JPS6244481A - Mechanism for adjusting printing gap in printer - Google Patents

Abstract

PURPOSE:To prevent the lowering in stop accuracy of a printing head caused by the generation of the bending deformation in each shaft, by arranging a compression sensor having conductivity by compressive displacement to the arm point of contact with a printing paper. CONSTITUTION:A compression sensor 20 is constituted so that a rubber member having a metal powder 23 scattered therein is provided between two conductive plates 21 and compressed upon the reception of compressive displacement, and the particles of the metal powder 23 are mutually contacted to show conductive effect. By arranging the compression sensor 20 to the top end of an arm 4, the contact of paper 2 with the arm 4 can be detected and control is performed on the basis of the output thereof by a control part and the rotation of the drive motor of an eccentric shaft can be stopped. Further, because the contact with the paper is sensed, the drive motor can be prevented from generating much unnecessary bending deformation in an arm push-in mechanism part through the eccentric shaft and a carrier unit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing gap adjustment mechanism for a printer, particularly a dot matrix printer.

[Prior Art] FIG. 4 shows a schematic side view of a printing gap adjustment mechanism of a conventional printer. FIG. 2 also shows a schematic plan view.

The carrier unit 5 carrying the printing plate 3 is supported by a shaft 6.7, and one shaft has an eccentric structure and is called an eccentric shaft 7. Further, an arm 4 for pressing the printing paper 2 against the platen 1 is arranged near the printing pad 3 and is held on a carrier unit 5. The eccentric shaft 7 is rotationally driven by a drive motor 10 via a ram 8 and a ram 9 each having a friction clutch therein. The operation will be explained below. The rotational drive of the drive motor 10 rotates the eccentric shaft 7, and further rotates the carrier unit 5 in the direction of the arrow in FIG. Arm 4 pushes platen 1 through paper 2. At this time, when the reaction force of pressing the paper exceeds a certain value, the friction clutch of the Nangun 8 operates to disconnect the power of the drive motor 10 from the eccentric shaft 7. Next, the drive motor 10 is rotated in the reverse direction, and the eccentric shaft 7 is also rotated in the reverse direction at the same time, so that the print head 3 is returned so as to maintain a constant print gap, thereby securing the print gap.

[Problems to be Solved] The print gap adjustment mechanism of the conventional printer described above uses a friction clutch, and therefore is greatly influenced by the clutch torque.

In addition, the clutch torque of a friction clutch is greatly affected by wear, temperature, variations in initial settings, etc., and its management requires a large number of man-hours, reduces parts accuracy, and increases costs. In addition, since the eccentric shaft 7 pushes up the carrier unit 5 with the clutch torque, the arm 4
Since the printing paper 2 is pushed in with a constant pressure, the arm, carrier unit, and each shaft are bent and deformed due to the reaction force at this time, resulting in a disadvantage that the stopping precision of the printing head is deteriorated.

[Means for Solving the Problems] The present invention has been made by focusing on the above-mentioned conventional problems, and is low in cost without being affected by clutch torque and requiring no man-hours for management unlike friction clutches.
It is an object of the present invention to provide a printing gap adjustment mechanism for a printer that can prevent deterioration of the stopping precision of the print head due to bending deformation of each shaft.

To this end, the present invention provides an arm that is disposed near a print head and presses printing paper against a platen, a carrier unit to which the arm is attached, an eccentric shaft that rotationally drives the carrier unit, and a drive motor. The present invention provides a printing gap adjustment mechanism for a printer having a printing gap adjustment mechanism, characterized in that a compression sensor that has conductivity due to compression displacement is arranged at a location of the arm that contacts the printing paper. .

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 3 is a schematic diagram of an embodiment of a well-known compression sensor that has electrical conductivity due to changes in compression. There is a rubber member 22 inlaid with metal powder 23 between two conductive plates 21, and when this is subjected to compressive displacement, the rubber member 22 contracts, and the metal powders 22 therein come into contact with each other, exhibiting a conductive effect. . FIG. 4 is a schematic diagram showing the effect of the compression sensor 20 described above. FIG. 5 shows an embodiment of the printing gap adjustment mechanism of the present invention. The configuration is the same as that described in the prior art section, so the explanation will be omitted, but the compression sensor 20 is disposed on the surface of the arm 4 that contacts the paper 2.

By disposing the compression sensor 20 at the tip of the arm 4 in this way, it is possible to detect the contact between the paper 2 and the arm 4, and the output is used to control the control unit (not shown) to rotate the drive motor of the eccentric shaft. It becomes possible to stop. This eliminates the conventionally used friction clutch and also overcomes the various drawbacks mentioned above caused by friction clutches. Furthermore, since contact with the paper is sensed, it is possible to avoid unnecessary bending and deformation of the pushing mechanism of the arm by the drive motor via the eccentric shaft and the carrier unit.

[Effects of the Invention] As explained above, the present invention includes an arm that is disposed near the print head and presses the print paper against the platen;
A printing gap adjustment mechanism for a printer including a carrier unit to which the arm is attached, an eccentric shaft for rotationally driving the carrier unit, and a drive motor,
The printer's printing gap adjustment mechanism is characterized by a compression sensor that is conductive due to compression displacement placed at the point where the arm contacts the printing paper, so there is no need to use a friction clutch, and therefore there is no need to use a friction clutch. The disadvantages caused by the friction clutch can be eliminated, and unnecessary bending deformation of the pushing mechanism can be prevented, resulting in high quality and low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the configuration of a compression sensor used in an embodiment of the present invention, Fig. 2 is a conceptual diagram showing how the compression sensor of Fig. 1 is used, and Fig. 3 is a printing gap adjustment according to the present invention. FIG. 4 is a schematic side view of a conventional printing gap adjustment mechanism, and FIG. 5 is a schematic plan view thereof. l Nib platen 2: Print paper 3: Print head 4: Arm 5: Carrier unit 6: Shaft 7: Eccentric shaft 8: Gear (including friction flange) 9: South 11j 102 Drive motor 20: Compression sensor Applicant "1 Denki Co., Ltd. Figure 1 Figure 22 Figure 39 s4 Figure 5

Claims (1)

[Claims] Printing gap adjustment for a printer that includes an arm that is placed near a print head and presses printing paper against a platen, a carrier unit to which the arm is attached, an eccentric shaft that rotationally drives the carrier unit, and a drive motor. 1. A printing gap adjustment mechanism for a printer, characterized in that a compression sensor that is electrically conductive due to compression displacement is disposed at a location of the arm that contacts the printing paper.