JP2007160715A - Liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejecting apparatus equipped with a structure capable of suppressing the deterioration in the position detection accuracy of an object to be detected and also restraining the occurrence of false detection. <P>SOLUTION: A printer is provided with a light emitting portion 41 that includes a light emitting surface 41a, a light receiving portion 42 that includes a light receiving surface 42a, a linear scale 31, and a cleaning member 83 that is fixed to the linear scale 31 to clean the light emitting surface 41a and the lithe receiving surface 42a. The linear scale 31 includes a position detecting pattern 31b, wherein a first transparent portion 31f and a first light shielding portion 31e are alternately formed to detect the position of a carriage, and a stain detection pattern 31c, wherein a second transparent portion 31h and a second light shielding portion 31g are alternately formed to detect the stain of the linear scale 31. When the stain of the linear scale 31 is detected by the stain detection pattern 31c, the printer allows the cleaning member 83 to clean the light emitting surface 41a or the light receiving surface 42a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus.

  An ink jet printer is known as a liquid ejecting apparatus that ejects a liquid onto a predetermined medium such as paper. This ink jet printer is equipped with various motors such as a paper feed motor for driving a transport roller for transporting a printing sheet as a medium and a carriage motor for driving a carriage on which a print head is mounted. . As such a motor, a DC motor is widely used for the purpose of noise reduction and the like. An ink jet printer equipped with a DC motor is a position detection device for performing position control, speed control, etc. of the DC motor, and a light sensor that transmits light from the light emitting element and a photosensor having a light emitting element and a light receiving element. And an encoder composed of a scale in which light shielding portions that block light from the light emitting elements are alternately formed.

  In addition, in an ink jet printer, when an ink droplet is ejected from a print head, until the ink droplet reaches a printing surface such as printing paper, or when the ink droplet reaches the printing surface, one of the ink droplets. It is known that an ink mist that floats in the air due to the mist is generated, and the generated ink mist adheres to each component inside the printer. And when this ink mist adheres to a photo sensor or a scale, erroneous detection is likely to occur in the encoder. Therefore, in order to suppress the occurrence of erroneous detection in the encoder, an ink jet printer provided with a cleaning member that removes ink mist adhering to the scale has been proposed (for example, see Patent Document 1).

  In the ink jet printer disclosed in Patent Document 1, a cleaning member such as urethane resin that contacts both sides of a linear scale is fixed to a photosensor attached to a carriage. As the carriage reciprocates, the cleaning member slides on both sides of the linear scale to clean the linear scale. In this ink jet printer, a cleaning member such as urethane resin that contacts both surfaces of the rotary scale is fixed to a photosensor attached to a predetermined bracket. As the rotary scale rotates, the cleaning member slides on both surfaces of the rotary scale, so that the rotary scale is cleaned. In the ink jet printer disclosed in Patent Document 1, the cleaning member always slides on the linear scale and the rotary scale even when the linear encoder or the rotary encoder detects the position of the carriage or the conveyance roller.

Japanese Patent Laid-Open No. 2002-361901 (see FIG. 5 to FIG. 7)

  However, in the ink jet printer described in Patent Document 1, the cleaning member is fixed to the photosensor, and the cleaning member slides on the scale when detecting the positions of the carriage and the conveyance roller. Therefore, in recent inkjet printers that require high-precision printing, the sliding resistance between the cleaning member and the scale, which has not been a significant problem in the past, becomes a problem. That is, there arises a problem that the position detection accuracy in the encoder is lowered due to vibration of the scale or photosensor due to sliding resistance between the cleaning member and the scale, or a decrease in the speed of the carriage or the conveyance roller. As a result, there arises a problem that printing with high accuracy becomes difficult.

  Accordingly, an object of the present invention is to provide a liquid ejection apparatus having a configuration capable of suppressing a decrease in position detection accuracy of an object to be detected and suppressing occurrence of erroneous detection.

  In order to solve the above-described problem, the present invention provides a position detection device that detects the position of an object to be detected and a liquid discharge portion that discharges liquid onto a predetermined medium. A light emitting unit having a light emitting surface for emitting light, a light receiving unit having a light receiving surface for receiving light from the light emitting unit, a scale disposed between the light emitting surface and the light receiving surface, and being fixed to the scale, A cleaning member that contacts at least one of the light emitting surface and the light receiving surface and cleans at least one of the light emitting surface and the light receiving surface, and the scale is configured to detect the position of the object to be detected. The position detection pattern in which the first light-transmitting part that transmits light from the first light-transmitting part and the first light-shielding part that blocks light from the light-emitting part are alternately formed at least within the detection range of the object to be detected and the stain on the scale are detected. Because of the light emission And a dirt detection pattern in which a second light-transmitting part that transmits light from the second light-transmitting part and a second light-shielding part that blocks light from the light-emitting part are alternately formed. And a cleaning member moving means for moving the cleaning member relative to the light emitting part and the light receiving part, and cleaning is performed when the dirt detecting means detects the dirt on the scale. It is characterized in that at least one of the light emitting surface and the light receiving surface is cleaned by a cleaning member that is relatively moved by the member moving means.

  The liquid ejection apparatus of the present invention includes a cleaning member that contacts the light emitting surface and the light receiving surface to clean the light emitting surface and the light receiving surface. Therefore, it is possible to remove dirt on the light emitting surface and the light receiving surface, and it is possible to suppress the occurrence of erroneous detection in the position detection device. In the position detection device of the present invention, the cleaning member is fixed to the scale. Therefore, the cleaning member can be fixed to the scale at a position that does not always contact the light emitting surface or the light receiving surface when detecting the position of the object to be detected. As a result, it is possible to suppress a decrease in the position detection accuracy of the detection object.

  In the liquid ejection apparatus of the present invention, the scale includes a stain detection pattern in which the second light transmitting portion and the second light shielding portion are alternately formed in addition to the position detection pattern for detecting the position of the detection object. When the dirt on the scale is detected by the dirt detecting means for detecting the dirt on the scale based on the light reception result at the light receiving portion in the dirt detection pattern, the light emitting surface and the light receiving surface are cleaned by the cleaning member. That is, in the liquid ejecting apparatus of the present invention, when the stain on the scale is detected from the detection result at the light receiving portion of the light emitted from the light emitting portion and transmitted through the second light transmitting portion (that is, the degree of the stain on the scale is constant). Therefore, the light emitting surface and the light receiving surface are cleaned. Therefore, the light emitting surface and the light receiving surface are cleaned. Therefore, the light emitting surface and the light receiving surface can be cleaned only at an appropriate time when the light emitting surface and the light receiving surface need to be cleaned. That is, when it is not necessary to clean the light emitting surface and the light receiving surface, it is possible not to perform the cleaning, and it is possible to omit a wasteful cleaning operation.

  In the present invention, the cleaning member is preferably fixed to the scale in a region different from the region where the position detection pattern is formed and the region where the dirt detection pattern is formed. If comprised in this way, a light emission surface and a light-receiving surface can be cleaned, without affecting the position detection of a to-be-detected object, and the detection of the stain | pollution | contamination of a scale. That is, the light emitting surface and the light receiving surface can be cleaned by the cleaning member without deteriorating the position detection accuracy of the detection object and the dirt detection accuracy of the scale.

  In the present invention, the scale is a linear scale formed in the shape of a long thin plate, the dirt detection pattern is disposed outside the position detection pattern in the longitudinal direction of the linear scale, and the cleaning member detects dirt in the longitudinal direction. It is preferable to be arranged outside the pattern. If comprised in this way, the stain | pollution | contamination of a linear scale can be detected, without affecting the position detection of a to-be-detected object. In addition, when detecting the position of the object to be detected, the light emitting section and the light receiving section that move relatively in the longitudinal direction of the linear scale are further moved relatively in the longitudinal direction of the linear scale, and the contamination of the linear scale is reduced. And the cleaning of the light emitting surface and the light receiving surface can be performed.

  In the present invention, the scale is a linear scale formed in a long thin plate shape, the dirt detection pattern is disposed outside the position detection pattern in the longitudinal direction of the linear scale, and the cleaning member is a short side of the linear scale. It is preferable that it is disposed adjacent to the position detection pattern and / or the dirt detection pattern in the direction. If comprised in this way, the stain | pollution | contamination of a linear scale can be detected, without affecting the position detection of a to-be-detected object. In addition, when detecting the position of the object to be detected, the light emitting section and the light receiving section that move relatively in the longitudinal direction of the linear scale are further moved relatively in the longitudinal direction of the linear scale, and the contamination of the linear scale Can be detected. Furthermore, the position of the position detection device can be reduced in the longitudinal direction of the linear scale by arranging the cleaning member adjacent to the position detection pattern and the dirt detection pattern in the short direction of the linear scale.

  In the present invention, the scale is a linear scale formed in a long thin plate shape, the dirt detection pattern is disposed adjacent to the position detection pattern in the short direction of the linear scale, and the cleaning member is the linear scale. It is preferable that they are arranged outside the position detection pattern and / or the dirt detection pattern in the longitudinal direction. If comprised in this way, the stain | pollution | contamination of a linear scale can be detected, without affecting the position detection of the to-be-detected object performed by a light emission part and a light-receiving part moving to the longitudinal direction of a linear scale. In addition, when detecting the position of the object to be detected, the light emitting surface and the light receiving portion can be moved with a simple structure in which the light emitting portion and the light receiving portion that move relatively in the longitudinal direction of the linear scale are further moved relatively in the longitudinal direction of the linear scale. The surface can be cleaned.

  In the present invention, the scale is a linear scale formed in a long thin plate shape, the dirt detection pattern is disposed adjacent to the position detection pattern in the short direction of the linear scale, and the cleaning member is in the short direction. It is preferable that the position detection pattern or the dirt detection pattern is disposed adjacent to the position detection pattern. If comprised in this way, the stain | pollution | contamination of a linear scale can be detected, without affecting the position detection of a to-be-detected object. Further, the position detection device can be downsized in the longitudinal direction of the linear scale.

  In the present invention, the scale is a rotary scale formed in a disk shape, the dirt detection pattern is disposed radially inward of the rotary scale with respect to the position detection pattern, and the cleaning member is a rotary scale relative to the dirt detection pattern. It is preferable that it is arrange | positioned at the radial inside. With this configuration, it is possible to detect the contamination of the rotary scale without affecting the position detection of the detection object. Further, the position detection device can be downsized in the radial direction of the rotary scale.

  In the present invention, the second light transmitting portion has a light transmission area from the light emitting portion of the second light transmitting portion smaller than a light transmission area from the light emitting portion of the first light transmitting portion, or the second light transmitting portion. It is preferable that a light-shielding pattern that lowers the transmittance of light from the light emitting portion of the light transmitting portion to be lower than the transmittance of light from the light emitting portion of the first light transmitting portion is formed. If comprised in this way, light will become easy to be interrupted | blocked by the stain | pollution | contamination of a scale in the 2nd translucent part compared with a 1st translucent part. For this reason, in the first light transmitting part used for detecting the position of the object to be detected, the light is blocked, and the light that passes through the second light transmitting part is received before erroneous detection by the position detecting device occurs. The stain on the scale can be detected from the detection result in the section.

  Hereinafter, a liquid ejection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Schematic configuration of liquid ejection device)
FIG. 1 is a perspective view showing a schematic configuration of a liquid ejection apparatus (printer) 1 according to an embodiment of the present invention. FIG. 2 is a schematic side view showing a schematic configuration of a portion related to paper feeding of the printer 1 of FIG. 3 is a schematic configuration diagram schematically showing a detection mechanism of the carriage 3 of FIG. 1 and the PF drive roller 6 of FIG.

  The liquid ejection apparatus 1 according to this embodiment is an ink jet printer that performs printing by ejecting liquid ink onto a printing paper P or the like as a medium. Hereinafter, the liquid ejection apparatus 1 of this embodiment is referred to as a printer 1. As shown in FIGS. 1 to 3, the printer 1 of this embodiment includes a carriage 3 on which a print head 2 that ejects ink droplets is mounted, and a carriage motor (CR motor) 4 that drives the carriage 3 in the main scanning direction MS. And a paper feed motor (PF motor) 5 that conveys the printing paper P in the sub-scanning direction SS, a PF drive roller 6 connected to the PF motor 5, and a nozzle surface (the lower surface in FIG. 2) of the print head 2 And a main body chassis 8 on which these components are mounted. In this embodiment, both the CR motor 4 and the PF motor 5 are direct current (DC) motors.

  Further, as shown in FIG. 2, the printer 1 includes a hopper 11 on which the printing paper P before printing is placed, and a paper feed roller for taking the printing paper P placed on the hopper 11 into the printer 1. 12, a separation pad 13, a paper detector 14 for detecting the passage of the printing paper P taken into the printer 1 from the hopper 11, and a paper discharge driving roller 15 for discharging the printing paper P from the inside of the printer 1. I have.

  In the printer 1, the right side in FIG. 1 (the front side in FIG. 2) is the home position side of the carriage 3. In the following, the home position side of the carriage 3 in the printer 1 is denoted as 0 digit side, and the opposite side of the carriage 3 home position in the printer 1 (left side in FIG. 1, back side in FIG. 2) is denoted as 80 digit side. To do.

  The carriage 3 is configured to be transportable in the main scanning direction MS by a guide shaft 17 supported by a support frame 16 fixed to the main body chassis 8 and a timing belt 18. That is, a part of the timing belt 18 is fixed to the carriage 3 (see FIG. 2), and the pulley 19 attached to the output shaft of the CR motor 4 and the pulley 20 attached to the support frame 16 to be rotatable. It is arrange | positioned so that it may have fixed tension in the state hung over. The guide shaft 17 slidably holds the carriage 3 so as to guide the carriage 3 in the main scanning direction MS. In addition to the print head 2, an ink cartridge 21 that stores various inks supplied to the print head 2 is mounted on the carriage 3.

  The print head 2 is provided with a plurality of nozzles (not shown). The print head 2 is provided with a piezoelectric element (not shown) that is one of electrostrictive elements and has excellent responsiveness so as to correspond to each nozzle, for example. More specifically, the piezoelectric element is disposed at a position in contact with a wall surface that forms an ink passage (not shown). When the wall surface is pushed by the operation of the piezo element, the print head 2 ejects ink droplets from the nozzles disposed at the end of the ink passage. As described above, in this embodiment, the print head 2 is a liquid ejection unit that ejects liquid ink onto the printing paper P. Further, the ink cartridge 21 contains, for example, dye-based ink that has good color development and excellent image quality, and pigment-based ink that has excellent water resistance and light resistance.

  The paper feed roller 12 is connected to the PF motor 5 through a gear (not shown) and is driven by the PF motor 5. As shown in FIG. 2, the hopper 11 is a plate-like member on which the printing paper P can be placed, and can swing around a rotation shaft 22 provided on the upper portion by a cam mechanism (not shown). ing. The lower end portion of the hopper 11 is elastically pressed against the paper feed roller 12 by the cam mechanism and is separated from the paper feed roller 12. The separation pad 13 is formed of a member having a high friction coefficient, and is disposed at a position facing the paper feed roller 12. When the paper feed roller 12 rotates, the surface of the paper feed roller 12 and the separation pad 13 are pressed against each other. Therefore, when the paper feeding roller 12 rotates, the uppermost printing paper P among the printing paper P placed on the hopper 11 passes through the pressure contact portion between the surface of the paper feeding roller 12 and the separation pad 13. Although it is sent to the paper discharge side, the printing paper P placed on the second and subsequent pages from the top is prevented from being conveyed to the paper discharge side by the separation pad 13.

  The PF drive roller 6 is connected to the PF motor 5 directly or via a gear not shown. As shown in FIG. 2, the printer 1 is provided with a PF driven roller 23 that conveys the printing paper P together with the PF drive roller 6. The PF driven roller 23 is rotatably held on the paper discharge side of the driven roller holder 24 configured to be swingable about the rotation shaft 25. The driven roller holder 24 is urged counterclockwise by an unillustrated spring so that the PF driven roller 23 always receives the urging force toward the PF drive roller 6. When the PF driving roller 6 is driven, the PF driven roller 23 is rotated together with the PF driving roller 6.

  As shown in FIG. 2, the paper detector 14 includes a detection lever 26 and a sensor 27, and is provided in the vicinity of the driven roller holder 24. The detection lever 26 is rotatable about the rotation shaft 28. When the printing paper P passes through the lower side of the detection lever 26 from the passage state of the printing paper P shown in FIG. 2, the detection lever 26 rotates counterclockwise. When the detection lever 26 rotates, the light that travels from the light emitting portion to the light receiving portion of the sensor 27 is blocked, and the passage of the printing paper P can be detected.

  The paper discharge drive roller 15 is disposed on the paper discharge side of the printer 1 and is connected to the PF motor 5 via a gear (not shown). As shown in FIG. 2, the printer 1 is provided with a paper discharge driven roller 29 that discharges the printing paper P together with the paper discharge driving roller 15. Similarly to the PF driven roller 23, the paper discharge driven roller 29 is always urged toward the paper discharge drive roller 15 by a spring (not shown). When the paper discharge driving roller 15 is driven, the paper discharge driven roller 29 is rotated together with the paper discharge driving roller 15.

  2 and 3, the printer 1 is a linear encoder having a linear scale 31 and a photosensor 32 as a position detection device that detects the position of the carriage 3 and the speed of the carriage 3 in the main scanning direction MS. 33 is provided. Further, as shown in FIG. 3, the printer 1 determines the position of the printing paper P in the sub-scanning direction SS, the conveyance speed of the printing paper P, and the like (specifically, the rotational position and rotational speed of the PF drive roller 6). As a position detection device for detection, a rotary encoder 36 having a rotary scale 34 and a photosensor 35 is provided. Signals output from the linear encoder 33 and the rotary encoder 36 are input to the control unit 37 as shown in FIG. 3, and various controls of the printer 1 are performed. In this embodiment, the carriage 3 is a detected object whose position is detected by the linear encoder 33, and the PF drive roller 6 is a detected object whose position is detected by the rotary encoder 36. In FIG. 1, the linear scale 31 is not shown for convenience.

  The linear scale 31 is formed in a long shape (elongated linear shape) from a thin plate such as a transparent resin. The linear scale 31 is attached to the support frame 16 in parallel with the main scanning direction MS. That is, in the printer 1, the linear scale 31 is attached to the support frame 16 with the short direction of the linear scale 31 being the height direction. Further, the linear scale 31 can be moved up and down with respect to the support frame 16 by a scale lifting mechanism 44 (see FIG. 4 and the like) described later. The linear scale 31 may be formed of a stainless steel sheet.

  As shown in FIGS. 2 and 3, the photosensor 32 constituting the linear encoder 33 includes a light emitting unit 41 and a light receiving unit 42, and is fixed to the carriage 3. More specifically, the photosensor 32 is fixed to the back surface of the carriage 3 (the surface on the back side in FIG. 1). Detailed configurations of the linear scale 31 and the photosensor 32 will be described later.

  As shown in FIG. 3, the photosensor 35 constituting the rotary encoder 36 includes a light emitting unit 81 having a light emitting element (not shown) and a light receiving unit 82 having a light receiving element (not shown), and a bracket not shown. It is being fixed to the main body chassis 8 etc. via.

  The rotary scale 34 is, for example, a stainless steel thin plate or a transparent resin thin plate formed in a disk shape. The rotary scale 34 of this embodiment is attached to the PF drive roller 6 so as to rotate integrally with the PF drive roller 6. That is, when the PF drive roller 6 makes one revolution, the rotary scale 34 also makes one revolution. The rotary scale 34 has a light transmitting part (not shown) that transmits light from the light emitting element of the photosensor 35 and a light shielding part (not shown) that blocks light from the light emitting element of the photosensor 35. They are formed alternately along the circumferential direction. In the rotary encoder 36, the light receiving element receives the light emitted from the light emitting element toward the rotary scale 34 and transmitted through the light transmitting portion of the rotary scale 34, and a predetermined output signal is output.

  When the rotary scale 34 is formed of a transparent resin thin plate, a light-transmitting portion and a light-shielding portion are formed on the surface by printing a predetermined width along the circumferential direction at a predetermined pitch. can do. Further, when the rotary scale 34 is formed of a stainless steel thin steel plate, the light transmitting portion and the light shielding portion are formed by forming slit holes penetrating the thin steel plate at a predetermined pitch along the circumferential direction. Can be formed. Further, the rotary scale 34 may be connected to the PF drive roller 6 through a gear or the like.

  The control unit 37 includes various memories such as a ROM and a RAM, drive circuits such as various motors, a CPU, an ASIC, and the like. Each output signal from the linear encoder 33, the rotary encoder 36, or the like is input to the CPU, the ASIC, and the like. In this embodiment, the control unit 37 stains the linear scale 31 based on the light reception result of the light receiving unit 42 when the photosensor 32 passes through a later-described stain detection pattern 31c formed on the linear scale 31. It is a dirt detection means for detecting

(Configuration of scale lifting mechanism)
FIG. 4 is a schematic perspective view showing an attached state of one end of the linear scale 31 of FIG. FIG. 5 is a schematic perspective view showing an attached state of one end portion of the linear scale 31 from the back side of FIG. FIG. 6 is a view showing the relationship between the cam 45 and the mounting bracket 46 of FIG.

  The printer 1 according to this embodiment includes a scale lifting mechanism 44 that lifts and lowers the linear scale 31 with respect to the support frame 16. That is, as described above, the linear scale 31 can be moved up and down with respect to the support frame 16 by the scale lifting mechanism 44. In this embodiment, the linear scale 31 in the initial state is disposed, for example, at a position close to the upper limit position, and can be lowered by the scale lifting mechanism 44.

  As shown in FIGS. 4 and 5, the scale lifting mechanism 44 includes an eccentric cam 45 fixed to the guide shaft 17 inside one side surface 16 a (the right side surface in FIG. 1) of the support frame 16, and one end of the linear scale 31. Is attached to the front end of the guide shaft 17 on the outside of the one side surface 16a, and a driven gear 47 is attached to the front end of the guide shaft 17. An intermediate gear 48 that transmits the power of a drive motor (not shown) to the gear 47 is provided on the side surface 16a side. Similarly, the scale lifting mechanism 44 has an eccentric cam 45, a mounting bracket 46, a driven gear 47, an intermediate gear 48, and a drive motor (not shown) on the other side surface 16b (left side in FIG. 1, see FIG. 1). It has. Since these configurations are the same as the configurations provided on the side surface 16a side, illustration and description are omitted below. In FIG. 1, the scale lifting mechanism 44 is not shown for convenience.

  In this embodiment, the driven gear 47 fixed to the guide shaft 17 is rotated by the power of a drive motor (not shown) transmitted through the intermediate gear 48. That is, in this embodiment, the guide shaft 17 rotates together with the driven gear 47. Further, the eccentric cam 45 fixed to the guide shaft 17 also rotates. The intermediate gear 48 may be directly connected to a drive motor (not shown) or may be connected to the drive motor via a predetermined gear train.

  The eccentric cam 45 is a substantially disk-shaped member having a cam surface 45a formed on the outer peripheral side. As shown in FIG. 6, the eccentric cam 45 is formed, for example, such that the radius with respect to the rotation center continuously changes from a radius r1 to a radius r2 larger than the radius r1 in a predetermined angle range θ.

  The mounting bracket 46 is formed of, for example, a flat metal member. As shown in FIG. 4, the mounting bracket 46 has a base portion 46 b on which a contact portion 46 a that contacts the cam surface 45 a of the eccentric cam 45 is formed, and an end of the linear scale 31. It is comprised from the attaching part 46c to which a part is attached.

  In the base portion 46b, an elongated through hole (not shown) that is long in the vertical direction is formed in order to insert the guide shaft 17 therethrough. The through hole is formed so that the mounting bracket 46 can move up and down with respect to the guide shaft 17. As shown in FIG. 4, the base 46 b is disposed between the eccentric cam 45 and the one side surface 16 a of the support frame 16 with the guide shaft 17 being inserted through the through hole. Further, the contact portion 46a is formed so as to rise from the base portion 46b toward the inside of the printer 1. The illustrated lower surface of the contact portion 46a is in contact with the cam surface 45a. Further, the attachment portion 46c is formed so as to rise from the upper end of the base portion 46b toward the inside of the printer 1. The mounting portion 46c is formed with a locking hook 46d that is locked in a mounting hole 31a described later formed in the linear scale 31. The mounting bracket 46 is configured to move up and down without being tilted by guide means (not shown).

  When a drive motor (not shown) is driven and the eccentric cam 45 rotates together with the guide shaft 17, the contact portion 46a moves up and down along the cam surface 45a. That is, the linear scale 31 attached to the attachment bracket 46 moves up and down. For example, as shown in FIG. 6, when the eccentric cam 46 rotates clockwise, the linear scale 31 rises. The mounting bracket 46 provided on the one side surface 16a side of the support frame 16 and the mounting bracket 46 provided on the other side surface 16b side are configured to move up and down in synchronization, and the linear scale 31 is horizontal. Ascend and descend while maintaining

(Configuration of linear encoder)
FIG. 7 is a schematic diagram showing a schematic configuration of the linear encoder 33 of FIG. 8A and 8B are diagrams showing the 80-digit side of the linear scale 31 in FIG. 3. FIG. 8A is a front view of the linear scale 31, and FIG. 8B is a top view of the linear scale 31. FIG. 9 is a diagram showing signal waveforms output from the linear encoder 33 in FIG. 3, and FIG. 9A is a diagram showing signal waveforms when the carriage 3 moves from the 0th digit side to the 80th digit side. ) Is a diagram showing signal waveforms when the carriage 3 moves from the 80th digit side to the 0th digit side.

  As described above, the linear scale 31 is formed in a long shape with a thin plate of transparent resin or the like. More specifically, the linear scale 31 of this embodiment is formed of, for example, transparent polyethylene terephthalate (PET) having a thickness of 180 μm. A substantially rectangular mounting hole 31a for locking the locking hook 46d of the mounting bracket 46 is formed on each end of the linear scale 31 in the longitudinal direction. The linear scale 31 includes a position detection pattern 31b for detecting the position of the carriage 3 and a dirt detection pattern 31c for detecting dirt on the linear scale 31, as shown in FIG.

  The position detection pattern 31b is formed as follows. That is, in the detection range L (see FIGS. 4 and 8) of the carriage 3 where the position needs to be detected in order to perform printing on the printing paper P, black or the like that blocks light on one surface of the linear scale 31 is printed. Are given at predetermined intervals. More specifically, in the detection range L, as shown in FIG. 7, black printing with a constant width H is performed at a constant pitch P on one surface (right surface in FIG. 7) of the PET base material 31 d. . That is, in the detection range L, black printing with a constant width H is performed on the linear scale 31 in a state where the pitch P is maintained in the main scanning direction MS so that the black printing portion forms vertical stripes (see FIGS. 4 and 5). It is given in the short direction. The black-printed portion is a first light shielding portion 31e that blocks light from the light emitting portion 41 of the photosensor 32. In addition, a portion where the black printing is not performed between the first light shielding portions 31 e is a first light transmitting portion 31 f that transmits light from the light emitting portion 41. Thus, in the detection range L, the first light shielding portions 31e and the first light transmitting portions 31f are alternately formed on the linear scale 31. In addition, the width | variety of the 1st translucent part 31f is also the fixed width H similarly to the 1st light-shielding part 31e.

  The dirt detection pattern 31 c is disposed on the outer side (end side) of the position detection pattern 31 b in the longitudinal direction of the linear scale 31. In this embodiment, as shown in FIG. 8A, the dirt detection pattern 31c is formed on the 80th digit side of the linear scale 31 so as to be adjacent to the outside of the position detection pattern 31b.

  The dirt detection pattern 31c is formed in substantially the same manner as the position detection pattern 31b. That is, outside the detection range L on the 80th digit side of the linear scale 31, printing such as black that blocks light is performed at a predetermined interval on the same surface as the surface on which the first light shielding portion 31e is formed. More specifically, black printing with a constant width H is applied at a constant pitch P on the right surface of the base material 31d in FIG. That is, as shown in FIG. 8 (A), even outside the detection range L on the 80-digit side, a black print with a constant width H is maintained with the pitch P maintained in the longitudinal direction so that the black print portion forms vertical stripes. Printing is performed in the short direction of the linear scale 31. The black printed portion is a second light shielding portion 31g that blocks light from the light emitting portion 41 of the photosensor 32. Further, a portion where the black printing is not performed between the second light shielding portions 31 g is a second light transmitting portion 31 h that transmits light from the light emitting portion 41. Thus, outside the detection range L on the 80th digit side of the linear scale 31, the second light shielding portions 31g and the second light transmitting portions 31h are alternately formed on the linear scale 31. In addition, the width | variety of the 2nd translucent part 31h is also the fixed width H similarly to the 2nd light-shielding part 31g.

  In the second light transmitting part 31h, the light transmission area and transmittance from the light emitting part 41 of the second light transmitting part 31h are set to be larger than the light transmission area and light transmittance from the light emitting part 41 of the first light transmitting part 31f. A light shielding pattern 31k to be reduced is formed. In this embodiment, the light shielding pattern 31k is formed by a light shielding portion 31m having a slanted line shape inclined with respect to the longitudinal direction of the linear scale 31. More specifically, the surface of the base material 31d is printed with black or the like that blocks light in a slanted line inclined at 45 ° with respect to the longitudinal direction and at a constant pitch. A light blocking part 31m is formed. A light shielding pattern 31k is formed by the plurality of light blocking portions 31m. Due to the light shielding pattern 31k, the light transmission area of the second light transmission part 31h is a constant ratio to the light transmission area of the first light transmission part 31f. That is, the light transmittance of the second light transmitting portion 31h is a constant ratio with respect to the light transmittance of the first light transmitting portion 31f. For example, the light transmission area of the second light transmission part 31h is 85% of the light transmission area of the first light transmission part 31f. Further, the light transmittance of the second light transmitting portion 31h may be, for example, 85% of the light transmittance of the first light transmitting portion 31f.

  In this embodiment, as shown in FIG. 8A, the linear scale 31 has a plurality (for example, three) of second light transmission parts 31h, and the transmission area of the plurality of second light transmission parts 31h. Or the transmittance is equal. However, the transmission areas or transmittances of the plurality of second light transmitting portions 31h are not necessarily equal, and the transmission areas or transmittances of the second light transmitting portions 31h may be different from each other. Moreover, the thickness of the black printing part which comprises the 1st light-shielding part 31e, the 2nd light-shielding part 31g, and the light shielding part 31m is 5 micrometers, for example, and is very thin compared with the thickness of the base material 31d. . Therefore, in FIG. 8B, illustration of the first light shielding part 31e, the second light shielding part 31g, and the light shielding part 31m is omitted.

  As shown in FIG. 8, cleaning members 83 and 83 that clean the light emitting unit 41 and the light receiving unit 42 are fixed to the linear scale 31. More specifically, the cleaning members 83, 83 formed in a flat rectangular parallelepiped shape are double-sided on both sides of the linear scale 31 on the outer side (end side) of the dirt detection pattern 31 c in the longitudinal direction of the linear scale 31. It is fixed by fixing means such as tape or adhesive. That is, the cleaning members 83 and 83 are fixed to the outside (end side) of the position detection pattern 31 b in the longitudinal direction of the linear scale 31. In other words, the cleaning members 83 and 83 are fixed to the linear scale 31 in an area different from the area where the position detection pattern 31b and the dirt detection pattern 31c are formed. In this embodiment, as shown in FIG. 8, the cleaning members 83 and 83 are fixed on the 80th digit side of the linear scale 31 so as to be adjacent to the outside of the dirt detection pattern 31c.

  The cleaning members 83 and 83 are made of, for example, a porous material such as urethane resin, felt, or rubber. 8B, the sum of the thickness of the two cleaning members 83 and 83 and the thickness of the base material 31d of the linear scale 31 is a light emitting surface 41a described later formed on the light emitting unit 41. The two cleaning members 83 and 83 are formed so as to be substantially the same as or slightly larger than the distance from a later-described light receiving surface 42a formed in the light receiving portion 42. Therefore, when the photosensor 32 moves in the longitudinal direction of the linear scale 31, the cleaning members 83 and 83 come into contact with the light emitting surface 41a and the light receiving surface 42a, and the light emitting surface 41a and the light receiving surface 42a are cleaned.

  As shown in FIGS. 2 and 3, the photosensor 32 includes a substantially rectangular parallelepiped housing. In this photosensor 32, a recess 32a is formed from one side of the housing (the lower surface in FIG. 2) to the center of the housing. The light emitting portion 41 is disposed on one of two opposing surfaces (two surfaces facing in the left-right direction in FIG. 2) of the recess 32a, and the light receiving portion 42 is disposed on the other. More specifically, as shown in FIG. 2 and the like, a light emitting unit 41 is disposed on the surface on the carriage 3 side. Of the two surfaces facing each other in the recess 32a, the surface on which the light emitting unit 41 is disposed is the light emitting surface 41a, and the surface on which the light receiving unit 42 is disposed is the light receiving surface 42a. The distance between the light emitting surface 41a and the light receiving surface 42a is, for example, 0.5 mm to 1.5 mm.

  2 and the like, the photosensor 32 is fixed to the carriage 3 so that the linear scale 31 is sandwiched between the light emitting surface 41a of the light emitting unit 41 and the light receiving surface 42a of the light receiving unit 42. In the linear encoder 33, the light receiving unit 42 receives the light emitted from the light emitting unit 41 toward the linear scale 31 and transmitted through the first light transmitting unit 31f and the second light transmitting unit 31k, and a predetermined output signal is generated. Is output.

  As shown in FIG. 7, the light emitting unit 41 includes a light emitting element 50 and a collimator lens 51 that collimates the light emitted from the light emitting element 50. A lens (not shown) that transmits light from the light emitting element 50 is fixed to the light emitting surface 41a. The light emitting element 50 is, for example, a light emitting diode. A current is supplied to the light emitting element 50 via a variable resistor 52. Therefore, the amount of light emitted from the light emitting element 50 can be increased or decreased by the variable resistor 52. In the initial state, it is preferable that the light emission amount from the light emitting element 50 be as low as possible within a range in which an appropriate position can be detected by the linear encoder 33. If it does in this way, the power consumption in the light emission part 41 can be reduced.

  As shown in FIG. 7, the light receiving unit 42 includes a substrate 53 and four light receiving elements 54 to 57 formed on the substrate 53. Further, a lens (not shown) that transmits light from the light emitting element 50 is fixed to the light receiving surface 42a. The light receiving elements 54 to 57 are, for example, photodiodes, and output a signal having a level corresponding to the amount of received light. As shown in FIG. 7, the light receiving unit 42 includes first to fourth amplifiers 58 to 61, a first differential signal generation circuit 62, and a second differential signal generation circuit 63. Yes. In the following description, when the four light receiving elements 54 to 57 are distinguished from each other, they are expressed as the first light receiving element 54, the second light receiving element 55, the third light receiving element 56, and the fourth light receiving element 57. To do.

  The four light receiving elements 54 to 57 are arranged on the substrate 53 along the movement direction of the carriage 3. Specifically, the first light receiving element 54 and the third light receiving element 56 are arranged so that the phase of the level signal output from each differs by 180 °. Further, the second light receiving element 55 and the fourth light receiving element 57 are arranged so that the phase of the level signal output from each differs by 180 °. For example, the arrangement pitch between the first light-receiving element 54 and the third light-receiving element 56 and the arrangement pitch between the second light-receiving element 55 and the fourth light-receiving element 57 are the same as the first light-shielding portion 31e and the first light-transmitting light. This is half of the bright / dark pitch P formed by the portion 31f. Further, the first light receiving element 54 and the second light receiving element 55 are arranged so that the phase of the level signal output from each of them differs by 90 °. For example, the first light receiving element 54 and the second light receiving element 55 are arranged at an arrangement pitch that is a quarter of the light / dark pitch P.

  Further, when the carriage 3 moves, the linear scale 31 relatively moves between the light emitting unit 41 and the light receiving unit 42. Along with the relative movement of the linear scale 31, the light receiving elements 54 to 57 output signals of a level corresponding to the amount of received light. That is, the light receiving elements 54 to 57 corresponding to the positions of the first light transmitting part 31f and the second light transmitting part 31h output high-level signals and correspond to the positions of the first light shielding part 31e and the second light shielding part 31g. The light receiving elements 54 to 57 that output the low level signal. As described above, the light receiving elements 54 to 57 output level signals that change in a cycle corresponding to the relative moving speed of the linear scale 31 (moving speed of the carriage 3).

  As shown in FIG. 7, the first to fourth amplifiers 58 to 61, the first differential signal generation circuit 62, and the second differential signal generation circuit 63 are disposed on the substrate 53.

  A first light receiving element 54 is connected to the first amplifier 58, and the first amplifier 58 outputs a signal obtained by amplifying the level signal output from the first light receiving element 54. The second light receiving element 55 is connected to the second amplifier 59, and the second amplifier 59 outputs a signal obtained by amplifying the level signal output from the second light receiving element 55. A third light receiving element 56 is connected to the third amplifier 60, and the third amplifier 60 outputs a signal obtained by amplifying the level signal output from the third light receiving element 56. A fourth light receiving element 57 is connected to the fourth amplifier 61, and the fourth amplifier 48 outputs a signal obtained by amplifying the level signal output from the fourth light receiving element 57.

  The first amplifier 58 and the third amplifier 60 output the amplified level signal to the first differential signal generation circuit 62. The level signal amplified by the first amplifier 58 is input to the non-inverting input terminal of the first differential signal generation circuit 62, and the level signal amplified by the third amplifier 60 is the first differential signal generation circuit. 62 is input to the inverting input terminal. In the first differential signal generation circuit 62, the level of the output signal of the first amplifier 58 input to the non-inverting input terminal is higher than the level of the output signal of the third amplifier 59 input to the inverting input terminal. The high level is output, and in the reverse case, the low level is output. That is, as shown in FIG. 9, the first differential signal generation circuit 62 has a digital waveform with a period T corresponding to the light / dark pitch P formed by the first light-shielding portion 31e and the first light-transmitting portion 31f. A-phase signal SG1 is output.

  The second amplifier 59 and the fourth amplifier 61 output the amplified level signal to the second differential signal generation circuit 63. The level signal amplified by the second amplifier 59 is input to the non-inverting input terminal of the second differential signal generation circuit 63, and the level signal amplified by the fourth amplifier 61 is input to the second differential signal generation circuit. 63 is input to the inverting input terminal. The second differential signal generation circuit 63 has a high level when the level of the output signal of the second amplifier 59 input to the non-inverting input terminal is higher than the level of the fourth amplifier 61 input to the inverting input terminal. Is output, and in the opposite case, a low level is output. That is, as shown in FIG. 9, the second differential signal generation circuit 63 has a digital waveform with a period T corresponding to the light / dark pitch P formed by the first light-shielding portion 31e and the first light-transmitting portion 31f. B-phase signal SG2 is output.

  As described above, the level signal output from the first light receiving element 54 and the level signal output from the second light receiving element 55 have a phase difference of 90 °. Therefore, as shown in FIG. 9, the phase A signal SG1 output from the first differential signal generation circuit 62 and the phase B signal SG2 output from the second differential signal generation circuit 63 have a phase of 90 °. It is off.

  9A shows a signal waveform when the carriage 3 moves from the 0-digit side to the 80-digit side, and FIG. 9B shows a case where the carriage 3 moves from the 80-digit side to the 0-digit side. The signal waveform is shown. That is, as shown in FIG. 9A, when the B-phase signal SG2 is low and the A-phase signal SG1 rises (or when the B-phase signal SG2 is high and the A-phase signal SG1 falls), for example. The carriage 3 has moved from the 0th digit side to the 80th digit side. Further, as shown in FIG. 9B, when the B-phase signal SG2 is low and the A-phase signal SG1 falls (or when the B-phase signal SG2 is high and the A-phase signal SG1 rises). The carriage 3 is moved from the 80th digit side to the 0th digit side.

  In addition, the light emitted from the light emitting unit 41 is incident on the linear scale 31 with a predetermined width W in the short direction of the linear scale 31 (vertical direction in FIG. 8A) as shown in FIG. Irradiated. More specifically, even if the oblique light shielding part 31m is formed in the second light transmitting part 31h, if the second light transmitting part 31h is not contaminated, the second in the longitudinal direction of the linear scale 31 is used. Light is emitted from the light emitting part 41 to the linear scale 31 with a predetermined width W in the short direction so that a part that completely blocks the light from the light emitting part 41 does not occur in a part of the light transmitting part 31h. Therefore, even if the light blocking portion 31m is formed in the second light transmitting portion 31h, if the linear scale 31 is not contaminated and the carriage 3 moves at a constant speed, When the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed, the A phase signal SG1 and the B phase having the same cycle as when the photosensor 32 passes through the portion where the position detection pattern 31b of the linear scale 31 is formed. The signal SG2 is output from the linear encoder 33.

(Outline of printer operation)
In the printer 1 configured as described above, the printing paper P taken into the printer 1 from the hopper 11 by the paper feed roller 12 and the separation pad 13 is sub-rotated by the PF driving roller 6 that is rotationally driven by the PF motor 5. While being sent in the scanning direction SS, the carriage 3 driven by the CR motor 4 reciprocates in the main scanning direction MS. When the carriage 3 reciprocates, ink droplets are ejected from the print head 2 and printing on the printing paper P is performed. When printing on the printing paper P is completed, the printing paper P is discharged to the outside of the printer 1 by the paper discharge drive roller 15 and the like.

  When the carriage 3 moves, the A-phase signal SG1 and the B-phase signal SG2 are output from the linear encoder 33. The output A-phase signal SG1 and B-phase signal SG2 are input to a predetermined processing circuit (for example, ASIC) of the control unit 37. Using the A phase signal SG1 and B phase signal SG2 from the input linear encoder 33, the predetermined processing circuit of the control unit 37 detects the position, speed, and moving direction of the carriage 3 (that is, the CR motor 4). Detection of rotational position, rotational direction and rotational speed). Based on the detection result, the printer 1 is controlled. For example, the rotational speed of the CR motor 4 is controlled.

(Printer operation when detecting linear scale contamination)
FIG. 10 is a flowchart showing a series of operations of the printer 1 when the contamination of the linear scale 31 of FIG. 3 is detected. FIG. 11 is a flowchart showing an example of the dirt detection operation of the linear scale 31 of FIG. FIG. 12 is a flowchart showing another example of the dirt detection operation of the linear scale 31 of FIG. FIG. 13 is a diagram illustrating an example of a signal waveform output from the linear encoder 33 when the linear scale 31 in FIG. 3 is contaminated. FIG. 14 is a partially enlarged view showing an E portion of FIG. 8 in an enlarged manner.

  When ink droplets are ejected from the print head 2 in order to perform printing on the printing paper P, when ink droplets are ejected from the print head 2, some of the ink droplets become mist-like in the air. A floating ink mist is generated. This ink mist floats inside the printer 1 and adheres to the light emitting surface 41a and the light receiving surface 42a of the linear scale 31 and the photosensor 32 as dirt. If the linear scale 31, the light emitting surface 41 a, and the light receiving surface 42 a are contaminated by ink mist, the position and speed of the carriage 3 cannot be detected properly. In the printer 1, the contamination of the linear scale 31 is detected. Is done. Hereinafter, a series of operations of the printer 1 when the linear scale 31 is detected will be described.

  As shown in FIG. 10, first, the control unit 37 determines whether or not it is the stain detection timing of the linear scale 31 (step S1). The stain detection timing of the linear scale 31 is, for example, after printing on one printing paper P or when the printer 1 is turned on. If the detection timing of the stain on the linear scale 31 is after the end of printing on one printing paper P, the number of detections can be increased, and the stain on the linear scale 31 can be detected at an appropriate timing. Further, if the contamination detection timing of the linear scale 31 is when the printer 1 is turned on, the contamination of the linear scale 31 can be detected by the initial operation of the printer 1 at the time of start-up. There is no need to perform any action. For this reason, it is possible to eliminate the loss time due to the dirt scale detection operation of the linear scale 31.

  The stain detection timing of the linear scale 31 may be, for example, after a certain time t1 has elapsed since the printer 1 was turned on, and thereafter after every certain time t2. In this case, the fixed time t1 and the fixed time t2 may be the same time or different times. Further, the stain detection timing of the linear scale 31 may be after the printing on the predetermined number n1 of the printing paper P after the power is turned on, and thereafter after the printing on the predetermined number n2 of the printing paper P is completed. . In this case, the fixed number n1 and the fixed number n2 may be the same number or different numbers. Furthermore, the detection timing of the contamination of the linear scale 31 is the earlier of the elapse of a predetermined time t1 after the power of the printer 1 is turned on or the end of printing on the predetermined number n1 of printing papers P, and thereafter The detection timing of the contamination of the linear scale 31 is determined by using both the elapsed time and the number of prints, such as the elapse of the fixed time t2 and the end of printing on the fixed number n2 of printing paper P, whichever comes first. It may be determined. When the detection timing is determined by the number of printed sheets, the predetermined number n1 or n2 may be determined in terms of the number of sheets when borderless printing is performed on A4 size paper.

  If it is determined in step S1 that it is not the detection timing, the contamination of the linear scale 31 is not detected, and the printer 1 is in a standby state or performs printing on the next printing paper P, for example. On the other hand, if it is determined in step S1 that the detection timing is reached, the carriage 3 moves to the home position or a predetermined position (step S2).

  Thereafter, predetermined preprocessing is performed (step S3). In step S3, for example, the amount of light emitted from the light emitting element 50 is increased or decreased by adjusting the variable resistor 52. As will be described later, due to the ink mist adhering to the second light transmitting part 31h (that is, due to the dirt of the second light transmitting part 31h), a part of the second light transmitting part 31h in the longitudinal direction of the linear scale 31 is When a portion that blocks light from the light emitting unit 41 occurs over a range of a predetermined width W, or light from the light emitting unit 41 is blocked over a range of a predetermined width W by the second light transmitting unit 31h. Then, it is detected that the linear scale 31 is contaminated. Therefore, if the amount of light emitted from the light emitting element 50 is large, even if ink mist adheres to the second light transmitting part 31h, the dirt of the linear scale 31 will be removed if the degree of dirt of the second light transmitting part 31h is not large. Not detected. Further, if the amount of light emitted from the light emitting element 50 is small, the contamination of the linear scale 31 is detected even if the degree of contamination of the second light transmitting portion 31h is small. As described above, by increasing or decreasing the amount of light emitted from the light emitting element 50, it is possible to detect the degree of contamination of the linear scale 31. Note that the preprocessing in step S3 is not necessarily required, and step S3 may be omitted.

  When the pre-processing in step S3 is completed, the detection of dirt on the linear scale 31 is actually performed, and processing as necessary is performed (step S4). In step S4, as shown in FIG. 11, first, the drive voltage of the CR motor 4 is set (step S11). More specifically, a constant drive voltage is set so that the carriage 3 after the acceleration is completed moves at a substantially constant speed. Further, the driving time of the CR motor 4 is set (step S12). More specifically, the driving time of the CR motor 4 so that the photosensor 32 fixed to the carriage 3 located at the home position or a predetermined location passes through the part of the dirt detection pattern 31c of the linear scale 31 at a substantially constant speed. Set.

  Thereafter, the CR motor 4 is driven with the drive voltage and drive time set as described above (step S13). The carriage 3 is moved by driving the CR motor 4, and the photo sensor 32 fixed to the carriage 3 moves relative to the linear scale 31. By this relative movement, the linear encoder 33 outputs, for example, an A-phase signal SG1 and a B-phase signal SG2 with a period T. The A-phase signal SG1 and the B-phase signal SG2 that are output signals of the linear encoder 33 are input to the control unit 37. That is, the control unit 37 acquires the output signal of the linear coder 33 (step S14).

  Thereafter, the control unit 37 determines whether or not the linear scale 31 is contaminated (step S15). When ink mist adheres to the linear scale 31, for example, as shown in FIG. 14, ink mist adhesion portions D1, D2, and D3 also occur in the second light transmitting portion 31h. Then, the light from the light emitting part 41 is blocked by the second light transmitting part 31h over a range of a predetermined width W in a part of the linear scale 31 in the longitudinal direction by the attached parts D1 and D2 and the light blocking part 31m. A part arises. Or the light from the light emission part 41 is interrupted | blocked by the 2nd translucent part 31h by adhesion of ink mist. When a portion that blocks light from the light emitting portion 41 is generated in a part of the longitudinal direction of the linear scale 31 over a range of a predetermined width W, or light is emitted over a range of a predetermined width W by the second light transmitting portion 31h. When the light from the unit 41 is blocked, the period of the A phase signal SG1 and the B phase signal SG2 output from the linear encoder 33 varies. In this embodiment, when a predetermined fluctuation occurs in the period of the A-phase signal SG1 and the B-phase signal SG2 output from the linear encoder 33, a part of the linear scale 31 in the longitudinal direction covers a range of a predetermined width W. It is determined that there is a portion that blocks the light from the light emitting unit 41 or that the light from the light emitting unit 41 is blocked by the second light transmitting unit 31h. In this state, it is determined that the linear scale 31 is dirty.

  More specifically, in step S15, a period T based on the period (or frequency) of the A-phase signal SG1 and the B-phase signal SG2 when the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed. It is determined whether or not (or frequency) is out of the range of ± x% (for example, ± 15%). If the period of the A-phase signal SG1 or the B-phase signal SG2 is not out of the range of ± x% of the basic period T, an accurate position in the linear encoder 33 even in the portion where the dirt detection pattern 31c is formed. Can be detected (that is, accurate reading is possible) (step S16). That is, in this case, the second light transmitting portion 31h does not have a portion that blocks light from the light emitting portion 41 over a predetermined width W in a part of the longitudinal direction of the linear scale 31. Further, since the light from the light emitting part 41 is not blocked over the range of the predetermined width W by the second light transmitting part 31h, it is determined that the linear scale 31 is not contaminated. Further, since the linear scale 31 is not contaminated, it is determined that an appropriate position can be detected by the linear encoder 33.

  If it is determined that the linear scale 31 is not contaminated, it is determined whether or not the driving time of the CR motor 4 is longer than the set time (step S17). When the driving time of the CR motor 4 is less than the set time, the control unit 37 returns to step S14 and acquires the output signal of the linear coder 33. If the driving time of the CR motor 4 is longer than the set time, the CR motor 4 is stopped (step S17). For example, the CR motor 4 is stopped with the carriage 3 positioned at the home position, and the detection of the contamination of the linear scale 31 in step S4 is completed.

  On the other hand, for example, as shown in FIG. 13A, when the period T1 of the A phase signal SG1 or the B phase signal SG2 is out of the range of ± x% of the period T, as shown in FIG. Due to the adhering portions D1 and D2 and the light blocking portion 31m, the second light transmitting portion 31h includes a portion that blocks light from the light emitting portion 41 over a predetermined width W in a part of the linear scale 31 in the longitudinal direction. In the portion where the dirt detection pattern 31c is formed, it is impossible to accurately detect the position with the linear encoder 33 (that is, accurate reading is impossible) (step S19). That is, in this case, it is determined that the linear scale 31 is contaminated. Further, since the linear scale 31 is contaminated, it is determined that there is a high possibility that erroneous position detection is performed by the linear encoder 33 in the state as it is. If it is determined that the linear scale 31 is contaminated, the CR motor 4 is stopped (step S20).

  As shown in FIG. 14, the light emitting unit 41 extends over a range of a predetermined width W in a part of the linear scale 31 in the longitudinal direction by the attached portions D1 and D2 and the light blocking unit 31m. When the part which interrupts | blocks the light from occurs, the period T1 of A phase signal SG1 and B phase signal SG2 becomes short compared with the period T, as shown to FIG. 13 (A). On the other hand, when the second translucent part 31h is blocked over the range of the predetermined width W by the ink mist, the period of the A phase signal SG1 and the B phase signal SG2 becomes longer than the period T.

  When the CR motor 4 is stopped in step S20, the printer 1 performs a predetermined process (step S21). When the linear scale 31 is contaminated, it is estimated that the light emitting surface 41a and the light receiving surface 42a of the photosensor 32 are also contaminated. Therefore, in step S21, the light emitting surface 41a and the light receiving surface 42a (specifically, a lens (not shown) fixed to the light emitting surface 41a and the light receiving surface 42a) are cleaned. More specifically, first, the CR motor 4 moves the carriage 3 to a predetermined position on the 80th digit side. Thereafter, the carriage 3 moves a predetermined number of times between the predetermined position and the position where the light emitting surface 41a and the light receiving surface 42a abut against the cleaning members 83 and 83 and the light emitting surface 41a and the light receiving surface 42a are cleaned. The CR motor 4 is driven with a predetermined voltage so as to reciprocate. That is, the light emitting surface 41 a and the light receiving surface 42 a are cleaned by the cleaning members 83 and 83 by the reciprocating movement of the carriage 3. Thus, in this embodiment, the carriage 3 is a cleaning member moving unit that moves the cleaning members 83 and 83 relative to the light emitting surface 41 a of the light emitting unit 41 and the light receiving surface 42 a of the light receiving unit 42.

  In step S21, the linear scale 31 may be further cleaned. By cleaning the linear scale 31, it is possible to reliably prevent erroneous detection by the linear encoder 33.

  In step S21, the following processing is performed.

  For example, in step S21, when printing is performed on how many sheets of printing paper P, the linear scale 31 is smudged, or the time when the stain detection timing of the linear scale 31 is every predetermined time. Then, it is confirmed whether or not the linear scale 31 is soiled when printing is performed. More specifically, the control unit 37 calculates the number of prints and the print time until the linear scale 31 is smudged. By this confirmation, it is possible to grasp the number of prints and the print time until the linear scale 31 is soiled.

  In step S21, for example, a warning message that the linear scale 31 is soiled on a display device (not shown) such as a liquid crystal display attached to the main body chassis 8 of the printer 1, or the linear scale 31 is soiled. Is displayed, or a message indicating that the linear scale 31 needs to be cleaned is displayed. By displaying these messages, it is possible to notify the user that the linear scale 31 is dirty, and it is possible to prevent malfunction of the printer 1 due to erroneous detection in the linear scale 33.

  Furthermore, in step S21, for example, the operation of the printer 1 is stopped and the printer 1 is disabled. By disabling the printer 1, it is possible to prevent malfunction of the printer 1 due to erroneous detection by the linear scale 33, and it is possible to prevent user injury due to the runaway of the carriage 3. In step S21, the control unit 37 may perform a predetermined setting so that the printer 1 stops operating after printing for a predetermined time or after a predetermined number of prints.

  Furthermore, in step S21, for example, the control unit 37 sets an upper limit of the moving speed of the carriage 3. Even if the linear scale 31 is contaminated and the amount of light received by the light receiving portion 42 through the first light transmitting portion 31f is reduced, if the moving speed of the carriage 3 is slow to some extent, the linear encoder 33 False detection can be avoided. Therefore, by setting the upper limit of the moving speed of the carriage 3, it is possible to prevent erroneous detection by the linear encoder 33 even if the linear scale 31 is contaminated. As a result, the printer 1 can further print a predetermined number of sheets or a predetermined time. In step S21, an upper limit of the feeding speed of the printing paper P by the PF driving roller 6 may be set.

  In step S21, for example, the variable resistor 52 is adjusted to increase the amount of light emitted from the light emitting element 50. By increasing the light emission amount of the light emitting element 50, even if the linear scale 31 is contaminated, if the degree of contamination is not so large, the printer 1 can further print a predetermined number of sheets or a predetermined time. In this case, since the light emission amount of the light emitting element 50 can be adjusted by the variable resistor 52, the light emission amount of the light emitting element 50 can be easily increased. Note that the light emission amount of the light emitting element 50 may be increased stepwise by the variable resistor 52 at an increase rate that allows printing for a predetermined number of sheets or for a predetermined time. In this case, power consumption in the light emitting unit 41 can be reduced.

  Furthermore, in step S21, for example, the scale lifting mechanism 44 lowers the linear scale 31. That is, in the linear scale 31, a portion having a predetermined width W (see FIG. 8A) irradiated with light from the light emitting unit 41 is relatively moved upward. Since the linear scale 31 is attached to the support frame 16 with the short direction of the linear scale 31 as the height direction, the ink mist generated by the ejection of ink from the print head 2 adheres to the lower part of the linear scale 31. The lower part of the linear scale 31 is likely to be contaminated. Therefore, the scale elevating mechanism 44 lowers the linear scale 31 so that the position of the carriage 3 can be detected using the upper portion of the linear scale 31 with little contamination. As a result, the printer 1 can further print a predetermined number of sheets or a predetermined time.

  When the processing in step S21 as described above is completed, the detection and processing of the contamination of the linear scale 31 in step S4 are completed.

  In the above-described example, in step S15, the period T (based on the period (frequency) of the A-phase signal SG1 and the B-phase signal SG2 when the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed. It is determined whether or not the linear scale 31 is contaminated by determining whether or not the frequency is out of the range of ± x% (for example, ± 15%). In addition to this, for example, as shown in the flowchart of FIG. 12, the phase of the A-phase signal SG1 and the B-phase signal SG2 is reversed when the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed. It may be determined whether or not the linear scale 31 is contaminated by determining whether or not the linear scale 31 is contaminated (step S25).

  More specifically, it may be determined whether the linear scale 31 is contaminated as follows. That is, for example, as shown in FIG. 13B, when the carriage 3 moves from the 0-digit side to the 80-digit side, the A-phase signal SG1 that has risen when the B-phase signal SG2 is at the low level is When the signal SG2 rises when it is at a high level (that is, when the phase of the A-phase signal SG1 and the B-phase signal SG2 is reversed), as shown in FIG. 14, the attached portions D1 and D2 and the light blocking unit 31m A portion of the linear scale 31 that blocks light from the light emitting portion 41 is formed over a range of a predetermined width W in a part in the longitudinal direction. Therefore, in the portion where the dirt detection pattern 31c is formed, it is impossible to accurately detect the position with the linear encoder 33 (that is, accurate reading is impossible) (step S19). In this case, it is determined that the linear scale 31 is dirty. Further, since the linear scale 31 is contaminated, it is determined that there is a high possibility that erroneous position detection is performed by the linear encoder 33 in the state as it is.

  Further, it may be determined whether the linear scale 31 is contaminated by a combination of step S15 and step S25. That is, from the range of ± x% of the period T (frequency) based on the period (frequency) of the A-phase signal SG1 and B-phase signal SG2 when the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed. It is determined whether or not the phase difference between the A phase signal SG1 and the B phase signal SG2 when the photosensor 32 passes through the portion where the dirt detection pattern 31c is formed is determined. By doing so, it may be determined whether or not the linear scale 31 is contaminated.

(Main effects of this form)
As described above, the linear encoder 33 of the present embodiment includes the cleaning members 83 and 83 that are in contact with the light emitting surface 41a and the light receiving surface 42a and clean the light emitting surface 41a and the light receiving surface 41a. Therefore, dirt on the light emitting surface 41a and the light receiving surface 41a can be removed, and occurrence of erroneous detection in the linear encoder 33 can be suppressed. In the present embodiment, the cleaning members 83 and 83 are fixed to the linear scale 31. Therefore, when the position of the carriage 3 is detected, the cleaning members 83 and 83 can be fixed to the linear scale 31 at a position not always in contact with the light emitting surface 41a or the light receiving surface 42a. A decrease in detection accuracy can be suppressed.

  In this embodiment, the linear scale 31 includes a dirt detection pattern 31c in addition to the position detection pattern 31b for detecting the position of the carriage 3, and light reception when the photosensor 32 passes through the dirt detection pattern 31c. Based on the light reception result of the unit 42, when the control unit 37 detects the contamination of the linear scale 31, the light emitting surface 41 a and the light receiving surface 42 a are cleaned by the cleaning members 83 and 83. That is, when contamination of the linear scale 31 is detected from the detection result of the light received from the light emitting unit 41 and transmitted through the second light transmitting unit 31h, the light emitting surface 41a and the light receiving surface 42a are also contaminated. Therefore, the light emitting surface 41a and the light receiving surface 42a are cleaned. Therefore, the light emitting surface 41a and the light receiving surface 42a can be cleaned only at an appropriate time when the light emitting surface 41a and the light receiving surface 42a need to be cleaned, and a useless cleaning operation can be omitted.

  In particular, in this embodiment, the cleaning members 83 and 83 are fixed to the linear scale 31 in a region different from the region where the position detection pattern 31b and the dirt detection pattern 31c are formed. Therefore, the light emitting surface 41a and the light receiving surface 42a can be cleaned without affecting the detection of the position of the carriage 3 and the detection of dirt on the linear scale 31. That is, the light emitting surface 41a and the light receiving surface 42a can be cleaned by the cleaning members 83 and 83 without lowering the position detection accuracy of the carriage 3 and the detection accuracy of dirt on the linear scale 31.

  In this embodiment, the dirt detection pattern 31 c is disposed outside the position detection pattern 31 b in the longitudinal direction of the linear scale 31, and the cleaning members 83 and 83 are disposed outside the dirt detection pattern 31 c in the longitudinal direction of the linear scale 31. ing. Therefore, the contamination of the linear scale 31 can be detected without affecting the position detection of the carriage 3. Further, the carriage 3 that moves from the 0-digit side to the 80-digit side when printing on the printing paper P is further moved in the longitudinal direction of the linear scale 31, that is, when the position of the carriage 3 is detected. The light emitting unit 41 and the light receiving unit 42 that move in the longitudinal direction of the linear scale 31 are further moved in the longitudinal direction of the linear scale 31 to detect the contamination of the linear scale 31 and clean the light emitting surface 41a and the light receiving surface 42a. And can be done.

  In this embodiment, the second light transmitting portion 31h has a light transmission area from the light emitting portion 41 of the second light transmitting portion 31h smaller than a light transmission area from the light emitting portion 41 of the first light transmitting portion 31f. That is, the light-shielding pattern 31k is formed to make the light transmittance from the light emitting portion 41 of the second light transmitting portion 31h lower than the light transmittance from the light emitting portion 41 of the first light transmitting portion 31f. For this reason, when ink mist adheres to the linear scale 31 as dirt, the second light transmitting portion 31h emits light over a predetermined width W in a part of the linear scale 31 in the longitudinal direction as compared with the first light transmitting portion 31f. The part where is blocked is likely to occur. In addition, in the second light transmitting part 31h, light is more easily blocked compared to the first light transmitting part 31f. For example, as shown in FIG. 14, a portion that blocks light from the light emitting unit 41 over a predetermined width W in a part of the linear scale 31 in the longitudinal direction by the adhering portions D1 and D2 and the light blocking unit 31m It tends to occur. Therefore, in the first light transmitting portion 31 f used for detecting the position of the carriage 3, light is blocked over a predetermined width W in part or all of the longitudinal direction of the linear scale 31, and erroneous detection by the linear encoder 33 is prevented. Before the occurrence, the stain on the linear scale 31 can be detected by the A-phase signal SG1 and the B-phase signal SG2 from the linear encoder 33 when the photosensor 32 passes through the portion where the stain detection pattern 31c is formed. .

(Other embodiments)
The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications and changes can be made without departing from the gist of the present invention.

  In the embodiment described above, the carriage 3 (specifically, the photosensor 32) moves in the longitudinal direction of the linear scale 31, so that the cleaning members 83 and 83 come into contact with the light emitting surface 41a and the light receiving surface 42a, and the light emitting surface 41a. In addition, the light receiving surface 42a is cleaned. In addition to this, for example, by aligning the cleaning members 83, 83 with the light emitting surface 41 a and the light receiving surface 42 a in the longitudinal direction of the linear scale 31, the linear scale 31 is moved up and down by the scale lifting mechanism 44. The light emitting surface 41a and the light receiving surface 42a may be cleaned by the cleaning members 83 and 83. In this case, the scale lifting mechanism 44 serves as a cleaning member moving unit that moves the cleaning members 83 and 83 relative to the light emitting unit 41 and the light receiving unit 42.

  In the embodiment described above, the cleaning members 83 and 83 are fixed on the 80th digit side of the linear scale 31, but on the 0th digit side of the linear scale 31, the cleaning member is disposed outside the main scanning direction MS of the position detection pattern 31b. 83 and 83 may be fixed.

  Furthermore, in the embodiment described above, the cleaning members 83 and 83 are fixed to the outside of the position detection pattern 31 b in the longitudinal direction of the linear scale 31. In addition, for example, as shown in FIG. 15, the cleaning members 83 and 83 may be fixed to both surfaces of the linear scale 31 so as to be adjacent to the position detection pattern 31 b in the short direction of the linear scale 31. . In this case, the linear encoder 33 can be downsized in the longitudinal direction of the linear scale 31. Even in this case, the cleaning members 83 and 83 are fixed to the linear scale 31 in an area different from the area where the position detection pattern 31b and the dirt detection pattern 31c are formed. The light emitting surface 41a and the light receiving surface 42a can be cleaned without affecting the contamination detection of the linear scale 31. That is, the light emitting surface 41a and the light receiving surface 42a can be cleaned by the cleaning members 83 and 83 without reducing the position detection accuracy of the carriage 3 and the contamination detection accuracy of the linear scale 31. The cleaning members 83, 83 may be fixed to the linear scale 31 so as to be adjacent to the dirt detection pattern 31 c in the short direction of the linear scale 31.

  Further, when the cleaning members 83 and 83 are fixed to the linear scale 31 so as to be adjacent to the position detection pattern 31b in the short direction of the linear scale 31, as shown in FIG. 15, the cleaning is performed below the position detection pattern 31b. The members 83 and 83 may be fixed, or the cleaning members 83 and 83 may be fixed above the position detection pattern 31b. Moreover, you may fix the cleaning members 83 and 83 to the up-and-down both sides of the position detection pattern 31b.

  As shown in FIG. 15, when the cleaning members 83 and 83 are fixed on both surfaces of the linear scale 31 so as to be adjacent to the position detection pattern 31 b in the short direction of the linear scale 31, printing on the printing paper P is performed. Sometimes, the light emitting unit 41 and the light receiving unit 42 face each other so as to sandwich the position detection pattern 31b of the linear scale 31. When the light emitting surface 41a and the light receiving surface 42a are cleaned, the linear scale 31 is moved up and down by the scale lifting mechanism 44 to bring the cleaning members 83 and 83 into contact with the light emitting surface 41a and the light receiving surface 42a. Then, the light receiving surface 42a is cleaned. Further, after the linear scale 31 is raised (or lowered) by the scale lifting mechanism 44, the CR motor 4 is driven to move the carriage 3 in the longitudinal direction of the linear scale 31, so that the cleaning members 83, 83 The light emitting surface 41a and the light receiving surface 42a can also be cleaned.

  Furthermore, in the embodiment described above, the dirt detection pattern 31 c is arranged outside the position detection pattern 31 b in the longitudinal direction of the linear scale 31. In addition to this, for example, as shown in FIGS. 16A and 16B, the dirt detection pattern 31 c may be disposed adjacent to the position detection pattern 31 b in the short direction of the linear scale 31. In this case, as shown in FIG. 16A, the cleaning members 83 and 83 are arranged outside the position detection pattern 31b and the dirt detection pattern 31c in the longitudinal direction of the linear scale 31 (for example, on the 80 digit side). Alternatively, as shown in FIG. 16B, the linear scale 31 may be disposed adjacent to the dirt detection pattern 31c in the short direction.

  When the cleaning members 83 and 83 are arranged as shown in FIG. 16A, the position detection of the carriage 3 performed by moving the carriage 3 in the longitudinal direction of the linear scale 31 is not affected. The contamination of the linear scale 31 can be detected. Further, when the position of the carriage 3 is detected, the carriage 3 that moves in the longitudinal direction of the linear scale 31 is further moved relatively in the longitudinal direction of the linear scale 31, and the light emitting surface 41a and the light receiving surface 42a are cleaned. It can be performed. Further, when the cleaning members 83 and 83 are arranged as shown in FIG. 16B, the linear encoder 33 can be downsized in the longitudinal direction of the linear scale 31. Note that the cleaning members 83 and 83 may be disposed adjacent to the position detection pattern 31b (that is, above the position detection pattern 31b in FIG. 16B).

  Further, in the above-described form, the light-shielding pattern 31k including the shaded light blocking part 31m is formed in the second light transmitting part 31h. In addition, for example, as shown in FIG. 16C, a light shielding pattern 31k may be formed by a rectangular light blocking portion 31q arranged in a checkered pattern together with a rectangular light transmitting portion 31p. Further, as shown in FIG. 16D, the width H1 of the second light transmitting portion 31h may be formed narrower than the width H of the first light transmitting portion 31e. In this case, the light shielding pattern 31k may not be formed in the second light transmitting portion 31h. When the width H1 of the second light transmitting part 31h is formed to be narrower than the width H of the first light transmitting part 31f, for example, the second light shielding part 31g is formed with a width H2, as shown in FIG. As described above, the sum of the width H1 of the second light transmitting part 31h and the width H2 of the second light shielding part 31g is the same as the light / dark pitch P formed by the first light transmitting part 31f and the first light shielding part 31e. It has become.

  Furthermore, in the above-described embodiment, the embodiment of the present invention has been described by taking the linear encoder 33 as an example. However, the present invention is also applicable to the rotary encoder 36. Hereinafter, an embodiment in which the configuration of the present invention is applied to the rotary encoder 36 will be described.

  For example, as shown in FIG. 17A, the photosensor 35 is fixed to a bracket 86 fixed to a rotatable rotating member 87 via a control board 85. Further, the rotary scale 34 has a position detection pattern 34b formed on the outer peripheral end side, and a dirt detection pattern 34c formed radially inside the position detection pattern 34b. Cleaning members 83 and 83 are fixed to both surfaces of the rotary scale 34 on the inner side in the radial direction of the dirt detection pattern 34c. Note that FIG. 17B illustrates a cross section taken along line FF in FIG. The position detection pattern 34 b is configured in the same manner as the position detection pattern 31 b of the linear scale 31, and the stain detection pattern 34 c is configured in the same manner as the stain detection pattern 31 c of the linear scale 31.

  In the rotary encoder 36 shown in FIG. 17, when detecting the position of the PF drive roller 6 that is a detection object during printing on the printing paper P, the light emitting unit 81 and the light receiving unit 82 are provided on the rotary scale 34. It faces to sandwich the position detection pattern 34b. Further, when detecting the dirt on the rotary scale 34, the photosensor 35 is rotated together with the bracket 86 around the rotating member 87 so that the light emitting part 81 and the light receiving part 82 face each other with the dirt detection pattern 34c interposed therebetween. When cleaning the light emitting surface 81a of the light emitting element 81 and the light receiving surface 82a of the light receiving element 82, the cleaning members 83 and 83 are moved to the light emitting surface 81a and the photosensor 35 together with the bracket 86 around the rotating member 87. The light emitting surface 41a and the light receiving surface 42a are cleaned in contact with the light receiving surface 82a. Further, after rotating the photo sensor 35 until the cleaning members 83 and 83 come into contact with the light emitting surface 81a and the light receiving surface 82a, the rotary scale 34 is rotated by driving the PF motor 5, thereby rotating the light emitting surface 81a and the light emitting surface 81a. The light receiving surface 82a may be cleaned. In this case, the driving means for rotating the rotating member 87 is a cleaning member moving means for moving the cleaning members 83 and 83 relative to the light emitting surface 81a of the light emitting portion 81 and the light receiving surface 82a of the light receiving portion 82. Become.

  As described above, even in the rotary encoder 36 shown in FIG. 17, when the position of the PF drive roller 6 is detected, the cleaning member 83 is attached to the rotary scale 34 at a position that does not always contact the light emitting surface 81 a or the light receiving surface 82 a. 83 can be fixed, and as a result, a decrease in position detection accuracy of the PF drive roller 6 can be suppressed. Further, since the cleaning members 83 and 83 are fixed to the rotary scale 34 in an area different from the area where the position detection pattern 34b and the dirt detection pattern 34c are formed, the position detection of the PF drive roller 6 and the dirt of the rotary scale 34 are detected. The light emitting surface 81a and the light receiving surface 82a can be cleaned without affecting the detection. Further, the dirt detection pattern 34c is arranged on the inner side in the radial direction of the rotary scale 34 than the position detection pattern 34b, and the cleaning members 83 and 83 are arranged on the inner side in the radial direction of the rotary scale 34 than the dirt detection pattern 34c. Therefore, the rotary encoder 36 can be downsized in the radial direction of the rotary scale 34.

  Furthermore, in the above-described form and the rotary encoder 36 of FIG. 17, the cleaning members 83 and 83 are fixed to both surfaces of the linear scale 31 and the rotary scale 34. In addition to this, for example, the cleaning member 83 may be fixed only to one side of the linear scale 31 or the rotary scale 34, and only one of the light emitting surfaces 41a and 81a or the light receiving surfaces 42a and 82a may be cleaned. .

  Further, in the above-described form, the A-phase signal SG1 that is a digital signal is generated from the differential between the output signal from the first amplifier 58 and the output signal from the third amplifier 60, and the second amplifier 59 A B-phase signal SG2, which is a digital signal, is generated from the difference between the output signal and the output signal from the fourth amplifier 61. In addition to this, for example, as shown in FIG. 18A, by setting a predetermined threshold C to the output signal of the amplifier such as the first amplifier 58, a phase A signal or the like that is a digital signal is generated. Also good. That is, a digital signal may be generated by outputting a high level signal if the value of the output signal is greater than the threshold value C, and outputting a low level signal if the value of the output signal is smaller than the threshold value C. In this case, the contamination of the linear scale 31 may be detected as follows.

  The amount of light emitted from the light emitting portion 41 and transmitted through the first light transmitting portion 31f is greater than the amount of light transmitted through the second light transmitting portion 31h. Therefore, when ink mist is not attached to the linear scale 31, for example, as shown in FIG. 18A, when the photosensor 32 passes through the portion where the position detection pattern 31b is formed, the amplifier When the signal SG11 is output and the photosensor 32 passes through the portion where the stain detection pattern 31c is formed, the signal SG12 having a level lower than the signal SG11 is output from the amplifier. Further, the digital signal SG13 shown in FIG. 18B is generated from the signal SG11 and the threshold C, and the digital signal SG14 shown in FIG. 18C is generated from the signal SG12 and the threshold C. Here, the higher the transmission amount of the light emitted from the light emitting unit 41 through the linear scale 31, the longer the high-level period of the digital signal. Therefore, the high-level period T11 of the digital signal SG13 is the high level of the digital signal SG14. It becomes longer than the period T12 of the level. Further, when the linear scale 31 is not contaminated, the ratio of the period T12 to the period T11 is, for example, 80%.

  Here, when the ink mist adheres evenly to the linear scale 31, the levels of the signals SG11 and SG12 output from the amplifier are reduced to the same extent. For example, as shown in FIG. 18D, the level is lowered from signal SG11 to signal SG21, and the level of signal SG12 is lowered to signal SG22. Further, as shown in FIG. 18E, the high-level period T21 of the digital signal SG23 generated from the signal SG21 and the threshold value C is shorter than the period T11. As shown in FIG. 18F, the high-level period T22 of the digital signal SG24 is shorter than the period T12.

  In this case, as shown in FIG. 18, the ratio of the period T22 to the period T21 is lower than the ratio of the period T12 to the period T11. For example, the ratio of the period T12 to the period T11 is 80%, whereas the ratio of the period T22 to the period T21 is 50%. Therefore, when the ink mist adheres to the linear scale 31, a high-level cycle (for example, cycle T21) of the digital signal based on the position detection pattern 31b and a high-level cycle (for example, the digital signal based on the stain detection pattern 31c) When the ratio with the period T22) becomes a predetermined value or less, it can be determined that the linear scale 31 is contaminated. As described above, when the digital signal is generated by setting the predetermined threshold C to the output signal of the amplifier, the contamination of the linear scale 31 can be detected by the method described above. It is also possible to detect the contamination of the linear scale 31 from the rate of decrease of the high-level period of the digital signal based on the contamination detection pattern 31c with respect to the initial state.

  In the above-described embodiment, the scale lifting mechanism 44 is fixed to the tip of the guide shaft 17 outside the one side surface 16a and the eccentric cam 45 fixed to the guide shaft 17 inside the one side surface 16a of the support frame 16. And a driven gear 47. In addition, for example, an eccentric cam 95 corresponding to the eccentric cam 45 and the driven gear 47 are integrally formed as in the scale lifting mechanism 94 shown in FIG. 19, and the integrated eccentric cam 95 and the driven gear 47 are integrated. May be rotatably attached to the tip of the guide shaft 17 outside the one side surface 16a. In this case, as shown in FIG. 19, the mounting bracket 46 is formed with a contact portion 46 a so as to rise from the base portion 46 b toward the outside of the printer 1, and contacts the cam surface 95 a of the eccentric cam 95. ing. The cam surface 95a is formed in the same manner as the cam surface 45a. In this case, the guide shaft 17 does not rotate. In FIG. 19, the same reference numerals are given to the same components as those shown in FIG. 5.

  Further, as shown in FIG. 15, in the configuration in which the cleaning members 83 and 83 are fixed so as to be adjacent to the position detection pattern 31 b in the short direction of the linear scale 31, the printer 1 is connected to the nozzle surface ( If the gap adjusting mechanism for adjusting the gap (gap) between the lower surface in FIG. 2 and the platen 7 is provided, the light emitting surface 41a and the light receiving surface 42a may be cleaned by this gap adjusting mechanism. In other words, the photo sensor 32 attached to the carriage 3 may be moved up and down together with the carriage 3 by the gap adjusting mechanism, and the light emitting surface 41a and the light receiving surface 42a may be cleaned by the cleaning members 83 and 83. In this case, the gap adjusting mechanism serves as a cleaning member moving unit that moves the cleaning members 83 and 83 relative to the light emitting unit 41 and the light receiving unit 42.

  Furthermore, the linear scale 31 may be translated to the light emitting unit 41 side or the light receiving unit 42 side in the sub-scanning direction SS as the pre-processing in step S3 when detecting the contamination of the linear scale 31 of the above-described form. As described above, the light receiving unit 41 includes the collimator lens 51. However, the light emitted from the light receiving unit 41 is not completely parallel light. Therefore, when the linear scale 31 is closer to the light receiving unit 42, it is easier to perform appropriate detection at the light receiving unit 42. Therefore, when the linear scale 31 is moved to the light emitting unit 41 side, the period of the A-phase signal SG1 and the B-phase signal SG2 output from the linear encoder 33 varies even if the degree of contamination of the second light transmitting unit 31h is small. Prone to occur. That is, dirt on the linear scale 31 is easily detected. Further, when the linear scale 31 is moved to the light receiving unit 42 side, the period of the A phase signal SG1 and the B phase signal SG2 output from the linear encoder 33 is changed unless the degree of contamination of the second light transmitting unit 31h is large. Hard to occur. That is, dirt on the linear scale 31 is difficult to detect. Thus, in step S3, it is possible to detect the degree of contamination of the linear scale 31 by moving the linear encoder 31 to the light emitting unit 41 side or the light receiving unit 42 side.

  Further, in the above-described embodiment, the configuration of the present invention has been described by taking the printer 1 as an example of the liquid ejection device. Various liquid ejection devices that apply inkjet technology such as processing devices, 3D modeling machines, liquid vaporizers, organic EL manufacturing devices (especially polymer EL manufacturing devices), display manufacturing devices, film forming devices, DNA chip manufacturing devices, etc. Is also applicable. The liquid discharged by these liquid discharge devices includes, for example, a liquid containing a metal material, an organic material (particularly a polymer material), a magnetic material, a conductive material, a wiring material, a film forming material, an electronic ink, It becomes processing solution, gene solution, etc.

1 is a perspective view showing a schematic configuration of a liquid ejection apparatus (printer) according to an embodiment. FIG. 2 is a schematic side view illustrating a schematic configuration of a portion related to paper feeding of the printer of FIG. 1. FIG. 3 is a schematic configuration diagram illustrating a detection mechanism of the carriage of FIG. 1 and the PF drive roller of FIG. 2. The schematic perspective view which showed the attachment state of the one end part of the linear scale of FIG. The schematic perspective view which showed the attachment state of the one end part of a linear scale from the paper back side of FIG. The figure which shows the relationship between the cam of FIG. 4, and a mounting bracket. The schematic diagram which shows schematic structure of the linear encoder of FIG. The figure which shows the 80th digit side of the linear scale of FIG. The figure which shows the signal waveform output from the linear encoder of FIG. FIG. 4 is a flowchart showing a series of operations of the printer at the time of detecting dirt on the linear scale of FIG. 3. FIG. 4 is a flowchart showing an example of a dirt detection operation of the linear scale of FIG. 5 is a flowchart showing another example of the dirt detection operation of the linear scale of FIG. The figure which shows the example of the signal waveform output from the linear encoder when dirt arises in the linear scale of FIG. The elements on larger scale which expand and show the E section of FIG. The figure which shows the 80-digit side of the linear scale concerning another form. The figure which shows the 80-digit side of the linear scale concerning another form. The figure which shows the rotary encoder concerning another form. The figure for demonstrating the contamination detection method of the linear scale concerning another form. The schematic perspective view which showed the attachment state of the one end part of the linear scale concerning another form.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Printer (liquid ejection apparatus) 2 Print head (liquid ejection part) 3 Carriage (detected object), 6 PF drive roller (detected object), 31 Linear scale (scale), 31b / 34b Position detection pattern, 31c 34c Dirt detection pattern, 31e first light shielding part, 31f first light transmitting part, 31g second light shielding part, 31h second light transmitting part, 31k light shielding pattern, 33 linear encoder (position detection device), 34 rotary scale (scale ), 36 Rotary encoder (position detection device), 41/81 light emitting unit, 41a / 81a light emitting surface, 42/82 light receiving unit, 42a / 82a light receiving surface, 83 cleaning member, P printing paper (medium).

Claims (8)

In a liquid ejection apparatus including a position detection device that detects a position of an object to be detected and a liquid ejection unit that ejects liquid onto a predetermined medium.
The position detecting device is disposed between a light emitting unit having a light emitting surface for emitting light, a light receiving unit having a light receiving surface for receiving light from the light emitting unit, and the light emitting surface and the light receiving surface. A scale, and a cleaning member fixed to the scale and cleaning at least one of the light emitting surface and the light receiving surface in contact with at least one of the light emitting surface and the light receiving surface;
In order to detect the position of the detected object, the scale includes at least a first light transmitting part that transmits light from the light emitting part and a first light shielding part that blocks light from the light emitting part. In order to detect the contamination of the scale and the position detection pattern formed alternately within the detection range, the second light-transmitting part that transmits light from the light-emitting part and the second light-blocking part that blocks light from the light-emitting part A dirt detection pattern in which two light shielding portions are alternately formed,
Further, a dirt detecting means for detecting dirt on the scale based on a light reception result at the light receiving section in the dirt detection pattern, and a cleaning member moving means for moving the cleaning member relative to the light emitting section and the light receiving section. And
When the dirt on the scale is detected by the dirt detecting means, at least one of the light emitting surface and the light receiving surface is cleaned by the cleaning member relatively moved by the cleaning member moving means. Liquid ejection device.   The liquid ejecting apparatus according to claim 1, wherein the cleaning member is fixed to the scale in a region different from a region where the position detection pattern is formed and a region where the dirt detection pattern is formed. The scale is a linear scale formed in a long thin plate shape,
The dirt detection pattern is disposed outside the position detection pattern in a longitudinal direction of the linear scale, and the cleaning member is disposed outside the dirt detection pattern in the longitudinal direction. 2. The liquid ejection device according to 2. The scale is a linear scale formed in a long thin plate shape,
The dirt detection pattern is disposed outside the position detection pattern in the longitudinal direction of the linear scale, and the cleaning member is adjacent to the position detection pattern and / or the dirt detection pattern in the lateral direction of the linear scale. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is disposed. The scale is a linear scale formed in a long thin plate shape,
The stain detection pattern is disposed adjacent to the position detection pattern in the short direction of the linear scale, and the cleaning member is disposed outside the position detection pattern and / or the stain detection pattern in the longitudinal direction of the linear scale. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is disposed on the surface. The scale is a linear scale formed in a long thin plate shape,
The dirt detection pattern is disposed adjacent to the position detection pattern in the lateral direction of the linear scale, and the cleaning member is disposed adjacent to the position detection pattern or the dirt detection pattern in the lateral direction. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The scale is a rotary scale formed in a disk shape,
The dirt detection pattern is disposed radially inward of the rotary scale with respect to the position detection pattern, and the cleaning member is disposed radially inward of the rotary scale with respect to the dirt detection pattern. The liquid discharge apparatus according to claim 2.   In the second light transmitting part, the light transmitting area of the second light transmitting part from the light emitting part is made smaller than the light transmitting area of the first light transmitting part from the light emitting part, or The light-shielding pattern which makes the transmittance | permeability of the light from the said light emission part of a 2nd translucent part lower than the transmittance | permeability of the light from the said light emission part of a said 1st translucent part is formed. The liquid ejection device according to any one of 1 to 7.

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