30  is automatically returned to the “non-coupling position”. In this way, the coupling gear  30  can be switched between the “coupling position” and the “non-coupling position” by way of the cam follower  48  due to a simple rocking or rotation operation of the cam  44 . 
     An example of the structure of the coupling gear  114  corresponding to the coupling gear  30  is shown in  FIGS. 13A and 13B . In this structure example, gear teeth  114   a  are formed in the lower side face thereof along its circular rim at equal intervals. A gear groove  114   b  is formed between each of the two adjoining gear teeth  114   a . This means that the gear teeth  114   a  of the coupling gear  114  are formed to protrude downward. A shaft hole  114   c  is formed at the center of the coupling gear  114  to be coaxial with the shaft hole of the corresponding coupling gear  30  at the time of coupling. The gear teeth  114   a  and the gear grooves  114   b  of the coupling gear  114  can be engaged with the gear grooves  30   b  and the gear teeth  30   a  of the corresponding coupling gear  30 , respectively. When the gear teeth  114   a  and the gear grooves  114   b  of the coupling gear  114  are respectively engaged with the gear grooves  30   b  and the gear teeth  30   a  of the corresponding coupling gear  30 , i.e., these two gears  114  and  30  are coupled, the driving force of the coupling gear  30  is transmitted to the corresponding coupling gear  114  and as a result, the rotary disk  112  of the coin ejection unit  110  connected to the said coupling gear  114  is drivingly rotated, thereby ejecting a coin or coins of the corresponding denomination from the said unit  110 . 
     In the structure example of  FIGS. 13A and 13B , the coupling gear  114  comprises an engagement face  114   g  formed on the opposite side to the gear teeth  114   a  and the gear grooves  114   b . Engagement holes  114   d  are formed in the engagement face  114   g  (i.e., the upper side face) to be arranged along the circular rim of the said gear  114  at equal intervals. The engagement face  114   g  is a face with which an engaging part  117   b  of an unnecessary rotation prevention member  117  of the unnecessary rotation prevention mechanism  80  which will be explained later is engaged. Each of the engagement holes  114   d  has two ends  114   e  and  114   f  formed apart from each other along the rim of the coupling gear  114 . The end  114   e  has a perpendicular face with respect to the engagement face  114   g  and the end  114   f  has an inclined face with respect to the same, which means that the coupling gear  114  comprises the engagement holes  114   d  each having the perpendicular end  114   e  and the inclined end  114   f . This is to realize the function of a one-way clutch. Specifically, when the coupling gear  114  is not coupled with the coupling gear  30 , there is a possibility that unintended slip of the coupling gear  114  occurs to result in a phenomenon of undesired dispensing of a coin or coins. The function of the one-way clutch is used for preventing such the phenomenon of undesired coin dispensing. For this reason, the engagement holes  114   d  may be omitted if the function of the one-way clutch is unnecessary. 
     The details of the one-way clutch that uses the engagement holes  114   d  of the coupling gear  114 , each of the engagement holes  114   d  has the perpendicular end  114   e  and the inclined end  114   f , will be explained later (see  FIGS. 23A to 29 ). 
     The camshaft  43  (to which the four cams  44  are fixed and which is drivingly rotated by the second motor M 2 ) and the four cam followers  48  (which are displaceable by the corresponding cams  44 ) constitute a coupling gear displacement mechanism  60 . The coupling gear displacement mechanism  60  selectively displaces the coupling gears  30 ,  31   32 , and  33  (which correspond to the second coupling gears) between the “coupling position” and the “non-coupling position”. At the “coupling position”, each of the coupling gears  30 ,  31   32 , and  33  is engaged to be coupled with a corresponding one of the four coupling gears  114  (which correspond to the first coupling gears), which means that the driving force of the first motor M 1  is transmitted to each of the four coupling gears  114  by way of the corresponding coupling gear  30 ,  31   32 , or  33 . On the other hand, at the “non-coupling position”, engagement and coupling between each of the coupling gears  30 ,  31   32 , and  33  and the corresponding coupling gear  114  is released and disengaged, which means that the driving force of the first motor M 1  is not transmitted to each of the four coupling gears  114  by way of the corresponding coupling gear  30 ,  31   32 , or  33 . 
     The engagement state (i.e., the coupling state) and the disengagement state (i.e., the non-coupling state) between the coupling gears  30 ,  31   32 , and  33  and the corresponding four coupling gears  114  are respectively switched by the coupling gear displacement mechanism  60  of the switching unit  40  in such the manner as explained above. To detect the switching situation of the engagement and disengagement between the coupling gears  30 ,  31   32 , and  33  and the corresponding four coupling gears  114 , in other words, to detect which one of the first to fourth coin ejection units  110  is in the driving state, four detection members  45  and four optical sensors  46  are provided in the switching unit  40 . The four detection members  45  and the four optical sensors  46  are provided for the first to fourth coin ejection units  110 , respectively. 
     As the optical sensors  46 , any known infrared sensors or the like may be used; however, any type of sensors other than the optical ones may be used for this purpose. It is sufficient for the sensors that they can detect the connection/disconnection of the first to fourth coin ejection units  110 . Here, the four detection members  45 , which are the same in shape and size, are fixed to the camshaft  43  at intervals, as shown in  FIG. 6 , for example. 
     In this first embodiment, each of the four detection members  45  is formed by a circular member having a protrusion which protrudes outwardly from a part of the said member. The camshaft  43  (or the shaft member  43   a ) is inserted into the central hole of the said circular member and fixed at a predetermined position. The optical sensors  46  that correspond to the detection members  45 , which are the same in structure and function, are fixed onto the inner surface of the frame body  42   a  at the opposite positions to the corresponding detection members  45 , Each of the sensors  46  has a gap formed between the light emitting part and the light receiving part thereof. When the protrusion of the detection member  45  is inserted into and passed through the gap, the infrared light emitted from the light emitting part toward the light receiving part is temporarily blocked by the said protrusion; as a result, the arrival and passing of the protrusion of the said detection member  45  at the corresponding sensor  46  is detected. Due to this detection, it is judged that the coupling gear  30  in question and its corresponding coupling gear  114  are engaged and coupled, in other words, it is judged that the relevant coupling gear  30  is disposed at the coupling position and that the relevant coin ejection unit  110  is in the driving state. In the case where this engagement and coupling state needs to be maintained, the rotational driving of the second motor M 2  is stopped at the same time as the detection of the arrival of the said protrusion at the said sensor  46 . In this way, the coupling gear  30  and its corresponding coupling gear  114  are coupled and the relevant coin ejection unit  110  is driven by the first motor M 1 . As far as this state is held, a coin or coins of a predetermined denomination which is/are dispensed from the same coin ejection unit  110 , When the aforementioned infrared light is not blocked by the said protrusion, it is judged that the coupling gear  30  in question and its corresponding coupling gear  114  are not engaged and coupled, in other words, it is judged that the relevant coupling gear  30  is disposed at the non-coupling position and that the relevant coin ejection unit  110  is in the non-driving state. 
     In this first embodiment, the state where the driving force of the first motor M 1  is transmitted to none of the first to fourth coin ejection units  110  can be set. When the state where the driving force of the first motor M 1  is transmitted to any one of the first to fourth coin ejection units  110  (in other words, a coin is ejected from the relevant unit  110 ) is termed the “operable mode”, the state where the driving force of the first motor M 1  is transmitted to none of the first to fourth coin ejection units  110  may be termed the “non-operable mode”. In the “non-operable mode”, all of the first to fourth coin ejection units  110  are mechanically disconnected from the driving mechanism  20 , as shown in  FIG. 21  and therefore, there arises an advantage that a desired one of the four coin ejection units  110  can be easily removed from the chassis  11  by sliding the desired unit  110  along the mounting surface  11   a , It is needless to say that this “non-operable mode” may be omitted. 
     In this embodiment, the shift or transition from the “operable mode” to the “non-operable mode” is realized by operating a lever  52  which is rockably provided on the front side face of the chassis  11 , as shown in  FIG. 14 . Specifically, the lever  52  having an operating member or piece  53  which is fixed to its back is rockably supported by a rocking shaft  55  fixed to the chassis  1 . The operating member or piece  53  of the lever  52  is displaced downward along with the downward motion of the lever  52 . Since a frame rocking member  54  is fixed to the frame body  42   a  on the back side of the lever  52  in such a way as to be overlapped with the lever  52 , the frame rocking member  54  is pressed downward along with the downward motion of the lever  52 . In this state, the entire frame  42  is slightly moved forward around the two supporting shafts  41  which are disposed at the respective ends of the frame  42  and thus, the camshaft  43  which is supported by the frame  42  is slightly displaced upward and the distances between the four cams  44  and their corresponding four cam followers  48  are increased. As a result, as shown in  FIG. 7 , all of the branching parts  48   a  of the cam followers  48  are moved downward by the elastic forces of the relevant springs  47  disposed just below the corresponding cam receiving parts  48   a . Due to this lowering motion of the branching parts  48   a , the four driven gears  23 ,  25 ,  27 , and  29  and their corresponding coupling gears  30 ,  31 ,  32 , and  33  are moved downward collectively. In this state, the driving force of the first motor M 1  is no longer transmitted to all of the first to fourth coin ejection units  110  regardless of the positions of the protruding parts of the four cams  44 . This means that the transition to the “non-operable mode” from the “operable mode” is completed in this way. The return to the “operable mode” can be easily carried out by operating the lever  52  upward to its initial position. 
     The lever  52  which is rockable around the rocking shaft  55  fixed to the chassis  1 , the operating member  53  which is fixed to the back of the lever  52 , and the frame rocking member  54  which is fixed to the frame body  42   a  on the back side of the lever  52  constitute a switching unit displacement mechanism  70  for relatively displacing the switching unit  40  with respect to the driving mechanism  20 . The lever  52  functions as a manipulating member of the mechanism  70  and the operating member  53  functions as a moving member of the mechanism  70 . The switching unit displacement mechanism  70  displaces the switching unit  40  with respect to the driving mechanism  20  between the “connection position” where the driving force of the first motor M 1  can be selectively transmitted to any one of the first to fourth coin ejection units  110  and the “separation position” where the driving force of the first motor M 1  can be transmitted to none of the first to fourth coin ejection units  110 . Accordingly, when the switching unit displacement mechanism  70  is disposed at the “connection position”, the multi-unit coin ejection apparatus  1  is placed in the aforementioned “operable mode”. When the mechanism  70  is moved to the “separation position”, the apparatus  1  is shifted to the aforementioned “non-operable mode”. When the mechanism  70  is returned to the “connection position”, the apparatus  1  is returned to the “operable mode”. 
     As explained above, the action for causing a desired displacement of the switching unit  40  using the switching unit displacement mechanism  70  is realized using only the mechanical structure and its function and therefore, electronic control by the control device for the multi-unit coin ejection apparatus  1  is unnecessary at all. For this reason, there is no need to conduct the control operation for interrupting and recoupling the selective transmission of the driving force of the first motor M 1  to the coin ejection units  10  by sending predetermined signals when detaching a desired one of the coin ejection units  110  from the chassis  11  for check and/or exchanging a desired one of the coin ejection units  110  for a new one. Moreover, the switching unit displacement mechanism  70  is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     In addition, on the back of the lever  52  as one of the structural elements of the switching unit displacement mechanism  70 , a lock pin (not shown) is provided to surely fix the lever  52  to the stop position of the lever  52  in the operable mode (i.e., the position shown in the upper part of  FIG. 14 ). This is to prevent the malfunction that engagement or connection between the four coupling gears  30 ,  31 , 32 , and  33  (which correspond to the second coupling gears) and the corresponding coupling gears  114  (which correspond to the first coupling gears) is released or becomes insufficient due to the displacement of the lever  52  to its stop position in the non-operable mode (i.e., the position shown in the lower part of  FIG. 14 ) or that to a deviated position from the stop position of the lever  52  in the operable mode, where these displacements are caused by unintentional manipulation applied to the lever  52  when the multi-unit coin ejection apparatus  1  is placed in the operable mode. Since the lock pin is mounted, the malfunction induced by a misoperation of the switching unit displacement mechanism  70  can be surely prevented and as a result, safety is greatly improved. Thus, it is preferred to provide the lock pin. 
     Next, the aforementioned one-way clutch  119  and the unnecessary rotation prevention mechanism  80  using this clutch  119  will be explained below with reference to  FIGS. 23A to 29 . 
     The reason why the one-way clutch  119  is provided is to prevent the phenomenon that when the coupling gear  114  and the corresponding coupling gear  30 ,  31 ,  32 , or  33  are not coupled (see  FIGS. 25A and 25B  and  FIGS. 27A and 27B ), unintentional idling (i.e., unnecessary normal rotation) of the said coupling gear  114  is caused to result in undesired or unnecessary dispensing. In this first embodiment, an unnecessary rotation prevention member  117  having the structure shown in  FIGS. 24A, 243, and 240  is provided to realize the aforementioned function of the one-way clutch  119 . The member  117  having such the structure is placed in such a way as to have the positional relationship shown in  FIGS. 23A and 233  with the coupling gears  114  and  23 . 
     As shown in  FIGS. 24A to 240 , the unnecessary rotation prevention member  117  comprises a body  117   a , an engaging part  117   b  fixed to the top end of the body  117   a , a supporting part  117   c  formed at the base end of the body  117   a , and a roller  117   d  rotatably mounted on the top end of the body  117   a . A vacant space or gap  117   e  is formed between the engaging part  117   b  and the opposing part of the body  117   a  to the engaging part  117   b . The roller  117   d  is rotatably supported by the body  117   a  at the position right below the vacant space  117   e . When the relevant coupling gear  114  and the corresponding coupling gear  30 ,  31 ,  32 , or  33  are not coupled (see  FIGS. 25A and 25B  and  FIGS. 27A and 27B ), the vacant space  117   e  of the unnecessary rotation prevention member  117  is overlapped with the outer peripheral part of the coupling gear  114 , in which the lower end of the engaging part  117   b  is engaged with one of the engagement holes  114   d  of the coupling gear  114 . Since each of the engagement holes  114   d  has the perpendicular end  114   e  on the one side and the inclined end  114   f  on the other side, the rotation of the relevant coupling gear  114  is permitted in the direction where the lower end of the engaging part  117   b  abuts on the inclined end  114   f  and is prevented in the direction where the lower end of the engaging part  117   b  abuts on the perpendicular end  114   e . In this way, the function of the one-way clutch  119  is realized by the combination of the engaging part  117   b  of the unnecessary rotation prevention member  117  and the engagement holes  114   d  of the relevant coupling gear  114 . 
     Specifically, in the case where the rotation direction of the relevant coupling gear  114  is a direction where the lower end of the engaging part  117   b  abuts on the perpendicular end  114   e  of the engagement holes  114   d  (for example, the opposite direction to the coin ejection direction), the motion of the lower end of the engaging part  117   b  is restrained by the abutment between the said lower end and the said perpendicular end  114   e  and as a result, the rotation of the said coupling gear  114  in this direction is prevented. On the other hand, in the case where the rotation direction of the relevant coupling gear  114  is a direction where the lower end of the engaging part  117   b  abuts on the inclined end  114   f  of the engagement holes  114   d  (for example, the coin ejection direction), the lower end of the engaging part  117   b  is able to slide upward on the inclined end  114   f  and then, to ride over the top (i.e., the engagement face  114   g ) of the said inclined end  114   f ; as a result, the rotation of the said coupling gear  114  in this direction is permitted. The function of the one-way clutch  119  (the unnecessary rotation prevention mechanism  80 ) is realized in this way. 
     When the lower end of the engaging part  117   b  which is engaged with one of the engagement holes  114   d  of the relevant coupling gear  114  rides over the top of the inclined end  114   f  to arrive at the next engagement hole  114   d  and is engaged with the same again, the engaging part  117   b  of the unnecessary rotation prevention member  117  is displaced upward and downward (i.e., displaced vertically). Thus, to make this displacement possible, a through hole  117   f  is formed in the supporting part  117   c  of the member  117 . A support shaft  118   a  is inserted into the through hole  117   f . The support shaft  118   a  is supported by a supporting member  118  which is fixed to the inner surface of the chassis  11 . The member  117  is rockably supported on the inner surface of the chassis  11  using the supporting member  118  in this way. 
     When the relevant coupling gear  114  and the corresponding coupling gear  30 ,  31 ,  32 , or  33  are coupled (see  FIGS. 26A and 26B  and  FIGS. 28A and 28B ), the lower face of the roller  117   d  is contacted with the peripheral part of the corresponding coupling gear  30 ,  31 ,  32 , or  33 . For this reason, in this coupling state, the roller  117   d  is displaced to an upper position from the lower position in the non-coupling state. Accordingly, the engaging part  117   b  of the unnecessary rotation prevention member  117  is detached from the relevant engagement hole  114   d  and thus, the engagement between the said engaging part  117   b  and the said relevant engagement hold  114   d  is eliminated. As a result, the function of the one-way clutch  119  (and the unnecessary rotation prevention mechanism  80 ) is stopped (i.e., the function of the one-way clutch  119  is disabled) and thus, not only the normal rotation of the relevant coupling gear  114  (and the relevant rotary disk  112 ) but also the reverse rotation thereof are possible. In this way, the unnecessary rotation prevention mechanism  80  is configured in such a way as to be effective or enabled only for the coupling gears  114  of the coin ejection units  110  which are placed in the non-driving state and to be ineffective or disabled for the coin ejection operation and the malfunction elimination operation of the coin ejection unit  110  which is placed in the driving state. 
     A spring  118   b  that urges downward the body  117   a  and the engaging part  117   b  of the engaging part  117   b  of the unnecessary rotation prevention member  117  is attached to the supporting shaft  118   a  which is supported by the supporting member  118 . Since the downward pressing force is always applied to the engaging part  117   b , the engaging part  117   b  is surely engaged with any one of the engagement holes  114   d  when the relevant coupling gear  114  is not coupled with the corresponding coupling gear  30 ,  31 ,  32 , or  33  (see  FIGS. 25A and 25B  and  FIGS. 27A  and  27 B). Accordingly, the one-way clutch  119  (and the unnecessary rotation prevention mechanism  80 ) operates with high-level reliability. Moreover, when the relevant coupling gear  114  is coupled with the corresponding coupling gear  30 ,  31 ,  32 , or  33  (see  FIGS. 26A and 26B  and  FIGS. 28A and 28B ), the engaging part  117   b  is easily displaced upward by the corresponding coupling gear  30 ,  31 ,  32 , or  33  against the elastic force of the spring  18   b  and as a result, the engagement between the engaging part  117   b  and one of the engagement holes  117   d  is surely eliminated. 
     The combination of the unnecessary rotation prevention member  117  having the aforementioned structure and function and the engagement holes  114   d  (each of which comprises the perpendicular end  114   e  and the inclined end  114   f ) formed on the relevant coupling gear  114  constitutes the unnecessary rotation prevention mechanism  80  that prevents the unnecessary rotation (normal rotation) of the rotary disk  112  provided in each of the first to fourth coin ejection units  110 . This mechanism  80  includes the function of conducting and stopping the function of the one-way clutch  119  (i.e., the ON/OFF function of the clutch  119 ) in response to the displacement of each of the coin ejection units  110  between the driving state (see  FIGS. 26A and 26B  and  FIGS. 28A and 28B ) and the non-driving state (see  FIGS. 25A and 25B  and  FIGS. 27A and 27B ). The ON/OFF switching of the one-way clutch  119  is carried out by the coupling gear displacement mechanism  60  (which includes the four cams  44 , the camshaft  43 , and the four cam followers  48 ). 
     As explained above, with the unnecessary rotation prevention mechanism  80 , when the relevant coin ejection unit  110  is in the non-driving state, the engaging part  117   b  of the unnecessary rotation prevention member  117  is engaged with one of the engagement holes  114   d  located in the engagement surface  114   g  of the corresponding coupling gear  114  and thus, the function of the one-way clutch  119  is performed. Because of this function, the unnecessary rotation of the relevant rotary disk  112  in the predetermined coin ejection direction (i.e., the unnecessary normal rotation) is prevented and at the same time, the rotation of the said disk  112  in the opposite direction to the coin ejection direction (i.e., the reverse rotation direction) is permitted. Moreover, when the relevant coin ejection unit  110  is in the driving state, the function of the one-way clutch  119  is unnecessary. Therefore, in response to the transition or shift of the relevant coin ejection unit  110  to the driving state from the non-driving state, the engaging part  117   b  of the unnecessary rotation prevention member  117  is disengaged from the one of the engagement holes  114   d  of the corresponding coupling gear  114  and thus, the function of the one-way clutch  119  (the unnecessary rotation prevention mechanism  80 ) is stopped. In this way, the unnecessary rotation prevention mechanism  80  surely prevents the unintentional normal rotation of the rotary disk  112  (which leads to incorrect coin dispensing) in each of the coin ejection units  110  which are placed in the non-driving state without affecting the normal and reverse rotations of the rotary disk  112  of the coin ejection unit  110  which is placed in the driving state. 
     Operation of Multi-Unit Coin Ejection Apparatus  1   
     Next, the coin ejection operation of the multi-unit coin ejection apparatus  1  according to the first embodiment of the present invention having the aforementioned structure will be explained below with reference to  FIGS. 15A to 15D . 
       FIGS. 15A to 15D  show the situation change where the driving state and the non-driving state of the fourth coin ejection unit  110  are switched in order in accordance with the rotational position (the rotational angle) of the corresponding cam  44  included in the switching unit  40  of the multi-unit coin ejection apparatus  1  while the said cam  44  is rotated once. In the following explanation, the situation change that occurs while the camshaft  43  is rotated counterclockwise once, as shown in  FIGS. 15A to 15D , will be described. 
     First, as shown in  FIG. 15A , when the protruding part of the cam  44  (the cam end) is in a diagonally downward right direction, the cam receiving part  48   a  of the cam follower  48  corresponding to the said cam  44  is disposed at its upper position. This is because the said cam receiving part  48   a  is always pressed upward by the elastic force of the corresponding spring  47  which is just below the said cam receiving part  48   a . In this state, the branching part  48   b  of the said cam follower  48  is disposed at its lower position, and the coupling gear  114  of the fourth coin ejection unit  110  is apart or disconnected from the corresponding coupling gear  33  of the driving mechanism  20  (which is disposed at the non-driving position) and therefore, these two coupling gears  114  and  33  are not coupled. Accordingly, the driving force of the first motor M 1  is not transmitted to the coupling gear  114  of the fourth coin ejection unit  110 , which means that no coin ejection occurs from the said unit  110 . 
     Next, when the camshaft  43  is rotated counterclockwise by 90° from the position of  FIG. 15A , in other words, the phase of the camshaft  43  is advanced by 90°, the protruding part of the said cam  44  is turned to a diagonally upward right direction, as shown in  FIG. 15B . At this time, the cam receiving part  48   a  of the said cam follower  48  is disposed at its upper position, which is the same as the state of FIG.  15 A, In this state also, the branching part  48   b  of the said cam follower  48  is disposed at its lower position and therefore, the coupling gear  114  of the fourth coin ejection unit  110  is disconnected from the corresponding coupling gear  33  of the driving mechanism  20 , which means that these two coupling gears  114  and  33  are not coupled and the said unit  110  is placed in the non-driving stare. For this reason, the driving force of the first motor M 1  is not transmitted to the coupling gear  114  of the fourth coin ejection unit  110  and no coin ejection occurs from the said unit  110 . This is the same as the state of  FIG. 15A . 
     Following this, when the camshaft  43  is further rotated counterclockwise by 90° from the position of  FIG. 15B , in other words, the phase of the camshaft  43  is advanced by 180° from the position of  FIG. 15A , the protruding part of the said cam  44  is turned to a diagonally upward left direction, as shown in  FIG. 15C . At this time also, the cam receiving part  48   a  of the said cam follower  48  is kept at its upper position, which is the same as the state of  FIG. 15A . In this state also, the branching part  48   b  of the said cam follower  48  is kept at its lower position and therefore, the coupling gear  114  of the fourth coin ejection unit  110  is kept disconnected from the corresponding coupling gear  33  of the driving mechanism  20 , which means that these two coupling gears  114  and  33  are kept non-coupled and the said unit  110  is kept in the non-driving stare. For this reason, in the state of  FIG. 150  also, the driving force of the first motor M 1  is not transmitted to the coupling gear  114  of the fourth coin ejection unit  110  and no coin ejection occurs from the said unit  110 . 
     Finally, when the camshaft  43  is further rotated counterclockwise by 90° from the position of  FIG. 150 , in other words, the phase of the camshaft  43  is advanced by 270° from the position of  FIG. 15A , the protruding part of the said cam  44  is turned to a diagonally downward left direction, as shown in  FIG. 150 . At this time, the cam receiving part  48   a  of the said cam follower  48  is moved to its lower position, which is different from the states of  FIGS. 15A to 15C . This is because the said cam receiving part  48   a  of the said cam follower  48  is pressed downward by the protruding part of the said cam  44  against the elastic force of the corresponding spring  47 . Due to this downward motion of the said cam receiving part  48   a , the branching part  48   b  of the said cam follower  48  is moved to its upper position. At this upper position, the coupling gear  114  of the fourth coin ejection unit  110  is coupled with the corresponding coupling gear  33  of the driving mechanism  20 , which means that these two coupling gears  114  and  33  are coupled and the said unit  110  is placed in the driving stare. For this reason, in the state of  FIG. 15D , the driving force of the first motor M 1  is transmitted to the coupling gear  114  of the fourth coin ejection unit  110  and thus, desired coin ejection occurs from the said unit  110  in response to a dispensing instruction. 
     As explained above, due to the rocking or rotation motion of the cam  44  which is caused by the rotation of the camshaft  43 , the coupling gear  114  of the fourth coin ejection unit  110  is coupled with the corresponding coupling gear  33  of the driving mechanism  20  (i.e., the fourth coin ejection unit  110  is displaced to the driving state), as shown in  FIG. 20A , or decoupled from the corresponding coupling gear  33  of the driving mechanism  20  (i.e., the fourth coin ejection unit  110  is displaced to the non-driving state), as shown in  FIG. 20B , In this way, the coin ejection operation in the fourth coin ejection unit  110  can be performed only at the limited time when both of the relevant coupling gears  114  and  33  are coupled, i.e., the fourth coin ejection unit  110  is placed in the driving state. This is applicable to the first to third coin ejection units  110  also. 
     The situation where the coupling and non-coupling states between the four coupling gears  110  of the first to fourth coin ejection units  110  and the corresponding four coupling gears  30 ,  31 ,  32 , and  33  of the driving mechanism  20  are changed by the rotation of the single camshaft  43  is shown in  FIGS. 16 to 19 . 
     In the state of  FIG. 16 , only the coupling gear  33  of the driving mechanism  20  corresponding to the fourth coin ejection unit  110  is displaced upward to the coupling position and only the fourth coin ejection unit  110  is in the driving state while the first to third coin ejection units  110  are in the non-driving state. In the state of  FIG. 17 , only the coupling gear  32  of the driving mechanism  20  corresponding to the third coin ejection unit  110  is displaced upward to the coupling position and only the third coin ejection unit  110  is in the driving state while the first, second, and fourth coin ejection units  110  are in the non-driving state. In the state of  FIG. 18 , only the coupling gear  31  of the driving mechanism  20  corresponding to the second coin ejection unit  110  is displaced upward to the coupling position and only the second coin ejection unit  110  is in the driving state while the first, third, and fourth coin ejection units  110  are in the non-driving state. In the state of  FIG. 19 , only the coupling gear  30  of the driving mechanism  20  corresponding to the first coin ejection unit  110  is displaced upward to the coupling position and only the first coin ejection unit  110  is in the driving state while the second to fourth coin ejection units  110  are in the non-driving state. In this way, any one of the first to fourth coin ejection units  110  can be selectively driven by simply changing the phase (the rotational position) of the four cams  44 . 
     Concretely speaking, for example, in the case where a dispensing instruction for dispensing the amount of 630 YEN as the change is sent, the control device (not shown) of the multi-unit coin ejection apparatus  1  controls or operates the switching unit  40  in accordance with the dispensing instruction in the following way. Specifically, first, the first coin ejection unit  110  for ejecting coins of 500 YEN is selected as the transmission destination of the driving force of the first motor M 1  and driven by the first motor M 1 , thereby ejecting one coin of 500 YEN, Next, the second coin ejection unit  110  for ejecting coins of 100 YEN is selected as the transmission destination of the said driving force and driven, thereby ejecting one coin of 100 YEN. Furthermore, the fourth coin ejection unit  110  for ejecting coins of 10 YEN is selected as the transmission destination of the said driving force and driven, thereby ejecting three coins of 10 YEN successively. In this way, the aforementioned dispensing instruction for the amount of 630 YEN can be executed. 
     In the case where the multi-unit coin ejection apparatus  1  is shifted to the “non-operable mode” from the “operable mode” in order to conduct an operation such as a detaching or exchanging operation of a desired one of the first to fourth coin ejection units  110 , it is sufficient to displace relatively the switching unit  40  with respect to the driving mechanism  20  using the switching unit displacement mechanism  70  shown in  FIG. 14 , thereby moving the switching unit  40  to the “separation position” from the “connection position”. Concretely speaking, it is sufficient for a user or a service engineer to rotate downward the lever  52  which is provided on the front side face of the chassis  11  to a predetermined limiting point shown in  FIG. 14 , Since the entirety of the switching unit  40  is relatively moved collectively by this action, the multi-unit coin ejection apparatus  1  can be shifted to the “non-operable mode” (see  FIG. 21 ) from the “operable mode” (see  FIGS. 16 to 19 ) easily and quickly by only doing so. Moreover, to return the apparatus  1  to the “operable mode” from the “non-operable mode”, it is sufficient to rotate upward the lever  52  to the initial position. Since the entirety of the switching unit  40  is relatively moved collectively in the opposite direction by only doing so, the apparatus  1  is returned to the “operable mode” easily and quickly. 
     Next, the operation of the aforementioned unnecessary rotation prevention mechanism  80  of the multi-unit coin ejection apparatus  1  will be explained below with reference to  FIGS. 23 to 29  while taking the aforementioned first coin ejection unit  110  as an example. 
     When the coupling gear  30  and the corresponding coupling gear  114  for the first coin ejection unit  110  are not coupled, in other words, the coupling gear  30  is placed and kept at the “non-coupling position” by the coupling gear displacement mechanism  60 , these two coupling gears  30  and  114  are disengaged from each other and therefore, the unnecessary rotation prevention mechanism  80  is in the state shown in  FIGS. 25A and 25B  and  FIGS. 27A and 27B . 
     In the state of  FIGS. 25A and 25B  and  FIGS. 27A and 27B , the engaging part  117   b  of the unnecessary rotation prevention member  117  is inserted into one of the engagement holes  114   d  of the relevant coupling gear  114  and engaged therewith, in which the roller  117   d  mounted on the top end of the body  117   a  is not contacted with the underlying coupling gear  30 . This is because the coupling gear  30  is disposed at the “non-coupling position” and thus, the roller  117   d  is apart from the coupling gear  30 . The roller  117   d  is located at such the position as to be overlapped with the circular peripheral part of the gear  30 . In this state, the engaging part  117   b , which is disposed at the top end of the unnecessary rotation prevention member  117 , is inserted into one of the engagement holes  114   d  of the relevant coupling gear  114  and engaged therewith and thus, the one-way clutch  119  is effective. Accordingly, the normal rotation of the relevant coupling gear  114  for coin ejection is prevented and at the same time, the reverse rotation of the same gear  114  is permitted. Since the rotary disk  120  of the first coin ejection unit  110  is fixed to its own rotational shaft  115  along with the relevant coupling gear  114 , the disk  120  is rotated in the same direction as that of the said gear  114 . For this reason, unintentional or undesired rotation of the disk  120  of the first coin ejection unit  110  placed in the non-driving state, which is usually occurs due to vibration or the like induced by the coin ejection operation in the second, third, or fourth coin ejection unit  110  placed in the driving state, can be surely prevented from occurring. This means that incorrect coin dispensing can be surely prevented. 
     In addition, the reason why the reverse rotation of the rotary disk  120  of the first coin ejection unit  110  in the non-driving state is permitted is that permitting the reverse rotation of the disk  120  and the coupling gear  114  is more convenient compared with preventing the same. Accordingly, it is possible to omit the one-way clutch  119  in order to prevent both of the normal and reverse rotations of the disk  112 . 
     On the other hand, when malfunction such as coin jam occurs in the second, third, or fourth coin ejection unit  110  which is in the driving state, it is often to eliminate or solve the malfunction by rotating the rotary disk  12  of the relevant coin ejection unit  110  in the reverse direction to the coin ejection direction. In this case, the unnecessary rotation prevention mechanism  80  is effective in the first coin ejection unit  110  which is in the non-driving state and as a result, the reverse rotation of the relevant coupling disk  114  is permitted. This means that the reverse rotation of the rotary disk  120  for eliminating the malfunction in the first coin ejection unit  110  is also permitted. Thus, the aforementioned malfunction can be eliminated or solved easily by the reverse rotation of the relevant disk  120 . 
       FIG. 29  shows the situation where the normal rotation of the coupling gear  114  for coin ejection is prevented and the reverse rotation thereof is permitted when the one-way clutch  119  is effective or enabled. 
     First, it is supposed that the engaging part  117   b  of the unnecessary rotation prevention member  117  is inserted into and engaged with one of the underlying engagement hole  114   d  of the relevant coupling gear  114 , in other words, the said engaging part  117   b  is inserted into between the inclined end  114   f  and the perpendicular end  114   e  of the said engagement hole  114   d  and engaged therewith (see the upper left diagram in  FIG. 29 ). When the reverse rotation of the said coupling gear  114  is slightly advanced in the direction of an arrow from this state, the said engaging part  117   b  is obliquely moved on the inclined end  114   f  of the said engagement hole  114   d , As a result, the member  117  is slightly moved upward around the support shaft  118   a  against the elastic force of the spring  118   b  and the engaging part  117   b  is slightly raised (see the upper right diagram in  FIG. 29 ). When the reverse rotation of the said coupling gear  114  is further advanced in the same direction, the said engaging part  117   b  reaches the top edge of the said inclined end  114   f . As a result, the unnecessary rotation prevention member  117  is further moved upward around the support shaft  118   a  against the elastic force of the spring  118   b  and the said engaging part  117   b  is further raised (see the lower right diagram in  FIG. 29 ). The height of the said engaging part  117   b  at this stage is the maximum. When the reverse rotation of the said coupling gear  114  is advanced in the same direction furthermore, the said engaging part  117   b  goes beyond the top edge of the said inclined end  114   f  into the adjoining next engagement hole  114   d  and is engaged therewith, in which the said engaging part  117   b  is positioned between the inclined end  114   f  and the perpendicular end  114   e  of the said next engagement hole  114   d  (see the lower left diagram in  FIG. 29 ). The same actions as explained above are repeated in accordance with the reverse rotation of the relevant coupling gear  114 . In this way, the said coupling gear  114  can be rotated in the reverse direction to the coin ejection direction. 
     When the said coupling gear  114  is about to rotate in the coin ejection direction (i.e., in the normal direction) in the state of the upper left or the lower left diagram in  FIG. 29 , the said engaging part  117   b  will abut on the perpendicular end  114   e  of the said engagement hole  114   d . However, the perpendicular end  114   e  does not have an inclined face like the inclined end  1141  and therefore, no raising force is applied to the said engaging part  117   b , which means that the said engaging part  117   b  will not be able to advance furthermore. In this way, the normal rotation (i.e., the rotation in the coin ejection direction) of the said coupling gear  114  is prevented. 
     When the coupling gear  30  and the corresponding coupling gear  114  for the first coin ejection unit  110  are coupled with each other, the coupling gear  30  is disposed at the “coupling position” by the coupling gear displacement mechanism  60 . In this state, the unnecessary rotation prevention mechanism  80  is in the state as shown in  FIGS. 26A and 26B  and  FIGS. 28A and 28B . 
     In the state of  FIGS. 26A and 26B  and  FIGS. 28A and 28B , the engaging part  117   b  of the unnecessary rotation prevention member  117  is apart from of the engagement holes  114   d  of the relevant coupling gear  114 , and the roller  117   d  mounted near the said engaging part  117   b  is contacted with the circular peripheral part of the underlying coupling gear  30 . This is because the coupling gear  30  is moved to the “coupling position” and therefore, the said gear  30  is raised to the higher position than that at the “non-coupling position”. In this state, the teeth  30   a  and the grooves  30   b  of the coupling gear  30  are respectively engaged with the grooves  114   b  and the teeth  114   a  of the corresponding coupling gear  114  and thus, the driving force of the first motor M 1  is transmitted to the said coupling gear  114  by way of the coupling gear  30 . Since the one-way clutch  119  (the unnecessary rotation prevention mechanism  80 ) is disabled or ineffective in this state, the said coupling gear  114  and the corresponding rotary disk  112  can be rotated in both of the coin ejection direction (i.e., the normal rotation direction) and in the opposite direction thereto (i.e., the reverse rotation direction). Accordingly, the rotary disk  112  of the first coin ejection unit  110  placed in the connection state can perform a desired coin ejection operation by the normal rotation and a malfunction elimination operation by the reverse rotation. 
     With the unnecessary rotation prevention mechanism  80  having the aforementioned structure and function, enabling (ON) and disabling (OFF) of the mechanism  80  can be realized by only the selectively shifting action of the coupling gears  30 ,  31 ,  32 , and/or  33  between the “coupling position” and the “non-coupling position” using the coupling gear displacement mechanism  60  and therefore, it is unnecessary for the unillustrated control device of the multi-unit coin ejection apparatus  1  to control the operation of the unnecessary rotation prevention mechanism  80 . Accordingly, there is an advantage that not only the structure and function of the mechanism  80  are highly simplified but also the control program which is incorporated into the control device of the apparatus  1  is simplified. 
     As explained above in detail, with the multi-unit coin ejection apparatus  1  according to the first embodiment of the present invention, the first to fourth coin ejection units  110  are structured in such a way that any one of the first to fourth coin ejection units  110  is selectively driven by switching the transmission destination of the driving force of the commonly used first motor M 1  using the switching unit  40  in response to instructions. In the one of the first to fourth coin ejection units  110  which is driven in this way, in other words, to which the driving force of the first motor M 1  is transmitted, a coin or coins of the corresponding denomination to an instruction is/are ejected. Accordingly, a coin or coins of a desired denomination can be ejected by selectively transmitting the driving force of the first motor M 1  to one of the first to fourth coin ejection units  110  that ejects coins of the desired denomination. 
     Moreover, the unnecessary rotation prevention mechanism  80 , which is provided in each of the first to fourth coin ejection units  110 , comprises the unnecessary rotation prevention member  117  that is formed to prevent the relevant rotary disk  112  from rotating unintentionally to result in incorrect coin ejection when the relevant coin ejection unit  110  is placed in the non-driving state. The member  117  is structured in such a way as to be engaged with the engagement face  114   g  of the relevant coupling gear  114  and disengaged therefrom in response to displacement of the relevant coupling gear  30  between the coupling position and the non-coupling position. Thus, the unnecessary rotation prevention mechanism  80  can be enabled or disabled by simply shifting the relevant coin ejection unit  110  between the driving state and the non-driving state, in other words, by simply moving the relevant coupling gear  30 ,  31 ,  32 , or  33  between the coupling position and the non-coupling position, using the coupling gear displacement mechanism  60 . Accordingly, the state where both of the normal rotation and the reverse rotation of the relevant rotary disk  112  are possible (i.e., where the unnecessary rotation prevention mechanism  80  is disabled) and the state where the normal rotation of the relevant rotary disk  112  is prevented (i.e., where the unnecessary rotation prevention mechanism  80  is enabled) can be switched by simply displacing the relevant coupling gear  30 ,  31 ,  32 , or  33  between the coupling position and the non-coupling position. 
     Furthermore, when the relevant coin ejection unit  110  is placed in the non-driving state where the relevant coupling gear  30 ,  31 ,  32 , or  33  is disposed at the non-coupling position, the engaging part  114   d  of the unnecessary rotation prevention member  117  is engaged with one of the engagement holes  114   d  formed in the engagement face  114   g  of the relevant coupling gear  114 , thereby preventing undesired normal rotation of the relevant rotary disk  112 . This means that the undesired normal rotation of the relevant rotary disk  112  can be surely prevented when the relevant coin ejection unit  110  is placed in the non-driving state. Accordingly, undesired normal rotation of the relevant rotary disks  112  for incorrectly ejecting coins to result in incorrect dispensing, which is likely to be caused by vibration from the coin ejection unit  110  and/or that from outside of the coin ejection unit  110  in the driving state, can be surely prevented when the remaining coin ejection units  110  are in the non-driving state. 
     On the other hand, when the relevant coin ejection unit  110  is placed in the driving state where the relevant coupling gear  30 ,  31 ,  32 , or  33  is disposed at the coupling position, the engaging part  117   b  of the unnecessary rotation prevention member  117  is disengaged from the engagement holes  114   d  of the relevant coupling gear  114 , thereby permitting both of normal rotation and reverse rotation of the relevant rotary disk  112 . This means that both of the normal rotation and the reverse rotation of the relevant rotary disk  112  can be performed when the relevant coin ejection unit  110  is placed in the driving state. Accordingly, both of normal rotation of a rotary disk  112  for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed when a designated one of the coin ejection units  110  is in the driving state. 
     As described above, with the multi-unit coin ejection apparatus  1  according to the first embodiment having the structure that the coin ejection units  110  are selectively driven using the single first motor M 1  in response to an instruction, both of normal rotation of the rotary disk  112  for ejecting desired coins and reverse rotation thereof for eliminating malfunction can be performed in a designated one of the first to fourth coin ejection units  110  which is in the driving state and at the same time, undesired normal rotation of the rotary disks  112  for incorrectly ejecting coins to result in incorrect dispensing can be surely prevented in the remainder of the first to fourth coin ejection units  110  which are in the non-driving state. 
     In addition, with the multi-unit coin ejection apparatus  1  according to the first embodiment, the function that both of the normal rotation of the rotary disk  112  for ejecting desired coins and the reverse rotation thereof for eliminating malfunction can be performed in a designated one of the first to fourth coin ejection units  110  which is in the driving state while surely preventing undesired normal rotation of the rotary disks  112  for incorrectly ejecting coins to result in incorrect dispensing in the remainder of the first to fourth coin ejection units  110  which are in the non-driving state is realized by switching the engagement and disengagement between the engaging part  117   d  of the unnecessary rotation prevention member  117  and the one of the engagement holes  114   d  formed in the engagement face  114   g  of the relevant coupling gear  114 . Moreover, since the state where both of the normal rotation and the reverse rotation of the relevant rotary disk  112  are possible (i.e., the unnecessary rotation prevention mechanism  80  is disabled) and the state where the normal rotation of the relevant rotary disk  112  is prevented (i.e., the unnecessary rotation prevention mechanism  80  is enabled) can be switched by simply moving the relevant coin ejection unit  110  between the driving state and the non-driving state, there is no need to provide a dedicated mechanism or device for switching these two states. Accordingly, the aforementioned function can be realized using only a mechanical structure. 
     Further in addition, it is sufficient for the aforementioned mechanical structure for realizing the aforementioned function to include the engaging part  117   b  of the unnecessary rotation prevention member  117  and the one of the engagement holes  114   d  of the relevant coupling gear  114 . Moreover, it is unnecessary to provide a dedicated mechanism or device for switching between the state where both of the normal rotation of the rotary disk  112  for ejecting coins and the reverse rotation thereof for eliminating malfunction can be performed and the state where the undesired normal rotation of the relevant rotary disk  112  can be surely prevented. Accordingly, the aforementioned mechanical structure is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     The multi-unit coin ejection apparatus  1  according to the first embodiment has the following additional advantages in addition to the aforementioned advantages: 
     Each of the four coupling gears  114  (the first coupling gears) has the teeth  114   a  and the grooves  114   b  formed on one side face thereof and is fixed to the rotation shaft  115  for the rotary disk  112  of the relevant coin ejection unit  110 , and each of the coupling gears  30 ,  31 ,  32 , and  33  (the second coupling gears) has the grooves  30   b  and the teeth  30   a  formed on one side face thereof to be engageable respectively with the teeth  114   a  and the grooves  114   b  of the corresponding coupling gear  114  and is fixed to the driven gear  23 ,  25 ,  27 , or  29  (which correspond to the relevant linking gear) of the driving mechanism  20 . Thus, the structure for realizing the engagement and disengagement between the four coupling gears  114  and the corresponding coupling gears  30 ,  31 ,  32 , and  33  can be realized easily. 
     Moreover, each of the four coupling gears  114  (the first coupling gears), which is fixed to the rotation shaft  115  for the rotary disk  112  of the relevant coin ejection unit  110 , has the teeth  114   a  and the grooves  114   b  which are formed on one side face thereof, and the engagement holes  114   d  which are arranged annularly in the engagement face  114   g  opposite to the side face. In addition, the engaging part  117   b  of the unnecessary rotation prevention member  117  is structured in such a way as to be engaged with any one of the engagement holes  114   d  of the relevant coupling gear  114 , Thus, the unnecessary rotation prevention mechanism  80  can be realized with a very simple structure. 
     Moreover, since the function of the one-way clutch  119  that permits only the normal rotation of the relevant rotary disk  112 , which is realized by engaging the engaging part  117   b  of the unnecessary rotation prevention member  117  with one of the engagement holes  114   d  formed in the engagement face  114   g  of the relevant first coupling gear  114 , is provided, only the normal rotation of the relevant rotary disk  112  in the non-driving state can be surely prevented. 
     Moreover, when one of the first to fourth coin ejection units  110  displaced to the driving state from the non-driving state by the switching unit  40 , the relevant unnecessary rotation prevention member  117  is moved in such a way that the engaging part  117   b  of the member  117  is disengaged from the one of the engagement holes  114   d  of the relevant first coupling gear  114  due to displacement of the relevant second coupling gear  30 ,  31 ,  32 , or  33  to the coupling position from the non-coupling position, thereby losing the function of the one-way clutch  119 . Thus, the normal rotation and the reverse rotation of the relevant rotary disk  112  in the driving state can be permitted with a very simple structure. 
     Moreover, the relevant unnecessary rotation prevention member  117  comprises the roller  117   d  which is rotatable on the engagement face  114   g  of the relevant coupling gear  114  in addition to the engaging part  117 . When one of the first to fourth coin ejection units  110  is moved to the driving state from the non-driving state by the switching unit  40 , the roller  117   d  of the relevant unnecessary rotation prevention member  117  is contacted with the engagement face  114   g  of the relevant first coupling gear  114  and moved such that the engaging part  117   b  of the member  117  is disengaged from one of the engagement holes  114   d  of the relevant coupling gear  114 , resulting in permission of the normal rotation and the reverse rotation of the relevant rotary disk  112 . The roller  117   d  which is contacted with the engagement face  114   g  of the relevant coupling gear  114  is rolled with rotation of the relevant coupling gear  114  on the engagement face  114   g  thereof. Accordingly, it is easy to enable the normal rotation and the reverse rotation of the relevant disk  112  in the coin ejection unit  110  which is moved to the driving state from the non-driving state. 
     Furthermore, the relevant unnecessary rotation prevention member  117   b  comprises the spring  118   b  having an elastic force that urges the engaging part  117   b  of the relevant unnecessary rotation prevention member  117  toward the engagement face  114   g  of the relevant coupling gear  114 . When the relevant coin ejection unit  110  is placed in the non-driving state, the engaging part  117   b  of the member  117  is engaged with one of the engagement holes  114   d  of the relevant coupling gear  114  by the elastic force of the spring  118   b . When the relevant coin ejection unit  110  is placed in the driving state, the engaging part  117   b  of the member  117  is separated from the one of the engagement holes  114   d  of the relevant coupling gear  114  against the elastic force of the spring  118   b , resulting in loss of engagement of the engaging part  117   b  of the member  117  with the one of the engagement holes  114   d  of the relevant coupling gear  114 . Accordingly, the engaging part  117   b  of the member  117  and one of the engagement holes  114   d  are surely engaged by the elastic force of the spring  118   b , which raises the reliability of the unnecessary rotation prevention mechanism  80 . 
     Furthermore, the coupling gear displacement mechanism  60  comprises the camshaft  43  which is rotationally driven by the second motor M 2 , in which the camshaft  43  has the four cams  44  which are respectively assigned to the first to fourth coin ejection units  110 ; and the four cam followers  48  which are respectively engaged with the four coupling gears  114  and which are displaceable by the corresponding cams  44 . The coupling gears  30 ,  31 ,  32 , and  33  are structured in such a way as to be displaced between the coupling position and the non-coupling position according to displacements of the corresponding cam followers  48  due to rotations of the corresponding cams  44 . Accordingly, the coupling gear displacement mechanism  60  can be realized with a very simple structure. 
     Furthermore, there are provided with the sensors  46  that detect respectively the rotational positions (or rotational angles) of the cams;  44  and which one of the coupling gears  30 ,  31 ,  32 , or  33  is disposed at the coupling position is judged based on the detected rotational positions (or rotational angles) of the cams  44  by the sensors  46  and the corresponding detection members  45  fixed to the camshaft  43 . Accordingly, the rotational position (rotational angle) of each of the cams  44  can be continuously detected with a simple structure and the coin ejection operation from the first to fourth coin ejection units  110  can be controlled precisely. 
     Furthermore, there is provided with the switching unit displacement mechanism  70  that is configured to displace the switching unit  40  between the connection position where the driving force of the first motor M 1  is selectively transmittable to a designated one of the first to fourth coin ejection units  110  and the separation position where the driving force of the first motor M 1  is transmittable to none of the first to fourth coin ejection units  110 . The switching unit displacement mechanism  70  comprises the operating member (e.g., the lever  52 ) mounted on the chassis  11 , and the moving member (e.g., the combination of the operating part  53  and the frame rocking member  54 ) that displaces mechanically the switching unit  40  between the connection position and the separation position in response to a predetermined action applied to the operating member. When a predetermined action is applied to the operating member in the state where the switching unit  40  is disposed at the connection position, the switching unit  40  is displaced to the separation position. 
     Accordingly, there is no need to conduct the control operation for interrupting and recoupling the selective transmission of the driving force of the first motor M 1  to any one of the coin ejection units  110  using the control device (not shown) of the multi-unit coin ejection unit  1  when moving the switching unit  40  to the connection position from the separation position. In addition, after the switching unit  40  is moved to the separation position, the driving force of the first motor M 1  can be transmitted to none of the first to fourth coin ejection units  110  and therefore, it is easy to detach a desired one of the first to fourth coin ejection units  110  for check and to exchange the same for a new one. 
     Moreover, when the switching unit  40  is moved to the separation position using the switching unit displacement mechanism  70 , the multi-unit coin ejection apparatus  1  is shifted to the “non-operable mode” where the driving force of the first motor M 1  is not transmitted to none of the first to fourth coin ejection units  110  and as a result, a desired one of the first to fourth coin ejection units  110  is detachable from the mounting surface  11   a  of the chassis  11 . When the switching unit  40  is returned to the connection position using the switching unit displacement mechanism  70 , the apparatus  1  is shifted to the “operable mode” where the driving force of the first motor M 1  is transmitted to any one of the first to fourth coin ejection units  110 . Accordingly, removal or exchange of these four coin ejection units  110  can be carried out easily according to the necessity by sliding a desired one of the units  110  along the mounting surface  11   a.    
     Furthermore, the switching unit displacement mechanism  70  is structured in such a way as to be rockable around the shaft  41  which is supported by the chassis  11  and the operable mode where the driving force of the first motor M 1  is selectively transmitted to a designated one of the first to fourth coin ejection units  110  and the non-operable mode where the driving force of the first motor M 1  is transmitted to none of these units  110  are switched by rocking the coupling gear displacement mechanism  60  around the shaft  41 . Accordingly, the switching operation between the operable mode and the non-operable mode can be easily and quickly. 
     Second Embodiment 
     Next, a coin ejection apparatus having a coin ejection unit according to a second embodiment of the present invention will be explained below. 
     Unlike the aforementioned multi-unit coin ejection apparatus  1  according to the first embodiment, the coin ejection apparatus according to the second embodiment has a single coin ejection unit  110  which is mounted on the mounting surface  11   a  of the base  11 . The single coin ejection unit  110  is selectively driven according to whether or not the driving force of the first motor M 1  is transmitted to the said unit  110  by displacing the coupling gear  30  between the coupling position and the non-coupling position using the switching unit  40 . Thus, the coin ejection unit  110  is switchable between the driving state and the non-driving state in response to instructions. 
     The overall structure of the coin ejection apparatus according to the second embodiment corresponds to the structure obtained by (a) removing the second to fourth coin ejection units  110  and their coin storing containers  120 , (b) reducing the lengths of the chassis  11  and the switching unit  40  (which includes the frame  42  and the camshaft  43 ) in such a way as to be matched with the length of the first coin ejection unit  110 , (c) removing the driven gears  25 ,  27 , and  29  and the intermediate gears  24 ,  26 , and  28  from the driving mechanism  20 , and (d) removing the three cams  44 , the three sensors  46 , and the three detection members  45  from the switching unit  40 , The unnecessary rotation prevention mechanism  80  is kept unchanged in the second embodiment. 
     Thus, the structure of the coin ejection apparatus of the second embodiment corresponds to the structure obtained by reducing the count of four in the aforementioned multi-unit coin ejection apparatus  1  according to the first embodiment to unity, and the function of the second embodiment is approximately the same as that of the first embodiment. Accordingly, it is apparent that the coin ejection apparatus of the second embodiment has approximately the same advantages as those of the coin ejection apparatus  1  according to the first embodiment. 
     Specifically, both of the normal rotation of the rotary disk  112  in the coin ejection unit  110  for ejecting desired coins and the reverse rotation thereof for eliminating malfunction can be performed in the driving state, and undesired normal rotation of the said disk  112  for incorrectly ejecting coins to result in incorrect dispensing can be surely prevented in the non-driving state. 
     In addition, the state where both of the normal and reverse rotations of the rotary disk  112  are possible (i.e., where the unnecessary rotation prevention mechanism  80  is disabled) and the state where normal rotation of the said disk  112  is prevented (i.e., where the unnecessary rotation prevention mechanism  80  is enabled) can be switched by simply moving the coupling gear  30  between the coupling position and the non-coupling position. 
     Moreover, the function that the normal and reverse rotations of the rotary disk  112  can be performed in the driving state and the undesired normal rotation of the said disk  112  for incorrectly ejecting coins can be surely prevented in the non-driving state can be realized using only a mechanical structure, in which the said mechanical structure is simplified, produced at low cost, unlikely to malfunction, and likely to have desired durability. 
     Modifications 
     The aforementioned first and second embodiments are exemplary embodied examples of the present invention. Thus, it is needless to say that the present invention is not limited to these embodiments and any other modification is applicable to the embodiments without departing the spirit of the invention. 
     For example, in the aforementioned first and second embodiments, to constitute the unnecessary rotation prevention mechanism  80  provided in each of the first to fourth coin ejection units  110 , the unnecessary rotation prevention member  117  that prevents the relevant rotary disks  112  in the non-driving state from unintentionally rotating to result in incorrect dispensing is provided, and the engagement and disengagement between the unnecessary rotation prevention member  117  and the engagement face  114   g  of the relevant coupling gear  114  are switched in response to the shift of the relevant coin ejection unit  110  between the driving state and the non-driving state. However, the present invention is not limited to this. Any structure may be used for this purpose if it can prevent the normal rotation of the rotary disk  112  when the coin ejection unit  110  is in the non-driving state and a the same time, it can permit the normal and reverse rotations of the said disk  112  when the coin ejection unit  110  is in the driving state. 
     Moreover, in the aforementioned first and second embodiments, the unnecessary rotation prevention mechanism  80  comprises the function of the one-way clutch  119 ; however, both of the normal and reverse rotations of the relevant rotary disk  112  may be prevented when the relevant coin ejection unit  110  is in the non-driving state without providing the function of the one-way clutch  119 . 
     Moreover, in the aforementioned first and second embodiments, the coupling gears  30 ,  31 ,  32 , and  33  each of which has the teeth  30   a  and the grooves  30   b  on one side face thereof as shown in  FIGS. 11A to 110  and the four coupling gears  114  each of which has the teeth  114   a  and the grooves  114   b  on one side face thereof as shown in  FIGS. 13A and 13B  are used; however, the present invention is not limited to this. Any coupling gear having a different structure from that of these coupling gears  30 ,  31 ,  32 , and  33  and  114  may be used for this purpose if it can transmit the driving force of the first motor M 1  to the side of the coin ejection unit or units  110  from the side of the driving mechanism  20 . 
     Moreover, in the aforementioned first and second embodiments, the coupling gear displacement mechanism  60  comprises the camshaft  43  which is rotatably driven by the second motor M 2  and to which the four corns  44  are fixed, and the four cam followers  48  which are displaced by the corresponding cams  44 ; however, the present invention is not limited to this. Any structure different from the said structure including the camshaft  43  and the cam follower  48  may be used if it realizes desired displacement operation of the coupling gear(s)  30 ,  31 ,  32 , and/or  33  and/or that of the coupling gear(s)  114 . 
     Moreover, there is no restriction on the structure of the coin ejection units  110 . Any coin ejection unit having any structure may be used if it can dispense coins as desired using the rotation of a rotary disk  112 . 
     Moreover, in the aforementioned first and second embodiments, the switching unit displacement mechanism  70  comprises the lever  52  fixed to the chassis  1 , and the operating member  53  and the frame rocking member  54  that displace relatively the switching unit  40  with respect to the driving unit  20  between the connection position and the separation position in response to a predetermined action applied to the lever  52 . However, the present invention is not limited to this. It is needless to say that the switching unit displacement mechanism  70  may have any other structure than this if it can displace relatively the switching unit  40  between the connection or transmittable position and the separation or non-transmittable position with respect to the driving unit  20 . 
     INDUSTRIAL APPLICABILITY 
     The coin ejection apparatus, which has one or more coin ejection units, according to the present invention is applicable not only to coins as currency but also to coin equivalents such as token and medals. Moreover, the coin ejection apparatus according to the present invention is applicable not only to any coin depositing/dispensing apparatus but also to any coin processing apparatus that necessitates selective ejection of coins of desired denominations. 
     While the preferred forms of the present invention have been described, it is to be understood that modifications will be apparent to those skilled in the art without departing from the spirit of the invention. The scope of the present invention, therefore, is to be determined solely by the following claims.