JP2012192613A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing apparatus that enables higher speed printing, by further accelerating a switching time of a thermal head pressure, without enlarging the apparatus.SOLUTION: The printing apparatus for transferring ink on a paper includes: a thermal head 204 and a platen roller 205, which are brought into pressure contact in printing and separated therefrom in returning the paper; a first drive unit 40 for switching a pressure contact state and a separation state of the thermal head 204 and the platen roller 205; a capstan 202 for transporting the paper; a pinch roller 201 for sandwiching the paper while facing to the capstan 202; a second drive unit 30 for driving the capstan 202; and a pressing force switching means, which is driven by a second drive unit 30, and which decreases the pressure of the capstan 202 and the pinch roller 201 in returning the paper more than the pressure of the capstan 202 and the pinch roller 201 in printing.

Description

  The present invention relates to a printing apparatus. In particular, the present invention relates to a thermal printer in which an image is formed by thermal transfer with a thermal head.

2. Description of the Related Art Conventionally, as a printer that prints a photograph taken with a digital camera or the like, a thermal printer that sublimates an ink ribbon with a thermal head and thermally transfers it onto a recording sheet is known.
A printing operation of the thermal printer will be described with reference to FIG. FIG. 11 is a side sectional view showing a configuration of a thermal printer related to the present invention.
When a print start instruction is input, the roll paper roller shaft 900 that rotates integrally with the roll paper 950 that is a recording paper is driven counterclockwise in the drawing, whereby the roll paper 950 is sent out, and the capstan unit 910 To reach.

  The capstan unit 910 includes a pinch roller 901 and a capstan 902. A plurality of protrusions are formed on the surface of the capstan 902 at predetermined intervals in the circumferential direction and the axial direction. By sandwiching the roll paper 950 between the capstan 902 and the pinch roller 901, a protrusion is stuck in the roll paper 950, and high-precision paper feeding is performed according to the rotation of the capstan 902. At this time, since the roll paper 950 does not come off from the protrusion, a strong clamping force is required. Therefore, a strong pressing force is applied to the pinch roller 901 by the elastic force of the pinch spring 922 via a bush 919 that holds the pinch roller 901 in a rotatable manner and is applied with a pressing force by the pinch lever 921. This pressure is hereinafter referred to as “nip pressure”.

The roll paper 950 that has reached the capstan unit 910 is conveyed to the print start position by the clockwise rotation of the capstan 902 in the drawing, and the paper feed by the capstan 902 is stopped.
When the roll paper 950 reaches the print start position, the capstan 902 is rotated counterclockwise in the drawing, and the roll paper 950 is conveyed from the print start position to the print end position. During the conveyance, the ink ribbon take-up shaft 927 rotates clockwise in the drawing, whereby the yellow ink ribbon 951 is pulled out from the ink ribbon supply shaft 928 while maintaining the overlapping state with the roll paper 950. At this time, the thermal head 904 is energized and yellow printing on the roll paper 950 is performed.

  In order to transfer the ink applied on the ink ribbon 951 to the roll paper 950 with high accuracy, the ink ribbon 951 and the roll paper 950 must be brought into sufficient contact with each other, and the thermal head 904 and the platen roller 905 are appropriately connected. It is necessary to pressurize with an appropriate pressure. This pressure is hereinafter referred to as “thermal head pressure”.

  When the yellow printing on the roll paper 950 is completed, the bracket 914 is rotated and the thermal head 904 is lifted to retract from the platen roller 905. After the thermal head 904 is retracted, the capstan 902 rotates clockwise in the drawing, whereby the roll paper 950 is returned to the print start position. In this way, yellow printing on the roll paper 950 and paper return are performed, and thereafter the same operation is performed in the order of magenta, cyan, and overcoat layer.

  The roll paper 950 after the overcoat layer printing is completed is conveyed in the paper discharge direction when the capstan 902 rotates clockwise in the figure. The roll paper 950 is conveyed until the boundary between the printing area and the non-printing area reaches the cutting position of the cutter unit 907, and the cutting process is performed after the conveyance is completed. The remainder of the roll paper 950 whose leading end is cut by the cutting process is discharged as the paper discharge roller 912 rotates clockwise in the drawing.

  As described above, the thermal printer has many steps necessary for forming one image, and has a problem that the printing time is long. Note that a motor different from the paper transport motor is used to change the position of the thermal head 904. This motor is hereinafter referred to as “thermal head pressure switching motor”.

  On the other hand, in a thermal printer, paper feed is performed a plurality of times from a predetermined print start position to a print end position. Therefore, if the paper feed amount is unstable, the print start position is shifted and color misregistration occurs. Therefore, very high accuracy is required for paper feeding. In order to perform accurate paper feeding, a nip pressure sufficient to transport the roll paper 950 without slipping is necessary. That is, at the time of printing, a nip pressure sufficient to prevent slippage of the roll paper 950 pressed by the thermal head 904 and the platen roller 905 is required. On the other hand, when the paper is returned, the nip pressure is sufficient to prevent the roll paper 950 released from the thermal head 904 and the platen roller 905 from slipping.

  However, in the thermal printer shown in FIG. 11, the roll paper 950 is sandwiched with a constant strong nip pressure both during printing and when returning the paper, so that the driving load of the capstan 902 is large not only during printing but also during paper returning. This is a barrier to speeding up. Focusing on this, a technique for switching between the nip pressure at the time of paper return and the nip pressure at the time of printing is disclosed.

  For example, Patent Document 1 discloses a method of switching the strength of the nip pressure in conjunction with the switching of the thermal head pressure. Specifically, a pin provided on the pinch lever that changes the nip pressure and a pin provided on the head lever that changes the thermal head pressure are respectively attached to the notch portion of the cam having two notch portions. The nip pressure and the thermal head pressure are switched at the same time as the cam rotates.

JP-A-6-15852

  However, in the technique disclosed in Patent Document 1 described above, since the nip pressure and the thermal head pressure are simultaneously switched from the paper returning process to the printing process, the torque that must be generated by the motor is extremely high. Will become bigger. Therefore, the motor speed at the time of switching becomes slow, and there is a problem that it takes a long time for switching. On the other hand, even if the reduction ratio of the motor is increased in order to reduce the torque that must be generated by the motor, a long time is required for switching. In order to shorten the switching time by this method, it is necessary to increase the size of the motor and the size of the cam. However, the increase in size of the device causes problems in terms of power consumption and cost.

  The present invention has been made to solve the above-described problems, and enables printing at higher speed by increasing the switching time of the thermal head pressure without increasing the size of the apparatus. An object is to provide an apparatus.

  The printing apparatus according to the present invention is a printing apparatus that transfers ink onto a sheet, and is in contact with and separated from a thermal head and a platen roller that are in press contact during printing and separated when the sheet is returned. A first drive unit that switches between, a capstan that conveys paper, a pinch roller that faces the capstan and sandwiches the paper, a second drive unit that drives the capstan, and the second It is driven by a driving unit, and has a pressure switching means for reducing the pressure between the capstan and the pinch roller at the time of returning the paper than the pressure between the capstan and the pinch roller at the time of printing. .

  According to the present invention, the time for switching the thermal head pressure can be shortened without increasing the size of the apparatus, and further high-speed printing can be performed.

It is a figure which shows the external appearance structure of a printing apparatus and a cartridge. It is a sectional side view showing the composition of a printing device. FIG. 2 is a block diagram illustrating a functional configuration of a printing apparatus. It is a side view which shows the structure of the drive mechanism of a printing apparatus. 2 is a block diagram illustrating a configuration of a drive mechanism of the printing apparatus. FIG. It is a figure which shows the nip pressure switching mechanism at the time of paper return. It is a figure which shows the nip pressure switching mechanism at the time of printing. It is a figure which shows the nip pressure switching mechanism in nip pressure switching. It is a flowchart which shows the whole flow of a printing process. It is a figure for demonstrating the marker of an ink ribbon. 1 is a side sectional view showing a configuration of a printing apparatus related to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each of the drawings, the roll paper discharge direction is indicated by an arrow as necessary.
FIG. 1 is a diagram illustrating an external configuration of a thermal printer 100 that is a printing apparatus according to the present embodiment and a cartridge 110 that is used in the thermal printer 100.
As shown in FIG. 1, the thermal printer 100 includes a housing 101 whose side surface is opened and closed, and a cartridge 110 can be attached and detached in the direction of an arrow 120, and a display unit 102 and an operation unit 103 are arranged on the upper part of the housing 101. Has been.

The display unit 102 includes a display screen such as an LCD, and displays image data to be printed and a menu for inputting setting data necessary for printing.
The operation unit 103 includes a power switch 104 for instructing to turn on / off the power of the thermal printer 100 and a selection switch 105 for selecting various menus displayed on the display unit 102. Further, a left / right key 106 and an up / down key 107 for moving the cursor displayed on the display unit 102 to a desired position are arranged around the selection switch 105.

  The cartridge 110 contains an ink ribbon to which ink is applied and roll paper as a recording medium. Further, in a state before the cartridge 110 is mounted on the thermal printer 100, the roll paper is completely covered by the housing 111, and the user cannot directly touch the roll paper. At the time of printing, the roll paper is pulled out from the cartridge 110, and the ink applied to the ink ribbon is transferred to the roll paper by the thermal head to perform printing.

  The cartridge 110 includes a roller rotation shaft 112, an ink ribbon supply roller rotation shaft 113, and an ink ribbon take-up roller rotation shaft 114. When the roll paper is wound and the cartridge 110 is mounted on the thermal printer 100, the roller rotation shaft 112 is coupled to the rotation mechanism of the paper transport motor included in the thermal printer 100, and the rotation is controlled by the thermal printer 100. . When the cartridge 110 is mounted on the thermal printer 100, the take-up roller rotation shaft 114 is coupled to the rotation mechanism of the paper transport motor included in the thermal printer 100, and the rotation is controlled by the thermal printer 100.

  FIG. 2 is a cross-sectional view of the thermal printer 100 according to the present embodiment as viewed from the side. The thermal printer 100 according to the present embodiment includes a nip pressure switching mechanism (pressing force switching means) described later. 2A shows the state when the paper is returned, and FIG. 2B shows the state when printing. The configuration of each unit that operates when the thermal printer 100 performs printing processing will be briefly described with reference to FIG.

As shown in FIG. 2, the thermal printer 100 is provided with a roll paper roller shaft 200 that rotates a roller rotation shaft 112 of the cartridge 110. In the thermal printer 100, a conveyance path 501 is formed through which the roll paper 500 passes when it is pulled out to the paper discharge position. A pinch roller 201 and a capstan 202 are disposed in the conveyance path 501. When the nip force (pressing force) is applied to the pinch roller 201, the roll paper 500 is sandwiched between the pinch roller 201 and the capstan 202.
A decal guide 203 is disposed above the pinch roller 201. The decurling guide 203 is formed with a curvature opposite to the curling direction of the roll paper 500, and corrects curl of the roll paper 500 during printing.

On the discharge direction side of the decurling guide 203, a thermal head 204 and a platen roller 205 are arranged. At the time of printing, the thermal head 204 and the platen roller 205 maintain a state in which the ink ribbon 510 and the roll paper 500 are overlapped therebetween. On the other hand, when the paper is returned, the thermal head 204 moves to the retracted position. The force applied to the thermal head 204 will be described later.
A paper guide 206 is disposed on the sheet discharge direction side of the platen roller 205. The roll paper 500 reciprocates on the paper guide 206. A cutter unit 207 is disposed on the paper discharge direction side of the paper guide 206. The cutter unit 207 includes a movable blade 208 and a fixed blade 209 disposed to face the movable blade 208. The movable blade 208 is moved vertically downward in the figure by a drive source (not shown), so that the upper and lower blades are rubbed together and the roll paper 500 is cut.
A paper discharge roller unit 210 is disposed on the paper discharge direction side of the cutter unit 207. The paper discharge roller unit 210 conveys the cut roll paper 500 in the paper discharge direction. The paper discharge roller unit 210 includes a paper discharge roller 212 and a driven roller 211 that are disposed at positions facing each other with the roll paper 500 interposed therebetween.

Here, the nip pressure applied to the pinch roller 201 will be described.
The pinch roller 201 is held in a rotatable state in the bush 219. The capstan 202 is held in a rotatable state by a base frame (not shown) of the thermal printer 100. The capstan 202 is inserted into the bush 219 with play in a direction perpendicular to the direction in which the roll paper 500 is conveyed. A pinch lever 221 is attached to the bush 219. The pinch lever 221 applies pressure to the bush 219 by the elastic force of the pinch spring 222 attached to the pinch lever 221 with the shaft 220 as a fulcrum. By applying a pressing force to the bush 219, a pressing force in a direction perpendicular to the conveyance direction of the roll paper 500 is applied to the pinch roller 201, and a nip pressure is generated. One end of the pinch spring 222 is attached to the pinch lever 221 and the other end is attached to a nip pressure switching mechanism described later. The bush 219, the pinch lever 221, the shaft 220 and the pinch spring 222 constitute a pressurizing mechanism (pressurizing unit).

  Further, in the thermal printer 100, an ink ribbon take-up shaft 227 and an ink ribbon supply shaft 228 are disposed before and after the thermal head 204 is sandwiched above the conveyance path 501. The ink ribbon take-up shaft 227 and the ink ribbon supply shaft 228 rotate the take-up roller rotating shaft 114 and the supply roller rotating shaft 113 of the cartridge 110, respectively. An ink ribbon 510 is disposed between the ink ribbon supply shaft 228 and the ink ribbon take-up shaft 227. The ink ribbon 510 is supplied from the ink ribbon supply shaft 228 and wound around the ink ribbon winding shaft 227. The thermal head 204 is supported by a thermal head support plate 215, and the thermal head support plate 215 is attached to the bracket 214. The bracket 214 rotates about the shaft 213 as a rotation center, whereby the thermal head 204 rotates and moves up and down as shown in FIG. 2A or 2B. A thermal head pressure switching motor 40 (first driving unit) that moves the thermal head 204 up and down is disposed at a position close to the bracket 214. A rotating shaft 216 is disposed above the thermal head 204, and the thermal head pressurizing lever 217 is rotated by the rotation of the rotating shaft 216. As shown in FIG. 2A, when the thermal head pressure lever 217 separates the thermal head 204 from above, the thermal head 204 and the platen roller 205 are separated from each other. On the other hand, as shown in FIG. 2B, when the thermal head pressure lever 217 presses the thermal head 204 from above, the thermal head 204 and the platen roller 205 are brought into a pressure contact state.

FIG. 3 is a block diagram illustrating a functional configuration of the thermal printer 100.
The thermal printer 100 includes a main controller 701 that controls the entire apparatus, a paper transport motor driver 708, a thermal head pressure switching motor driver 709, a cutter drive motor driver 710, and a display control unit 711. The thermal printer 100 also includes a ROM 702, a RAM 703, an end detection sensor 704, a roll paper detection sensor 705, a roll paper cue sensor 706, and a ribbon cue sensor 707. Further, the thermal printer 100 includes the above-described operation unit 103, image data input unit 712, IC read / write unit 713, driver controller 715, thermal head drive circuit 716, and the like. In addition to each driver, the driver controller 715 controls a thermal head driving circuit 716 that drives the thermal head 204 according to the contents of the image memories 714Y, 714M, and 714C.

  The paper transport motor driver 708 is a driver for driving the paper transport motor 30 (second drive unit). The paper transport motor 30 is coupled to the roll paper roller shaft 200, the capstan 202, the paper discharge roller 212, and the like via a rotation mechanism, and transports the roll paper 500 by driving these rollers. Further, the paper transport motor 30 drives the ink ribbon winding shaft 227 via the rotation mechanism, and winds the ink ribbon 510. Further, the paper transport motor 30 switches the nip pressure according to the rotation direction.

The thermal head pressure switching motor driver 709 controls the rotation of the thermal head pressure switching motor 40 that moves the thermal head 204 up and down to move the thermal head 204 to the printing position and the retracted position.
The cutter drive motor driver 710 cuts the roll paper 500 by controlling the cutter motor 50 that drives the movable blade 208 of the cutter unit 207.
The end detection sensor 704 is arranged in the roll paper roller shaft 200 of the cartridge 110, and the remaining amount of the roll paper 500 wound around the roll paper roller shaft 200 is less than one roll after the roll paper 500 is consumed. If this is the case, this is detected. When the end is detected, a message that the remaining amount of the roll paper 500 is low is displayed on the display unit 102.

The roll paper cueing sensor 706 is disposed between the platen roller 205 and the capstan 202 provided to face the thermal head 204 shown in FIGS. The roll paper cueing sensor 706 detects that the leading end portion of the roll paper 500 drawn from the cartridge 110 at the start of printing has passed behind the capstan 202.
Ribbon cue sensor 707 detects an identification band applied to the tip of each color of ink ribbon 510. The winding operation of the ink ribbon 510 by the paper transport motor 30 is controlled based on the detection result of the ribbon cue sensor 707.

The drive system of this embodiment will be described with reference to FIGS.
FIG. 4 is a side view showing the configuration of the drive mechanism of the thermal printer 100. 4 is a view as seen from the side opposite to FIG. 2, and the paper discharge direction is different from FIG. FIG. 5 is a block diagram showing the configuration of the drive mechanism of the thermal printer 100.
As shown in FIG. 4, the pinion 300 is rotated by the rotation of the paper transport motor 30, and the gear 301 and the gear 308 that mesh with the pinion 300 are rotated. The gear 301 meshes with the gear 302, and the capstan 202 rotates together with the gear 302.
The gear 302 meshes with the gear 303, and the gear 303 meshes with the gear 304 and the planetary gear 306. The gear 304 meshes with the gear 305, and the roll paper roller shaft 200 of the roll paper 500 rotates with the gear 305.

The planetary gear 306 is mounted on the bracket 3032. The bracket 3032 rotates about the shaft 3031 as the gear 303 rotates. By rotating the bracket 3032, the planetary gear 306 is engaged with the gear 307 or rotated to a position away from the gear 307.
The planetary gear 306 meshes with the gear 307 only when the paper transport motor 30 rotates clockwise in the drawing, and the ink ribbon take-up shaft 227 rotates together with the gear 307 so that the ink ribbon 510 is taken up.

On the other hand, the gear 308 meshes with the gear 309. The gear 309 meshes with the gear 310 and the gear 312. The gear 310 meshes with the gear 311, and the paper discharge roller 212 rotates together with the gear 311.
The gear 312 meshes with the gear 313, and the gear 313 meshes with the sun gear 314 of the planetary gear mechanism. The sun gear 314 meshes with the planetary gear 315 (first planetary gear) and the planetary gear 316 (second planetary gear). The bracket 3141 rotates according to the rotation direction of the sun gear 314, and either the planetary gear 315 or the planetary gear 316 attached to the bracket 3141 meshes with the notched gear 317, and the notched gear 317 rotates. The rotation shaft 223 is rotated by the rotation of the notched gear 317, and the nip pressure is switched. The nip pressure switching mechanism will be described later.

  On the other hand, rotation of the thermal head pressure switching motor 40 causes the gear 400 attached coaxially to the motor 40 to rotate. Gear 400 meshes with gear 401, and gear 401 meshes with gear 402. The gear 402 meshes with the gear 403, and the gear 403 meshes with the sector gear 404. The rotation shaft 216 with which the sector gear 404 is fitted is rotated by the rotation of the sector gear 404.

Next, returning to FIGS. 2A and 2B, the thermal head pressure applied to the thermal head 204 will be described.
The rotation shaft 216 is rotated by the rotation of the sector gear 404, and the thermal head pressure lever 217 is rotated by the rotation of the rotation shaft 216. At the time of printing, the thermal head pressure lever 217 is rotated from the state shown in FIG. 2A as shown in FIG. 2B, and the thermal head pressure spring 218 is contracted, and the thermal head pressure spring 218 is elastic. A force is applied to the thermal head 204 by the force.

  On the other hand, when the paper is returned during non-printing, the thermal head pressure lever 217 is rotated from the state shown in FIG. 2B as shown in FIG. 2A, and the pressure applied to the thermal head 204 is released. The Here, an elastic body (not shown) is attached to either the thermal head support plate 215 supporting the thermal head 204 or the bracket 214 to which the thermal head support plate 215 is coupled to the base frame. . The thermal head 204 is biased by the elastic body in a direction away from the platen roller 205. Therefore, when the paper is not pressed by the thermal head pressure lever 217, the bracket 214 rotates about the shaft 213 as a rotation center by the elastic force, so that the thermal head 204 moves to the retracted position.

Next, the nip pressure switching mechanism 319 will be described with reference to FIGS. The nip pressure switching mechanism 319 can increase the nip pressure when printing and can decrease the nip pressure when returning paper. The transport direction during printing is opposite to the paper discharge direction shown in the drawings, and the transport direction when returning paper is the same as the paper discharge direction shown in the drawings.
FIG. 6 is a diagram showing the nip pressure switching mechanism 319 when the nip pressure is weak, that is, when the paper is returned. FIG. 7 shows the nip pressure switching mechanism 319 when the nip pressure is strong, that is, during printing. FIG. 8 is a view showing the nip pressure switching mechanism 319 in the middle of switching from a weak nip pressure state to a strong nip pressure state. 6A to 8B are views seen from directions opposite to each other.

The nip pressure switching mechanism 319 includes a sun gear 314, a bracket 3141, planetary gears 315 and 316, and a notched gear 317, a rotating shaft 223, a cam 224, a swinging shaft 225, and a swinging shaft guide, which are components of the planetary gear mechanism. 226.
As shown in FIG. 6A, the notched gear 317 has a notch 318, and when the planetary gear 315 or the planetary gear 316 is positioned in the notch 318, the planetary gear 315 or the planetary gear 316 is Idle. The rotating shaft 223 is fitted to the notched gear 317 and rotates in synchronization with the rotation of the notched gear 317. Further, the cam 224 shown in FIG. 6B is fitted to the rotating shaft 223 and rotates in synchronization with the rotation of the rotating shaft 223.

  As shown in FIG. 6B, the swing shaft 225 is regulated in the horizontal direction by the hollow regulating portion 229 of the swing shaft guide 226 and moves only in the vertical direction along the outer periphery of the cam 224. A pinch spring 222 is attached to the swing shaft 225, and an elastic force always acts in a direction in which the pinch lever 221 is pulled up. At least two recesses 230a and 230b are formed on the outer periphery of the cam 224, and the swing shaft 225 is held by the recesses 230a and 230b. The recesses 230a and 230b have different distances from the rotation shaft 223.

The nip pressure switching mechanism 319 at the time of paper return with a weak nip pressure will be described.
When the paper transport motor 30 rotates counterclockwise as viewed from the direction shown in FIG. 4, the capstan 202 also rotates counterclockwise. Accordingly, when viewed from the direction shown in FIG. 2, the capstan 202 rotates clockwise, so that the roll paper 500 is conveyed in the paper return direction. On the other hand, since the sun gear 314 rotates clockwise as viewed from the direction shown in FIG. 4, after the planetary gear 316 meshes with the notched gear 317 and rotates the notched gear 317, FIG. As shown in the figure, the gear rotates at the notch 318 of the notched gear 317. At this time, the cam 224 moves to the position (first position) shown in FIG. 6B in conjunction with the notched gear 317, and the swing shaft 225 is positioned in the recess 230 a of the cam 224. Since the distance between the swing shaft 225 on the recess 230a and the pinch lever 221 is close, the extension amount of the pinch spring 222 is maintained in a small state.

The nip pressure switching mechanism 319 during printing with a strong nip pressure will be described.
When the paper transport motor 30 rotates clockwise as viewed from the direction shown in FIG. 4, the capstan 202 also rotates clockwise. Accordingly, when viewed from the direction shown in FIG. 2, the capstan 202 rotates counterclockwise, and the roll paper 500 is conveyed in the printing direction. On the other hand, since the sun gear 314 rotates counterclockwise when viewed from the direction shown in FIG. 4, after the planetary gear 315 meshes with the notched gear 317 and rotates the notched gear 317, FIG. ) As shown in FIG. At this time, the cam 224 moves to the position (second position) shown in FIG. 7B in conjunction with the notched gear 317, and the swing shaft 225 is positioned in the recess 230 b of the cam 224. Since the distance between the rocking shaft 225 and the pinch lever 221 on the recess 230b is separated, the pinch spring 222 is maintained in a state in which the extension amount is large.

Next, the switching operation of the nip pressure switching mechanism 319 will be described with reference to FIGS.
First, the operation of the nip pressure switching mechanism 319 when the nip pressure is switched from a strong state to a weak state will be described.
The nip pressure switching mechanism 319 after printing is in a state shown in FIG. After the thermal head 204 has moved from the printing position to the retracted position, the paper transport motor 30 rotates counterclockwise as viewed from the direction shown in FIG. When the paper conveyance motor 30 rotates counterclockwise when viewed from the direction shown in FIG. 4, the sun gear 314 rotates clockwise, and the bracket 3141 swings clockwise. As the bracket 3141 swings, the planetary gear 315 and the planetary gear 316 also swing integrally in the clockwise direction. As shown in FIG. 7A, the planetary gear 315 located at the notch 318 of the notched gear 317 is separated from the notched gear 317 by the bracket 3141 swinging clockwise. On the other hand, the planetary gear 316 approaches the notched gear 317 and meshes with the teeth of the notched gear 317. Here, since the planetary gear 316 rotates counterclockwise, the notched gear 317 rotates clockwise when the notched gear 317 meshes with the planetary gear 316. As the notched gear 317 rotates, the rotating shaft 223 also rotates, and the cam 224 rotates in the same manner.

That is, since the cam 224 rotates counterclockwise when viewed from the direction shown in FIG. 7B, the swing shaft 225 held by the recess 230b of the cam 224 is regulated by the swing shaft guide 226. Then, the cam 224 moves in the vertical direction. That is, since the swing shaft 225 moves downward in the vertical direction, the amount of extension of the pinch spring 222 decreases, and the nip pressure applied to the pinch roller 201 decreases.
When the notched gear 317 rotates clockwise by a predetermined angle when viewed from the direction shown in FIG. 4, the planetary gear 316 is positioned at the notched portion 318 of the notched gear 317 as shown in FIG. . The planetary gear 316 idles at the notch 318 of the notched gear 317, and the rotation of the notched gear 317 is completed. When the rotation of the notched gear 317 is completed, the nip pressure switching operation is completed, and the swing shaft 225 is held by the recess 230a of the cam 224 as shown in FIG. It becomes constant in the state.

Next, the operation of the nip pressure switching mechanism 319 when the nip pressure is switched from a weak state to a strong state will be described. FIG. 8 is a diagram showing a state in the middle of switching from a weak nip pressure state to a strong state.
The nip pressure switching mechanism 319 after completion of paper return is in the state shown in FIG. After the thermal head 204 has moved to the printing position, the paper transport motor 30 rotates clockwise as viewed from the direction shown in FIG. 4, whereby the paper transport motor 30 starts accelerating to a predetermined printing speed. When the paper conveyance motor 30 rotates clockwise as viewed from the direction shown in FIG. 4, the sun gear 314 rotates counterclockwise, and the bracket 3141 swings counterclockwise. As the bracket 3141 swings, the planetary gear 315 and the planetary gear 316 also swing integrally counterclockwise. As shown in FIG. 6A, the planetary gear 316 located in the notch 318 of the notched gear 317 is separated from the notched gear 317 when the bracket 3141 swings counterclockwise. On the other hand, the planetary gear 315 approaches the notched gear 317 and meshes with the teeth of the notched gear 317. Here, since the planetary gear 315 rotates clockwise, when the notched gear 317 is engaged with the planetary gear 315, the notched gear 317 is counterclockwise as shown in FIG. Rotate to. As the notched gear 317 rotates, the rotating shaft 223 also rotates, and the cam 224 rotates in the same manner.

That is, since the cam 224 rotates in the clockwise direction when viewed from the direction shown in FIG. 6B, the swing shaft 225 held by the recess 230a of the cam 224 is regulated by the swing shaft guide 226. The cam 224 moves in the vertical direction. That is, since the swing shaft 225 moves upward in the vertical direction, the extension amount of the pinch spring 222 increases, and the nip pressure applied to the pinch roller 201 increases.
When the notched gear 317 rotates counterclockwise by a predetermined angle when viewed from the direction shown in FIG. 4, the planetary gear 315 is positioned at the notched portion 318 of the notched gear 317 as shown in FIG. To do. The planetary gear 315 idles at the notch 318 of the notched gear 317, and the rotation of the notched gear 317 is completed. When the rotation of the notched gear 317 is completed, the nip pressure switching operation is completed, and the swing shaft 225 is held by the recess 230b of the cam 224 as shown in FIG. 7B, and the nip pressure is high. It becomes constant at.

  Next, an overall flow of the printing process in the thermal printer 100 will be described with reference to FIG. FIG. 9 is a flowchart showing an overall flow of printing processing in the thermal printer 100. After the cartridge 110 is mounted on the thermal printer 100 and the power is turned on, when the capture of the image data to be printed is completed, the processing shown in FIG. 9 is started.

In step S <b> 801, the main controller 701 receives information related to image data selected as a print target by the user via the operation unit 103 from the image data displayed on the display unit 102.
In step S <b> 802, the main controller 701 determines whether there is a print instruction from the user via the operation unit 103. If it is determined in step S802 that there is a print instruction, the process advances to step S803.

In step S803, the main controller 701 determines whether printing is possible. Here, the main controller 701 determines whether all of the image data selected in step S801 can be printed based on the remaining amount of the roll paper 500.
If it is determined in step S803 that printing is not possible, the main controller 701 displays a message indicating that printing is not possible on the display unit 102, and proceeds to step S807.
On the other hand, if it is determined in step S803 that printing is possible, the process advances to step S804, and the main controller 701 generates print data for each color based on the selected image data.

In step S805, the main controller 701 performs a printing process using the generated print data. Details of the printing process will be described later.
In step S806, the main controller 701 determines whether there is the next image data selected as a print target. If it is determined in step S806 that there is the next image data selected as a print target, the process returns to step S803, and the main controller 701 repeats the above processing.

On the other hand, if it is determined in step S806 that there is no next image data selected as a print target, or if it is determined in step S803 that printing is not possible, the process proceeds to step S807.
In step S807, the main controller 701 performs end processing. Specifically, the main controller 701 winds up the roll paper 500 so that the leading end of the roll paper 500 comes to the conveyance path 501.

Next, the operation of the thermal printer 100 in the printing process in step S805 will be described.
The cueing of the ink ribbon 510 performed first will be described with reference to FIG.
On the ink ribbon 510, a marker 511 as an identification band is applied at the cueing position of each surface of the yellow ink ribbon Y512, the magenta ink ribbon M513, the cyan ink ribbon C514, and the overcoat layer 515. The marker 511 is a black line, and the marker 511 is detected by the ribbon cue sensor 707. Two markers 511 are applied to the head portion of the ink surface of the ink ribbon Y512 to distinguish it from the head portions of other colors. These distinctions are identified by the ribbon cue sensor 707 and cue the ink ribbon Y512 to be printed first.

  Hereinafter, the printing operation will be described with reference to FIG. First, a paper feeding operation performed after the cueing of the ink ribbon 510 is completed will be described. When the paper conveyance motor 30 rotates counterclockwise as viewed from the direction shown in FIG. 4, the roll paper roller shaft 200 that rotates integrally with the roll paper 500 rotates counterclockwise as viewed from the direction shown in FIG. By rotating clockwise, the roll paper 500 rotates. As the roll paper 500 rotates, the roll paper 500 is sent out from the cartridge 110 and conveyed to the capstan 202. The roll paper 500 gripped by the capstan 202 is further conveyed by the capstan 202 that rotates clockwise as viewed from the direction shown in FIG. 2A, and the thermal head 204 and the platen roller 205 that are separated from each other. Pass between.

A roll paper cueing sensor 707 (not shown) is disposed on the paper discharge direction side of the capstan 202. When the leading end of the roll paper 500 passes through the roll paper cueing sensor 707, the roll paper cueing sensor 707 is turned off. Switches from ON to ON.
Using the ON signal of the roll paper cue sensor 707 as a trigger, the roll paper 500 is transported according to the print size and then stopped. At this time, in consideration of the distance required for accelerating to the printing speed during printing, the paper is transported more than the print start position and reaches the standby position.

When the roll paper 500 reaches the standby position, the thermal head pressure switching motor 40 is driven, the bracket 214 is rotated, and the thermal head 204 fixed integrally with the bracket 214 is moved to a predetermined printing position.
After the thermal head 204 has moved to a predetermined printing position, the paper transport motor 30 is rotated clockwise as viewed from the direction shown in FIG. 4 to accelerate to a predetermined printing speed. During acceleration of the paper transport motor 30, the nip pressure switching mechanism 319 switches the state from a weak nip pressure to a strong state. When the acceleration is completed, the roll paper 500 reaches the print start position.

  The thermal head 204 is energized until the roll paper 500 reaches the printing start position and is conveyed to the printing end position. During the conveyance, the ink ribbon take-up shaft 227 rotates, whereby the ink ribbon Y512 is pulled out from the ink ribbon supply shaft 228 while being superposed on the roll paper 500, and yellow printing on the roll paper 500 is performed. .

When the yellow printing on the roll paper 500 is completed, the thermal head pressure switching motor 40 is driven, the bracket 214 is rotated, and the thermal head 204 fixed integrally with the bracket 214 is moved to a predetermined retracted position. .
After the movement of the thermal head 204 to the predetermined retracted position is completed, the roll paper 500 is returned to the standby position by driving the capstan 202. In the process of returning the roll paper 500 to the retracted position, the nip pressure switching mechanism 319 returns the nip pressure from a strong state to a weak state.

In this way, yellow printing on the roll paper 500 and paper return are performed, and thereafter the same operation is performed in the order of magenta, cyan, and overcoat layer.
When the printing of the overcoat layer is completed, the thermal head pressure switching motor 40 is driven, the bracket 214 is rotated, and the thermal head 204 fixed integrally with the bracket 214 is moved to a predetermined retracted position.

  After the movement of the thermal head 204 to the predetermined retreat position is completed, the roll paper 500 is conveyed in the paper discharge direction. At this time, the roll paper 500 is conveyed so that the boundary between the printing area and the unprinting area is at the cutting position of the cutter unit 207. After a predetermined amount of conveyance is performed by the capstan 202, the roll paper 500 is cut by the cutter unit 207.

  The remainder of the roll paper 500 having the leading end cut by the cutting process is gripped by the paper discharge roller 212. From this state, the paper discharge roller 212 rotates clockwise as viewed from the direction shown in FIG. 2A, and the roll paper 500 is conveyed in the paper discharge direction. Here, the leading end of the roll paper 500 on the cartridge 110 side is conveyed in the paper discharge direction simultaneously with the paper feed at the time of paper discharge. As a result, the printed roll paper 500 is conveyed in the paper discharge direction by the paper discharge roller 212, and then pushed out of the front end of the unprinted roll paper 500 coming from the upstream side and discharged out of the thermal printer 100.

Next, the operation of the thermal printer 100 during the printing process in steps S806 and S807 in FIG. 9 will be described.
After the paper discharge operation is completed, the roll paper 500 is pulled out. When the next printing is not performed, the roll paper 500 must be completely stored in the cartridge 110 so that the cartridge 110 is detachable. Therefore, the winding operation of the roll paper 500 is performed.
The winding operation of the roll paper 500 is performed by rotating the roll paper roller shaft 200 counterclockwise when the capstan 202 is viewed from the direction shown in FIG. During the winding of the roll paper 500, the roll paper cueing sensor 707 used in the roll paper cueing is used. The roll paper 500 can be accurately stored in the cartridge 110 by additionally driving the capstan 202 and the roll paper roller shaft 200 by a predetermined amount starting from the place where the roll paper is changed to the state without the roll paper. One sheet is printed as described above.

  As described above, according to the thermal printer 100 of the present embodiment, the force that the thermal head pressure switching motor 40 must generate when switching the thermal head pressure that is performed at least once between the end of paper return and the start of printing. Becomes smaller. Therefore, according to the thermal printer 100 of this embodiment, the thermal head pressure switching time can be shortened without increasing the size of the thermal printer 100, and further high-speed printing can be performed.

In the present embodiment, the thermal printer 100 using the roll paper 500 as the recording paper has been described. However, a cut paper may be used as the recording paper.
In the present embodiment, the case where the rotation direction of the paper conveyance motor 30 and the rotation direction of the sun gear 314 are opposite to each other as the nip pressure switching mechanism 319 has been described, but the rotation direction of the sun gear 314 depends on the rotation direction of the paper conveyance motor 30. The same direction as the rotation direction may be used.

In the present embodiment, the number and configuration of the gears are arbitrary, and are not necessarily the same as those in the present embodiment.
Further, in the present embodiment, the ink ribbon is wound up by the paper transport motor 30, but other motors or ink ribbon winding motors may be used.
In this embodiment, the nip pressure is adjusted by applying pressure to the pinch roller. However, the nip pressure may be adjusted by pressing the capstan roller instead of the pinch roller.

  DESCRIPTION OF SYMBOLS 100: Thermal printer 201: Pinch roller 202: Capstan 204: Thermal head 205: Platen roller 207: Cutter unit 212: Paper discharge roller 214: Bracket 215: Thermal head support plate 217: Thermal head pressure lever 218: Thermal head addition Pressure spring 219: Bush 221: Pinch lever 222: Pinch spring 223: Rotating shaft 224: Cam 225: Swing shaft 226: Swing shaft guide 30: Paper transport motor 314: Sun gear 3141: Bracket 315: Planetary gear 316: Planetary gear 317: Notched gear 40: Thermal head pressure switching motor 500: Roll paper 501: Conveying path 510: Ink ribbon

Claims (7)

A printing device for transferring ink to paper,
A thermal head and a platen roller that are in pressure contact during printing and separated when paper is returned;
A first drive unit that switches between a pressed state and a separated state between the thermal head and the platen roller;
A capstan that transports paper,
A pinch roller facing the capstan and sandwiching the paper;
A second drive unit for driving the capstan;
Drive pressure switching means that is driven by the second drive unit and that reduces the pressure between the capstan and the pinch roller when returning the paper than the pressure between the capstan and the pinch roller during printing. A printing apparatus characterized by the above.   The pressing force switching means switches the pressing force between the capstan and the pinch roller during printing and paper return by switching the pressing force by the pressing force applying means for applying a pressing force to the capstan or the pinch roller. The printing apparatus according to claim 1, wherein the pressure is changed. The pressure switching means is
A planetary gear mechanism having a first planetary gear and a second planetary gear;
A notched gear that has a notch and meshes with the first planetary gear and the second planetary gear;
The printing apparatus according to claim 2, further comprising a cam that is driven in conjunction with rotation of the notched gear. The cam moves to at least two positions;
The printing apparatus according to claim 3, wherein the pressing force switching unit switches the pressing force between a first position and a second position of the cam.   The switching of the applied pressure is performed by either the first planetary gear or the second planetary gear rotating the notched gear according to the rotation direction of the capstan. 5. The printing apparatus according to 4.   When the first planetary gear or the second planetary gear is idled at the notch portion of the notch gear, the rotation of the notch gear is stopped, and the cam is in the first position or the The printing apparatus according to claim 4, wherein the printing apparatus is held in a second position.   The printing apparatus according to claim 1, wherein the printing by the thermal head is performed after the switching of the pressing force by the pressing force switching unit is completed.

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