Motion detection apparatus and entertainment system having a pulse counting unit

There are provided an infrared light emitting diode 42 operable to emit light in a predetermined cycle; a phototransistor 44 operable to receive light which is emitted by the infrared light emitting diode 42 and reflected from a retroreflective sheet 40 of the operation article 3, and output a light reception signal “Sp”; and a highpass filter unit 116 operable to pass a high frequency component of the light reception signal “Sp”, output the high frequency component as a light reception signal “Ss” and operable to generate a reference voltage. The highpass filter unit 116 supplies the reference voltage to a node to which the light reception signal “Ss” is output, and the processor 110 counts the number of pulses included in the light reception signal “Ss”, and calculates the speed of the operation article 3.

TECHNICAL FIELD

The present invention relates to a motion detection apparatus, an entertainment system and the related arts in which the motion of an operation article is detected by illuminating the operation article with light and detecting the reflected light therefrom.

BACKGROUND ART

The Japanese Patent Published Application No. 2004-85524 by the present applicant discloses a golf game system including a game apparatus and golf-club-type input device (operation article), and the housing of the game apparatus houses an imaging unit which comprises an image sensor, infrared light emitting diodes and so forth. The infrared light emitting diodes intermittently emit infrared light to a predetermined area above the imaging unit while the image sensor intermittently captures images of the reflecting object of the golf-club-type input device which is moving in the predetermined area.

The motion of the golf-club-type input device can be detected by processing the stroboscopic images of the reflecting object.

However, the scope of costs as required differs from business to business, and thereby it is sometimes required to develop and manufacture a product at a lower cost.

DISCLOSURE OF INVENTION

It is therefore an object of the present invention to provide a motion detection apparatus, an entertainment system and the related arts wherein the cost can be reduced by detecting the motion of an operation article without the use of an imaging device.

In accordance with another aspect of the present invention, a motion detection apparatus operable to detect a motion of an operation article which is held and given motion by an operator, comprises: a light emitting unit operable to emit light in a predetermined cycle; a light receiving unit operable to receive light which is emitted by said light emitting unit and reflected from the operation article, and output a first light reception signal; and a counting unit operable to receive the first light reception signal and count the number of pulses included in the first light reception signal.

In accordance with this configuration, the number of pulses included in the first light reception signal varies depending upon the speed of the operation article as a target of detection. Accordingly, it is possible to detect the speed of the operation article only by counting the number of pulses included in the first light reception signal. As thus described, even if an imaging device is not provided, the motion of the operation article can be detected by a simple structure so that the cost can be reduced.

The above motion detection apparatus may further comprises: a light emitting range regulation unit operable to regulate the light emitting range of the light emitted by said light emitting unit; and a light receiving range regulation unit operable to regulate the light receiving range of said light receiving unit.

In accordance with this configuration, since the light emitting range and the light receiving range can be arbitrarily set, the speed of the operation article can be appropriately detected by narrowing the detection range which is regulated by the light emitting range and the light receiving range, irrespective of the height of the operation article passing over the light emitting unit and the light receiving unit.

The above motion detection apparatus may further comprises: a highpass filter operable to pass a high frequency component of the first light reception signal and output the high frequency component as a second light reception signal; and a reference voltage generation unit operable to generate a reference voltage, wherein said reference voltage generation unit supplies the reference voltage to a node to which the second light reception signal is output, and wherein said counting unit counts the number of pulses included in the second light reception signal.

In accordance with this configuration, since the pulses appear on the reference voltage, it is possible to stably count the number of pulses while avoiding the influence of an environmental light source as little as possible. In other words, it is possible to stably detect the speed of the operation article irrespective of the type of the environmental light source.

In accordance with this motion detection apparatus, said reference voltage generation unit is formed by connecting a first resistor element and a second resistor element in series between a first line for supplying a first voltage and a second line for supplying a second voltage, wherein said highpass filter is formed of a capacitor and the second resistor element, and wherein the connection point between the first resistor element and the second resistor element is the node to which the second light reception signal is output.

In accordance with this configuration, since the number of components of which the highpass filter and the reference voltage generation unit are made up can be limited as few as possible, it is possible to further reduce the cost.

In accordance with the above motion detection apparatus, said reference voltage generation unit is formed by connecting a first resistor element and a second resistor element in series between a first line for supplying a first voltage and a second line for supplying a second voltage, wherein said highpass filter is formed of a capacitor and the second resistor element, and wherein the connection point between the first resistor element and the second resistor element is the node to which the second light reception signal is output.

In accordance with this configuration, the circuit configuration can be further simplified, and thereby it is possible to further reduce the cost.

In accordance with another aspect of the present invention, an entertainment system comprising: a light emitting unit operable to emit light to illuminate a light emitting range; a light receiving unit operable to receive the light of said light emitting unit reflected in a light receiving range from a reflection surface which is moved by a player of the entertainment system, and output a light reception signal; and a signal processing unit connected to said light receiving unit, and operable to receive the light reception signal, process the light reception signal, obtain information about the motion of the reflection surface by the player, and generate a video signal in accordance with the information, wherein a detection area is defined as an area where the light emitting range and the light receiving range overlap each other, wherein said signal processing unit calculates the duration for which the reflection surface is in the detection area on the basis of the light reception signal output from said light receiving unit, and calculates the speed of the reflection surface which is moved by the player on the basis of the duration.

In accordance with this configuration, it is possible to provide an entertainment system at a low cost in which the motion speed of the player can be detected.

BEST MODE FOR CARRYING OUT THE INVENTION

In what follows, an embodiment of the present invention will be explained in conjunction with the accompanying drawings. Meanwhile, like references indicate the same or functionally similar elements throughout the respective drawings, and therefore redundant explanation is not repeated.

FIG. 1is a block diagram showings the entire configuration of a game system in accordance with an embodiment of the present invention. As shown inFIG. 1, this game system includes a game apparatus1, an operation article3, and a television monitor7.

In the example of the present embodiment, a golf game is played with the game apparatus1such that a player11swings the operation article3shaped in the form of a golf club for playing the golf game. Accordingly, the operation article3is referred to as the “golf club3”.

The game apparatus1is connected to the television monitor7by an AV cable9. Furthermore, although not shown in the figure, the game apparatus1is supplied with a power supply voltage from an AC adapter or a battery.

This game apparatus1detects the speed of the golf club3which is swung, and calculates the moving speed of a ball object65(refer toFIG. 9described below) as displayed on the television monitor7.

FIG. 2is a perspective view for showing the game apparatus1ofFIG. 1. As shown inFIG. 2, the game apparatus1includes an upper housing20and a lower housing22. A rotatable member28and a spherical body24shaped in the form of a golf ball are placed on the upper surface of the upper housing20in the longitudinal direction thereof. The rotatable member28is formed in a columnar shape with four claw portions30which are shaped in the form of triangle poles which are arranged at even intervals along the periphery on the end face of the rotatable member28. The side surfaces of the claw portions30adjacent to each other are parallel to each other and spaced at a predetermined distance. Accordingly, the end face of the rotatable member28provides a cross-shaped surface in a plan view.

As described below, when the player11inserts the head5of the golf club3into the cross-shaped portion (refer toFIG. 14described below) and rotates the golf club3, the side surfaces of the head5come in contact with the side surfaces of the claw portions30whereby the rotatable member28is rotated. In addition to this, when the player11inserts the head5of the golf club3into the cross-shaped portion (refer toFIG. 14described below), the rubber switch88to be described below is turned on by pushing down the head5and turned off by releasing the head5.

A circular infrared filter26is exposed through the top of the spherical body24and serves to transmit only infrared light. As described below, an optical sensor for detecting the golf club3is located inside of this spherical body24. Incidentally, a power supply switch32and a DC Jack34are provided in the rear side surface of the game apparatus1.

The game apparatus1detects the speed of the golf club3, swung by the player11, by the optical sensor. Accordingly, the player11can adjust the moving distance and speed of the ball by adjusting the swinging speed of the golf club3.

Also, the game apparatus1makes a ball direction setting object rotate in accordance with the rotation direction and rotation amount of the rotatable member28. Accordingly, the player11can set the ball moving direction by rotating the rotatable member28.

FIG. 3is an explanatory schematic diagram for showing the bottom surface of the head5of the golf club3ofFIG. 1. As shown inFIG. 3, the bottom surface of the head5is provided with a rectangular indent section having a flat bottom surface, and a rectangular retroreflective sheet40(shaded portion) is attached to this indent section. Since the retroreflective sheet40is attached to the indent section as described above, the breakage of the retroreflective sheet40can be prevented even if the head5collides with the surface of the rotatable member28ofFIG. 2.

FIG. 4andFIG. 5are explanatory views for showing the method of detecting the speed of the golf club3ofFIG. 1. As shown inFIG. 4, the infrared light as emitted from an infrared light emitting diode42located inside of the spherical body24ofFIG. 2is directed to the retroreflective sheet40of the head5through the infrared filter26, and then reflected to enter the phototransistor44through the infrared filter26.

This phototransistor44is driven by a pulse signal as shown in (b) ofFIG. 5, and turned on when the pulse signal is in a high level and turned off when the pulse signal is in a low level. In other words, the infrared light emitting diode42is turned on and off repeatedly in a predetermined cycle. Accordingly, the phototransistor44intermittently receives light reflected from the retroreflective sheet40of the head5. Because of this, as illustrated in (a) ofFIG. 5, the phototransistor44outputs a detection signal (light reception signal) which includes pulses corresponding to the reflected light as received. While the number of the pulses varies depending upon the speed of the head5as swung, the number of pulses decreases as the speed of the head5increases, and the number of pulses increases as the speed of the head5decreases. Accordingly, it is possible to detect the speed of the head5as swung by counting the number of pulses included in the detection signal.

FIG. 6is a perspective view for showing an optical sensor unit installed in the game apparatus1ofFIG. 2.FIG. 7is a cross sectional view along I-I line ofFIG. 2. As shown inFIG. 6, the optical sensor unit includes the infrared filter26, a detection range setting unit46, the infrared light emitting diode42, and the phototransistor44. The optical sensor is made up of the infrared light emitting diode42and the phototransistor44. The detection range setting unit46includes two cylindrical sections48and50.

Also as illustrated inFIG. 7, optical paths52and54are formed respectively through the cylindrical sections48and50. The optical paths52and54are tapered respectively in a cross sectional view.

The infrared filter26is attached to the detection range setting unit46so that the ends of the cylindrical sections48and50are located in contact with or close to the rear surface of the infrared filter26. Also, the infrared light emitting diode42is inserted into the optical path52at the base end of the cylindrical section48, and the phototransistor44is inserted into the optical path54at the base end of the cylindrical section50.

Also, the infrared light emitting diode42and the phototransistor44are attached respectively to a substrate56, from which wires (not shown in the figure) are connected to a substrate58. The substrate58is fixed to the upper housing20, the substrate56is fixed to the detection range setting unit46, and the detection range setting unit46is fixed to the upper housing20.

FIG. 8AandFIG. 8Bare explanatory views for showing the detection range of the above optical sensor.

As shown inFIG. 8AandFIG. 8B, the detection range of this optical sensor is the range (hatched range) where the light emitting range of the infrared light emitting diode42and the light receiving range of the phototransistor44overlap each other. Also, the level at a height “H” from the head of the detection range setting unit46is regarded as the lowest level through which the head5of the golf club3passes, and a vertical range from the lowest level to an additional height “R” is regarded as the range within which the head5passes. As illustrated inFIG. 8A, in the case where the detection range setting unit46is short in height, there is a large difference in the detection range in the horizontal direction between the case where the head5passes through the level at the height “H” and the case where the head5passes through the level at the height (H+R). Because of this, even if the speed of the head5is equal therebetween, a substantial difference can occur between the number of pulses (refer to (a) ofFIG. 5) included in the detection signal when the head5passes through the level at the height “H” and the number of pulses (refer to (a) ofFIG. 5) included in the detection signal when the head5passes through the level at the height (H+R). This is undesirable because the speed of the head5is calculated on the basis of the number of pulses included in the detection signal as described above.

Thus, by increasing the height of the detection range setting unit46as shown inFIG. 8B, the difference of the detection range in the horizontal direction is reduced between the case where the head5passes through the level at the height “H” and the case where the head5passes through the level at the height (H+R). By this configuration, even if there is a difference in the height at which the head5passes, the same or approximately same number of pulses can be obtained as long as the speed is the same. Accordingly, it is possible to calculate an accurate speed irrespective of whether high or low the level in which the head5passes is.

The height of the detection range setting unit46can be determined in accordance with the height “H” and the height “H+R” and the specifications (the light emitting range and/or the intensity of light emission) of the infrared light emitting diode42.

In this description, the cylindrical section48of the detection range setting unit46can be used to regulate the light emitting range of the infrared light emitting diode42by adjusting the length thereof, and thereby it can be called as a light emitting range regulation section. On the other hand, the cylindrical section50of the detection range setting unit46can be used to regulate the light receiving range of the phototransistor44by adjusting the length thereof, and thereby it can be called also as a light receiving range regulation section.

FIG. 9andFIG. 10are views showing examples of a game screen as displayed on the television monitor7ofFIG. 1. As shown inFIG. 9, this game screen includes a golf course on which a plurality of objects “obj” is arranged. Furthermore, a ball object65and a batted ball direction setting object64for setting the moving direction of the ball are displayed at a starting point. The game apparatus1detects the speed of the golf club3which is swung by the player11by the above optical sensor, and makes the ball object65move the ball object65in the direction indicated by the batted ball direction setting object64in accordance with the speed.

Accordingly, the player11can adjust the moving distance and speed of the ball object65by adjusting the swinging speed of the golf club3. Also, the game apparatus1makes the batted ball direction setting object64rotate around the ball object65in accordance with the rotation direction and rotation amount of the rotatable member28ofFIG. 2. Accordingly, the player11can set the ball moving direction by rotating the rotatable member28in order to rotate the batted ball direction setting object64. In this case, as shown inFIG. 10, the game apparatus1updates the background as displayed in accordance with the direction of the batted ball direction setting object64. In other words, the background is updated in order that the scene, to which the batted ball direction setting object64is oriented, is widely viewed.

The ball object65moves from the starting point in accordance with the swing of the golf club3, and when it stops the batted ball direction setting object64is displayed in the position where the ball object65stops. Also, if the ball object65collides with an object “obj”, the moving direction of the ball object65is changed in accordance with the direction and the speed.

In this case, the initial direction of the batted ball direction setting object64is, at the starting point, the direction (refer toFIG. 9) which is predetermined in accordance with the starting point, otherwise the direction which is predetermined in accordance with the area where the ball object65stops. Thereafter, the direction can be arbitrarily changed by rotating the rotatable member28.

FIG. 11is an explanatory view for showing a rotation detecting mechanism and a push mechanism of the rotatable member28which is installed in the game apparatus1ofFIG. 2. As shown inFIG. 11, a cylindrical member72is fixed to the rear surface of the rotatable member28. Accordingly, when the rotatable member28is rotated, the cylindrical member72is also rotated integrally with the rotatable member28. The side wall portion of this cylindrical member72is shaped in a comb structure (comb member74) to alternately form light blocking sections (light shielding sections) and light transmissive sections.

A rotary encoder118is made up of the cylindrical member72and a photo interrupter90, and serves to detect the amount of rotation and the rotation direction of the cylindrical member72, i.e., the amount of rotation and the rotation direction of the rotatable member28. The photo interrupter90is made up of a light emitting diode92and a photo transistor unit94, which is made up of two phototransistors150and152.

Also, a boss84protruded from the center of the rear surface of the rotatable member28can be passed through an opening78, which is formed in the center of the cylindrical member72, in order to come in contact with a rubber switch88which is used as an enter button and the like. Accordingly, when the rotatable member28is pushed down, the rubber switch88is pushed down by the boss84, turned on by depressing the rotatable member28and turned off by releasing the rotatable member28.

As has been discussed above, the rotatable member28functions also as a button for turning on/off the rubber switch88in addition to the function of rotating the cylindrical member72of the rotary encoder118. By this configuration, there is no need for creating separate spaces in the surface of the game apparatus1respectively for placing the rotatable member28and for placing a button which turns on/off the rubber switch88, so that a small-footprint structure and an aesthetic improvement can be realized. In addition to this, the player11can rotate the rotatable member28and turn on/off the rubber switch88only by a single action of mounting the head5of the golf club3on the rotatable member28. The structure as described above will be explained in detail.

FIG. 12is an exploded perspective view for showing the game apparatus1ofFIG. 2. However,FIG. 12illustrates only components relating to the rotation detecting mechanism and the push mechanism of the rotatable member28, but illustration of other components is omitted.FIG. 13is a perspective view for showing the game apparatus1ofFIG. 2from which the rotatable member28is removed.

As shown inFIG. 12, the cylindrical member70through which the opening83is formed is attached to the upper housing20such that it covers the opening81. The diameter of the opening83is smaller than the diameter of the lower half of the cylindrical member72(i.e., the comb member74) but larger than the diameter of the upper half. Also, the diameter of the opening81is larger than the diameter of the lower half of the cylindrical member72(i.e., the comb member74).

Accordingly, the cylindrical member72is attached to the rotatable member28through the openings81and83. More specifically speaking, also as illustrated inFIG. 11, these components are fixed to each other by inserting two bosses82of the rotatable member28into two cylindrical members76, which are formed on the upper surface of the cylindrical member72, through the openings81and83, and threading screws. In this case, the boss84of the rotatable member28is inserted through the opening78of the cylindrical member72.

Support members100support urging members96and springs98respectively corresponding to them, and fixed to the inner surface of the upper housing20. In this case, as illustrated inFIG. 13, the urging members96are exposed respectively from openings80corresponding thereto of the upper housing20, and forces are applied to the urging members96in the upward direction by the elastic forces of the springs98fitted onto them. Since the rear surface of the rotatable member28comes in contact with the urging members96, when the rotatable member28is pushed down against the elastic forces of the springs98, the boss84of the rotatable member28pushes the rubber switch88to turn on it. And, when the force pushing down is released, the rotatable member28is pushed back to turn off the rubber switch88by the elastic forces of the springs98.

Meanwhile, the upper housing20, the lower housing22and the rotatable member28are made of, for example, ABS (acrylonitrile butadiene styrene). Also, the cylindrical members70and72is made, for example, of POM (polyacetal). When comparing the case where ABS members are rubbed with each other and the case where POM members are rubbed with each other, there is a smaller amount of debris when the POM members are rubbed than there is when the ABS members are rubbed. Accordingly, the amount of debris as generated is reduced, as few as possible, by making use of POM for forming the cylindrical members70and72, and thereby it is possible to prevent the detection by the photo interrupter90from being affected by debris as little as possible.

FIG. 14is a view for showing the situation in which the rotatable member28of the game apparatus1ofFIG. 2is rotated by the head5of the golf club3. As shown inFIG. 14, the player11can rotate the batted ball direction setting object64displayed on the television monitor7by placing the head5on the rotatable member28and rotating it. Also, the player11can turn on the rubber switch88by placing the head5on the rotatable member28and pushing down it.

FIG. 15is a view showing the electric configuration of the game apparatus1ofFIG. 2. As shown inFIG. 15, the game apparatus1includes a processor110, a ROM (read only memory)112, a bus114, the phototransistor44, a highpass filter unit116, the infrared light emitting diode42, and the rotary encoder118.

The processor110intermittently drives the infrared light emitting diode42to intermittently irradiate the retroreflective sheet40of the golf club3with infrared light. The phototransistor44receives the infrared light reflected from the retroreflective sheet40, and outputs a detection signal (light reception signal) to the processor110through the highpass filter unit116. The processor110detects whether or not the golf club3is swung and the speed of the swing on the basis of the detection signal as input. Also, the processor110receives two pulse signals from the rotary encoder118, and detect the amount and direction of rotation of the rotatable member28.

Although not shown in the figure, the processor110includes various functional blocks such as a CPU (central processing unit), a graphics processor, a sound processor and a DMA controller, and in addition to this, includes an A/D converter for accepting analog signals and an input/output control circuit for receiving input signals from external electronic circuits and electronic elements and outputting output signals to them.

The detection signal is input to this A/D converter from the highpass filter unit116through an analog input port, and converted into digital data. Also, the infrared light emitting diode42is controlled by the CPU through this input/output control circuit. Furthermore, a counter (referred to as “built-in counter” in the following description) included in the input/output control circuit but not shown in the figure receives two pulse signals from the rotary encoder, and detects the amount and direction of rotation of the rotatable member28. The input/output operations of the input/output control circuit are performed through input/output ports.

The CPU runs a game program stored in the ROM112, and performs various types of arithmetic operations. The graphics processor and the sound processor read image data and sound data stored in the ROM112in accordance with the results of the operations performed by the CPU, generate a video signal and an audio signal, and outputs them through the AV cable9.

Furthermore, the processor110is provided with an internal memory, which is for example a RAM (random access memory) but not shown in the figure. The internal memory is used to provide a working area, a counter area, a resister area, a temporary data area, a flag area and/or the like.

FIG. 16shows circuit diagrams including the phototransistor44, the highpass filter unit116and the infrared light emitting diode42ofFIG. 15. As shown inFIG. 16, the phototransistor44and the resistor element121are connected in series between a power supply Vcc0(for example, 3.3V) and ground. The connection point is connected to one terminal of a capacitor124while the other terminal of the capacitor124is connected to the connection point between resistor elements120and122. The resistor elements120and122are connected in series between the power supply Vcc0and ground. The highpass filter unit116is made up of the resistor element120, the resistor element122and the capacitor124, and the connection point between the resistor elements120and122is connected to the analog input port of the processor110.

On the other hand, the infrared light emitting diode42and the resistor element142are connected in series between ground and the connection point between the collector of a transistor136and a diode138. The transistor136, the diode138and a resistor element140are connected in series between ground and a power supply Vcc1(for example, 6V). The collector of the transistor134is connected to the base of the transistor136, and the emitter of the transistor134is connected to the cathode of the diode138. The base of the transistor134is connected to the negative electrode of an electrolytic capacitor130and one terminal of a resistor element132. The positive electrode of the electrolytic capacitor130is connected to a particular input/output port of the processor110.

When the processor110inputs a pulse signal “Pls” to the positive electrode of the electrolytic capacitor130through the above particular input/output port, the transistor134alternately repeats on/off operations. When the pulse signal “Pls” is at a low level, the transistors134and136are turned off to put off the infrared light emitting diode42. On the other hand, when the pulse signal “Pls” is at a high level, the transistors134and136are turned on to put on the infrared light emitting diode42. Accordingly, the processor110can adjust the cycle of turning on/off the infrared light emitting diode42by adjusting the frequency of the pulse signal “Pls”. Incidentally, the electrolytic capacitor130serves to prevent the lighting state of the infrared light emitting diode42from continuing even if the processor110is abnormally running to continuously output a high level signal.

On the other hand, the resistor element122and the capacitor124of the highpass filter unit116constitute a highpass filter, which transmits only the high frequency component of the detection signal (light reception signal) “Sp” output from the phototransistor44, and outputs it to the above analog input port of the processor110as a detection signal (light reception signal) “Ss”. Also, the resistor elements120and122of the highpass filter unit116constitutes a reference voltage generation circuit to constantly supply a reference voltage Vref to the connection point between the resistor elements120and122.

Accordingly, when the phototransistor44receives no light, the level of the detection signal “Ss” is returned to the level of the reference voltage Vref, which is then input to the processor110. On the other hand, when the phototransistor44intermittently receives infrared light, pulses each of which has amplitude corresponding to the level of the infrared light as received appear on the reference voltage Vref and are input to the processor110as the detection signal “Ss”. Next is an explanation of why the highpass filter unit116is provided.

FIG. 17is a time chart for showing the detection signals “Ss” and “Sp” appearing before and after the highpass filter unit116ofFIG. 15when there is no incandescent light source, and for showing the pulse signal “Pls” for turning on/off the infrared light emitting diode42.FIG. 18is a time chart for showing the detection signals “Ss” and “Sp” appearing before and after the highpass filter unit116ofFIG. 15when there is an incandescent light source and a fast swing is taken, and for showing the pulse signal “Pls” for turning on/off the infrared light emitting diode42.FIG. 19is a time chart for showing the detection signals “Ss” and “Sp” appearing before and after the highpass filter unit116ofFIG. 15when there is an incandescent light source and a slow swing is taken, and for showing the pulse signal “Pls” for turning on/off the infrared light emitting diode42.

As illustrated inFIG. 17toFIG. 19, when the infrared light emitting diode42is turned on by the pulse signal “Pls” from the processor110, the phototransistor44receives the infrared light which is reflected from the retroreflective sheet40of the golf club3, and outputs the detection signals “Sp” and “Ss” including pulses. Then, the processor110receives the detection signal “Ss”, counts the number of the pulses that exceed a predetermined level “Lev”, and calculate the speed of the golf club3as swung on the basis of this counter value.

In this case, the predetermined level “Lev” is determined by adding a predetermined value to the average value of the reference voltage Vref generated by the highpass filter unit116.

As illustrated inFIG. 17, in the case where there is no incandescent light source near the game apparatus1so that the phototransistor44is not influenced by such an incandescent light source, the detection signals “Ss” and “Sp” appearing before and after the highpass filter unit116have the substantially same waveform. Accordingly, under such an environment, it is possible to count the number of pulses also by the use of the detection signal “Sp” on the basis of a predetermined reference count value (corresponding to the predetermined level “Lev”), and thereby the highpass filter unit116may be dispensed with. For example, this is true when, like in Japan, a fluorescent light source is customary utilized as a light source in a room.

Contrary to this, as shown inFIG. 18andFIG. 19, in the case where there is an incandescent light source near the game apparatus1(for example, like in the United States of America, an incandescent light source is customary utilized as a light source in a room), the phototransistor44is influenced by such an incandescent light source so that the detection signal “Sp” contains a component corresponding to light from the incandescent light source. This is because the light included in the incandescent light source has wavelengths covering a wide range, and thereby the incandescent light source emits light in a range of wavelengths which is sensible by the phototransistor44(for example, 700 nm to 1050 nm).

In addition to this, the influence of this incandescent light source is not stable, but can vary depending upon the intensity, number and position of the light source, and other factors of the environment of the room, and also depending upon the location and motion of the player11.

Because of this, the counting process with reference to the above predetermined reference count value (corresponding to the predetermined level “Lev”) becomes difficult, so that there is the possibility that the pulses included in the detection signal “Sp” cannot stably be counted. In other words, it is impossible to determine the predetermined reference count value for detecting whether or not the pulses appear.

With this regard, in the case of the present embodiment, the detection signal “Sp” is passed through the highpass filter unit116, and thereby the pulses included in the detection signal “Ss” appear on the reference voltage Vref. Accordingly, the processor110can stably count the pulses with reference to the predetermined level “Lev”.

Meanwhile, in the example shown inFIG. 17, the number of the pulses exceeding the predetermined level “Lev” is 6. Also, in the example shown inFIG. 18, the player11has a fast swing, and the number of the pulses exceeding the predetermined level “Lev” is 7. On the other hand, in the example shown inFIG. 19, the player11has a slow swing, and the number of the pulses exceeding the predetermined level “Lev” is 14.

Also, as illustrated inFIG. 17toFIG. 19, the processor110stops outputting the pulse signal “Pls” after the swing of the golf club3, i.e., when the level of the pulses included in the detection signal “Ss” is lower than or equal to the predetermined level “Lev”. Then, when the next scene in which the player11strikes the ball object65arrives, the pulse signal “Pls” is output again to drive the infrared light emitting diode42. By this configuration, it is possible to reduce the power consumption.

FIG. 20is a circuit diagram for showing the rotary encoder118ofFIG. 15.

As shown inFIG. 20, the rotary encoder118includes the light emitting diode92and the phototransistors150and152. The resistor element158and the light emitting diode92are connected in series between the power supply Vcc0and ground. The collectors of the phototransistors150and152are connected to the power supply Vcc0, and the emitters thereof are connected respectively to particular input/output ports of the processor110.

When the cylindrical member72ofFIG. 12is rotated, the light from the light emitting diode92is intermittently input to the phototransistors150and152by means of the comb member74of the cylindrical member72. By this configuration, the pulse signals are output from the emitters of the phototransistors150and152. However, since the phototransistors150and152are spaced at a predetermined interval, the phases of the two pulse signals are shifted each other in accordance with the distance between the phototransistors150and152and the distance between the adjacent light shielding sections of the comb member74.

As has been discussed above, the processor110detects the amount and direction of rotation of the cylindrical member72on the basis of the two pulse signals.

FIG. 21is a flow chart showing an example of the process of detecting the golf club3by the processor110ofFIG. 15. As shown inFIG. 21, in step S1, the processor110calculates the average value of the level of the detection signal “Ss” (i.e., the level of the reference voltage Vref) without illumination of the infrared light emitting diode42by running a BIOS (basic input/output system). For example, the digital data of the detection signal “Ss” is acquired without illumination of the infrared light emitting diode42every time the video frame is updated, and calculates the average value of the detection signal “Ss” over eight video frames. In step S2, the processor110adds the predetermined value to the average value as calculated to obtain the predetermined level “Lev” (refer to step S13to be described below).

In step S3, the processor110performs processes in accordance with an application program (i.e., a golf game program). When the BIOS is called during running the application program, in step S4, the processor110sets a pulse input flag in the internal memory to a value indicating that no pulse is input (in the initial state). This pulse input flag is a flag indicative of whether or not a pulse is included in the detection signal “Ss” which is input from the highpass filter unit116ofFIG. 15.

In this case, the BIOS is called for processing in step S4when it is determined that the current state is before swing in step S103ofFIG. 22to be described below. Accordingly, the BIOS is not called for processing in step S4in other states, and thereby the infrared light emitting diode42is not turned on so that the power consumption can be reduced.

In step S5, the processor110clears a pulse counter defined in the internal memory. The pulse counter is a counter for counting the number of pulses included in the detection signal “Ss”. In step S6, the processor110sets a timer for controlling the infrared light emitting diode42. This timer is incorporated in the processor110. In the following description, this timer is called a built-in timer.

Then, when returning from the BIOS to the calling routine, in step S7, the processor110performs processes in accordance with the application program. And, when an interrupt is issued by the built-in timer during running the application program, the BIOS is called, and the processor110outputs a high level signal to the positive electrode of the electrolytic capacitor130ofFIG. 16in step S8to turn on the infrared light emitting diode42.

In step S9, the processor110sets the built-in timer again in order to acquire the detection signal “Ss” from the highpass filter unit116ofFIG. 16. Then, when returning from the BIOS to the calling routine, in step S10, the processor110performs processes in accordance with the application program. And, when an interrupt is issued again by the built-in timer during running the application program, the BIOS is called, and the processor110converts the detection signal “Ss” into digital data by the above A/D converter which is incorporated in the processor110in step S11.

In step S12, the processor110outputs a low level signal to the positive electrode of the electrolytic capacitor130ofFIG. 16in step S12to turn off the infrared light emitting diode42. In step S13, the processor110determines whether or not the level of the detection signal “Ss” converted into the digital data exceeds the predetermined level “Lev” (refer toFIG. 17toFIG. 19), and if it exceeds, the process proceeds to step S14otherwise proceeds to step S17.

In step S14, the processor110sets the pulse input flag to a value indicating that pulses are being input. In step S15, the processor110increments the pulse counter by one, and sets the built-in timer again in order to control the infrared light emitting diode42in step S16, and the process proceeds to step S7.

On the other hand, in step S17, the processor110determines whether or not the current value of the pulse counter is “0”, and if it is “0” the process proceeds to step S16otherwise proceeds to step S18.

In other words, if the detection signal “Ss” is lower than or equal to the predetermined level “Lev” and the current value of the pulse counter is “0”, it means that the golf club3is not detect yet (there is no swing), and thereby the process proceeds to step S16for detecting a swing. On the other hand, if the detection signal “Ss” is lower than or equal to the predetermined level “Lev” and the current value of the pulse counter is larger than “0”, it means that a pulse exceeding the predetermined level “Lev” is detected in the previous cycle but no longer detected in the current cycle, and thereby it means that the swing of the golf club3is finished.

Accordingly, in step S18, the processor110turns off the built-in timer. This is because the ball object65is moving so that it is not needed to detect the swing of the golf club3, and thereby this process is taken for the purpose of reducing the power consumption by turning off the infrared light emitting diode42. In step S19, the processor110sets the pulse input flag to a value indicating that the input of pulses is halted, and the process proceeds to step S3.

FIG. 22is a flow chart for showing an example of the game process by the processor110ofFIG. 15. As shown inFIG. 22, in step S100, the processor110performs the initial settings of the system. In step S101, the processor110acquires the value of the built-in counter. As has been discussed above, this built-in counter receives two pulse signals indicative of the amount of rotation and the direction of rotation from the rotary encoder118, and counts the number of input pulses by counting up (for example, the rotatable member28is rotated in the clockwise direction) or counting down (for example, the rotatable member28is rotated in the counter clockwise direction) in accordance with the phase relationship between the two pulse signals. In step S102, the processor110clears the built-in counter.

In step S103, the processor110proceeds to either one of steps S104, S105, S107and S108in accordance with the current state. However, the first state is a state for selecting a game mode (the number of players, course and the like), and the processor110proceeds to step S104in which the process for selecting a game mode is performed.

In the state before swing, the processor110proceeds to step S105in which the process of setting the batted ball direction of the ball object65is performed, and then proceeds to step S106in which the process of determining whether or not there is a swing of the golf club3is performed. In the state after swing, the processor110proceeds to step S107in which the next display position of the ball object65is calculated on the basis of the speed of swing as detected in step S106, the batted ball direction and the virtual frictional force of the course. In the state in which a score is calculated, in step S108, the processor110calculates the score.

In step S109, if a video system synchronous interrupt occurs (for example, at 1/60 second intervals), the process proceeds to step S110in which the display image is updated by generating a video signal anew, and if the system is waiting for the interrupt the process repeats the same step S109. In step S110, the processor110performs the process of updating the screen (video frame) displayed on the television monitor7in accordance with the processing result in steps S104to S108.

The sound process in step S111is performed when a sound interrupt is issued, the processor110generates an audio signal, and thereby a music sound or a sound effect is outputted.

FIG. 23is a flow chart for showing an example of the process of setting the batted ball direction in step S105ofFIG. 22. As shown inFIG. 23, in step S200, the processor110determines whether or not the batted ball direction setting object64has been displayed such that it is oriented to a predetermined direction, and if it has been displayed the process proceeds to step S203otherwise proceeds to step S201. In this case, the predetermined direction is the initial direction of the batted ball direction setting object64which is, at the starting point, the direction which is determined in accordance with the starting point, otherwise the direction which is determined in accordance with the area where the ball object65stops. Particularly, the predetermined direction at the starting point is sometimes called as the “standard direction”. However, when simply saying the predetermined direction of the batted ball direction setting object64, it can be the standard direction.

In step S201, the processor110sets the moving direction of the ball object65to the predetermined direction of the batted ball direction setting object64. In step S202, the processor110sets the display position of the batted ball direction setting object64such that it is oriented to the predetermined direction.

On the other hand, in step S203, the processor110adjusts the moving direction as currently set of the ball object65in accordance with the value of the built-in counter (i.e., the amount of rotation of the rotatable member28) acquired in step S101. In step S204, the processor110sets the display position of the batted ball direction setting object64such that it is oriented to the moving direction of the ball object65after the adjustment.

FIG. 24is a flow chart for showing an example of the swing determination process in step S106ofFIG. 22. As shown inFIG. 24, in step S300, the processor110checks the pulse input flag. In step S301, if the pulse input flag indicates the end of input (refer to step S19), the processor110proceeds to step S302, otherwise the process returns to the main routine.

In step S302, the processor110acquires the value of the pulse counter (refer to step S15). In step S303, the processor110determines whether or not the counter value as acquired is larger than a predetermined threshold value (for example, “3”), and if it is larger the process proceeds to step S304otherwise returns to the main routine. In step S304, the processor110calculates the initial velocity of the ball object65in accordance with the counter value acquired in step S302. In step S305, the processor110calculates and sets the next display position of the ball object65on the basis of the initial velocity as calculated, the virtual frictional forcee and the batted ball direction as set in step S105.

By the way, in the case of the present embodiment as has been discussed above, the number of pulses included in the detection signal (light reception signal) “Ss” varies depending upon the speed of the swing of the golf club3as a target of detection. Accordingly, it is possible to detect the speed of the golf club3only by counting the number of pulses included in the detection signal “Ss”. As thus described, even if an imaging device (for example, an image sensor) is not provided, the motion of the golf club3can be detected by a simple structure so that the cost can be reduced.

Also, in the case of the present embodiment, the speed of the head5can be appropriately detected by providing the detection range setting unit46which is used to narrow the detection range, irrespective of the height of the head5passing over the infrared light emitting diode42and the phototransistor44.

Furthermore, in the case of the present embodiment, while the reference voltage Vref is generated and supplied to the node (the connection point between the resistor elements120and122) through which the detection signal “Ss” is output, the highpass filter unit116is provided for passing only the high frequency component of the detection signal “Sp” to extract the necessary signals (pulses). Therefore, the pulses appear on the reference voltage Vref. Accordingly, while avoiding the influence of an environmental light source such as an incandescent lamp as little as possible, it is possible to stably count the number of pulses. In other words, it is possible to stably detect the speed of the golf club3irrespective of the type of the environmental light source.

Meanwhile, the present invention is not limited to the above embodiments, and a variety of variations and modifications may be effected without departing from the spirit and scope thereof, as described in the following exemplary modifications.

(1) In the above description, while the golf club3is used as an example of the operation article, the shape of the operation article is not limited thereto. Also, the profile of the retroreflective sheet to be attached to the operation article is not limited to the profile of the above retroreflective sheet40.

(2) In the above description, while the golf game is described as an example, the application program run by the processor110is not limited thereto.

While the present invention has been described in terms of embodiments, those skilled in the art will recognize that the invention is tot limited to the embodiments described. The present invention can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting in any way on the present invention.