JP2014188794A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suggest a printer having a platen gap adjustment mechanism including a synchronous rotation mechanism in which the number of components is small and which does not require large installation space.SOLUTION: A platen gap adjustment mechanism 70 of a printer 1 adjusts a gap by moving a first and a second guide shafts 57 and 58 supporting a head carriage 59 in a gap adjustment direction with respect to a platen 25. A synchronous rotation mechanism, which rotationally drives the first and the second guide shafts 57 and 58 in a synchronous manner for gap adjustment, includes: a rotary shaft 101 orthogonal to the first and the second guide shafts 57 and 58; a first and a second driving side gears 104 and 105 provided coaxially at the rotary shaft 101; a first driven side gear 106 provided coaxially at the first guide shaft 57 and meshing with the first driving side gear 104; and a second driven side gear 107 provided coaxially at the second guide shaft 58 and meshing with the second driving side gear 105.

Description

  The present invention relates to a printer including a platen gap adjustment mechanism that adjusts a gap between a print head and a platen.

  A printer, for example, an inkjet printer, includes a platen gap adjustment mechanism that adjusts a gap between a nozzle surface of an inkjet head and a platen (or a gap between a nozzle surface and a printing surface of a print medium conveyed on the platen). ing. The platen gap adjustment mechanism uses a control signal from the printer's built-in control unit or host device according to the print media specifications (thickness, surface state), printer state (error state), etc. The gap (or the gap between the nozzle surface and the printing surface of the print medium) can be adjusted.

  Patent Documents 1 and 2 disclose a printer having such a platen gap adjustment mechanism. In the printers disclosed in Patent Documents 1 and 2, a carriage on which a recording head is mounted is supported by two carriage guide shafts. The two carriage guide shafts are attached to an elevating frame, and the elevating frame is attached to a side frame of the printer main body so as to be movable up and down.

  The platen gap adjusting mechanism transmits the rotation of the lifting motor attached to the printer main body to one carriage guide shaft through a gear-type transmission mechanism. The rotation transmitted to the carriage guide shaft is transmitted to the other carriage guide shaft via a gear train composed of a plurality of spur gears. A cam mechanism for changing the rotation of the carriage guide shaft to the lifting and lowering motion of the carriage guide shaft is disposed at the shaft end portion of each carriage guide shaft. When each carriage guide shaft rotates synchronously, each carriage guide shaft moves up and down synchronously by the cam mechanism, and the gap between the recording head mounted on the carriage and the stationary platen increases or decreases.

  In Patent Document 1, as a mechanism for transmitting rotation from one carriage guide shaft to the other carriage guide shaft, a timing spanned between two carriage guide shafts in addition to a gear train composed of a plurality of spur gears. A mechanism using a belt and a mechanism using a connecting rod spanned between rotating disks attached to the shaft ends of two carriage guide shafts are disclosed.

Japanese Patent Laying-Open No. 2005-280206 JP 2005-280209 A

  Here, the conventional platen gap adjusting mechanism has the following problems to be solved. First, in a synchronous rotation mechanism that synchronously rotates two carriage guide shafts connected by a gear train composed of spur gears, a plurality of spur gears must be disposed between the two carriage guide shafts. Accordingly, the number of spur gears constituting the synchronous rotation mechanism increases with an increase in the inter-axis distance, and the lifting frame for attaching these components also increases. Further, since it is necessary to decelerate and transmit the rotation of the elevating motor, a predetermined number or more of spur gears are necessary for the deceleration. For this reason, the installation space of a synchronous rotation mechanism will also become large.

  Even in the mechanism using the timing belt, it is necessary to secure an installation space for the timing belt that spans between the two axes. Therefore, when the distance between the axes is large, the installation space increases greatly. Similarly, in a mechanism in which a connecting rod is bridged on a rotating disc attached to two axes, it is necessary to secure a moving space for the connecting rod that moves with the rotating disc, so that the installation space is increased.

  Second, since the synchronous rotation mechanism consisting of spur gears has backlash in meshing with each gear, both carriage guide shafts are accurately synchronized due to the backlash at the start of transmission of rotation and during reverse rotation. Can not take and rotate. If both the carriage guide shafts do not rotate synchronously, the lift amount of each carriage guide shaft generated with the rotation also varies. As a result, the platen gap may vary between one carriage guide shaft side and the other carriage guide shaft side.

  Even in the mechanism using the timing belt, there is a possibility that the same trouble may occur due to the backlash between the teeth of the timing belt and the gear around which the timing belt is stretched. Further, even in a mechanism in which a connecting rod is bridged on a rotating disk, there is a risk that the same adverse effect may occur due to rattling of the connecting shaft portion between the rotating disk and the connecting rod.

  In order to avoid such variations in synchronous drive, it is necessary to provide a play (dead zone) in the cam mechanism for converting the rotation of each axis into the raising / lowering operation of each axis. In this way, both shafts can be moved up and down after the backlash between the gears in the synchronous rotation mechanism at the start of rotation of each axis and at the time of reversal is eliminated and the synchronous rotation state is formed. Can be performed with high accuracy. However, since play is provided in the rotating cam, the diameter of the rotating cam increases and the installation space for the cam mechanism increases.

  Thirdly, in the conventional platen gap adjusting mechanism, the rotation of the fixed lifting motor attached to the printer body is transmitted to the lifting carriage guide shaft via the gear transmission mechanism. In the gear transmission mechanism, the fixed-side spur gear and the lift-side spur gear are held in mesh. Since it is necessary to maintain the meshing state of the stationary and elevating gears, the elevating amount of the elevating side spur gear cannot be increased. For this reason, it may be difficult to increase the platen gap adjustment amount.

  Fourth, the gear-type transmission mechanism includes a plurality of spur gears that rotate about an axis parallel to the central axis of the carriage guide shaft. When the rotational force from the fixed raising / lowering motor side is transmitted to a gear coaxially fixed to the carriage guide shaft, a force acts on the gear in the rotational direction from the driving gear. Accordingly, a force acts in the direction in which the carriage guide shaft is raised and lowered. In order to prevent the carriage guide shaft from moving up and down by such force, it is necessary to arrange a spring member capable of generating a large spring force and press the carriage guide shaft. Since such a large force acts, the durability of the parts supporting the carriage guide shaft and parts such as gears is reduced, and a large installation space for the spring member is also required.

  In view of the above, an object of the present invention is to propose a printer having a platen gap adjustment mechanism including a synchronous rotation mechanism that has a small number of parts and does not require a large installation space.

  Another object of the present invention is to propose a printer having a platen gap adjustment mechanism provided with a synchronous rotation mechanism capable of synchronously rotating two carriage guide shafts with high accuracy.

  Another object of the present invention is to propose a printer including a platen gap adjustment mechanism with a large gap adjustment amount.

  Still another object of the present invention is to propose a printer having a platen gap adjustment mechanism provided with a rotation transmission mechanism in which a large force does not act in the gap adjustment direction.

  In order to solve the above problems, a printer of the present invention includes a print head, a head carriage on which the print head is mounted, and a first guide shaft and a second guide shaft that extend in parallel and support the head carriage. The platen facing the print head and the gap adjustment between the print head and the platen are performed by moving the first and second guide shafts in the gap adjustment direction approaching and separating from the platen. A platen gap adjusting mechanism. The platen gap adjusting mechanism includes a synchronous rotation mechanism that drives the first guide shaft and the second guide shaft to rotate synchronously. The synchronous rotation mechanism includes: a rotation shaft extending in a direction perpendicular to the first guide shaft and the second guide shaft; a first drive side gear and a second drive side gear provided coaxially with the rotation shaft; A first driven gear provided coaxially with one guide shaft and meshed with the first drive side gear, and a second driven gear provided coaxially with the second guide shaft and meshed with the second drive side gear. And a side gear.

  The first drive side gear and the first driven side gear mesh with each other in a state where their rotation center lines are orthogonal to each other. Similarly, the second drive side gear and the second driven side gear mesh with each other in a state where their rotation center lines are orthogonal to each other. In order to form such an engagement, it is desirable that the first drive side gear and the second drive side gear are worms, and the first driven side gear and the second driven side gears are worm wheels. Instead of such a cylindrical worm gear pair, a bevel gear can be used.

  In the synchronous rotation mechanism of the present invention, the first and second drive-side gears are provided on the rotation shaft arranged in a state orthogonal to the first and second guide shafts. That is, the first and second driving gears are coaxially fixed to the rotating shaft, or are integrally formed coaxially. The rotation of the rotation shaft is transmitted from the first and second drive gears to the first and second driven gears on the first and second guide shaft sides. When the distance between the first and second guide shafts is large, the shaft length of the rotating shaft may be increased, and there is no need to increase the number of gears. Therefore, compared to a conventional synchronous rotation mechanism such as a synchronous rotation mechanism composed of a plurality of spur gears, the synchronous rotation mechanism can be configured with a small number of parts, and the installation space can be reduced.

  Further, since the first and second drive side gears are provided on the same rotation shaft, they rotate integrally with the rotation shaft in complete synchronization. Since the first and second drive side gears are meshed with the first and second driven gears whose rotation center lines are orthogonal to each other, the meshing backlash is larger than that in the case where the spur gears whose rotation center lines are parallel to each other. Few. In particular, in the case of a cylindrical worm gear pair, the backlash is substantially zero. Therefore, since the first and second guide shafts can be rotated synchronously with high accuracy, the platen gap can be adjusted with high accuracy.

  Further, when a worm is used for the first and second drive side gears and a worm wheel is used for the first and second driven side gears, in order to obtain a predetermined reduction ratio as compared with the case of meshing of spur gears. Requires fewer gears. Therefore, it is advantageous for reducing the size and size of the platen gap mechanism.

  Furthermore, the first and second drive side gears and the first and second driven side gears mesh with each other in a state where the rotation center lines are orthogonal to each other. The force in the direction of moving the driven side gear in the rotational direction from the driving side gear to the driven side gear does not substantially act. A force to move the guide shaft to which the driven gear is attached in the gap adjustment direction does not act. Therefore, unlike the case of a gear-type transmission mechanism consisting of meshing spur gears, a large force is not applied to the guide shaft in the gap adjustment direction, and a large spring force is applied so that the guide shaft does not move in the gap adjustment direction. There is no need to hold it down.

  Here, the platen gap adjusting mechanism includes a first cam mechanism that converts rotation of the first guide shaft into movement of the first guide shaft in the gap adjusting direction, and rotation of the second guide shaft. It can be set as the structure provided with the 2nd cam mechanism converted into the movement of the said gap adjustment direction of 2 guide shafts. In this case, the first and second cam mechanisms can be cam mechanisms having the same configuration. The cam mechanism is coaxially fixed to the first guide shaft or the second guide shaft, and is disposed at a fixed position in the gap adjustment direction, and a rotating cam having an outer peripheral cam surface, and the outer peripheral cam surface A cam follower that is slidably abutted on the outer cam surface, and the abutting position of the outer cam surface and the cam follower moves in the gap adjustment direction as the rotating cam rotates. It can be set as the structure by which the shape of the outer periphery cam surface was set.

  In the platen gap adjusting mechanism of the present invention, as described above, the first and second guide shafts rotate synchronously with high accuracy. Therefore, in the rotating cam type cam mechanism that converts the rotation of the first and second guide shafts into movement of the shafts in the gap adjustment direction, the play for absorbing the variation in the synchronous rotation of the two guide shafts is absorbed. There is no need to provide. Therefore, the diameter of the rotating cam can be reduced, which is advantageous for downsizing the platen gap adjusting mechanism. In addition, the platen gap can be adjusted efficiently in a short time.

  Here, in the platen gap adjusting mechanism, the first driven gear is fixed to one first shaft end portion of the first guide shaft, and the second driven gear is connected to the first guide shaft on the second guide shaft. The first cam mechanism is fixed to the shaft end on both sides of the first guide shaft, and the second cam mechanism is connected to the second guide. It is desirable to arrange at the shaft end portions on both sides of the shaft.

  The first and second guide shafts move in the gap adjustment direction in synchronization with the rotation by the first and second cam mechanisms at the shaft end portions on both sides thereof. Therefore, the platen gap can be accurately adjusted without variation even in the axial direction of the first and second guide shafts.

  Next, it is desirable that the platen gap adjusting mechanism includes a driving side rotating shaft connected to the rotating shaft via a universal joint, and a rotation driving source for rotating the driving side rotating shaft.

  The rotation drive source and the drive side rotation shaft are generally arranged at fixed positions in the gap adjustment direction, and the rotation shaft on the first and second guide shaft side moves in the gap adjustment direction together with the first and second guide shafts. . The fixed drive side rotary shaft and the movable side rotary shaft are connected via a universal joint. Even if the moving side rotating shaft is displaced in the gap adjusting direction, the rotational force is transmitted from the driving side rotating shaft to the moving side rotating shaft. Increase the amount of movement in the gap adjustment direction of the rotating shaft on the moving side compared to moving the moving spur gear relative to one driving spur gear while maintaining the meshing of the spur gears. Is easy. Therefore, a platen gap adjustment mechanism with a large gap adjustment amount can be easily realized.

1 is a front perspective view showing a printer to which the present invention is applied. FIG. 2 is a rear perspective view showing the printer of FIG. 1. FIG. 2 is a schematic longitudinal sectional view and a partial sectional view showing the printer of FIG. 1. FIG. 2 is a rear perspective view showing the printer of FIG. 1, showing a state where a reversing unit is opened. It is a top view which shows the printer mechanism part of the printer of FIG. FIG. 6 is a front perspective view illustrating the printer mechanism unit of FIG. 5. FIG. 6 is a rear perspective view illustrating the printer mechanism unit of FIG. 5. FIG. 2 is a rear perspective view showing a platen gap adjustment mechanism of the printer of FIG. 1. It is a front perspective view which shows the platen gap adjustment mechanism of FIG. It is a fragmentary perspective view which shows the principal part of the platen gap adjustment mechanism of FIG. It is a fragmentary perspective view which shows the principal part of the platen gap adjustment mechanism of FIG. It is a partial side view which shows the principal part of the platen gap adjustment mechanism of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the present invention is applied to an inkjet printer including a reversing unit capable of duplex printing. The present invention can be similarly applied to an inkjet printer that does not include a reversing unit and a printer other than the inkjet printer.

[Entire printer configuration]
FIG. 1 is an external perspective view when an ink jet printer (hereinafter simply referred to as “printer”) according to the present embodiment is viewed from the front, and FIG. 2 is an external perspective view when the printer is viewed from the rear. . 3A is a schematic longitudinal sectional view showing the internal configuration of the printer, and FIG. 3B is a partial longitudinal sectional view.

  The overall shape of the printer 1 will be described mainly with reference to FIGS. 1 and 2. The printer 1 includes a printer main body 2 and a reversing unit 3. The printer main body 2 is covered with a main body case 2A having a rectangular parallelepiped shape that is long in the printer width direction X as a whole, and a concave portion 4 is formed in the central portion of the back surface thereof, and the reversing unit 3 is attached thereto. Has been. The reversing unit 3 is a unit for returning the paper to the printer main body 2 with the front and back sides of a printing paper (hereinafter simply referred to as “paper”) being a sheet-like medium reversed. The reversing unit 3 is an open / close reversing unit as will be described later, and can be opened rearward in the front-rear direction Y of the printer with the lower end portion of the printer in the vertical direction as the center.

  A paper cassette mounting portion 5 is provided on the front surface of the printer main body portion 2. The paper feed cassette mounting unit 5 is opened forward of the printer longitudinal direction Y in the lower part of the printer vertical direction Z on the front surface of the printer body 2. A paper feed cassette 6 is detachably attached to the paper feed cassette mounting portion 5 from the front. A paper discharge tray 7 is attached to the upper side of the paper cassette mounting unit 5. The paper discharge tray 7 protrudes substantially horizontally forward. A rectangular paper discharge port 8 extending to the rear of the printer is formed on the upper side of the paper discharge tray 7.

  The front surface of the printer above the paper discharge port 8 is an operation surface 9. On the operation surface 9, a power switch 9a, a plurality of status display lamps 9b, and the like are arranged. Rectangular opening / closing lids 10 a and 10 b are attached to the front surface of the printer on both sides of the paper discharge tray 7 and the paper discharge port 8. When these opening / closing lids 10a and 10b are opened, an ink cartridge mounting portion (not shown) is opened, and the ink cartridge (not shown) can be replaced. The upper surface portion of the printer is a substantially flat surface, and a maintenance opening / closing lid 11 is attached to the center portion thereof.

[Printer paper path]
With reference to FIG. 3, an internal configuration of the printer 1, in particular, a paper conveyance path will be described. Inside the printer 1, a paper supply path 12, a main body side conveyance path 13 and a reverse conveyance path 14 are formed. The paper supply path 12 and the main body side conveyance path 13 are formed inside the printer main body 2, and the reverse conveyance path 14 is formed inside the reversing unit 3.

  The paper supply path 12 is a transport path for supplying paper P having a predetermined size stored in the paper feeding cassette 6 in a stacked state to the main body side transport path 13. The paper supply path 12 extends obliquely upward toward the rear of the printer from the rear end portion of the printer front-rear direction Y in the paper feed cassette mounting portion 5, curves to the front of the printer, and is connected to the main body-side transport path 13. The paper P stored in the paper feed cassette 6 is sent out to the paper supply path 12 by the paper feed roller 15. The fed sheets are fed one by one through the nip portion between the retard roller 16 and the transport roller 17 which are medium separation rollers. The paper P sent out through the nip portion between the retard roller 16 and the transport roller 17 is transported toward the main body side transport path 13 through the nip portion between the transport roller 17 and the driven roller 18.

  The main body side conveyance path 13 is a conveyance path that extends substantially horizontally in the front-rear direction Y of the printer and reaches the paper discharge port 8. A paper detection lever 20, a paper feed roller pair 21, a print head 22, a first paper discharge roller pair 23, and a second paper discharge roller pair 24 are arranged in order from the upstream side in the paper transport direction along the main body side transport path 13. Has been placed. The print head 22 is an inkjet head, and the platen 25 is arranged with a certain gap with respect to the nozzle surface.

  The paper fed from the paper supply path 12 to the main body side conveyance path 13 is fed by the conveyance roller 17 to the paper feed roller pair 21 while pushing up the paper detection lever 20. The paper fed to the paper feed roller pair 21 is transported toward the first paper discharge roller pair 23 via the printing position of the print head 22 by the paper feed roller pair 21. The sheet fed to the first discharge roller pair 23 is discharged from the discharge port 8 to the discharge tray 7 via the first discharge roller pair 23 and the second discharge roller pair 24.

  On the other hand, the reversing conveyance path 14 formed in the reversing unit 3 is arranged below the printer vertical direction Z with respect to the main body side conveyance path 13 and loops in the printer vertical direction Z as a whole. It is a conveyance path which draws. The reversing conveyance path 14 is continuous to the upstream end of the main body-side conveyance path 13 and extends substantially horizontally behind the printer front-rear direction Y, and continues to the upper path 26 below the printer vertical direction Z. A downward path 27 that is curved and extends linearly, a lower path 28 that curves and extends forward in the front-rear direction Y of the printer continuously to the downward path 27, and an upward direction that curves upward from the lower path 28 and extends upward A path 29 is provided.

  The upward path 29 has an upper portion that curves obliquely forward of the printer and joins the intermediate position of the paper supply path 12. Therefore, the upstream path 29 and the downstream portion of the paper supply path 12 form a common path 30. The common path 30 is a curved path extending along the outer peripheral surface of the paper transport roller 17.

  A first transport roller 31 and a driven roller 32 are disposed between the upper path 26 and the downward path 27, and a second transport roller 33 and a driven roller 34 are disposed between the lower path 28 and the upward path 29. ing. The paper fed from the main body side conveyance path 13 to the reversal conveyance path 14 is fed to the nip portion between the first conveyance roller 31 and the driven roller 32, and the first conveyance roller 31 causes the second conveyance roller 33 and the driven roller 34 to move. It is sent to the nip portion, and is sent to the nip portion between the transport roller 17 and the driven roller 18 by the second transport roller 33. Thereafter, the sheet is again fed into the main body side conveyance path 13 by the conveyance roller 17.

  By passing through the loop-shaped reversing conveyance path 14, the sheet is returned to the main body-side conveyance path 13 with the front and back sides reversed. Therefore, double-sided printing of paper can be performed by passing through the reversing conveyance path 14.

  Here, a path switching flap 36 is disposed at the junction 35 at the downstream end of the main body side transport path 13, the upstream end of the reversal transport path 14, and the downstream end of the common path 30. The path switching flap 36 is arranged so as to be rotatable in the printer vertical direction Z around the rear end portion of the printer longitudinal direction Y. In a normal state, the path switching flap 36 is held in the state of the first switching position where the front flap main body portion in the printer front-rear direction Y is placed on the outer peripheral surface of the transport roller 17 by its own weight.

  In this state, the paper that is back-fed from the main body side conveyance path 13 side is guided to the reversal conveyance path 14 side by the path switching flap 36. The sheet returns to the merging unit 35 again via the reversing conveyance path 14. The path switching flap 36 is moved up from the first switching position to the second switching position by being pushed up by the sheet returning to the merge section 35. When the path switching flap 36 is pushed up to the second switching position, the common path 30 on the downstream end side of the reversing conveyance path 14 communicates with the main body side conveyance path 13. Accordingly, the sheet is fed into the main body side conveyance path 13 while pushing up the path switching flap 36. After the sheet passes, the path switching flap 36 returns to the first switching position by its own weight again.

  Similarly, when the paper is supplied from the paper feed cassette 6, the path switching flap 36 is pushed up by the paper from the paper supply path 12 toward the main body side conveyance path 13. After the sheet passes, the path switching flap 36 returns to the first switching position by its own weight. Therefore, the sheet fed back from the main body side conveyance path 13 does not enter the reversal conveyance path 14 or the sheet supply path 12 via the common path 30. Further, the sheet path can be switched with a simple configuration without using a drive source, an urging member, or the like.

[Opening and closing inversion unit]
FIG. 4 is an external perspective view when the printer 1 is viewed from the rear, and shows a state where the reversing unit 3 is in the open position.

  As can be seen from FIGS. 2 and 4, the reversing unit 3 can be opened and closed with an opening / closing center line 40 located at the lower end portion in the printer vertical direction Z as the center. In the closed position 3A shown in FIG. 2, the reversing unit 3 stands upright in the up-down direction Z of the printer, and the back cover 42 of the unit case 41 is positioned substantially on the same plane as the left and right back portions of the printer main body 2. . In the open position 3B shown in FIG. 4, the reversing unit 3 is in a posture of being tilted substantially horizontally rearward in the front-rear direction Y of the printer. At the open position 3B, as can be seen from FIG. 4, the downstream upward path 29 and the common path 30 in the reversing conveyance path 14 are opened. Problems such as paper jams in these paths can be easily handled by opening the reversing unit 3.

  As shown in FIG. 2, the reversing unit 3 has an opening 42 a at the center of the upper end portion of the back cover 42 in the printer vertical direction Z. A pair of lever operation portions 43 are exposed from the opening 42a. When the pair of lever operation portions 43 are operated in a direction to approach each other, the left and right lock pieces 44 (see FIG. 4) protruding laterally from the left and right side surfaces of the reversing unit 3 are formed on the left and right side surfaces of the apparatus main body portion 2. The lock hole 45 (see FIG. 4) formed is removed. Thereby, the reversing unit 3 is unlocked and can be opened.

[Printer mechanism]
5 to 7 are a plan view, a front perspective view, and a rear perspective view showing the printer mechanism portion covered by the main body case 2A in the printer 1. FIG. 5 shows a state in which the main body case 2A, the paper discharge tray 7 and the unit case 41 of the reversing unit 3 are removed, and FIGS. 6 and 7 show a state in which the main body case 2A and the paper discharge tray 7 are removed.

  Referring to these drawings, the printer mechanism unit 50 includes a sheet metal printer main body frame 51, and each component is assembled to the printer main body frame 51. The printer main body frame 51 includes a base frame 52 and side frames 53 and 54 that stand vertically from both sides of the base frame 52 in the printer width direction X. A front frame 55 and a rear frame 56 are spanned between the side frames 53 and 54 in the printer width direction.

  Between the front frame 55 and the rear frame 56, two carriage guide shafts 57, 58 are spanned in parallel with the printer width direction X between the upper ends of the side frames 53, 54 in the vertical direction of the printer. In the following description, the carriage guide shaft 57 positioned on the rear frame 56 side is referred to as a first guide shaft 57, and the carriage guide shaft 58 positioned on the front frame 55 side is referred to as a second guide shaft 58. A head carriage 59 is mounted on the first and second guide shafts 57 and 58.

  The head carriage 59 is slidable in the printer width direction X along the first and second guide shafts 57 and 58. The head carriage 59 is connected to a timing belt 60 that extends in the printer width direction X at a position near the first guide shaft 57. The timing belt 60 is driven by a carriage drive motor 61.

  A print head 22 is mounted on the head carriage 59. The print head 22 is mounted on the head carriage 59 with its nozzle surface 22a (see FIG. 3) facing downward from the printer. A platen 25 is disposed below the print head 22. The platen 25 is a divided type platen that includes a plurality of divided platens 25 a arranged in the printer width direction X that is the moving direction of the print head 22. With the head carriage 59, the print head 22 can move from the home position HP on the side frame 53 side to the outer position on the side frame 54 side. That is, the print head 22 can reciprocate in the width direction of the main body side conveyance path 13 (print medium conveyance path) formed between the side frames 53 and 54.

  Here, the power transmission mechanism of the medium transport roller is assembled to the outer surface 53c of the one side frame 53 facing the outside of the printer. In this example, the power transmission mechanism 140 of the paper feed roller pair 21 and the first paper discharge roller pair 23 which are medium transport rollers is assembled. The paper feed roller pair 21 and the first paper discharge roller pair 23 are disposed on the upstream side and the downstream side of the platen 25 in the main body side conveyance path 13 which is a print medium conveyance path, and the first and second guides are also provided. It is located below the shafts 57 and 58 (see FIG. 3).

  The power transmission mechanism 140 will be described with reference to FIGS. A paper feed motor 141 is mounted on a portion of the base frame 52 on the side frame 53 side. The paper feed motor 141 is disposed so as to face outward in the printer width direction X, and a pinion 142 is coaxially fixed to the tip of the motor shaft. The shaft end portion 143 of the roller shaft of the roller on the driving side of the paper feed roller pair 21 is supported by the side frame 53 in a rotatable state, and protrudes outward. A transmission gear 144 is coaxially fixed to the protruding shaft end portion 143. Similarly, the shaft end portion 145 of the roller shaft of the driving-side roller of the first paper discharge roller pair 23 is also supported by the side frame 53 in a rotatable state and protrudes outward. A transmission gear 146 is coaxially fixed to the protruding shaft end 145. Further, a timing belt 147 is stretched over the pinion 142, the transmission gear 144, and the transmission gear 146.

[Platen gap adjustment mechanism]
Next, a platen gap adjusting mechanism 70 capable of adjusting the gap between the print head 22 and the platen 25 is mounted on the printer mechanism unit 50. The gap between the print head 22 and the platen 25 is the distance from the nozzle surface 22a of the print head 22 to the surface of the platen 25, or the distance from the nozzle surface 22a to the print surface of the paper P conveyed along the platen 25. It is. In the present specification, these distances are referred to as “platen gaps”.

  In this example, the platen 25 is mounted on the printer frame 51 side, and is disposed at a fixed position in the printer vertical direction Z. The platen gap adjusting mechanism 70 moves the two first and second guide shafts 57 and 58 located above the platen 25 in the vertical direction Z of the printer, thereby increasing or decreasing the platen gap. . Therefore, the printer vertical direction Z is the gap adjustment direction. It is also possible to adjust the platen gap by fixing the first and second guide shafts 57 and 58 to the printer frame 51 side and moving the platen 25 in the vertical direction Z of the printer.

  8 and 9 are partial perspective views showing the main part of the platen gap adjusting mechanism 70 taken out from the printer mechanism 50. FIG. In these drawings, the main part of the platen gap adjusting mechanism 70 is shown from different directions. The platen gap adjusting mechanism 70 is integrated with the fixed-side unit 80 having fixed-side components mounted on the printer body frame 51 side, and the first and second guide shafts 57 and 58, and is integrated with the printer vertical direction Z. The movable side unit 100 is provided with a movable component, a universal joint unit 90 that transmits rotational force from the fixed side unit 80 to the movable side unit 100, and rotary cam mechanisms 110 and 120.

  The fixed side unit 80 is arranged at the end of the side frame 53 on the rear side of the rear frame 56. The movable unit 100 is disposed along the inner surface 53 d of the side frame 53. The movable unit 100 includes a rotation transmission mechanism that transmits rotation to the first and second guide shafts 57 and 58. The rotation transmission mechanism of this example is a synchronous rotation mechanism that synchronously rotates the first and second guide shafts 57 and 58. Each of the rotating cam mechanisms 110 and 120 is disposed on both the inner surface of the side frame 53 and the inner surface of the side frame 54. The rotating cam mechanisms 110 and 120 are cam mechanisms that convert the rotation of the first and second guide shafts 57 and 58 into movement of the guide shafts 57 and 58 in the gap adjustment direction.

  Next, FIGS. 10, 11 and 12 are a partial perspective view when the main part of the platen gap adjusting mechanism 70 is viewed from the front side of the printer, a partial perspective view when viewed from the rear side of the printer, and the printer, respectively. It is a partial side view at the time of seeing from the width direction. The structure of the platen gap adjusting mechanism 70 will be described in detail mainly with reference to FIGS.

(Fixed side unit)
The fixed side unit 80 of the platen gap adjusting mechanism 70 includes a motor 81 that is a rotational drive source, a transmission gear train 82, and a fixed side rotating shaft 83. Each of these parts is fixed to the printer main body frame 51 via a unit frame (not shown). The motor 81 is horizontally arranged with the printer facing rearward. The fixed rotation shaft 83 is arranged at a position adjacent to the motor 81 such that the rotation center line 83a extends horizontally in the front-rear direction of the printer. The transmission gear train 82 includes a pinion 84 fixed to the output shaft of the motor 81, an intermediate transmission gear 85 that meshes with the pinion 84, and a shaft-side transmission gear 86 that meshes with the intermediate transmission gear 85. The shaft side transmission gear 86 is coaxially fixed to the shaft end portion on the rear side of the fixed side rotation shaft 83.

  A worm 87 is integrally formed at an intermediate portion of the fixed-side rotating shaft 83 in the axial direction. A compound gear 130 having a rotation center line extending in the printer width direction X orthogonal to the fixed rotation shaft 83 is disposed below the worm 87. The worm wheel 131 of the compound gear 130 is engaged with the worm 87. The compound gear 130 includes an external gear 132 in which external teeth are formed in a predetermined angular range in the circumferential direction. The external gear 132 can mesh with the fan-shaped external gear 133 within a predetermined angle range during one rotation. The fan-shaped external gear 133 is a gear having external teeth formed on a circular arc surface extending at a predetermined angle. A rotating shaft 134 that extends horizontally in the printer width direction X is disposed on the rear side of the first guide shaft 57. A rotating roller support plate 135 is attached to the rotating shaft 134 at regular intervals along the axial direction. The roller support plate 135 supports the driven roller 18 that is pressed by the transport roller 17 (see FIG. 3). By rotating the rotation shaft 134 within a predetermined angle range, the driven roller 18 supported by the roller support plate 135 is switched between a position pressed by the conveyance roller 17 and a release position away from the conveyance roller 17. It is possible.

(Universal joint unit)
The universal joint unit 90 includes a fixed side universal joint part 91 and a movable side universal joint part 92. The fixed side universal joint portion 91 is connected to the shaft end portion on the rear side of the printer of the fixed side rotation shaft 83 of the fixed side unit 80. The movable side universal joint portion 92 of the universal joint unit 90 passes through a through hole formed in the rear frame 56 with sufficient play and protrudes toward the movable side unit 100 located in front of the printer.

(Movable unit)
The movable unit 100 is guided by the side frames 53 and 54 and is movable in the gap adjustment direction (printer vertical direction Z). As can be seen from FIGS. 6 and 7, the side frame 53 is formed with guide holes 53 a and 53 b extending in parallel to the printer vertical direction Z that is the gap adjustment direction. One shaft end portions 57a, 58a of the first and second guide shafts 57, 58 penetrate the guide holes 53a, 53b in a slidable manner and project outward. Similarly, a pair of guide holes (not shown) are formed in the opposite side frame 54, and the other shaft end portions 57b and 58b of the first and second guide shafts 57 and 58 are formed in these guide holes. (Refer to FIG. 8 and FIG. 9) penetrates in a slidable state and protrudes outward.

  The first and second guide shafts 57 and 58 are guided by the guide holes 53a and 53b and are slidable in the vertical direction Z of the printer. Further, as shown in FIGS. 6 to 10, a torsion coil spring 62 is fixed to the outer surface 53 c of the side frame 53 at an upper portion of the power transmission mechanism 140. By the torsion coil spring 62, the shaft end portions 57a and 58a of the first and second guide shafts 57 and 58 are always urged downward of the printer. Similarly, as shown in FIGS. 8 and 9, between the other shaft end portions 57b and 58b of the first and second guide shafts 57 and 58 and the portion of the side frame 54 on the lower side, The tension coil springs 63 and 64 are bridged, respectively. The shaft end portions 57b and 58b are always urged toward the lower side of the printer.

  The movable unit 100 includes a movable rotating shaft 101 that extends horizontally in the longitudinal direction Y of the printer. The movable-side rotating shaft 101 is positioned above the shaft end portions 57a, 58a on the side frame 53 side of the first and second guide shafts 57, 58, and is along the inner surface 53d of the side frame 53 in the longitudinal direction Y of the printer. Are arranged horizontally. That is, it extends in a direction perpendicular to the first and second guide shafts 57 and 58. The movable side rotating shaft 101 is supported by the first bracket 102 and the second bracket 103 in such a manner that the shaft end portions 101 a and 101 b on both sides thereof are rotatable. The inter-axis distance (positional relationship) between the movable rotating shaft 101 and the first and second guide shafts 57 and 58 is maintained via the first and second brackets 102 and 103.

  As shown in FIG. 11, the first bracket 102 includes a top plate portion 102a, front and rear end plate portions 102b and 102c, and a side plate portion 102d. The movable side rotating shaft 101 is rotatably supported by the front and rear end plate portions 102b and 102c. The shaft end portion 57a of the first guide shaft 57 passes through the lower end portion of the side plate portion 102d in a rotatable state. The same applies to the second bracket 103, and the top plate portion 103a, the front and rear end plate portions 103b and 103c that support the movable rotary shaft 101 in a rotatable state, and the shaft end portion 58a of the second guide shaft 58. Is provided with a side plate portion 103d penetrating in a rotatable state.

  Spring hooks 102e and 103e are formed on the upper end portions of the side plate portions 102d and 103d of the first and second brackets 102 and 103, respectively. Spring ends 62a and 62b on both sides of the torsion coil spring 62 attached to the outer side surface of the side frame 53 are locked to the spring hooks 102e and 103e from above. Due to the spring force of the torsion coil spring 62, the moving side unit 100 is always urged downward of the printer.

  Next, the shaft end portion 101 a on the rear side of the printer on the movable side rotating shaft 101 is connected to the movable side universal joint portion 92 of the universal joint unit 90. The rotation of the movable side rotation shaft 101 is transmitted from the fixed side rotation shaft 83 via the universal joint unit 90. By the universal joint unit 90, the movable rotating shaft 101 can move within a predetermined range in the printer vertical direction Z that is the gap adjusting direction with respect to the fixed rotating shaft 83. In addition, the movable rotation shaft 101 can move within a predetermined range in the printer width direction X with respect to the fixed rotation shaft 83. In this example, as can be seen from FIG. 5, the movable rotating shaft 101 is horizontally aligned along the printer longitudinal direction Y at a position slightly offset from the fixed rotating shaft 83 to the outside in the printer width direction X. Has been placed.

  As can be seen from FIGS. 10 and 11, a first worm 104 (first drive side gear) is integrally formed on the movable rotating shaft 101 on the outer peripheral surface of the shaft end portion 101a on the rear side of the printer. . A second worm 105 (second drive side gear) is integrally formed on the outer peripheral surface on the other shaft end 101b side. The first and second worms 104 and 105 are the same worm. The first and second worms 104 and 105 are covered with the first and second brackets 102 and 103 from the three directions of the upper side, the front and rear, and the outer side.

  The first worm 104 meshes with a first worm wheel 106 (first driven gear) fixed coaxially to the shaft end portion 57 a of the first guide shaft 57. Similarly, the second worm 105 meshes with the second worm wheel 107 fixed coaxially to the shaft end portion 58 a of the second guide shaft 58. The first and second worm wheels 106 and 107 are the same worm wheel. The rotation of the movable rotating shaft 101 is transmitted to the first and second guide shafts 57 and 58 via the first and second worms 104 and 105 and the first and second worm wheels 106 and 107, respectively. The first and second guide shafts 57 and 58 are rotationally driven in synchronization. As described above, the first and second guide shafts 57 and 58 are driven to rotate synchronously by the movable-side rotating shaft 101, the first and second worm wheels 104 and 105, and the first and second worm wheels 106 and 107. A synchronous rotation mechanism is configured.

(Rotating cam mechanism)
Next, as shown in FIGS. 8, 9, and 12, the rotary cam mechanisms 110 having the same configuration are respectively assembled to the shaft end portions 57 a and 57 b on both sides of the first guide shaft 57. Similarly, the rotary cam mechanism 120 having the same configuration is also assembled to the shaft end portions 58 a and 58 b on both sides of the second guide shaft 58. The rotating cam mechanism 110 and the rotating cam mechanism 120 are rotating cam mechanisms having the same configuration.

  The rotation cam mechanism 110 is a conversion mechanism that converts the rotation of the first guide shaft 57 into a movement in the gap adjustment direction that is the printer vertical direction Z of the first guide shaft 57. Similarly, the rotating cam mechanism 120 is a conversion mechanism that converts the rotation of the second guide shaft 58 into the movement of the second guide shaft 58 in the gap adjustment direction.

  The rotation cam mechanism 110 on the shaft end portion 57a side of the first guide shaft 57 includes a rotation cam 111 fixed to the shaft end portion 57a. An outer peripheral cam surface 112 is formed on the rotating cam 111. On the inner side surface of the side frame 53, a cam follower 113 that is in contact with the outer peripheral cam surface 112 in a slidable state from below is fixed. The shape of the outer peripheral cam surface 112 is set so that the contact position between the outer peripheral cam surface 112 and the cam follower 113 moves in the gap adjustment direction (printer vertical direction Z) as the rotary cam 111 rotates. The rotating cam mechanism 110 having the same configuration is also disposed at the other shaft end portion 57 b of the first guide shaft 57.

  As can be seen from FIG. 12, the outer peripheral cam surface 112 is set to have a shape in which the distance from the rotation center (the rotation center of the first guide shaft 57) gradually increases over a predetermined angular range along the circumferential direction. ing. When the rotating cam 111 is rotated in the clockwise direction in the drawing from the rotational phase state shown in FIG. 12, the outer peripheral cam surface 112 comes into contact with the cam follower 113. When the rotating cam 111 further rotates, the outer peripheral cam surface 112 is pushed up by the fixed cam follower 113 along with the rotation. As a result, the shaft end portion 57a of the first guide shaft 57 moves upward.

  As shown in FIGS. 8, 9, and 12, the rotating cam mechanism 120 disposed on the shaft end portion 58 a side of the second guide shaft 58 has the same configuration as the rotating cam mechanism 110 described above. The outer peripheral cam surface 122 formed on the rotating cam 121 and a cam follower 123 are provided. The rotating cam mechanism 120 disposed on the other shaft end portion 58b side is configured in the same manner.

  The rotating cam 121 and the cam follower 123 are arranged in the same rotational phase as the rotating cam 111 and the cam follower 113 of the rotating cam mechanism 110. Therefore, when the first and second guide shafts 57 and 58 are rotationally driven in synchronization, the rotary cam mechanisms 110 and 120 rotate in the same rotational phase, and the shaft end portions on both sides of the first guide shaft 57 are rotated. 57a, 57b and the shaft end portions 58a, 58b on both sides of the second guide shaft 58 are moved in the printer up-down direction Z, which is the gap adjustment direction, by the same amount. Accordingly, the movable unit 100 as a whole moves in the printer vertical direction Z while maintaining the same horizontal posture. Therefore, the movable print head 22 moves relative to the fixed platen 25, and the platen gap is adjusted.

(Function and effect)
In the platen gap adjusting mechanism 70 configured as described above, the rotation of the motor 81 of the fixed side unit 80 is transmitted from the fixed side rotation shaft 83 to the movable side rotation shaft 101 of the movable side unit 100 via the universal joint unit 90. In the movable side unit 100, a synchronous rotation mechanism that synchronously drives the first and second guide shafts 57 and 58 includes the movable side rotation shaft 101, the first and second worms 104 and 105, and the first and second worms. The wheels 106 and 107 are configured. Compared with the synchronous rotation mechanism in which a gear train composed of a plurality of spur gears is bridged between the first and second guide shafts 57 and 58, the synchronous rotation mechanism can be configured with a small number of parts, and the installation space is small. That's it.

  Further, since the first and second worms 104 and 105 are integrally formed with the movable side rotating shaft 101, they rotate integrally with the movable side rotating shaft 101 in complete synchronization. Further, since the first and second worms 104 and 105 are engaged with the first and second worm wheels 106 and 107 whose rotation center lines are orthogonal to each other, compared to the case where the spur gears whose rotation center lines are parallel are engaged with each other. There is little backlash of engagement. In particular, in this example, since the cylindrical worm gear pair is used, the backlash is substantially zero. Therefore, since the first and second guide shafts 57 and 58 can be rotated synchronously with high accuracy, the platen gap can be adjusted with high accuracy.

  Further, the two gear configurations of the worm and the worm wheel can provide a large reduction ratio similar to the case where a large number of spur gears are arranged. Therefore, the number of gears required to obtain a predetermined reduction ratio can be reduced, which is advantageous in reducing the size and size of the platen gap adjusting mechanism 70.

  Furthermore, the first and second worm wheels 104 and 105 and the first and second worm wheels 106 and 107 are engaged with each other in a state where the rotation center lines are orthogonal to each other. With respect to the first and second worm wheels 106 and 107 as the driven gears from the first and second worm wheels 104 and 105 as the driving side gears, the first and second worm wheels 106 and 107 in their rotational directions. The moving force does not act substantially. In other words, the force for moving the first and second guide shafts 57 and 58 in the gap adjustment direction does not act. Therefore, unlike the case of the gear type transmission mechanism formed by meshing of spur gears, a large force does not act on the first and second guide shafts 57 and 58 in the gap adjustment direction. Further, the torsion coil spring 62 and the tension coil springs 63 and 64 that hold the first and second guide shafts 57 and 58 so as not to move in the gap adjusting direction can be small springs.

  In the platen gap adjusting mechanism 70, the first and second guide shafts 57, 58 rotate synchronously with high accuracy. Therefore, the rotation cam mechanisms 110 and 120 that convert the rotation of the first and second guide shafts 57 and 58 into the movement of the shafts in the gap adjustment direction have variations in the synchronous rotation of both the guide shafts 57 and 58. There is no need to provide play to absorb the water. Therefore, the diameters of the outer peripheral cam surfaces 112 and 122 of the rotating cams 111 and 121 can be reduced. Therefore, the rotary cams 111 and 121 having a small diameter can be used, which is advantageous for downsizing the platen gap adjusting mechanism 70. Further, the gap adjustment can be performed efficiently in a short time.

  Next, the fixed side rotary shaft 83 of the fixed side unit 80 and the movable side rotary shaft 101 of the movable side unit 100 are connected via a universal joint unit 90. Even if the movable rotating shaft 101 is displaced in the gap adjustment direction, the rotational force is transmitted from the fixed rotating shaft 83 to the movable rotating shaft 101. When the rotation is transmitted from the fixed-side rotary shaft 83 to the movable-side rotary shaft 101 by the engagement of the spur gears, the movement amount of the movable-side rotary shaft 101 in the gap adjustment direction is maintained in order to maintain the engagement of the spur gears. Cannot be increased. On the other hand, by using a universal joint, the moving range of the movable rotary shaft 101 can be increased compared to the conventional case, and thus a platen gap adjustment mechanism with a large gap adjustment amount can be easily realized.

  Further, since the universal joint unit 90 is used, the movable side rotation shaft 101 of the movable side unit 100 can be arranged at a position offset in the printer width direction X with respect to the fixed side rotation shaft 83 of the fixed side unit 80. Therefore, there is an advantage that the degree of freedom of the layout of the platen gap adjusting mechanism 70 is increased.

  Next, the movable side unit 100 and the rotating cam mechanisms 110 and 120 of the platen gap adjusting mechanism 70 are disposed along the inner surface 53 d of the side frame 53. A power transmission mechanism 140 for conveying a medium is disposed on the outer surface of the printer side frame 53. By utilizing the space inside the printer side frame 53, the platen gap adjusting mechanism 70 can be placed on either side of the printer side frames 53, 54 on both sides of the print medium conveyance path 13 regardless of the presence or absence of the power transmission mechanism 140. Can also be placed. In this way, the position of the platen gap adjustment mechanism 70 is not limited by the medium conveyance power transmission mechanism 140, and the platen gap adjustment mechanism 70 can be arranged on either side of the print medium conveyance path. As a result, the degree of freedom in the layout of the platen gap adjusting mechanism 70 is increased.

  Here, since the movable side unit 100 of the platen gap adjusting mechanism 70 is disposed inside the side frame 53, the components of the movable side unit 100 can be used as a contact member that can contact the head carriage 59. Is possible. Alternatively, an abutting member can be disposed on the movable unit 100.

  For example, inner end surface portions of the first and second brackets 102 and 103 of the movable side unit 100 in the printer width direction X can be used as contact portions with the head carriage 59. In other words, when the head carriage 59 moves to the side of the side frame 53 when the head carriage 59 moves to the side of the side frame 53 beyond a predetermined movement limit, the side of the head carriage 59 is moved to the first and second brackets 102 and 103. What is necessary is just to make it contact | abut the formed contact part.

  In the printer 1 of the above-described embodiment, the head carriage 59 is supported by the two guide shafts 57 and 58 so as to be slidable in the printer width direction, and the print head 22 is mounted thereon. The present invention is also applicable to a printer having a configuration in which a head carriage is supported by a single guide shaft so as to be slidable in the printer width direction. In this case, instead of the synchronous rotation mechanism described above, a movable side rotation shaft having a worm formed at one place and a worm wheel attached to the shaft end of the guide shaft may be used. Even in this case, the movable side rotating shaft and the fixed side rotating shaft may be connected via a universal joint unit.

  Further, the present invention can be used as a platen gap adjustment mechanism in a line type printer.

  Furthermore, in the above embodiment, a worm and a worm wheel are used to transmit the rotation of the movable side rotation shaft to the guide shaft. Alternatively, a driving bevel gear can be arranged coaxially with the guide shaft, and a driven bevel gear meshing with the driving bevel gear can be arranged on the guide shaft side.

DESCRIPTION OF SYMBOLS 1 Printer, 2 Printer main-body part, 2A main body case, 3 reversing unit, 3A closed position, 3B open position, 4 recessed part, 4a inner side surface, 4b inner side surface, 5 paper feed cassette mounting part, 6 paper feed cassette, 7 paper discharge Tray, 8 paper discharge port, 9 operation surface, 10a, 10b open / close lid, 11 open / close lid, 12 paper supply path, 13 main body side transport path, 14 reverse transport path, 15 paper feed roller, 16 retard roller, 17 transport roller , 18 driven roller, 20 paper detection lever, 21 paper feed roller pair, 22 print head, 22a nozzle surface, 23 first paper discharge roller pair, 24 second paper discharge roller pair, 25 platen, 26 upper path, 27 downward path 28 lower path, 29 upward path, 30 common path, 31 first transport roller, 31a low -Axis, 32 driven roller, 33 2nd transport roller, 33a roller shaft, 34 driven roller, 35 merging section, 36 path switching flap, 40 opening / closing center line, 41 unit case, 42 back cover, 42a opening, 43 operation lever , 44 Lock piece, 45 Lock hole, 50 Printer mechanism, 51 Printer body frame, 52 Base frame, 53 Side frame, 53a Guide hole, 53b Guide hole, 53c Outer surface, 53d Inner surface, 54 Side frame, 55 Front frame , 56 Rear frame, 57 First guide shaft, 57a Shaft end, 57b Shaft end, 58 Second guide shaft, 58a Shaft end, 58b Shaft end, 59 Head carriage, 60 Timing belt, 61 Carriage drive motor, 62 Torsion coil bar , 63 tension coil spring, 64 tension coil spring, 70 platen gap adjustment mechanism, 80 fixed side unit, 81 motor, 82 transmission gear train, 83 fixed side rotation shaft, 83a rotation center line, 84 pinion, 85 intermediate transmission gear, 86 shaft Side transmission gear, 87 Worm gear, 90 Universal joint unit, 91 Fixed side universal joint, 92 Movable side universal joint, 100 Movable side unit, 101 Movable side rotating shaft, 101a Shaft end, 101b Shaft end, 102 1 bracket, 102a top plate portion, 102b end plate portion, 102c end plate portion, 102d side plate portion, 102e spring hook, 103 second bracket, 103a top plate portion, 103b end plate portion, 103c end plate portion, 103d side plate portion, 103e Spring hook, 104 1st worm, 105 2nd c 106, first worm wheel, 107 second worm wheel, 110 first rotating cam mechanism, 111 rotating cam, 112 outer cam surface, 113 cam follower, 120 second rotating cam mechanism, 121 rotating cam, 122 outer cam surface, 123 cam follower, 130 compound gear, 131 external gear, 132 external gear, 133 external gear, 134 rotating shaft, 135 roller support plate, 140 power transmission mechanism, 141 motor, 142 pinion, 143 shaft end, 144 Transmission gear, 145 shaft end, 146 transmission gear, 147 timing belt, HP home position, X printer width direction, Y printer longitudinal direction, Z printer vertical direction

Claims (5)

A print head;
A head carriage mounted with the print head;
A first guide shaft and a second guide shaft that support the head carriage and extend parallel to each other;
A platen facing the print head;
A platen gap adjusting mechanism for adjusting a gap between the print head and the platen by moving the first and second guide shafts in a gap adjusting direction approaching and separating from the platen;
Have
The platen gap adjustment mechanism includes a synchronous rotation mechanism that rotates the first guide shaft and the second guide shaft in synchronization with each other,
The synchronous rotation mechanism is
A rotating shaft extending in a direction orthogonal to the first guide shaft and the second guide shaft;
A first drive side gear and a second drive side gear provided coaxially on the rotating shaft;
A first driven gear provided coaxially with the first guide shaft and meshing with the first driving gear;
A second driven gear provided coaxially with the second guide shaft and meshing with the second drive gear;
A printer characterized by comprising:   2. The printer according to claim 1, wherein the first driving gear and the second driving gear are worms, and the first driven gear and the second driven gears are worm wheels. The platen gap adjusting mechanism includes a first cam mechanism that converts rotation of the first guide shaft into movement of the first guide shaft in the gap adjusting direction, and rotation of the second guide shaft. A second cam mechanism that converts the movement in the gap adjustment direction of
The first and second cam mechanisms are cam mechanisms having the same configuration,
The cam mechanism is
A rotating cam fixed coaxially to the first guide shaft or the second guide shaft and having an outer peripheral cam surface;
A cam follower disposed at a fixed position in the gap adjusting direction and slidably contacting the outer peripheral cam surface;
With
The shape of the outer peripheral cam surface is set so that the contact position of the outer peripheral cam surface and the cam follower moves in the gap adjustment direction as the rotating cam rotates. Printer. The first driven gear is fixed to one first shaft end of the first guide shaft,
The second driven gear is fixed to a shaft end portion on the same side as the first shaft end portion of the second guide shaft;
The first cam mechanisms are respectively disposed at shaft end portions on both sides of the first guide shaft,
The printer according to claim 3, wherein the second cam mechanism is disposed at each of shaft end portions on both sides of the second guide shaft. The platen gap adjusting mechanism is
A rotational drive source disposed at a fixed position in the gap adjustment direction, and a fixed-side rotational shaft that is rotationally driven by the rotational drive source;
A universal joint for connecting the fixed rotation shaft to the rotation shaft of the synchronous rotation mechanism;
The printer according to any one of claims 1 to 4, further comprising:

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