JPH05138982A - Printer head pressing mechanism - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of a cam and a cam follower which comes in contact with the former and ameliorate the ease of assembly in a printer head pressing mechanism. CONSTITUTION:A heat sink 25 with a thermal head 24 installed on the lower surface of the front is supported in a freely rotatable manner on a platen 23 so that both parts can become detached from each other. Further, a head pressing member 30 is retained in the downstream of the heat sink 25 so that the member 30 can be attached from above the device. In addition, a cam follower 33 is installed at the lower part of the head pressing member 30, and a leaf cam 39 is arranged at an opposite position to the cam follower 33. Also a head pressing spring 38 is suspended between the head pressing member 30 and a frame 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for pressing or separating a thermal head of a thermal transfer printer against a platen.

[0002]

2. Description of the Related Art As a head pressing mechanism for a printer that presses or separates a thermal head of a thermal transfer printer against a platen, for example, a mechanism described in JP-A-2-2021 has been conventionally known.

4 and 5 are side views of the head pressing mechanism described in the above publication. In the figure, 1 is a recording paper, 2
Is an ink sheet, and the recording paper 1 and the ink sheet 2 are superposed and wound on the platen 3.
A thermal head 4 which is pressed against the platen 3 via the recording paper 1 and the ink sheet 2 is arranged at a position facing the platen 3 above. The thermal head 4 is joined to the lower surface of the front end of the heat sink 5. The heat sink 5 has a stopper 5 protruding upward to the front.
A is provided, and a connecting portion 5b is extended rearward (to the left in the drawing). And this connecting portion 5b
Is attached to a rotatable main shaft 6 supported by a frame (not shown).

Further, the main shaft 6 is inserted into a hole 7a provided at the rear end portion of the head pressing member 7, thereby rotatably supporting the head pressing member 7.
A stopper 7b and a bent portion 7c are provided on the front portion of the head pressing member 7. The stopper 7b is arranged so as to face the stopper 5a of the heat sink 5 from below, and regulates the head pressing member 7 so as not to be separated from the heat sink 5 by a predetermined distance or more. A head pressing spring 8 is inserted between the heat sink 5 and the head pressing member 7. A latch 9 is provided on the side of the bent portion 7c of the head pressing member 7. The latch 9 is rotatably supported by the bent portion 7c by a pin 10 and has a U-shaped groove 9a that opens rearward in the lower portion, and a head pressing member. A latch spring 11 suspended between the bent portion 7c and the bent portion 7c of 7 always urges it to rotate clockwise.

A T-shaped cam lever 13 whose rear end is rotatably supported by a shaft 12 is disposed below the heat sink 5. A latch pin 14 is fixed to the upper portion of the front end of the cam lever 13, and the latch pin 14 can be engaged with and disengaged from the U-shaped groove 9 a of the latch 9. A cam pin 15 is fixed to the lower part of the front end of the cam lever 13. The tip of the cam pin 15 is inserted into the cam groove 16a of the cam 16 arranged at the lower side portion of the cam lever 13.

With the above-described structure, the thermal head 4 as shown in FIG.
When the cam 16 is rotated in the direction of the arrow A by a drive source such as a DC motor (not shown) from the state separated from, the cam pin 15 moves along the cam groove 16a,
The cam lever 13 rotates clockwise around the shaft 12 according to the cam curve of the cam groove 16a. As a result, the head pressing member 7 rotates clockwise via the latch 9,
The engagement between the stopper 7b of the head pressing member 7 and the stopper 5a of the heat sink 5 is released, and the head pressing spring 8 is released.
The thermal head 4 is pressed against the platen 3 via the ink sheet 2 and the recording paper 1 by the urging force of, and becomes a printable state as shown in FIG. When the cam 16 reaches a predetermined position, the drive source stops according to an instruction from a detection circuit (not shown).

After the printing is completed, the cam 16 is again moved to the arrow A in FIG.
When rotated in the direction, the cam lever 13 and the head pressing member 7 rotate counterclockwise, and the stopper 7b of the head pressing member 7 and the stopper 5a of the heat sink 5 are engaged with each other, so that the thermal head 4 moves from the platen 3 to the platen 3. Release it to return to the original state.

When the latch pin 14 and the latch 9 are disengaged, the thermal head 4 becomes rotatable around the main shaft 6.

[0009]

Since the conventional head pressing mechanism is constructed as described above, the thermal head 4
There is a problem in that the surface pressure between the cam groove 16a and the cam pin 15 becomes high and the cam 16 and the cam pin 15 are worn when the plate is pressed against the platen 3. Further, in the above-mentioned conventional configuration, when the cam pin 15 is assembled in the cam groove 16a, it is necessary to incorporate the cam pin 15 from the direction perpendicular to the cam 16, so that workability is poor, and a space for assembling is required, so that internal space is required. There were restrictions on the layout of mechanical parts, and there were problems with maintainability.

The present invention has been made in view of the above problems, and it is possible to improve the wear resistance of the cam and the cam pin (cam follower) contacting the cam, and to improve the assemblability. It is an object of the present invention to obtain a head pressing mechanism for a printer that can be used.

[0011]

In a printer head pressing mechanism according to the present invention, a head pressing member is disposed below a heat sink, and the thermal head is pressed and released by a driving mechanism including a plate cam and a cam follower, for example. It is configured to do.

[0012]

According to the present invention, the head pressing member is provided below the heat sink, and the thermal head is pressed against the platen and released from the platen by a driving mechanism including, for example, a plate cam and a cam follower. As a result, the surface pressure of the cam and the cam follower is reduced to improve wear resistance, and the head pressing member can be assembled from above the device, improving workability.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a head pressing mechanism according to an embodiment of the present invention while the printer is printing, and FIG. 2 is a side view showing the head pressing mechanism when the printer is on standby. FIG. 3 is an exploded perspective view of the head pressing mechanism.

In the figure, 21 is a recording paper, and 22 is an ink sheet. Further, 23 is a platen 23 that winds up the recording paper 21 and the ink sheet 22.
A thermal head 24 is arranged above the platen 23 so as to face it. This thermal head 2
4 is joined to the lower surface of the front end of the heat sink 25.
The heat sink 25 is rotatably attached around a main shaft 26 provided at the rear end portion, and the side surface of the heat sink 25 is provided with a latch 2 provided on a side of the heat sink 25.
A stopper 25a is provided so as to restrict the rotation of the pin 7, and the pin hole 25 is provided above the stopper 25a.
b is provided, and a connecting hole 25c is provided at the rear end.

The latch 27 has a U-shaped groove 2 at the bottom.
7a and a hole 27b at the top. A pin 28 is provided penetrating the hole 27b and press-fitted into the pin hole 25b of the heat sink 25. The pin 28 rotatably supports the latch 27 with respect to the heat sink 25. In addition, the latch 27
Is always urged to rotate clockwise in the figure by a latch spring 29 suspended between the upper end of the latch 27 and the heat sink 25.

A head pressing member 30 is arranged below the heat sink 25. This head pressing member 3
No. 0 has a support hole 30a on the upper surface of the rear part and a pin hole 30b on the side surface of the front part. A latch pin 31 is fixed in the pin hole 30b on the front side surface, and the latch pin 31 can be engaged with and disengaged from the U-shaped groove 27a of the latch 27. A cam follower pin 32 is fixed to the lower surface of the front portion of the head pressing member 30 by a fulcrum 30c, and the cam follower pin 32 has a cam follower 33.
Is rotatably supported. A Z-shaped head bracket 34 is provided so as to face the rear portion of the head pressing member 30. This head bracket 34 is
It has a mounting hole 34a in the front part, and has a V-shaped recess 34b in the center of the rear part.
Has holes 34c on both sides. And this hollow 3
The head bracket pin 35 is fixed to the holes 34c provided on both sides of the head bracket 4b.
Is inserted into the support hole 30a of the head pressing member 30. Further, the head bracket 34 is fixed to the frame 36 by a screw 37 penetrating a hole 34a provided in a front portion of the head bracket 34 and a screw hole 36a on the upper surface of the lower frame 36. A spring hook 36b is provided on the front portion of the frame 36, and a head pressing spring 37 is suspended between the spring hook 36b and the center of the front end of the head pressing member 30. In addition, the cam follower 33
A plate cam 38 that rotates by receiving a driving force from a driving source such as a DC motor (not shown) is disposed at the lower facing position.

Next, the operation of the head pressing mechanism having the above structure will be described.

First, when the plate cam 38 is rotated in the direction of arrow B by a drive source such as a DC motor (not shown) with the thermal head 24 separated from the platen 23 as shown in FIG. By moving the cam follower 33 along the cam curve of the plate cam 38 by the urging force of the head pressing member 30, the head pressing member 30 rotates clockwise around the head bracket pin 35. As a result, the heat sink 25 rotates clockwise via the latch 27, so that the thermal head 24 moves to the ink sheet 22.
1 and the recording paper 21 and the platen 23 under pressure.
The printable state is as shown in. The plate cam 38
When reaches a predetermined position, the drive source is stopped by an instruction from a detection circuit (not shown).

When the plate cam 38 is rotated again in the direction of arrow B in FIG. 1 after printing is completed, the head pressing member 30 and the heat sink 25 rotate counterclockwise via the cam follower 33, and the thermal head 24 causes the platen 23 to rotate. It is separated from and returns to the original state. When the plate cam 38 reaches a predetermined position, the drive source is stopped by an instruction from a detection circuit (not shown) as in the above case.

When the latch pin 31 and the latch 27 are disengaged from each other, the thermal head 24 moves to the main shaft 26.
It becomes possible to rotate around.

[0022]

As described above, according to the present invention, the head pressing member is provided below the heat sink, and the plate cam rotated by the driving force of the drive source is provided below the head pressing member, and the head is provided. Since the cam follower that engages with the peripheral surface of the plate cam is provided under the pressing member, it is possible to prevent the plate cam from being worn and to drive the plate cam with a small force. Further, since the head pressing member can be attached from above the device, the assembling workability can be improved and the device can be downsized because a space in the left and right direction for assembling and maintenance is unnecessary.

[Brief description of drawings]

FIG. 1 is a side view showing a head pressing mechanism according to an embodiment of the present invention while a printer is printing an image.

FIG. 2 is a side view showing a head pressing mechanism according to an embodiment of the present invention in a state where the printer is in a standby state.

FIG. 3 is an exploded perspective view of a head pressing mechanism according to an embodiment of the present invention.

FIG. 4 is a side view showing a conventional head pressing mechanism in a state where a printer is printing an image.

FIG. 5 is a side view showing a conventional head pressing mechanism in a standby state of the printer.

[Explanation of symbols]

 21 Recording Paper 22 Ink Sheet 23 Platen 24 Thermal Head 25 Heat Sink 30 Head Pressing Member 33 Cam Follower 37 Head Pressing Spring 38 Plate Cam

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[Procedure amendment]

[Submission date] June 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

A head pressing member 30 is arranged below the heat sink 25. This head pressing member 3
No. 0 has a support hole 30a on the upper surface of the rear part and a pin hole 30b on the side surface of the front part. A latch pin 31 is fixed in the pin hole 30b on the front side surface, and the latch pin 31 can be engaged with and disengaged from the U-shaped groove 27a of the latch 27. A cam follower pin 32 is fixed to the lower surface of the front portion of the head pressing member 30 by a fulcrum 30c, and the cam follower pin 32 has a cam follower 33.
Is rotatably supported. A Z-shaped head bracket 34 is provided so as to face the rear portion of the head pressing member 30. This head bracket 34 is
It has a mounting hole 34a in the front part, and has a V-shaped recess 34b in the center of the rear part.
Has holes 34c on both sides. And this hollow 3
The head bracket pin 35 is fixed to the holes 34c provided on both sides of the head bracket 4b.
Is inserted into the support hole 30a of the head pressing member 30. Further, the head bracket 34 is fixed to the frame 36 by a screw 37 penetrating a hole 34a provided in a front portion of the head bracket 34 and a screw hole 36a on the upper surface of the lower frame 36. A spring hook 36b is provided on the front portion of the frame 36, and a head pressing spring 38 is suspended between the spring hook 36b and the center of the front end of the head pressing member 30. In addition, the cam follower 33
A plate cam 39 that rotates by receiving a driving force from a driving source such as a DC motor (not shown) is disposed at the lower facing position.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

Firstly, as shown in FIG. 2, from the state where the thermal head 24 is released to open from the platen 23, to rotate the plate cam 39 in the direction of arrow B by a driving source of the DC motor or the like (not shown), the head pressing spring 38 By moving the cam follower 33 along the cam curve of the plate cam 39 by the urging force of the head pressing member 30, the head pressing member 30 rotates clockwise around the head bracket pin 35. As a result, the heat sink 25 rotates clockwise via the latch 27, so that the thermal head 24 moves to the ink sheet 22.
1 and the recording paper 21 and the platen 23 under pressure.
The printable state is as shown in. The plate cam 39
When reaches a predetermined position, the drive source is stopped by an instruction from a detection circuit (not shown).

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

When the plate cam 39 is rotated again in the direction of arrow B in FIG. 1 after printing is completed, the head pressing member 30 and the heat sink 25 rotate counterclockwise via the cam follower 33, and the thermal head 24 causes the platen 23 to rotate. It is separated from and returns to the original state. When the plate cam 39 reaches a predetermined position, the drive source is stopped by an instruction from a detection circuit (not shown), as described above.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of reference numerals] 21 recording paper 22 ink sheet 23 platen 24 thermal head 25 heat sink 30 head pressing member 33 cam follower 38 head pressing spring 39 plate cam

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 25/304 8604-2C B41J 25/30 U

Claims (1)

[Claims] 1. A platen for winding a recording paper and an ink sheet which are superposed on each other, a thermal head for pressing the ink of the ink sheet onto the recording paper by being pressed against the platen via the recording paper and the ink sheet, and the thermal head. A heat sink to which a head is attached and which is rotatably supported so that the thermal head can be brought into contact with and separated from the platen, a head pressing member which is arranged below the heat sink and which can be mounted from above and below, and the head pressing member. In a state in which a shaft supporting member that rotatably supports a member, a head pressing spring that applies a pressure contact force to the platen with respect to the thermal head, and a thermal head in cooperation with the head pressing member, are in the pressure contact position. Positioning the head pressing member with respect to the heat sink A head pressing mechanism for a printer, comprising a drive mechanism for releasing pressure contact of the head.