Recording medium transfer apparatus

A recording medium transfer apparatus includes a motor control unit for controlling the motor to rotate at higher speed when the recording medium is fed to the liquid ejection area than that when the recording medium is discharged out of the liquid ejection area, and a feed control unit for controlling a next recording medium to be fed simultaneously with discharge of the recording medium, if a position of a rear end of the recording medium when recording or printing has been finished is situated upstream of a predetermined position, which is upstream of the discharge roller as much as a distance between a feed start position of the recording medium and the liquid ejection area, whereas controlling the next recording medium to start to be fed after discharge of the recording medium has been finished, if the position of the rear end of the recording medium when recording or printing has been finished is situated downstream of the predetermined position.

This patent application claims priority from a Japanese patent application No. 2003-123776 filed on Apr. 28, 2003, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium transfer apparatus. More particularly, the present invention relates to a recording medium transfer apparatus for transferring a recording medium on which recording or printing is performed by ejecting liquid to a liquid ejection area where the liquid is ejected onto the recording medium.

2. Description of the Related Art

A liquid ejecting apparatus such as an inkjet type recording apparatus includes a recording medium transfer apparatus. In order to improve the recording throughput of the liquid ejecting apparatus, it is effective to increase the speed of transferring the recording medium by the recording medium transfer apparatus. However,the transfer speed of the recording medium is restricted depending on the operation state of the liquid ejecting apparatus.

When many recording mediums are discharged, it is necessary to obtain the stackability by which the discharged recording mediums are stacked at approximately the same position on a discharge stacker. In order to obtain the stackability, the discharge speed at which the discharge roller discharges the recording mediums to the discharge stacker is necessarily restricted to a specific value or less, e.g. 10[ips] (inch per second). If the discharge speed of the recording medium exceeds the specific value, the electrostatic force caused by electrification of the recording medium mainly decreases the stackability. Meanwhile, when the recording medium is fed to the liquid ejection area where liquid is ejected onto the recording medium, in order to increase the throughput, it is preferable that the feed roller should transfer the recording medium at higher speed, e.g. 14[ips], than the discharge roller during discharge.

For the purpose of cost-down, a technology in which the liquid ejecting apparatus drives both the discharge roller for discharging the recording medium on which recording has been finished and the feed roller for feeding the next recording medium by one motor has been recently developed as disclosed, for example, in Japanese Patent Application Publication No. 2002-283649.

If the discharge and feed rollers are driven by one motor, both the rollers rotate at the same speed. In this case, when the rotation speed of the feed roller becomes high to improve the throughput, the rotation speed of the discharge roller also becomes high, so there is such a problem that the stackability cannot be obtained.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a recording medium transfer apparatus, which is capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.

According to the first aspect of the present invention, a recording medium transfer apparatus for feeding a recording medium, on which recording or printing is performed by ejecting liquid, to a liquid ejection area in which the liquid is ejected onto the recording medium includes a feed roller for feeding the recording medium towards the liquid ejection area, a discharge roller for discharging the recording medium, on which recording or printing has been performed, out of the liquid ejection area, a motor for driving the feed and discharge rollers, a motor control unit for controlling the motor to rotate at higher speed when the recording medium is fed to the liquid ejection area than that when the recording medium is discharged out of the liquid ejection area, and a feed control unit for controlling a next recording medium to be fed simultaneously with discharge of the recording medium, if a position of a rear end of the recording medium when recording or printing has been finished is situated upstream of a predetermined position, which is upstream of the discharge roller as much as a distance between a feed start position of the recording medium and the liquid ejection area, whereas controlling the next recording medium to start to be fed after discharge of the recording medium has been finished, if the position of the rear end of the recording medium when recording or printing has been finished is situated downstream of the predetermined position.

Accordingly, in the recording medium transfer apparatus, while the recording medium which will be recorded next is being fed to the liquid ejection area, the recording medium on which recording has been finished is prevented from being discharged out of the discharge roller at high speed. Therefore, the rear end of the recording medium is discharged at lower speed than the feed speed. Thus, the recording medium transfer apparatus can obtain the stackability the discharged recording medium as well as improving the transfer throughput.

The recording medium transfer apparatus may further include a recording medium sensor disposed at the predetermined position for detecting the recording medium, wherein the feed control unit controls the next recording medium to be fed simultaneously with discharge of the recording medium, if the recording medium sensor detects the recording medium when recording or printing has been finished, whereas controlling the next recording medium to be fed after discharge of the recording medium has been finished, if the recording medium sensor does not detect the recording medium when recording or printing has been finished. Accordingly, it is possible to easily judge whether the next recording medium should start to be fed or not based on the detection result by the recording medium sensor.

The recording medium transfer apparatus may further include a roller lock mechanism driven by the motor for preventing the feedroller from being rotated by the motor or stopping rotation prevention of the feed roller by reverse rotation of the motor, wherein when the motor rotates forward, the feed and discharge rollers are rotated in such direction that the recording medium is transferred forward, and the feed control unit uses, as the predetermined position, a position situated further downstream of the feed start position of the next recording medium than a sum of a reverse transfer amount by which the recording medium is transferred reversely due to the reverse rotation of the motor while the rotation prevention is being stopped and width of the liquid ejection area in a transfer direction of the recording medium. Accordingly, the rear end of the recording medium on which recording has been finished and the front end of the recording medium which will be recorded next are not overlapped during transfer, and when recording starts to be performed on the next recording medium, it is prevented that liquid is unnecessarily ejected onto the rear end of the recording medium on which recording has been finished.

According to the second aspect of the present invention, a recording medium transfer apparatus for feeding a recording medium, on which recording or printing is performed, to a liquid ejection area in which a liquid ejecting head ejects the liquid onto the recording medium to perform recording or printing includes a feed roller for feeding the recording medium to the liquid ejection area, a discharge roller for discharging the recording medium, on which recording or printing has been performed, out of the liquid ejection area, a motor for driving the feed and discharge rollers to be rotated in such direction that the recording medium is transferred forward when the motor rotates forward, a roller lock mechanism driven by the motor for preventing the feed roller from being rotated by the motor or stopping rotation prevention of the feed roller by reverse rotation of the motor, and a feed control unit for controlling a next recording medium, which will be fed next, to be fed simultaneously with discharge of the recording medium, if a distance between a rear end of the recording medium when recording or printing has been finished and a feed start position of the next recording medium is larger than a sum of a reverse transfer amount by which the recording medium is transferred reversely due to the reverse rotation of the motor while the rotation prevention is being stopped and width of the liquid ejection area in a transfer direction of the recording medium.

Accordingly, since it is prevented that the rear end of the recording medium on which recording has been finished and the front end of the recording medium which will be recorded next are overlapped during transfer, and that when recording starts to be performed on the next recording medium, liquid is unnecessarily ejected onto the rear end of the recording medium on which recording has been finished, the transfer throughput can be improved.

The recording medium transfer apparatus may further include a recording medium sensor disposed further downstream of the feed start position of the next recording medium than a sum of the reverse transfer amount and the width of the liquid ejection area in the transfer direction of the recording medium for detecting the recording medium, wherein the feed control unit controls the next recording medium to be fed simultaneously with discharge of the recording medium, if the recording medium sensor does not detect the recording medium when recording or printing has been finished, where as controlling the next recording medium to start to be fed after discharge of the recording medium has been finished, if the recording medium sensor detects the recording medium when recording or printing has been finished. Accordingly, it is possible to easily judge whether the next recording medium should start to be fed or not based on the detection result by the recording medium sensor.

The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a perspective view of an inkjet type recording apparatus10which is an example of a liquid ejecting apparatus. The inkjet type recording apparatus10of this embodiment includes a recording medium transfer apparatus therein. The recording medium transfer apparatus includes a feed roller for feeding recording mediums towards a liquid ejection area, a discharge roller for discharging the recording mediums on which recording or printing has been finished out of the liquid ejection area, and a step motor60for driving the feed and discharge rollers. When the recording medium transfer apparatus feeds the recording medium to the liquid ejection area, it allows the step motor60to rotate at higher speed than that when discharging the recording mediums out of the liquid ejection area. And if the position of a rear end of the recording medium when recording or printing has been finished is situated upstream of a predetermined position, which is upstream of the discharge roller as much as the distance between a feed start position of the recording medium and the liquid ejection area, the next recording medium is fed at high speed simultaneously with the discharge of the recording medium. Meanwhile, if the position of the rear end of the recording medium when recording or printing has been finished is situated downstream of the predetermined position, which is upstream of the discharge roller as much as the distance between the feed start position of the recording medium and the liquid ejection area, the next recording medium is fed at high speed after the discharge of the recording medium is finished at low speed.

Accordingly, while the recording medium transfer apparatus is feeding the recording medium which will be recorded next towards the liquid ejection area, it prevents the recording medium on which recording has been finished from being discharged out of the discharge roller at high speed. Therefore, the rear end of the recording medium is discharged at lower speed than the feed speed. Owing to this, the recording medium transfer apparatus can obtain the stackability of the discharged recording mediums as well as improving the transfer throughput.

Further, the inkjet type recording apparatus10is an example of a liquid ejecting apparatus for performing recording or printing by ejecting liquid onto the recording mediums. And the recording head of the inkjet type recording apparatus10is an example of a liquid ejecting head of the liquid ejecting apparatus. Nozzles provided on the recording head are an example of the ejection holes of the liquid ejecting head.

However, the present invention is not limited to this. As another example of the liquid ejecting apparatus, there is a color filter manufacturing apparatus for manufacturing a color filter of a liquid crystal display. In this case, a color material ejecting head of the color filter manufacturing apparatus is an example of the liquid ejecting head. Further another example of the liquid ejecting apparatus is an electrode forming apparatus for forming electrodes such as an organic EL display, a FED (Field Emission display)or the like. In this case, an electrode material (conduction paste) ejecting head of the electrode forming apparatus is an example of the liquid ejecting head. Further another example is a biochip manufacturing apparatus for manufacturing biochips. In this case, a bio organism ejecting head of the biochip manufacturing apparatus and a sample ejecting head as a minute pipette are examples of the liquid ejecting head. The liquid ejecting apparatus of the present invention includes other liquid ejecting apparatuses used for industrial purposes. In addition, the recording medium is a material on which recording or printing is performed by ejection of liquid, which includes a recording paper, a circuit board on which circuit patterns such as display electrodes are formed, a CD-ROM for label recording, a preparation on which a DNA circuit is recorded, etc.

Next, another configuration of the inkjet type recording apparatus10is shown inFIGS. 1 and 2.FIG. 2is a side view of the inkjet type recording apparatus10.FIG. 2shows the inkjet type recording apparatus10together with the recording medium11during recording.

The inkjet type recording apparatus10, as shown inFIGS. 1 and 2, includes a recording medium tray12for holding a plurality of recording mediums11, a feed unit20for feeding the recording mediums11being pushed out of the recording medium tray12towards the liquid ejection area, a transfer unit30for transferring the recording mediums11being fed by the feed unit20to the liquid ejection area, a recording unit40for performing recording onto the recording mediums11within the liquid ejection area, a discharge unit50for discharging the recording mediums out of the liquid ejection area, a discharge stacker300for stacking the recording mediums11discharged out of the discharge unit50, a step motor60, a lock lever70for locking a carriage, a control unit80for controlling the entire inkjet type recording apparatus10, and a detecting unit200. The recording medium tray12includes a hopper124for pushing out the recording mediums11stacked on the recording medium tray12. The control unit80is an example a motor control unit and a feed control unit of this invention. In addition, the step motor60is an example of a motor of this invention.

The feed unit20includes a feed roller22and a retarder roller24which is rotated accompanying the feed roller22. The feed roller22and the retarder roller24hold one on top of the stack of the recording mediums11therebetween, which is being pushed out of the recording medium tray12by the hopper124, and feed it one by one towards the liquid ejection area via the transfer unit30.

The transfer unit30includes a transfer roller32driven by the step motor60and a driven transfer roller34which is rotated accompanying the transfer roller32, and a drive shaft36of the transfer roller32. The transfer roller32rotates interposing the recording mediums11being fed by the feed roller20between itself and the driven transfer roller34, and transfers it to the liquid ejection area.

The recording unit40includes a carriage42shown inFIG. 1, a recording head44, and a motor48for moving the carriage42. Further, it includes a guide plate46for supporting the carriage42to be slidable in a main scanning direction which is approximately perpendicular to the transfer direction of the recording medium11.

The discharge unit50includes a discharge roller52driven by the step motor60and a driven discharge roller54which is rotated accompanying the discharge roller52. The discharge roller52and the driven discharge roller54rotate holding the recording medium11after recording therebetween, and discharge it out of the liquid ejection area. The discharge stacker300stacks a plurality of recording mediums11discharged by the discharge unit50.

Further, power is transmitted from the step motor60to the transfer roller32and the discharge roller52via a belt62. The belt62is applied with tension by a tensioner64. The step motor60, the tensioner64, the transfer roller32, and the discharge roller52are sequentially arranged along the flowing direction of the belt. Meanwhile, to the feed roller22power is transmitted from the step motor60via a gear and clutch mechanism. When the step motor60rotates forward, it makes the feed roller22, the transfer roller32, and the discharge roller52rotated in a forward transfer direction of the recording medium11.

The lock lever70projects into the orbit of the carriage42when the inkjet type recording apparatus10is not in operation so as not to allow the carriage42to move towards the liquid ejection area. The lock lever70is turned by the step motor60via the drive shaft36of the transfer roller32and a gear mechanism38provided at an end of the drive shaft36. When the step motor60rotates in a reverse transfer direction of the recording medium11, the lock lever70is turned in the direction to lock the carriage42, whereas when the step motor60rotates in the forward transfer direction of the recording medium11, the lock lever70is turned in the direction to unlock the carriage42. Further, the lock lever70locks a clutch mechanism for transmitting the power of the step motor60to the feed roller22so as to prevent the rotation of the feed roller22.

The detecting unit200includes a contact lever210which is turned by being pushed downwards by the carriage42or turned in the same direction by contacting the recording medium11, a sensor220for detecting the turning of the contact lever210, and a judging unit230for recognizing the carriage42or the recording medium11based on the detection result of the sensor220.

Here, one end of the contact lever210projects into the orbit of the carriage42, so that it is pushed downwards by the carriage42. In addition, the contact lever210is positioned between the feed unit20and the transfer unit30in the transfer direction of the recording medium11. And the contact lever210is positioned between the liquid ejection area and the standby position of the carriage42in the main scanning direction of the carriage42.

The contact lever210is pushed downwards by the carriage42and pushed out of the movement path of the carriage42, and thus the sensor220detects the movement, so the detecting unit200detects the carriage42. And when the recording medium is transferred towards the liquid ejection area, the contact lever210is turned in such a direction that it is pushed out of the movement path of the carriage42by the recording medium. Accordingly, the detecting unit200can detect the recording medium.

In the above configuration, the control unit80controls the nozzles of the recording head44to eject liquid while reciprocating the carriage42along the guide plate46. And since the control unit80controls the recording medium11to be transferred whenever the carriage42performs one scanning, recording is performed on the entire recording medium11. Further, the inkjet type recording apparatus10may perform recording in both the forward and backward paths of the recording head44or in either the forward or backward path.

Next, a roller lock mechanism for transmitting the power of the step motor60to the feed roller22will be described.FIG. 3shows a perspective view of the configuration of a part of the roller lock mechanism400. The roller lock mechanism400includes a feed gear153which is coupled to the step motor60via the gear mechanism, and a clutch110switches whether to transmit the driving force transmitted to the feed gear153to the feed roller shaft151. One end of the feed roller shaft151is integrally formed with the feed roller22, while the other end of the feed roller shaft151is engaged with the clutch110and the feed gear153in this order. Further, a cam152for moving the hopper up and down is integrally formed with the feed roller shaft151near the clutch110between the feed roller22and the clutch110. The cam152for moving the hopper up and down transmits the rotation force of the feed roller shaft151to the hopper124as the power to push out the recording medium11stacked on the recording medium tray12.

FIG. 4shows a perspective view of the feed gear153in detail. The feed gear153includes a flange-shaped gear153aand a boss-shaped gear153bintegrally formed with the gear153a. The gear153ais coupled to the step motor60via the gear mechanism, and rotated accompanying the step motor60. The clutch110shown inFIG. 3switches whether to be coupled to the gear153b, so that it switches whether to transmit the driving force of the feed gear153to the feed roller shaft151. In other words, the clutch110transmits the power of the step motor60to the feed roller22via the feed roller shaft151when coupled to the gear153b, whereas disconnecting the power of the step motor60to the feed roller22when not coupled to the gear153b.

FIG. 5shows a perspective view of the clutch110in detail. The clutch110includes a disc111, a ring112, and a clutch spring113. The disc111includes a ring support shaft111afor rotatably supporting the ring112on its surface and a spring hanger111bfor fixing one end of the clutch spring113, and has a cross-shaped opening111cwhich is to be engaged with a cross-shaped end of the feed roller shaft151in the middle thereof. The clutch spring113is disposed opposite the ring support shaft111awith regard to the circumferential section of the ring112. The ring112includes a projection112afor geared engagement with the gear153bof the feed gear153on its inner circumferential section, a spring hanger112bfor fixing the other end of the clutch spring113on its outer circumferential section, and an engagement section112cfor engagement with the locklever70. The engagement section112cis disposed opposite the ring support shaft111awith regard to the circumferential section of the ring112. The ring112is rotatable in the longitudinal extension direction of the clutch spring113with the ring support shaft111abeing considered as a pivot.

FIG. 6shows a perspective view of the lock lever70in detail. The lock lever70includes a rotation section71and an arm section72extending from the rotation section71. The arm section72includes a holding claw72afor locking the carriage42and an engagement claw72bfor engagement with the engagement section112cof the ring112on its end section.

FIG. 7shows a perspective view of the roller lock mechanism400while preventing the rotation of the feed roller22. The rotation section71of the lock lever70is coupled to the step motor60via the drive shaft36of the transfer roller32and the gear mechanism38provided at the drive shaft36, and driven in the direction where the engagement claw72bis engaged with the engagement section112cof the ring112by the forward rotation of the step motor60. While the engagement claw72bof the lock lever70is being engaged with the engagement section112cof the ring112, the ring112is standing by with the ring support shaft111afunctioning as a pivot, and the projection112aof the ring112being separated from the gear153b. In this case, the rotation of the feed gear153is not transferred to the disc111via the ring112. Accordingly, the roller lock mechanism400prevents the rotation of the feed roller22.

Meanwhile, when the step motor60rotates reversely, the feed gear153and the lock lever70are rotated reversely, i.e. counterclockwise in the drawing. Accordingly, the engagement claw72bis separated from the engagement section112c. When the engagement claw72bis separated from the engagement section112c, the ring112of the clutch110is rotated clockwise by the spring force of the clutch spring113with the ring support shaft111afunctioning as a pivot, whereby the projection112ais geared with the gear153b. Accordingly, the rotation force of the feed gear153rotating reversely is transmitted to the ring112.

Here, the shape of the projection112aof the gear153bis designed to disperse the reverse rotation of the feed gear153in the circumferential direction of the feed gear153and the direction away from the center of the feed gear153. Accordingly, the ring112which is receiving the rotation force of the feed gear153rotating reversely allows the disc111to be rotated reversely while rotating counterclockwise against the disc111with the ring support shaft111afunctioning as a pivot. At this time, accompanying the reverse rotation of the disc111the feed roller shaft151and the feed roller22are also rotated in reverse direction. Accordingly, the recording medium11shown inFIG. 2is transferred reversely accompanying the reverse rotation of the feed roller22.

Since the ring112is turned counterclockwise against the disc111with the ring support shaft111afunctioning as a pivot, the projection112ais not geared to the gear153b, and the ring112idly rotates against the reverse rotation of the feed gear153.

Next, when the step motor60rotates forward, the feed gear153and the lock lever70start to rotate forward, i.e. clockwise in the drawing. Here, since the projection112ais geared to the gear153bby the spring force of the clutch spring113, the engagement section112cstarts to rotate forward. At this time, the engagement section112cis positioned ahead the engagement claw72bof the arm section72in the forward rotation direction as much as the idle rotation of the projection112aduring the reverse rotation of the gear153b. Therefore, before the engagement claw72breturns to the position to lock the engagement section112cby the forward rotation of the lock lever70, the engagement section112cpasses by the engagement position with the engagement claw72b. As above, the roller lock mechanism400stops preventing the rotation of the feed roller22.

After the engagement section112cpasses by the engagement position with the engagement claw72b, in approximately one rotation, the lock lever70returns to the position to lock the engagement section112cof the clutch110by the power of the step motor60. Then the engagement section112cof the clutch110which has performed one rotation is engaged with the engagement claw72bof the lock lever70again. In other words, when the feed roller22performs approximately one rotation in the forward rotation direction after stopping the prevention of the rotation by the roller lock mechanism400, the rotation is prevented again. While the feed roller22performs one rotation in the forward rotation direction, the recording medium11is fed towards the liquid ejection area.

In the inkjet type recording apparatus10described above, an example of control to improve the transfer throughput, will be hereinafter described. In this embodiment, the control unit80improves the transfer throughput by controlling the rotation direction and rotation speed of the step motor60and the movement of the lock lever70in response to the position of the rear end of the recording medium11when recording has been finished.

FIG. 8shows a first example of controlling the transfer operation of the recording medium11in response to the position of the rear end of the recording medium11. A path L is defined as the transfer path along which the recording medium11is discharged via the feed roller22, the transfer unit30, and the discharge unit50. A distance A is defined as the distance between a feed start position310on the path L at which the feed roller22starts to transfer the recording medium11and a boundary312of the liquid ejection area formed by the recording head44. The distance A is the transfer distance when the recording medium11is transferred to the liquid ejection area. Further, the feed start position310is the position of the recording medium11when the recording medium11contacts the feed roller22because the hopper124moves upwards.

If the position of the rear end of the recording medium11on which recoding has just been finished is situated downstream of a position314which is upstream of the discharge roller52as much as the distance A along the path L, when the feed operation starts for the recording medium11which will be recorded next, the recording medium11is discharged before the feed operation is finished.

Accordingly, the inkjet type recording apparatus10of this embodiment includes a detecting unit200afor detecting the recording medium11at the position322which is upstream of the position314, whereby when recording or printing is finished, it controls the timing for feeding the next recording medium11in response to whether the detecting unit200adetects the recording medium11or not. Further, the detecting unit200ais an example of a recording medium sensor of this invention and a first example of the installation position of the detecting unit200described in connection withFIG. 2.

FIG. 9is a flowchart showing an example of the control operation described in connection withFIG. 8. First, the control unit80detects whether recording or printing has been finished on the recording medium11or not (S100). Then, it checks whether the detecting unit200adetects the recording medium11(S102). If it is considered in the step102that the detecting unit200ahas detected the recording medium11(S102: Yes), the control unit80controls the step motor60to rotate reversely so that the roller lock mechanism400stops preventing the rotation of the feed roller22, and feeds the recording medium11which will be recorded next at high speed, e.g. 14[ips] to the liquid ejection area simultaneously with the discharge of the recording medium11on which recording has been finished (S104). Further, the discharge of the recording medium11is not finished when the step104is finished, but it is finished accompanying the transfer operation during the recording operation on the next recording medium11fed into the liquid ejection area.

Meanwhile, if it is considered in the step102that the detecting unit200ahas not detected the recording medium11yet (S102: No), the control unit80controls the step motor60to rotate forward so as to rotate the discharge roller52while maintaining the rotation prevention of the feed roller22by the roller lock mechanism400, and discharges the recording medium11at the speed which guarantees the stackability, e.g. 10[ips] (S106). Then, it controls the step motor60to rotate reversely so that the rotation prevention of the feed roller22is stopped, and feeds the recording medium11which will be recorded next at high speed, e.g. 14[ips] by controlling the step motor60to rotate at higher speed than that of the discharge in the step106(S108). Then the flow is finished. According to the above operation, the inkjet type recording apparatus10can obtain the stackability as well as improving the throughput.

FIG. 10shows a second example of controlling the transfer operation of the recording medium11in response to the position of the rear end of the recording medium11. The inkjet type recording apparatus10of this embodiment includes a detecting unit200bin replace of the detecting unit200ainFIG. 9. Other configurations are the same as those in connection withFIG. 8, so they will be described. In this embodiment, an ejection area width B is defined as the width of the liquid ejection area in the transfer direction of the recording medium11, and a transfer amount C as the distance by which the recording medium11is transferred since the step motor60rotates reversely when the rotation prevention of the feed roller22is stopped. The detecting unit200bis situated at a position326further downstream of a position316which is downstream of the feed start position310of the recording medium11, which will be recorded next, as much as the sum (B+C) of the ejection area width B and the transfer amount C.

When the inkjet type recording apparatus10of this embodiment finishes recording on the recording medium11, it controls the timing for transferring the next recording medium11in response to whether the detecting unit200bdetects the recording medium11or not. Further, the detecting unit200bis another example of the recording medium sensor of this invention, and a second example of the installation position of the detecting unit200described in connection withFIG. 2.

FIG. 11is a flowchart showing an example of the control operation described in connection withFIG. 10. First, the control unit80detects whether recording or printing has been finished on the recording medium11or not (S200). Then, it checks whether the detecting unit200bhas detected the recording medium11or not (S202). If it is considered in the step202that the detecting unit200bhas not detected the recording medium11yet (S202: No), the control unit80controls the step motor60to rotate reversely so that the roller lock mechanism400stops preventing the rotation of the feed roller22, and feeds the recording medium11which will be recorded next at high speed, e.g. 14[ips] simultaneously with the discharge of the recording medium11on which recording has been finished (S204).

Meanwhile, if it is considered in the step202that the detecting unit200bhas detected the recording medium11, (S202: Yes), the control unit80controls the step motor60to rotate forward so as to rotate the discharge roller52while maintaining the rotation prevention of the feed roller22by the roller lock mechanism400, and discharges the recording medium11at the speed which guarantees the stackability, e.g. 10[ips] (S206). Then, it controls the step motor60to rotate reversely so that the rotation prevention of the feed roller22is stopped, and feeds the recording medium11which will be recorded next at high speed, e.g. 14[ips] by controlling the step motor60to rotate at higher speed than that of the discharge in the step206(S208). Then the flow is finished.

According to the above operation, although the step motor60rotates reversely so as to start the feed of the next recording medium11, the recording medium11on which recording has been finished is not transferred reversely until it is overlapped on the end of the next recording medium11. Further, although the recording medium11on which recording has been finished due to the reverse rotation of the step motor60is transferred, the distance between the end of the next recording medium11and the rear end of the recording medium11on which recording has been finished is sure to be more than the width B of the ejection area. Accordingly, since the rear end of the recording medium11on which recording has been finished is positioned out of the liquid ejection area of the recording head44when recording is performed on the next recording medium11, unnecessary liquid ejection is prevented.

FIG. 12shows a third example of controlling the transfer operation of the recording medium11in response to the position of the rear end of the recording medium11. In this embodiment, the inkjet type recording apparatus10calculates the position of the rear end of the recording medium11based on the transfer distance of the recording medium11, and controls the timing for feeding the next recording medium11based on the position of the rear end of the recording medium11on which recording has been finished. In this embodiment, the detecting unit200for recognizing the recording medium11is positioned upstream of the feed start position310in order to recognize the existence of the recording medium11upstream of a boundary position312of the liquid ejection area. The feed start position310, the position316, the position314, and the boundary position312as well as the distance A, the ejection area width B, and the transfer amount C are the same as those of the first or second example, so they will not be described.

The control unit80in this embodiment calculates the position of the rear end of the recording medium11on which recording has been finished based on the transfer amount of the recording medium11, and controls the timing for feeding the recording medium11based on whether the calculated position of the rear end is situated further downstream of the feed start position310than B+C and further upstream of the discharge roller52than the distance A or not. Accordingly, both the overlap and stain of the recording mediums11can be prevented, and with regard to the stackability the transfer throughput of the recording medium transfer apparatus can be improved.

FIG. 13is a flowchart showing an example of the control operation described in connection withFIG. 12. First, the control unit80starts to transfer the recording medium11(S300). Then, the control unit80detects the recording medium11(S302). Then, the control unit80calculates the end position of the recording medium11based on the rotation amount of the step motor60from when the detecting unit200detects the recording medium11and the position201at which the detecting unit200detects the recording medium11, and starts to calculate the position of the rear end of the recording medium11based on the calculated end position and the length of the recording medium11in the transfer direction (S304).

Then, when the feed of the recording medium11is finished (S306), the control unit80performs recording on the recording medium11(S308). Next, the control unit80checks whether recording has been finished on the recording medium11or not (S310). If it is considered in the step310that recording has not been finished yet (S310: No), recording is performed back in the step308. If it is considered in the step310that recording has been finished (S310: Yes), the control unit80checks whether the position of the rear end of the recording medium11on which recording has been finished is situated upstream of the position314or not (S312).

If it is considered in the step312that the position of the rear end is situated upstream of the position314(S312: Yes), then the control unit80checks whether the position of the rear end of the recording medium11on which recording has been finished is situated downstream of the position316(S314). If it is considered in the step314that the position of the rear end is situated downstream of the position316(S314: Yes), the control unit80controls the step motor60to rotate reversely so that the roller lock mechanism400stops preventing the rotation of the feed roller22, and feeds the recording medium11which will be recorded next at the speed of 14[ips] simultaneously with the discharge of the recording medium11on which recording has been finished (S316).

Meanwhile, if it is considered in the step312that the position of the rear end is not situated upstream of the position314(S312: No) or it is considered in the step314that the position of the rear end is not situated downstream of the position316(S314: No), the control unit80controls the step motor60to rotate forward so as to rotate the discharge roller52while maintaining the rotation prevention of the feed roller22by the roller lock mechanism400, and discharges the recording medium11at the speed which guarantees the stackability, e.g. 10[ips] (S318)

Then, it controls the step motor60to rotate reversely so as to stop preventing the rotation of the feed roller22, and feeds the recording medium11which will be recorded next at the speed of 14[ips] by controlling the step motor60to rotate at higher speed than that during the discharge of the step318(S320). Then the flow is finished. According to the above operation, the inkjet type recording apparatus10can improve the recording throughput while obtaining the stackability and preventing both the overlap and stain of the recording mediums

As obvious from the description above, according to the present invention, it is possible to improve the recording throughput by way of the inkjet type recording apparatus.