JP2009057147A - Liquid discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism capable of allowing a photo-interrupter to be hardly degraded as a large printer for business is used. <P>SOLUTION: A liquid discharging device comprises a medium conveying passage, a detection means having a light-emission unit for emitting the light corresponding to the power supplied thereto to the first position between a starting end and a terminating end of the conveying passage and a light-reception unit for outputting the signal corresponding to the intensity of the light reflected at the first position or transmitted through the position to detect presence/absence of any medium at the first position based on the output level of the signal, and a control means for controlling suppression of the operating time of the light-emission unit by stopping the power supply to the light-emission unit at every elapse of the predetermined time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus.

Large-sized single-cut sheets such as A0, A1, A2, etc., large-sized ink jet printers for business use that can record images on continuous paper, roll paper, etc. have become widespread, improving the convenience of this type of printer Various techniques have been proposed. For example, Patent Document 1 discloses a technique that can prevent the occurrence of a recording position shift accompanying the recording of an image on continuous paper that is folded in a paper tray in a highly accurate manner.
JP 2005-111681 A

  By the way, a large business-use ink jet printer is also equipped with a photo interrupter as a paper edge detection sensor, like other types of printers. This photo interrupter continues to irradiate light toward the end detection position on the paper tray side slightly on the paper transport path from the paper tray to the recording head, and based on the change in the intensity of the reflected light. Detects whether or not the front and rear edges of the paper are routed. The detection signal of the photo interrupter is used for specifying the sheet feed amount when passing under the recording head.

  However, in the case of large commercial printers, unlike so-called consumer small printers, they are often used with the power on for a long time, and the photo interrupter irradiates light even during image recording. As a result, the photo interrupter deteriorates faster than a small printer.

  The present invention has been devised under such a background, and an object of the present invention is to provide a mechanism that makes it difficult for photo interrupters to deteriorate due to the use of a large business printer.

  A liquid ejection apparatus according to a preferred aspect of the present invention includes a medium transport path, and a light emitting unit that irradiates light according to power supplied to the medium toward a first position between a start end and a terminal end of the transport path. And a light receiving unit that outputs a signal corresponding to the intensity of the light reflected at the first position or the light transmitted through the position, and the presence or absence of the medium at the first position is determined based on the output level of the signal. Detection means for detecting, and control means for performing control to suppress the operation time of the light emitting unit by stopping the supply of power to the light emitting unit every time a predetermined time passes. According to the present invention, since the operation time of the light emitting unit is suppressed every time a predetermined time has passed, the consumption can be prevented.

  The detecting means determines whether or not the output level of the signal exceeds a specified threshold value, and the detecting means determines that the medium is detected when the determination that the output level exceeds the specified threshold value continues for a specified number of times. You may make it judge that it exists. According to the present invention, since it is determined that the medium exists only when the number of times that the output level of the signal exceeds the threshold value continues for a specified number of times, it is possible to prevent erroneous detection of the presence or absence of the medium.

  A liquid ejection apparatus according to another preferred embodiment of the present invention irradiates a medium conveyance path and light corresponding to the power supplied to the medium toward a first position between a start end and a termination end of the conveyance path. Detecting means for detecting the presence or absence of the medium at the first position based on the intensity of the light reflected at the first position or the light transmitted through the position, and between the end of the conveyance path and the first position. A pair of rollers that are detachably supported so that their peripheral surfaces abut between the first position and the second position of the transport path, and a discharge means that discharges the liquid toward the second position And when the detecting means detects that there is a medium at the first position, an actuator that moves one or both of the pair of rollers so that the peripheral surfaces of the rollers abut each other, and a second position from the second position side. Rotational force sufficient to transport the medium through the space between the peripheral surfaces of the pair of rolls toward the position of 1 Includes a motor for providing to one or both of the pair of rolls, the supply of power to the detecting means and a power supply unit to repeat its interruption. According to this invention, since electric power is intermittently supplied to the detecting means, it is possible to suppress the power consumption rather than continuing to supply electric power.

  The medium is a cut sheet, and the distance between the first position of the conveyance path and the position where the peripheral surfaces of the pair of rollers abut each other is more than the distance between the front end and the rear end of the cut sheet. May be shorter. According to the present invention, it is possible to reliably convey the cut sheet that has reached the first position to the second position where the droplets are discharged from the discharge means.

  In addition, the conveyance path may have an inclined section that is inclined such that the start end side is positioned higher than the end end side between at least the first position and the pair of rollers. According to the present invention, it is possible to prevent inconvenience that the cut sheet falls down when the cut sheet is sandwiched between the pair of rollers.

  The detecting means further includes a specifying means for specifying the total time during which the light is irradiated, and the power supply means corresponds to a ratio between a time for supplying power to the detecting means and a time for interrupting the supply according to the specified total time. May be changed. According to the present invention, the power consumption can be more efficiently suppressed by dynamically changing the amount of power supplied to the detection means.

(Embodiment of the Invention)
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an ink jet printer according to the present embodiment, in which a block diagram showing an electrical configuration and a right side view showing a mechanical configuration are shown side by side.

  As shown in FIG. 1, this printer fixes casters 92 and 93 to the four corners of the lower surface of a flat plate-shaped base 91, and moves the printing unit 10 upward from the left and right ends of the upper surface of the base 91. A mechanical structure is supported from the outside by both leg frames 95 extending in a straight line. The casing 11 of the printing unit 10 has a shape in which a bottom portion of a rectangular parallelepiped is cut off by using a straight line drawn in parallel to the ground from the front end side of the bottom surface to the rear. The housing 11 is sandwiched between both leg frames 95 with the upper surface inclined slightly rearward. Further, a hollow portion 12 that opens to the front side is formed above the housing 11, and a roll paper 13 is attached to the hollow portion 12. In addition, a paper conveyance path 14 is formed below the hollow portion 12 on the front surface of the housing 11, and a paper edge detection sensor 15 (“detection means”) is provided between the beginning and end of the paper conveyance path 14. PF (Paper Feed) roller pair 16, carriage 17 (corresponding to “ejection means”), and rotary cutter 18 are provided. In the following description, the side closer to the hollow portion 12 of the paper conveyance path 14 is appropriately referred to as “upstream side”, and the side away from the hollow portion 12 is appropriately referred to as “downstream side”.

  This printer has a roll paper printing mode in which roll paper 13 (corresponding to “medium”) mounted in the hollow portion 12 is sent to the side of the paper conveyance path 14 for printing, and has a size such as A0, A1, A2, etc. The cut sheet paper P (corresponding to “medium”) is operated in two modes, namely, a single sheet paper printing mode in which the user inserts the cut sheet paper P one by one into the sheet conveyance path 14 for printing. Hereinafter, the cut sheet P and the roll paper 13 are appropriately referred to as “paper”.

  The paper edge detection sensor 15 is a reflection type photo interrupter, and a light emitting element 20 whose irradiation direction is matched with a concave portion 19 which is recessed slightly below the opening portion of the hollow portion 12, and a light incident direction in the concave portion 19. And a light receiving element 21 combined. The intensity of light emitted from the light emitting element 20 toward the recess 19 is proportional to the magnitude of current flowing from the power source (not shown) into the light emitting element 20. In addition, the light receiving element 21 supplies a signal obtained by photoelectric conversion of light incident from the concave portion 19 side to a control unit 40 described later, and the voltage of the signal is strong for light incident on the light receiving element 21. It gets higher. Therefore, it can be determined that the front edge of the sheet has passed when the voltage of the signal output from the light receiving element 21 exceeds a preset threshold value, and that the trailing edge has passed when the voltage falls below the threshold value.

  The PF roller pair 16 includes a PF driven roller 23 and a PF drive roller 24. The PF roller pair 16 is provided on the downstream side of the paper edge detection sensor 15. Further, the distance between the sheet edge detection sensor 15 and the PF roller pair 16 is shorter than the distance between the front edge and the rear edge of the cut sheet P. The left and right ends of the rotation shaft of the PF driven roller 23 are respectively locked in the holes of the both leg frames 95. These holes are formed on the downstream side of the sheet edge detection sensor 15 and at a position slightly away from the front surface of the housing 11. On the other hand, the left and right ends of the rotating shaft of the PF drive roller 24 are fitted into the rails 25 of the both leg frames 95, respectively. These rails 25 extend from the position downstream of the sheet edge detection sensor 15 and slightly rearward from the front surface of the housing 11 toward the rear surface of the housing 11, and the front end of the inner periphery of the rail 25. The distance between the rear end and the rear end of the PF drive roller 24 is greater than the shaft diameter. In other words, on the inner periphery of these rails 25, a slight “play” that allows the PF drive roller 24 to slide from a position where the peripheral surface of the PF drive roller 24 and the peripheral surface of the PF driven roller 23 contact each other to a position where they are completely separated from each other. Is secured.

  The PF drive roller 24 is supported by an actuator 26, and the rotation shaft thereof is connected to the rotation shaft of the PF motor 27 through a plurality of gears (not shown). In the actuator 26, the front end of the roll paper 13 or the cut sheet P is a position between the paper end detection sensor 15 and the recess 19 (hereinafter referred to as “end detection position” as appropriate: corresponding to “first position”). Is passed, the PF drive roller 24 is moved in a direction to approach the PF driven roller 23. The determination of the presence / absence of the passage is performed according to a sheet end detection process described in detail later. Further, the actuator 26 moves the PF drive roller 24 in a direction away from the PF driven roller 23 when the rear end of the cut sheet P passes the end detection position. The PF motor 27 rotates the PF drive roller 24 counterclockwise in FIG. 1 under the control of the control unit 40 described later. When operating the printer in the roll paper printing mode, it is necessary to prepare for inserting the front end of the roll paper 13 between the roller pair 16 through the edge detection position. When operating in the cut paper printing mode, Therefore, it is necessary to prepare for inserting the front edge of the cut sheet P one by one between the roller pair 16 through the edge detection position. Then, after the preparatory work, the actuator 26 moves the PF drive roller 24 to the PF driven roller 23 side, and the PF drive roller 24 is in a state where the front end of the paper is sandwiched between the nip portions between the rollers 23 and 24. When the sheet rotates, the sheet is conveyed downstream.

  The carriage 17 provided on the downstream side of the PF roller pair 16 accommodates, for example, four color ink cartridges (not shown) of yellow (Y), magenta (M), cyan (C), and black (B). In addition, a recording head 28 connected to these ink cartridges via a flow path (not shown) is provided on the side of the paper conveyance path 14. The recording head 28 includes a nozzle plate in which a series of nozzle openings for each color are arranged, a piezoelectric element that expands and contracts in response to charge and discharge, a cavity that is sandwiched between the nozzle plate and the piezoelectric element, and the like. When the piezoelectric element is expanded and contracted in a state where the ink supplied from the ink cartridge is stored in the cavity, ink droplets are ejected from the nozzle opening toward the paper conveyance path 14.

  A guide shaft 29 spanned between both leg frames 95 is inserted into holes formed in the right and left surfaces of the carriage 17, and the carriage 17 is slidably connected to the guide shaft 29. . The carriage 17 is fixed to a part of a belt (not shown) wound around two pulleys (not shown) in a direction substantially parallel to the guide shaft 29, and one of the two pulleys is fixed. The rotation shaft is connected to the rotation shaft of a CR (Carriage) motor 30. Accordingly, when the CR motor 30 rotates forward and backward, the carriage 17 changes from the left end position (hereinafter referred to as “moving left limit position”) of the paper transport path 14 to the right end position (hereinafter referred to as “moving right limit position”). It is guided by the guide shaft 29 and reciprocates. In addition, the rotary cutter 18 provided on the downstream side of the carriage 17 cuts the paper at a timing designated by the control unit 40.

  In FIG. 1, a control unit 40 (corresponding to “a part of“ detection means ”,“ control means ”,“ power supply means ”) includes an interface circuit 41, a first motor driver 42, a second motor driver 43, and a recording head driver. 44, a CPU (Central Processing Unit) 45, a RAM (Random Access Memory) 46, a ROM (Read Only Memory) 47, an EEPROM (Electrically Erasable Programmable Read-Only Memory) 48, and an ASIC (Application Specific Integrated Circuit) 49.

  The interface circuit 41 receives, from a personal computer (not shown), print data indicating the drawing contents of each size image such as A0, A1, A2, and the like, and indicates the print mode selected through the personal computer customization screen. Receive mode selection data. In the customize screen, you can select one of the roll paper printing mode and cut sheet printing mode that relate to the paper feed method, and one of the default mode and photo mode that relates to print quality. Can be selected. The photo mode is a mode for recording dots with a higher density than the default mode, and is suitable for outputting print data of a high-density color image such as a photograph. The recording head driver 44 supplies a signal for instructing ejection of ink droplets to the recording head 28 based on the interpretation of the print data.

  The first motor driver 42 applies a DC voltage obtained from a power supply (not shown) to the PF motor 27 as a pulse corresponding to a PWM (Pulse Width Modulation) signal. The PWM signal is a rectangular wave whose period is constant and the ratio of the high level time and the low level time in one period changes. The proportion of the high level time in one cycle of the PWM signal is called “duty ratio”. The PF motor 27 rotates in response to application of a pulse from the first motor driver 42, and the torque increases as the duty ratio increases.

  The configuration of the second motor driver 43 is the same as that of the first motor driver 42, and a DC voltage obtained from a power source (not shown) is applied to the CR motor 30 as a pulse corresponding to a PWM signal supplied to itself. To do. The CR motor 30 rotates in response to the application of a pulse from the second motor driver 43, and the torque increases as the duty ratio increases.

  While using the RAM 46 as a work area, the CPU 45 refers to data stored in the ROM 47 and the EEPROM 48 and executes various programs stored in these memories. The ROM 47 stores a relatively simple program such as IPL (Initial Program Loader). The EEPROM 48 stores a control program describing a control procedure from when print data is supplied to the interface circuit 41 until an image indicated by the print data is recorded. The ASIC 49 has an input / output port connected to the paper edge detection sensor 15, the rotary cutter 18, the first motor driver 42, the second motor driver 43, and the recording head driver 44. Signals are exchanged with each other.

  The CPU 45 intermittently drives both the PF motor 27 and the CR motor 30 while synchronizing each other, and ejects ink droplets from the recording head 28 in accordance with the driving of the CR motor 30, thereby indicating the print data. Record the image on paper.

  FIGS. 2A and 2B are diagrams showing how the motors 27 and 30 work together when a single image indicated by the print data is recorded on paper. In both figures, the vertical axis represents the rotational speeds of the motors 27 and 30, and the horizontal axis represents the drive time of the motors 27 and 30. For convenience of illustration, the horizontal scale in FIG. 2B is smaller than that in FIG. 2A, and the vertical scale in FIG. 2B is opposite to that in FIG.

  When the print data indicating the image drawing contents is supplied from the personal computer in a state where the front end of the sheet is sandwiched between the nip portion between the PF driving roller 24 and the PF driven roller 23, as shown in FIG. The PF motor 27 that has been in the non-rotating state (speed = 0) is almost proportionally accelerated until reaching a predetermined upper limit speed. The PF motor 27 that has been accelerated to the upper limit speed continues to rotate for a while at the rotation speed, and then is decelerated almost proportionally until it reaches the non-rotation state. As a result of this series of rotations of the PF motor 27, the sheet sandwiched between the nip portions is located at a position behind the front end by a distance corresponding to the blank area to receive ink droplets ejected by the recording head 28 (hereinafter, “ It is called “ink droplet discharge position”: equivalent to “second position”).

  As shown in FIG. 2B, when the PF motor 27 becomes non-rotating and the conveyance of the paper stops, the CR motor 30 is accelerated almost proportionally to the upper limit speed, and after that speed is maintained for a while, no rotation occurs. It is decelerated almost proportionally until it reaches a state. With this series of rotations of the CR motor 30, the carriage 17 moves from the moving left limit position toward the moving right limit position. Further, while the carriage 17 is moving at the upper limit speed in the stroke from the movement left limit position to the movement right limit position, ink droplets are ejected from the recording head 28 toward the sheet, and 1 in the main scanning direction of the image. A sequence of dots corresponding to a line is recorded.

  As shown in FIG. 2B, the rotation of the CR motor 30 is repeated twice while the conveyance of the paper is stopped, and the rotation direction of the second CR motor 30 is opposite to that of the first time. Then, the carriage 17 that has moved to the moving right limit position by the second rotation of the CR motor 30 moves toward the moving left limit position. Whether ink droplets are ejected while the carriage 17 returns from the movement right limit position to the movement left limit position depends on various customizations through the customization screen.

  When the carriage 17 returns to the moving left limit position, the non-rotating PF motor 27 is almost proportionally accelerated to the upper limit speed, and after maintaining that speed for a while, it is decelerated approximately proportionally until it reaches the non-rotating state. (See FIG. 2A). By this series of rotations of the PF motor 27, the sheet is conveyed downstream by a distance corresponding to one line in the sub-scanning direction of the image. The distance corresponding to one line, that is, the paper feed amount, is specified based on the relationship between the image size indicated by the print data and the mode related to the print quality. In the case of the photo mode, since the high density ink droplet dots are recorded, the feed amount is smaller than that in the default mode.

  Thereafter, the CR motor 30 and the PF motor 27 rotate alternately until the arrangement of dots corresponding to all the lines in the sub-scanning direction of the image has been recorded on the paper, so that the moving left limit position and the moving right limit position are changed. The reciprocating movement of the carriage 17 between them and the conveyance of the sheet at a distance corresponding to one line in the sub-scanning direction are repeated. The number of repetitions of the reciprocating movement of the carriage 17 and the conveyance of the sheet at a distance corresponding to one line is also specified based on the relationship between the image size indicated by the print data and the mode related to the print quality. When the dot arrangement corresponding to the lowest line in the sub-scanning direction of the image is recorded on the paper, the non-rotated PF motor 27 rotates and the image-recorded paper is conveyed downstream. The paper is discharged. When the image is recorded in the roll paper printing mode, the roll paper 13 is cut by the rotary cutter 18 and then discharged, whereas the image is recorded in the cut paper printing mode. The cut sheet P is discharged without undergoing such cutting.

<Process of Embodiment>
A paper edge detection process that is a characteristic process of the present embodiment will be described. FIG. 3 is a flowchart showing the paper edge detection process. In the paper edge detection process, the light emitting element 20 is repeatedly turned on and off through intermittent supply of power to the light emitting element 20 of the paper edge detection sensor 15, and the light receiving element 21 receives the reflected light of the light to be turned on. This is processing for detecting whether or not a sheet has passed at the edge detection position based on the voltage of the signal to be detected.

  First, the control unit 40 sets the variable n to the initial value 1 and sets the variable Judge to the initial value 0 (S100). Subsequently, the control unit 40 determines whether the variable n is equal to or smaller than the constant pe_off (S101). This constant pe_off is set to 96. Since the initial variable n at which the process is started is the initial value 1, the result of the determination in step S101 that has advanced from step S100 is “Yes”. When it is determined that the variable n is equal to or smaller than the constant pe_off (S101: Yes), the control unit 40 waits for a preset waiting time t1 (S102). The standby time t1 is set to 10 milliseconds, for example.

  Subsequently, the control unit 40 increments the variable n by 1 (S103), and then returns to step S101. Thereafter, the loop from step S101 to step S103 is repeated until the incremented variable n becomes larger than the constant pe_off. Since the constant pe_off is 96, the number of loop iterations required for the variable n to be incremented from 1 to 96 is 96, and the total waiting time t1 during that time is 960 milliseconds.

  When it is determined in step S101 that the variable n is larger than the constant pe_off (S101: No), the control unit 40 determines whether the variable n is a value obtained by adding 1 to the constant pe_off, that is, 97 ( S201). Since the variable n immediately before proceeding from step S101 to step S201 is 97, the result of the determination in step 201 proceeding from step S101 is “Yes”.

  When it is determined that the variable n is a value obtained by adding 1 to the constant pe_off (S201: Yes), the control unit 40 reads the current default value DA_standby from the memory (S202), and binary data indicating the default value DA_standby Is set in the DAC (not shown) of the sheet edge detection sensor 15 (S203). Then, a current having a current value indicated by DA_standby flows into the light emitting element 20 of the paper edge detection sensor 15 and light having an intensity corresponding to the current starts to be emitted toward the edge detection position.

  Subsequently, the control unit 40 waits for the standby time t1 to elapse (S204). Then, the variable n is incremented by 1 to 98 (S205), and the process returns to step S101. The result of determination in step S101 advanced from step S205 is “No”, and the result of determination in step S201 advanced from step S101 is also “No”.

  When it is determined in step S201 that the variable n is not a value obtained by adding 1 to the constant pe_off (S201: No), the control unit 40 determines whether the variable n is the same as the value obtained by adding the constant pe_on to the constant pe_off. It is judged whether it is smaller than (S301). Since the constant pe_on is set to 4, the value obtained by adding 4 to 96 is 100. Since the variable n immediately before proceeding from step S201 to step S301 is 98, the result of the determination in step S301 proceeding from step S201 is “Yes”.

  When it is determined that the variable n is equal to or smaller than the value obtained by adding the constant pe_on to the constant pe_off (S301: Yes), the control unit 40 outputs the voltage of the signal output from the light receiving element 21 of the sheet edge detection sensor 15. The value V_temp is acquired (S302). Then, after waiting for the standby time t1 to elapse (S303), the control unit 40 determines whether the voltage value V_temp is larger than the threshold value V_standby (S304).

  When determining in step S304 that the voltage value V_temp is not greater than the threshold value V_standby, that is, equal to or smaller than the threshold value V_standby (S304: No), the control unit 40 increments the variable Judge by one (S305). After incrementing the variable n by 1 (S306), the process returns to step S101. On the other hand, when it is determined in step S303 that the voltage value V_tem is greater than the threshold value V_standby (S304: Yes), the control unit 40 proceeds to step S306 without executing step S305, and returns to step S101. Since the variable n immediately before proceeding from step S306 to step S101 is 98, the determination result of step S101 proceeding from step S305 is “No”, and the determination result of step S201 proceeding from step S101 is also “No”. And return to step S301. Thereafter, the loop from step S101 to step S306 is repeated until the incremented variable n becomes a value obtained by adding the constant pe_on to the constant pe_off. Since the value obtained by adding the constant pe_on to the constant pe_off is 100, the number of loop iterations required for the variable n to be incremented from 97 to 100 is four.

  When it is determined in step S301 that the variable n is larger than the value obtained by adding the constant pe_on to the constant pe_off (S301: No), the control unit 40 converts the binary data indicating 255 into the DAC of the sheet end detection sensor 15. (S401). Then, the light irradiation by the light emitting element 20 of the paper edge detection sensor 15 stops. Further, the control unit 40 determines whether or not the variable Judge is a value obtained by subtracting 1 from the constant pe_on (S402). Since the constant pe_on is set to 4, the value obtained by subtracting 1 from 4 is 3. When it is determined in step 402 that the variable Judge is a value obtained by subtracting 1 from the constant pe_on (S402: Yes), the control unit 40 determines that there is a sheet at the edge detection position (S501). On the other hand, when it is determined that the variable Judge is not a value obtained by subtracting 1 from the constant pe_on (S402: No), the process returns to step S100.

  According to the paper edge detection process described above, it is possible to detect that the front edge of the paper has passed the edge detection position while suppressing power consumption of the paper edge detection sensor 15.

  This principle will be described in detail with reference to FIG. FIG. 4 is a timing chart showing the on / off transition of the sheet edge detection sensor 15. While the paper edge detection sensor 15 is on, that is, while power is being supplied to the light emitting element 20, the timing chart is at a high level and the paper edge detection sensor 15 is off. That is, while the supply of power to the light emitting element 20 is stopped, the timing chart is at a low level.

  Referring to FIG. 4, the paper edge detection sensor 15 repeats 960 milliseconds off (step S101 to step S103 in FIG. 3) and 40 milliseconds on (step S201 to step S306 in FIG. 3). The voltage value V_temp is acquired every 10 milliseconds during the 40-second ON period (step S302 in FIG. 3). When it is determined that any of the three voltage values V_temp is equal to or smaller than the threshold value V_standby, it is determined that there is a sheet at the edge detection position (step S402 in FIG. 3). In this way, by inserting 960 milliseconds off between 40 milliseconds on, the amount of power supplied to the sheet edge detection sensor 15 can be suppressed by the amount of time that it is off. In addition, by making all the voltage values V_temp acquired continuously during the ON state the same or smaller than the threshold value V_standby, it is possible to reliably detect false detections due to the influence of noise, etc. Can be prevented.

(Other embodiments)
The present invention can be modified in various ways.

  The paper edge detection sensor 15 of the printer according to the above embodiment is a reflective photointerrupter in which a light emitting element 20 whose irradiation direction is aligned with the edge detection position and a light receiving element 21 whose alignment direction is aligned with that position are arranged. is there. On the other hand, the paper edge detection sensor 15 may be replaced with a translucent photo interrupter in which the light emitting element 20 and the light receiving element 21 are arranged to face each other.

  The PF roller pair 16 of the printer according to the above-described embodiment has a configuration in which a PF driving roller 24 that rotates by receiving a force from a PF motor 27 and a PF driven roller 23 that rotates around the PF driving roller 24 are supported in a detachable manner. It has become. On the other hand, you may make it support the two rollers which each receive the force of a motor and rotate freely. Further, not only the PF drive roller 24 is moved by the actuator 26, but both the PF driven roller 23 and the PF drive roller 24 may be moved so that their peripheral surfaces are in contact with each other.

  The casing 11 of the printer according to the above-described embodiment is sandwiched between the leg frames 95 with the upper surface inclined slightly rearward, and the front surface is flat. Therefore, the sheet conveyance path 14 extending from the lower end of the hollow portion 12 of the housing 11 to the front surface thereof is positioned higher than the end side, that is, has the same inclination angle as the housing 11 itself. Inclined backwards. On the other hand, it is not necessary that the entire section between the start end and the end of the paper transport path 14 be inclined as such, and at least the section between the end detection position and the ink droplet ejection position may be inclined. That's fine.

  The printer casing 11 according to the above-described embodiment is repeatedly switched to turn on the paper edge detection sensor 15 for 960 milliseconds and then on for 40 milliseconds. Yes. On the other hand, the time during which the paper edge detection sensor 15 is turned on may be longer or shorter. Further, the time for turning off the paper edge detection sensor 15 may be lengthened or shortened. Furthermore, the total time that the light emitting element 20 of the paper edge detection sensor 15 radiates light is specified, and the ratio of the time for turning the paper edge detection sensor 15 on and the time for turning it off is changed according to the total time. You may do it.

1 is a diagram illustrating a schematic configuration of an ink jet printer according to an embodiment of the present invention. It is a figure which shows a mode that a PF motor and CR motor drive in cooperation. 6 is a flowchart illustrating a paper edge detection process. 6 is a timing chart showing transition of on and off of a paper edge detection sensor.

Explanation of symbols

91 ... Base, 92, 93 ... Casters, 95 ... Leg frame, 10 ... Printing unit, 11 ... Housing, 12 ... Hollow part, 13 ... Roll paper, 14 ... Paper transport path, 15 ... Paper end detection sensor, DESCRIPTION OF SYMBOLS 16 ... Roller pair, 17 ... Carriage, 18 ... Rotary cutter, 19 ... Recessed part, 20 ... Light emitting element, 21 ... Light receiving element, 23 ... PF driven roller, 24 ... PF drive roller, 25 ... Rail, 26 ... Actuator, 27 ... PF motor, 28 ... recording head, 29 ... guide shaft, 30 ... CR motor, 40 ... control unit, 41 ... interface circuit, 42 ... first motor driver, 43 ... second motor driver, 44 ... recording head driver, 45 ... CPU, 46 ... RAM, 47 ... ROM, 48 ... EEPROM, 49 ... ASIC

Claims (6)

A medium transport path;
A light emitting unit that irradiates light according to the power supplied to itself toward a first position between the start and end of the transport path, and light reflected at or transmitted through the first position. A light receiving unit that outputs a signal according to the intensity of the detection unit, and detecting means for detecting the presence or absence of the medium at the first position based on the output level of the signal;
Control means for controlling the operation time of the light emitting unit by stopping the supply of power to the light emitting unit every time a predetermined time passes;
A liquid ejection apparatus comprising: The detection means determines whether or not the output level of the signal exceeds a specified threshold value, and when the determination that the output level exceeds the specified threshold value continues for a specified number of times, the medium exists. Judging
The liquid ejection apparatus according to claim 1, wherein A medium transport path;
The intensity of the light reflected at the first position or transmitted through the position by irradiating light corresponding to the power supplied to itself toward the first position between the start and end of the transport path. Based on the detection means for detecting the presence or absence of the medium in the first position,
Discharge means for discharging liquid toward a second position between the end of the transport path and the first position;
A pair of rollers supported so as to be able to come into contact with each other so that their peripheral surfaces come into contact with each other between the first position and the second position of the transport path;
An actuator that moves one or both of the pair of rollers so that their peripheral surfaces come into contact with each other when the detection unit detects that there is a medium at the first position;
A motor that applies to one or both of the pair of rolls a rotational force sufficient to transport the medium from the second position side to the first position side through the peripheral surfaces of the pair of rolls. When,
Power supply means for repeating the supply and interruption of power to the detection means;
A liquid ejection device comprising: The medium is a cut sheet,
The distance between the first position of the conveyance path and the position where the peripheral surfaces of the pair of rollers contact each other is shorter than the distance between the front end and the rear end of the cut sheet,
The liquid discharge apparatus according to claim 3. The transport path is
Having at least a slope section between the first position and the pair of rollers such that the start end side is located above the end side.
The liquid ejecting apparatus according to claim 4, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. Further comprising a specifying means for specifying a total time during which the detection means is irradiated with light;
The power supply means
The ratio of the time for supplying power to the detection means and the time for interrupting the supply is changed according to the specified total time,
The liquid ejecting apparatus according to claim 3, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.

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