JPH0629842U - Printer - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a printer that maintains a constant line feed amount even if the paper thickness changes by providing a platen moving mechanism. [Structure] Square holes 27 are formed in the side frame 26, and a platen shaft 28 is slidably fitted therein. In addition, an automatic paper thickness detection mechanism 39 is provided that moves the platen 40 closer to and away from the print head 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a printer that prints by pressing a sheet against a platen with a pressing member before the printing position.

[0002]

[Prior art]

 Some conventional printers have a mechanism that appropriately secures the gap between the print head and the paper, and some use a pressure contact member that presses the paper before the printing position. A conventional printer configuration will be described below with reference to the drawings. FIG. 5 is a side view showing a conventional printer device having an automatic paper thickness detection mechanism.

In FIG. 5, the printer device 1 is provided with a platen 4 at a position facing the print head 3 mounted on the carriage 2. A protector bracket 5 is fixed at a position facing the platen 4 at one end of the carriage 2. The carriage 2 is guided by a guide 8 on which a main shaft 6 and a bearing 7 run, and is movable in parallel with the platen 4.

A paper chute 9 is installed below the platen 4, and a paper pressure 11 which is a pressure contact member is fixed to one end of the paper chute 9. The paper pressure 11 has a function of bringing the printing paper 10 into close contact with the platen 4 before the printing position. The printing paper 10 guided and fed by the paper chute 9 passes between the platen 4 and the paper pressure 11, passes through the gap between the platen 4 and the protector bracket 5, and is conveyed in the direction of arrow D by the pulling tractor 12. It has become so. While the printing operation is being performed, a certain distance is secured between the printing surface of the printing paper 10 and the print head 3, which is performed by the automatic paper thickness detection mechanism described below.

Here, the automatic paper thickness detection mechanism will be described. The side frame 13 is provided with a square hole 14, and the main shaft 6 is slidably fitted in the square hole 14. A slide cam 15 is fixed to the end surface of the main shaft 6 outside the square hole 14. The slide cam 15 is pressed against a cam follower 18 by a tension spring 17 suspended around a post 16 provided in the center of the main shaft 6 and the side frame 13. The cam follower 18 is pivotally supported by an eccentric roller 19. A gear 20 is fixed to the outside of the slide cam 15. Gears 21, 22, and 23 mesh with the gear 20 in order, and the gear 23 meshes with a motor gear 24 a of the drive motor 24. With the above configuration, the automatic paper thickness detection mechanism 25 of the printer device 1 is realized.

Next, the operation of the above configuration will be described. The drive motor 24 of the automatic paper thickness detection mechanism 25 is rotated in the direction of arrow A, the rotational force is transmitted to the gears 23, 22 and 21, and the slide cam 15 is rotated via the drive gear 20. Since the slide cam 15 is pressed against the cam follower 18 by the tension spring 17, when the slide cam 15 rotates in the arrow A direction, the main shaft 6 slides in the square hole 14 of the side frame 13 in the arrow B direction. By this operation, the carriage 2 also moves in the direction of arrow B, and the protector bracket 5 is pressed against the printing surface of the printing paper 10 wound around the platen 4.

The printer device 1 is provided with a slit board and a sensor (not shown), and monitors the above-described rotation operation of the automatic paper thickness detection mechanism 25. Therefore, when the protector bracket 5 hits the printing surface of the printing paper 10 and the sensor output is stopped by the above operation, the drive motor 24 is rotated in the direction of arrow A ', and the carriage 2 is returned by a certain amount in the direction of arrow B'. As a result, the gap C between the printing surface of the printing paper 10 and the protector bracket 5 (hereinafter referred to as the protector gap) is always kept constant regardless of the thickness of the printing paper 10. Printing is started in this state. During the printing operation, the paper pressure 11 brings the printing paper 10 into close contact with the platen 4 so as not to float from the platen 4. This enables accurate printing operation.

[0008]

[Problems to be solved by the device]

 By the way, since the paper pressure 11 is fixed to the paper chute 9 in the apparatus having the above structure, the positional relationship between the paper pressure 11 and the platen 4 is kept constant. Therefore, the positional relationship between the printing surface of the printing paper 10 and the paper pressure 11 changes depending on the thickness of the printing paper 10. As shown in FIG. 6, when the printing paper 10 is a thin paper 10a, the warp of the paper pressure 11 is small. The pressing force F of the paper pressure 11 against the printing paper 10a is also small. Further, as shown in FIG. 7, when the printing paper 10 is the thick paper 10b, the warp of the paper pressure 11 becomes large, and therefore the pressing force F'of the paper pressure 11 becomes larger than the pressing force F shown in FIG.

Since the pulling tractor 12 shown in FIG. 5 operates regardless of the paper thickness, when the pressing force of the paper pressure 11 against the printing paper 10 changes depending on the paper thickness, the frictional force by the paper pressure 11 changes, and the pulling tractor. The feed force of the printing paper 10 by 12 changes. As a result, if the paper pressure 11 is provided based on the feed force for thin paper, the pressing force of the paper pressure 11 will be overloaded when thick paper is used, and the line feed amount will be less than the standard. Further, if the paper pressure 11 is provided based on the feeding force for the thick paper, the pressing force of the paper pressure 11 when using the thin paper becomes a minute load, and the line feed amount becomes larger than the reference. As described above, there is a problem that the line feed amount varies depending on the thickness of the printing paper 10. 6 is an explanatory diagram showing a conventional example when thin paper is used, and FIG. 7 is an explanatory diagram showing a conventional example when thick paper is used.

In order to eliminate the above-mentioned problems, the present invention improves the automatic paper thickness detection mechanism, keeps the pressing force of the paper pressure 11 constant, and keeps the line feed amount constant even if the paper thickness changes. The purpose is to provide a device.

[0011]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides a printer for performing printing by pressing a sheet, which is wound around a platen supported by a side frame and conveyed, to the platen by a pressure contact member before the printing position. A support body that slidably guides the shaft and a platen moving mechanism that moves the platen toward and away from the print head according to the sheet thickness are provided.

[0012]

[Action]

 After the paper is wound around the platen, the platen moving mechanism first causes the shaft of the platen slidably fitted in the square hole of the side frame to approach the print head. The platen shaft is then separated from the printhead by a fixed amount. As a result, the distance between the print head and the printing surface of the paper is kept constant, and the positional relationship between the printing surface of the paper and the pressure contact member is also held constant. Therefore, the pressing force of the pressing member against the paper can be made constant regardless of the paper thickness.

[0013]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same reference numerals are given to the elements common to each drawing. FIG. 1 is a diagram showing a printer according to an embodiment of the present invention, and FIG. 2 is a plan view showing an automatic paper thickness detection mechanism of this embodiment.

The configuration of the automatic paper thickness detection mechanism (platen moving mechanism) of the printer 45 will be described with reference to FIGS. 1 and 2. In FIG. 1, a square hole 27 is formed in the side frame 26, and the platen shaft 28 is slidably fitted in the square hole 27. The square hole 27 is a support for slidably guiding the platen shaft 28. A cam follower 30 is fixed to the end surface of the platen shaft 28 in the square hole 27 via a collar 29. Further, the cam follower 30 is pressed against the slide cam 31 by a tension spring 33 that is hung between a cam post 32 rotatably attached to the side frame 26 and a shaft 30a fixed to the cam follower 30. A slide cam 31 and a gear 34 are fixed to the cam post 32. The gears 35, 36, and 37 mesh with the gear 34 in this order, and the gear 37 meshes with the motor gear 38 a of the drive motor 38. With the above configuration, the automatic paper thickness detecting mechanism 39 of the printer 45 is realized. Since the paper chute 9 to which the paper pressure 11 is fixed is attached at a predetermined position of the printer 45, the distance between the paper pressure 11 and the protector bracket 5 is constant. That is, the automatic paper thickness detection mechanism 39 of this embodiment moves the platen 40. Other structures are similar to those of the conventional art.

Next, the operation of the embodiment having the above configuration will be described with reference to FIGS. 1, 3 and 4. FIG. 3 is an explanatory view showing an embodiment when thin paper is used, and FIG. 4 is an explanatory view showing an embodiment when thick paper is used. In FIG. 1, when the drive motor 38 of the automatic paper thickness detection mechanism 39 is rotated in the arrow E direction, the gear 34 and the slide cam 31 are rotated in the arrow E direction via the gears 37, 36 and 35. Since the cam follower 30 is pressed against the slide cam 31 by the tension spring 33, the cam follower 30 is moved by the rotation of the slide cam 31, and the platen shaft 28 moves the square hole 27 formed in the side frame 26 in the arrow G direction. Slip to By this operation, the printing surface of the printing paper 10 wound around the platen 40 is pressed against the protector bracket 5.

The printer 45 is provided with a slit board and a sensor (not shown), and monitors the above rotation operation. That is, when the drive motor 38 rotates, the slit board also rotates, and the sensor detects this rotation. When the rotation stops, the sensor output stops. Therefore, when the printing surface of the printing paper 10 hits the protector bracket 5 by the above operation and the rotation of the drive motor 38 is stopped, the sensor output is stopped. At this time, as shown in FIGS. 3 and 4, the position of the platen 40 is farther from the protector bracket 5 when the printing paper 10 is thicker than when it is thin, by the difference in the thickness.

Thereafter, the automatic paper thickness detection mechanism 39 rotates the drive motor 38 in the arrow E ′ direction by a certain amount, and moves the platen shaft 28 in the arrow G ′ direction by a certain amount. This keeps the protector gap C shown in FIGS. 3 and 4 constant.

By the above operation, the positional relationship between the paper pressure 11 and the printing surface of the printing paper 10 is kept constant regardless of the thickness of the printing paper 10. Therefore, since the warp of the paper pressure 11 with respect to the printing surface of the printing paper 10 becomes constant, the pressing force F becomes constant. The friction force of the paper pressure 11 with respect to the printing paper 10 becomes constant, so that the feeding force by the pulling tractor 12 shown in FIG. 1 also becomes constant regardless of the thickness of the printing paper 10.

[0019]

[Effect of device]

 As described above in detail, according to the present invention, the platen moving mechanism is provided in the printer device, and the platen is moved toward and away from the print head according to the paper thickness, so that the protector gap is kept constant. The pressing force of the pressure contact material installed in front of the printing position against the paper can also be kept constant. As a result, the paper feed force can be kept constant, and therefore stable paper traveling can be secured and the line feed amount can be kept constant.

[Brief description of drawings]

FIG. 1 is a side view showing a printer according to an embodiment of the present invention.

FIG. 2 is a plan view showing an automatic paper thickness detection mechanism according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example in which thin paper is used.

FIG. 4 is an explanatory diagram showing an example in which thick paper is used.

FIG. 5 is a side view showing a conventional printer device.

FIG. 6 is an explanatory diagram showing a conventional example when thin paper is used.

FIG. 7 is an explanatory diagram showing a conventional example when thick paper is used.

[Explanation of symbols]

 3 Printing Head 10 Printing Paper 11 Paper Pressure 27 Square Hole 28 Platen Shaft 30 Cam Follower 31 Slide Cam 39 Automatic Paper Thickness Detection Mechanism 40 Platen

Continued Front Page (72) Inventor Shinichi Nunodome 1-7-12 Toranomon, Minato-ku, Tokyo Inside Oki Electric Industry Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A printer for performing printing by pressing a sheet wound around a platen supported by a side frame and conveyed to the platen by a pressure contact member before a printing position to guide the shaft of the platen slidably. And a platen moving mechanism for moving the platen toward and away from the print head according to the thickness of the paper. 2. The platen moving mechanism includes a drive motor, a plurality of gears for transmitting the driving force, a cam rotating through the gears, and a press contact with the cam fixed to a shaft of the platen. The printer according to claim 1, further comprising a cam follower.