JP2006264037A - Moving mechanism and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving mechanism capable of moving, for example, a group of large-sized printing heads without rattling (blurring) while it holds the same posture, and with a relatively simple constitution. <P>SOLUTION: Bushes 137a and 137b and a bush 137c are arranged not on the same plane but are shifted in a slide direction (arrow mark D direction). Namely, the bush 137c separated most from the bush 137a between the bushes 137b and 137c is positioned on a different plane from a plane on which the bush 137a positions to a plane intersecting at right angles to the moving direction (the arrow mark D direction). Three guide posts 134a, 134b and 134c extend in the direction other than the horizontal direction. The uppermost part 139c of a part where the bush 137c comes into contact with the guide post 134c, is positioned upper than the uppermost part 139a of a part where the bush 137a comes into contact with the guide post 137a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a moving mechanism in which a slide unit moves while being guided by a plurality of guide posts, and an image forming apparatus incorporating the moving mechanism.

  2. Description of the Related Art Inkjet image forming apparatuses (inkjet recording apparatuses) that form images by ejecting ink onto recording media such as recording paper are widely used. An inkjet image forming apparatus performs recording (image formation) by discharging ink from a print head (recording head) to a recording medium. As the print head, there are known a fixed type that is fixed during recording (during printing) and does not move, and two movement types in which the print head is mounted and moved on a carriage that scans in a predetermined main scanning direction. Fixed type print heads tend to increase because they are advantageous for high-speed printing and downsizing of the entire apparatus.

  When the print head continues to eject ink repeatedly, ink or paper dust may adhere to the periphery of the ink ejection port, thereby preventing normal ink ejection. In order to prevent normal ink ejection from being disturbed in this manner and always eject ink in an optimal state, an ink jet image forming apparatus usually recovers the ink ejection state of the print head to the initial normal state. A recovery mechanism is provided. The recovery mechanism includes a cap that seals the ink discharge port of the print head, and a cleaning member that cleans the ink discharge port and its periphery.

  In general, the fixed type print head has a recording position for ejecting ink onto a recording medium to form an image, a cap position for sealing an ink ejection port by the cap, and a cleaning position for cleaning by the cleaning member. It is configured to be able to selectively move to either. When the print head is located at the recording position, the print head is closest to the recording medium as compared with other positions. When the print head is positioned at the cap position, it is a standby state in which the print head is on standby without image formation. In order for the print head located at the recording position to shift to the standby state (move to the cap position), the print head located at the recording position moves away from the recording medium (generally, rises). Further, when the print head is located at the cleaning position, preliminary discharge is performed on the cap and the nozzle surface is cleaned by the wiping blade. Therefore, the print head is separated from the recording medium than the cap position (generally, further rising) To do.)

  Incidentally, a plurality of print heads are required as the color and speed of the image forming apparatus increase, and the plurality of print heads are configured to move simultaneously from a recording position to a cap position, for example. The plurality of print heads positioned at the recording positions are preferably equidistant from the recording medium in order to improve the image quality. Further, when a plurality of print heads are positioned at the cap position, it is desirable that each print head be positioned on a plane parallel to the cap in order to improve the sealing degree of the ink discharge port by the cap. Similarly, when a plurality of print heads are positioned at the cleaning position, it is desirable that each print head be positioned on a plane that is equidistant from the cleaning blade in order to sufficiently clean the ink ejection openings and the periphery thereof.

  In order to position a plurality of print heads on a predetermined plane as described above, when the plurality of print heads are moved together, it is necessary to move or stop them while maintaining the same posture. By the way, as the number of print heads increases and the width of print heads increases along with the use of color and light color inks, the size of multiple print heads (print head groups) that move simultaneously is large. It has become. For this reason, the configuration for moving the print head group while maintaining the same posture is increased in size and complexity, and driving units are required at a plurality of locations.

  In view of the above circumstances, the present invention provides a moving mechanism having a relatively simple configuration that allows a large print head group to move while maintaining the same posture without rattling (without shaking), and an image incorporating this moving mechanism. An object is to provide a forming apparatus.

In order to achieve the above object, the moving mechanism of the present invention moves in the moving direction while contacting a plurality of guide posts arranged in parallel to each other and extending in a predetermined moving direction. In a moving mechanism comprising a plurality of contact moving members and a slide unit that connects and moves the plurality of contact moving members simultaneously,
(1) Provided with a drive unit that drives one of the plurality of contact moving members to move in the moving direction;
(2) Of the plurality of contact moving members, the contact moving member that is farthest from the driving side contact moving member driven by the driving unit is the driving side contact moving with respect to a plane orthogonal to the moving direction. The member is located on a plane different from the plane on which the member is located.

here,
(3) The plurality of guide posts extend in the horizontal direction,
(4) The length in the moving direction in which the driving side contact moving member contacts the guide post is longer than the length in the moving direction in which the contact moving member farthest from the driving side contact moving member contacts the guide post. Is also short, and
(5) Of the portion where the contact moving member farthest from the drive side contact moving member contacts the guide post, the drive side contact moving member contacts the guide post at the most upstream portion in the moving direction. Is located on the upstream side in the movement direction from the most upstream part in the movement direction among the parts, and
(6) Of the portion where the contact moving member farthest from the drive side contact moving member contacts the guide post, the drive side contact moving member contacts the guide post at the most downstream portion in the moving direction. You may be located in the movement direction downstream rather than the most downstream part of the said movement direction among the parts.

further,
(7) The plurality of guide posts extend in a direction other than the horizontal direction,
(8) The uppermost portion of the portion where the contact moving member farthest from the driving side contact moving member contacts the guide post is the uppermost portion of the portion where the driving side contact moving member contacts the guide post. It may be located above the portion.

An image forming apparatus of the present invention for achieving the above object is an image forming apparatus for forming an image by ejecting ink from a print head onto a recording medium.
(9) The print head is mounted on the slide unit,
(10) The moving mechanism described above is provided.

here,
(11) A head holder for holding the print head is provided.
(12) The head holder may be mounted on the slide unit.

further,
(13) a base plate to which one end in the longitudinal direction of the plurality of guide posts is fixed;
(14) An upper plate to which the other longitudinal ends of the plurality of guide posts are fixed,
(15) The base plate, the upper plate, and the slide unit may have the same thermal expansion coefficient.

Furthermore,
(16) The plurality of contact moving members may be cylindrical bushes into which the guide posts are inserted.

Furthermore,
(17) You may provide the stopper which stops the said slide unit in a predetermined position.

Furthermore,
(18) The driving unit includes:
(18-1) a rack formed integrally with the drive side contact moving member;
(18-2) A pinion gear that meshes with the rack may be provided.

Furthermore,
(19) a flag fixed to the slide unit;
(20) A photo interrupter that is turned on / off by the flag may be provided.

  According to the present invention, since the plane on which the drive-side contact moving member is located (the plane perpendicular to the moving direction) is different from the plane on which the contact-moving member farthest from the drive-side contact moving member is located, the drive-side contact movement The farthest contact moving member can smoothly follow the movement of the member, and the slide unit moves smoothly while keeping the same posture without rattling (without shaking).

  The present invention has been realized in an ink jet printer that forms an image by ejecting ink onto a recording medium such as recording paper.

  With reference to FIG. 1, an example of a printer incorporating the moving mechanism of the present invention will be described.

  FIG. 1 is a perspective view schematically showing an example of a printer in which the moving mechanism of the present invention is incorporated.

  A recording unit 20 that ejects ink to form an image on a recording medium is disposed at the top of the printer 10. A recording medium is placed below the recording unit 20 in the direction of arrow A (or the opposite direction). A conveying device 40 for conveying is disposed. The recording unit 20 is disposed on the base plate 24, and moves together with the base plate 24 in a direction approaching the transport device 40 or a direction away from the transport device 40 as necessary. As a mechanism for moving the recording unit 20, the moving mechanism of the present invention is incorporated.

  In the recording unit 20, print heads (print heads) 22K, 22C, 22lC, 22M, 22lM, and 22Y (see FIG. 2) for discharging ink are directions of an arrow A (the movement direction of an endless belt 42 described later). It is mounted side by side in the transport direction). The print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y eject black, cyan, light cyan, magenta, light magenta, and yellow ink from the upstream side in the recording medium conveyance direction, respectively. Each of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is provided with nozzles arranged in a line in a direction orthogonal to the recording medium transport direction (width direction of the recording medium), and six print heads An image is formed by overlaying the ink ejected from 22K, 22C, 22lC, 22M, 22lM, and 22Y. Each of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is in a standby state in a state where the ejection port (nozzle opening) is blocked by a cap (not shown) in the recording unit 20, and the recording medium is After being set on the conveying device 40 and immediately before printing, it moves to a predetermined printing position and starts printing.

  On the back side of the printer 10, an ink supply unit 26 that supplies ink to the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is disposed. Inside the ink supply unit 26, an ink tank (not shown) for each color, an ink pump (not shown) for transporting ink to the recording unit 20, and the print heads 22K, 22C, 22lC, 22M, 22lM , 22Y is provided with a sub-tank (not shown) for applying a predetermined negative pressure due to a water head difference.

  When the recording medium passes below the recording unit 20, black, cyan, light cyan, magenta, light magenta, and yellow inks are sequentially ejected onto the recording medium to form a color image. Each of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is appropriately supplied with ink from the ink tank via the ink flow path 26a by a supply pump (not shown).

  The conveying device 40 includes an endless belt (conveying belt) 42 on which a recording medium is placed, a driving roller 44 and a driven roller 46 around which the endless belt 42 is stretched. In the printer 10, the four endless belts 42 are arranged in parallel in a direction orthogonal to the rotation direction of the endless belt 42, but may be three or less or five or more. The drive roller 44 is located upstream in the recording medium conveyance direction (arrow A direction), and the driven roller 46 is located downstream in the recording medium conveyance direction.

  Both ends in the longitudinal direction of the rotating shaft of the drive roller 44 are supported by a frame (not shown) so as to be rotatable via bearings (not shown). A pulley 45 is attached to one end in the longitudinal direction of the rotation shaft of the drive roller 44, and a timing belt 50 is stretched between the pulley 45 and the drive motor (conveyance motor) 48. When the drive motor 48 is driven, the timing belt 50 and the pulley 45 rotate and the drive roller 44 rotates. With this rotation, the four endless belts 42 rotate in the directions of arrows A and B. Note that both end portions in the longitudinal direction of the rotation shaft of the driven roller 46 are also supported by a frame (not shown) through a bearing (not shown) in the same manner as the drive roller 44.

  A chamber 52 for adsorbing (sucking) the recording medium being conveyed by the endless belt 42 to the endless belt 42 is disposed below the endless belt 42. A fan unit 54 is disposed below the chamber 52, and the chamber 52 and the fan unit 54 are connected (connected) by a hose 53. The endless belt 42 is formed with a plurality of openings 42 a for adsorbing the recording medium to the endless belt 42. When the fan unit 54 is driven, air is sucked from the plurality of openings 42 a via the hose 53 a and the chamber 52, so that the recording medium is adsorbed to the endless belt 42.

  The electrical system of the printer 10 will be described with reference to FIG.

  FIG. 2 is a block diagram showing an electrical system of the printer of FIG.

  Recording data and commands transmitted from the host PC 12 are received by the CPU 100 via the interface controller 102. The CPU 100 is an arithmetic processing unit that performs overall control such as recording data reception, recording operation, and recording medium handling of the printer 10. After analyzing the received command, the CPU 100 renders the image data of each color component of the recording data by developing a bitmap on the image memory 106. As an operation process before recording, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor driving unit 116, and the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y are capped. It is moved away from a not-shown recording position (printing position, image forming position).

  Subsequently, a roll motor (not shown) that feeds the recording medium through the output port 114 and the motor driving unit 116, a conveyance motor 120 that conveys the recording medium at a constant speed, and the like are driven to convey the recording medium to the recording position. To do. The leading edge detection sensor (not shown) for determining the timing (recording timing) at which ink starts to be ejected onto the recording medium conveyed at a constant speed detects the leading edge position of the recording medium. Thereafter, in synchronism with the conveyance of the recording medium, the CPU 100 sequentially reads the recording data of the corresponding color from the image memory 106, and the read data is sent to each print head via the print head control circuit 112. Transfer to 22K, 22C, 22lC, 22M, 22lM, 22Y.

  The operation of the CPU 100 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores processing programs and tables corresponding to the control flow. A work RAM 108 is used as a working memory. During the cleaning and recovery operations of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y, the CPU 100 drives the pump motor 124 via the output port 114 and the motor drive unit 116 to pressurize and suck ink. Take control.

  The internal structure of the recording unit 20 in which the moving mechanism is incorporated will be described with reference to FIGS.

  FIG. 3 is a perspective view showing the internal structure of the recording unit during printing standby. 4 is a perspective view showing a housing and a slide unit of the recording unit of FIG. FIG. 5 is a top view showing the slide unit of FIG. FIG. 6 is a side view showing the slide unit of FIG. FIG. 7 is a perspective view showing a housing and a cap slide unit of the recording unit of FIG. FIG. 8 is a perspective view showing a schematic configuration of the head holder.

  The recording unit 20 includes a rectangular base plate 130 corresponding to the bottom wall of the recording unit 20, an upper plate 132 corresponding to the upper wall of the recording unit 20, and three guide posts 134 a that fix the base plate 130 and the upper plate 132. A housing is constituted by 134b and 134c. The two guide posts 134a and 134b rise from both ends in the longitudinal direction of the short side of the rectangular base plate 130, and the one guide post 134c rises from the longitudinal center of the other short side. The guide posts 134a, 134b, and 134c are parallel to each other, and one end (lower end) in the longitudinal direction is fixed to the base plate 130, and the other end (upper end) in the longitudinal direction is fixed to the upper plate 132. .

  On each guide post 134a, 134b, 134c, slide bearing portions 136a, 136b, 136c having a length of about one-fourth of the guide posts 134a, 134b, 134c are attached so as to freely move up and down (moves in the direction of arrow D). It has been. Each guide post 134a, 134b, 134c penetrates each slide bearing portion 136a, 136b, 136c. The slide bearing portions 136a, 136b, and 136c are connected by a plate-like slide unit 138. The slide bearing portions 136a, 136b, and 136c and the slide unit 138 are simultaneously guided by the guide posts 134a, 134b, and 134c in the vertical direction. Is configured to move. That is, the slide unit 138 moves the slide bearing portions 136a, 136b, and 136c simultaneously. The base plate 130, the upper plate 132, and the slide unit 138 are made of a material having the same thermal expansion coefficient. For this reason, the same degree of expansion and contraction is performed according to changes in the surrounding temperature, so that the positional relationship is maintained with high accuracy.

  A rack 140 is fixed to the slide bearing portion 136a, and a pinion gear 142 is engaged with the rack 140. The pinion gear 142 is connected to the motor 146 via a plurality of gears 144. The pinion gear 142, the plurality of gears 144, and the motor 146 constitute a drive unit referred to in the present invention. When the motor 146 is driven, the gear 144 rotates to rotate the pinion gear 142, and the rotation of the pinion gear 142 causes the rack 140 to move up and down, and the slide bearings 136a, 136b, and 136c move along with the vertical movement. The slide unit 138 moves up and down.

  The slide unit 138 has four rectangular sides, and a rectangular parallelepiped head holder 150 is detachably mounted inside the four sides. As shown in FIG. 8, the six print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y (see FIG. 2) are fixed to the head holder 150 with screws or the like.

  Below the head holder 150, a cap slide unit 160 is fixed to the base plate 130 so as to be movable in the direction of arrow C in order to clean the six print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y. As shown in FIG. 7, the cap slide unit 160 includes a cap member 162 for capping the face surfaces (discharge port surfaces) of the six print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y, and urethane for wiping the face surfaces. Blade 164 is provided. When the recording unit 20 is on standby, the six print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y are capped by the cap member 162.

  A CPU (control board) 100 that controls the operation of the recording unit 20 is attached to the top of the recording unit 20. A print head control circuit (control board) 112 that controls ink ejection of the six print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is mounted on the head holder 150.

  As shown in FIGS. 4 and 5, the slide unit 138 includes slide bearing portions 136a, 136b, and 136c, and four connecting plates 138a, 138b, 138c, and 138d that connect them. The four connecting plates 138a, 138b, 138c, 138d are rectangular. The slide unit 138 is provided with a flag 138f for recognizing the moving position and a rack 140 serving as a drive transmission member. The flag 138f recognizes the position of the slide unit 138 by turning on / off the photo interrupter 148 shown in FIG. The photo interrupter 148 is fixed to a support plate (not shown).

  Cylindrical bushes 137a, 137b, and 137c are fixed inside the slide bearing portions 136a, 136b, and 136c. Guide posts 134a, 134b, and 134c are inserted into the bushes 137a, 137b, and 137c, and the bushes 137a, 137b, and 137c move up and down while contacting the guide posts 134a, 134b, and 134c, respectively. The bushes 137a and 137b and the bush 137c are located on different planes with respect to the plane orthogonal to the moving direction (arrow D direction). As shown in FIG. 6, the bushes 137a and 137b are attached at positions lower than the bush 137c. The bushes 137a and 137b are in a range indicated by La, and the bush 137c is in a range indicated by Lc. That is, the bushes 137a and 137b are closer to the base plate 130 than the bush 137c, and conversely, the bush 137c is farther from the base plate 130 than the bushes 137a and 137b. Of the bushes 137a, 137b, and 137c that directly contact the guide posts 134a, 134b, and 134c as described above, the bush 137a that is directly moved up and down by the motor 146 (this is an example of the drive-side contact moving member in the present invention). Since the most distant position of the bush 137c is positioned above the bush 137a, the bush 137c can smoothly follow the movement of the bush 137a, and the slide unit 138 maintains the same posture without rattling (without shaking). Moves smoothly while standing.

  Further, between the bushes 137a, 137b, 137c and the guide posts, there is a linear motion type bearing (not shown) made of a ball or a roller that moves at a relatively half speed between them. It may be inserted. The length (La) of the bush 137a is set to such a length that the bare link (bearing that contacts the bush 137a) does not protrude from the end of the bush 137a even if the slide unit 138 moves to the maximum possible range. For this reason, the contact area (contact area) between the bearing and the bush 137a is increased, and the inclination of the slide unit 138 is prevented. Further, if all the lengths of the three bushes 137a, 137b, and 137c have the same long configuration, the slide unit 138 may not move smoothly even if the parallelism of the bushes or the guide posts is slightly different. Therefore, the setting of the bush having the above length is necessary and sufficient with only one bush 137a. When the slide unit 138 is moved up and down, it is guided and moved by the guide posts 134a, 134b, and 134c. Therefore, in order to ensure the positional accuracy of the slide unit 138, the guide posts 134a, 134b, and 134c with respect to the base plate 130 are moved. Verticality is required. The above-described guide posts 134a, 134b, 134c, bushes 137a, 137b, 137c, a slide unit 138, a motor 146, and the like constitute a moving mechanism.

  As shown in FIG. 7, the cap slide unit 160 is configured by mounting various components and members on a plate-like cap slide base 166. To the cap slide base 166, two bearing portions 168 and 168 spaced apart from each other by a predetermined distance are fixed to a portion extending in parallel with the moving direction (arrow C direction), and further, the position of the cap slide base 166 is recognized. The flag 169 is fixed in the vicinity of one bearing portion 168. Further, two slide rollers 170, 170 are attached to the cap slide base 166 at a portion opposite to the two bearing portions 168, 168. The cap member 162 and the blade 164 described above are also fixed to the cap slide base 166.

  The two bearing portions 168 and 168 are movably fixed to a guide rod 172 extending in the direction of arrow C. Both ends in the longitudinal direction of the guide rod 172 are supported by a pair of support members 174 and 174 fixed to the base plate 130. A guide rail 176 extending in the direction of arrow C is formed on the base plate 130, and two slide rollers 170, 170 roll on the upper surface of the guide rail 176. The cap slide unit 160 moves freely in the direction of arrow C while being guided by the guide rod 172 and the guide rail 176 by the drive force of the drive unit 180 using the motor 178 as a drive source. The position where the cap slide unit 160 has been moved is detected by the flag 169 and the photo interrupters 182a and 182b.

  The cleaning operation of the recording unit 20 will be described with reference to FIG.

  FIG. 9 is a perspective view showing the recording unit 20 in which the cleaning operation is performed. In this figure, the same components as those shown in FIG. 3 are denoted by the same reference numerals.

  The cleaning operation of the recording unit 20 is executed before printing starts, at a predetermined timing, or when necessary. In this cleaning operation, the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y are cleaned.

  When the cleaning operation is executed, the head holder 150 is raised from the position of the cap state during standby, and the flag 138f of the slide unit 138 blocks the photo interrupter 149, so that the slide unit 138 and the head holder 150 are predetermined. Stop at the height position. The position of the predetermined height is a position suitable for each blade 164 on the cap slide unit 160 to wipe off the face surfaces of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y. At this position, the cap slide unit 160 receives the drive of the motor 178 and moves in the direction of the arrow C2 to perform wiping. At the time of this wiping, the blades 164 move in parallel uniformly, so that the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y are flat and parallel to the cap slide unit 160 (the face of each print head). The surface is parallel to the plane of the cap slide unit 160). If the flatness and the parallelism are not obtained, it causes unwiping of the face surface and uneven wiping, which causes a recovery failure of the print head. In this embodiment, in each of the head holder 150 and the cap slide unit 160, the print heads 22K, 22C, 22lC, 22M, 22lM, 22Y and the blades 164 are secured in parallel, and the slide unit 138 and the guide posts 134a, 134b are secured. , 134c (the guide posts 134a, 134b, 134c rising vertically from the slide unit 138) are also secured, so that no wiping residue or uneven wiping of the face surface occurs.

  Thereafter, the head holder 150 rises and the cap slide unit 160 returns to the same position as when the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y are capped. This position is detected by the flag 169 of the cap slide unit 160 blocking the photo interrupter 182a. When the cap slide unit 160 returns to the cap position, the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y perform a predetermined number of preliminary discharges toward the cap members 162, and the cleaning is completed. The ink discharged to each cap member 162 is collected in a sub tank (not shown) by a collection pump (not shown) through a collection tube (not shown) connected to each cap member. After the preliminary ejection from the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y is finished, printing is started or returns to the capping state.

  The recording operation (printing operation) of the recording unit 20 will be described with reference to FIG.

  FIG. 10 is a perspective view showing the recording unit 20 in which the recording operation is executed. In this figure, the same components as those shown in FIG. 3 are denoted by the same reference numerals.

  When the recording unit 20 shifts from the standby state to the recording state, the head holder 150 is once raised, and the cap slide unit 160 is moved in the direction of the arrow C1 by driving the motor 178 in this state. The base plate 130 is formed with openings through which the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y pass downward. For this reason, the head holder 150 moves to a predetermined recording position together with the slide unit 138. The fact that the slide unit 138 has reached the recording position together with the head holder 150 is recognized (detected) by the photo interrupter 148 provided on the main body of the recording unit 20 and the flag 138f provided on the slide unit 138. When the slide unit 138 is positioned at the recording position, the slide unit 138 is stopped by the stopper 131.

  The higher the parallelism with respect to the recording medium (medium), the higher the image quality of the face surfaces of the print heads 22K, 22C, 22lC, 22M, 22lM, and 22Y in the print state. For this reason, the print heads 22K, 22C, 22lC, 22M, 22lM, 22Y, and thus the head holder 150 and the slide unit 138 in the print state are required to have high parallelism with respect to the recording medium, and it is necessary to increase the positional accuracy.

  The positional relationship between the bushes 137a, 137b, and 137c will be described with reference to FIGS.

  FIG. 11 is a schematic diagram showing the positional relationship and moments of the three bushes. FIG. 12 is a schematic diagram illustrating another example of the moving mechanism.

  As shown in FIG. 11, the bushes 137a and 137b and the bush 137c are arranged not on the same plane but shifted in the sliding direction (arrow D direction). That is, of the bushes 137b and 137c, the bush 137c farthest from the bush 137a is located on a plane different from the plane on which the bush 137a is located with respect to the plane orthogonal to the moving direction (arrow D direction). In FIG. 12, the three guide posts 134a, 134b, and 134c extend in the horizontal direction. The uppermost portion 139c of the portion where the bush 137c contacts the guide post 134c is located above the uppermost portion 139a of the portion where the bush 137a contacts the guide post 137a. The reason for this arrangement will be described.

  In FIG. 11, an arrow indicated by a two-dot chain line indicates a force direction or the like in a state where the slide unit 138 (see FIG. 3 or the like) is held.

  In the slide unit 138 (see FIG. 3 and the like) that moves up and down as guided by the guide posts 134a, 134b, and 134c, the bush 137a of the slide bearing portion 136a and the slide unit 138 have their own weight W with respect to the slide bearing portion 136a. A moment m1 around the contact point P1 with the guide post 134a is generated. Further, due to the moment m1, a moment m2 is also generated at the contact P2 between the bush 137c of the slide bearing portion 136c and the guide post 134c.

  The moment m2 generates a component force F1 that pushes the guide post 134c in the direction of the arrow F1. Since this component force F1 balances with the drag force F2 from the guide post 134c, a moment m3 that cancels the moment m2 acting on the slide bearing portion 136c is obtained. As a result, it is possible to prevent the slide bearing portion 136c from shaking (rattle) due to the moment. On the other hand, the bushes 137a and 137c of the slide bearing portions 136a and 136c are arranged on the same plane (so that the bushes 137a and 137c are located on the same plane with respect to a plane orthogonal to the moving direction (arrow D direction)). In this case, the moment m3 that cancels the drag F2 and the moment m2 does not occur. For this reason, the moving and stopped slide bearing portion 136c becomes unstable due to the influence of the moment m2 (a state in which rattling (blur) occurs). In this way, by disposing the bushes 137a and 137c in direct contact with the guide posts 134a and 134c in the moving direction, the slide unit 138 always obtains a stable state even in the up and down operation and holding state. It is done.

  In the above-described example, the example in which the three guide posts 134a, 134b, and 134c extend in the substantially vertical direction (an example of directions other than the horizontal direction) has been described. With reference to FIG. 12, the case where the three guide posts 134a, 134b, 134c extend in the horizontal direction (arrow H1, H2 direction) will be described.

  Here, it is assumed that the three guide posts 134a, 134b, 134c extend in the horizontal direction (arrow H1, H2 direction). Further, the length of the bush 137a (137b) in contact with the guide post 134a (134b) in the moving direction (arrow H1, H2 direction) is L1, and the moving direction of the bush 137c in contact with the guide post 134c (arrow) The length of (H1, H2 direction) is L2. The moving direction length L2 here refers to the distance from the most upstream contact position in the moving direction to the most downstream contact position, and the portion that is not in contact with the intermediate portion (non-contact portion). Even if it exists, the length includes this non-contact portion.

  Here, L1 and L2 are in a relationship of L1 <L2, and both end portions in the L2 moving direction (arrow H1, H2 direction) are always upstream and downstream of both end portions in the L1 moving direction (arrow H1, H2 direction). To position. By moving the bush 137a in the direction of the arrow H1, a moment m3 is generated at the bearing center P3. At this time, component forces f1 and f2 that press the guide posts 134c are generated in M21 and N21, respectively, and balance with the drag forces f11 and f22, so the moment m3 generated at the bearing center P3 is canceled by the drag forces f11 and f22. A moment m4 in the direction is generated. Since the moment m4 increases as the distance between the bearing center P3 and M21 and N21 increases, the force to cancel the moment m3 also increases. As L2 increases, the state of the slide unit 138 during horizontal movement can be kept stable. Further, when the bush 137a is moved in the direction of the arrow 2, it is possible to keep the state of the slide unit 138 in a stable state by the same effect. M21 is a portion of the portion where the bush 137c contacts the guide post 134c, which is the most downstream side in the direction of the arrow H1 (the most upstream side in the direction of the arrow H2, hereinafter the same), and the portion closest to the bush 137a. Say. M22 refers to a portion of the portion where the bush 137c contacts the guide post 134c that is the most downstream side in the direction of the arrow H1 and is farthest from the bush 137a. N21 refers to a portion of the portion where the bush 137c is in contact with the guide post 134c which is the most downstream side in the direction of the arrow H2 and is farthest from the bush 137a. N22 refers to a portion which is the most downstream side in the direction of the arrow H2 among the portions where the bush 137c contacts the guide post 134c and which is closest to the bush 137a.

  A second embodiment will be described with reference to FIGS. 13 to 15.

  FIG. 13 is a perspective view showing the moving mechanism of the second embodiment, and the same components as those shown in FIG. 4 are denoted by the same reference numerals. FIG. 14 is a top view showing the moving mechanism of FIG. 13, and the same reference numerals are given to the same components as those shown in FIG. FIG. 15 is a side view showing the moving mechanism of FIG. 13, and the same reference numerals are given to the same components as those shown in FIG.

  The moving mechanism 200 according to the second embodiment is different from the moving mechanism according to the first embodiment in that the moving mechanism 200 according to the second embodiment includes four guide posts 234a, 234b, 234c, and 234d, and each guide post 234a. , 234b, 234c, 234d are attached with slide bearings 236a, 236b, 236c, 236d. Further, bushes 237a, 237b, 237c, and 237d are incorporated in the slide bearing portions 236a, 236b, 236c, and 236d. The bushes 237a and 237b are located at the lower ends (ranges indicated by L3 in FIG. 15) of the slide bearing portions 236a and 236b, and the bushes 237c and 237d are the upper ends of the slide bearing portions 236c and 236d (L4 in FIG. 15). (Range indicated by). The positional relationship between the bushes 237a and 237b and the bushes 237c and 237d is the same as the positional relationship between the bushes 137a and 137b and the bush 137c described in the first embodiment.

  The slide bearing portions 236a and 236b are connected by a connecting plate 238a, and the slide bearing portions 236b and 236c are connected by a connecting plate 238b. The slide bearing portions 236c and 236d are connected by a connecting plate 238c, and the slide bearing portions 236d and 236a are connected by a connecting plate 238d. A rack 140 is fixed to the slide bearing portion 236a.

  The moving mechanism 200 according to the second embodiment includes the four guide posts 234a, 234b, 234c, and 234d and the four slide bearing portions 236a, 236b, 236c, and 236d. Although it becomes complicated, rigidity is improved and better accuracy can be secured.

1 is a perspective view schematically illustrating an example of a printer in which a moving mechanism of the present invention is incorporated. FIG. 2 is a block diagram illustrating an electrical system of the printer of FIG. 1. It is a perspective view which shows the internal structure of the recording unit at the time of printing standby. It is a perspective view which shows the housing | casing and slide unit of the recording unit of FIG. It is an upper view which shows the slide unit of FIG. It is a side view which shows the slide unit of FIG. It is a perspective view which shows the housing | casing and cap slide unit of the recording unit of FIG. It is a perspective view which shows schematic structure of a head holder. FIG. 6 is a perspective view illustrating a recording unit that performs a cleaning operation. It is a perspective view which shows the recording unit with which recording operation is performed. It is a schematic diagram which shows the positional relationship and moment of three bushes. It is a schematic diagram which shows the other example of a moving mechanism. FIG. 13 is a perspective view illustrating the moving mechanism of the second embodiment. It is a top view which shows the moving mechanism of FIG. It is a side view which shows the moving mechanism of FIG.

Explanation of symbols

10 Printer 20 Recording unit 22K, 22C, 22lC, 22M, 22lM, 22Y Print head 130 Base plate 131 Stopper 132 Upper plates 134a, 134b, 134c Guide posts 136a, 136b, 136c Slide bearings 137a, 137b, 137c Bush 138 Slide unit 140 Rack 142 Pinion gear 146 Motor 150 Head holder

Claims (10)

A plurality of guide posts that are arranged in parallel to each other and extend in a predetermined movement direction, a plurality of contact movement members that move in the movement direction while contacting each of the plurality of guide posts, and a plurality of the contact movement members. In a moving mechanism comprising a slide unit that is connected and moved simultaneously,
A driving unit for driving one of the plurality of contact moving members to move in the moving direction;
Of the plurality of contact moving members, the contact moving member farthest from the driving side contact moving member driven by the drive unit is positioned on the plane perpendicular to the moving direction. A moving mechanism characterized in that the moving mechanism is located on a plane different from the plane to be moved. The plurality of guide posts extend horizontally.
The length in the moving direction in which the driving side contact moving member contacts the guide post is shorter than the length in the moving direction in which the contact moving member farthest from the driving side contact moving member contacts the guide post. And
Of the portion where the contact moving member farthest from the driving side contact moving member contacts the guide post, the most upstream portion in the moving direction is the portion where the driving side contact moving member contacts the guide post. It is located on the upstream side in the movement direction with respect to the most upstream part in the movement direction, and
Of the portions where the contact moving member farthest from the drive side contact moving member contacts the guide post, the most downstream portion in the moving direction is the portion where the drive side contact moving member contacts the guide post. The moving mechanism according to claim 1, wherein the moving mechanism is located on the downstream side in the moving direction with respect to the most downstream portion in the moving direction. The plurality of guide posts extend in a direction other than the horizontal direction,
The uppermost part of the part where the contact moving member farthest from the drive side contact moving member contacts the guide post is higher than the uppermost part of the part where the drive side contact moving member contacts the guide post. The moving mechanism according to claim 1, wherein the moving mechanism is also located above. In an image forming apparatus for forming an image by discharging ink from a print head to a recording medium,
The print head is mounted on the slide unit,
An image forming apparatus comprising the moving mechanism according to claim 1. A head holder for holding the print head;
The image forming apparatus according to claim 4, wherein the head holder is mounted on the slide unit. A base plate to which longitudinal ends of the plurality of guide posts are fixed;
An upper plate to which the other longitudinal ends of the plurality of guide posts are fixed;
The image forming apparatus according to claim 4, wherein the base plate, the upper plate, and the slide unit have the same thermal expansion coefficient. The image forming apparatus according to claim 4, wherein the plurality of contact moving members are cylindrical bushes into which the guide posts are inserted. The image forming apparatus according to claim 4, further comprising a stopper that stops the slide unit at a predetermined position. The drive unit is
A rack formed integrally with the drive side contact moving member;
The image forming apparatus according to claim 4, further comprising a pinion gear that meshes with the rack. A flag fixed to the slide unit;
The image forming apparatus according to claim 4, further comprising a photo interrupter that is turned on / off by the flag.

Images