JPH0440188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a printing device, and particularly to a printing device that handles sheets and forms of different thicknesses.

[Background of the invention]

Conventionally, as a technique for keeping the distance between the print head and the print medium constant in this type of printing device, for example, as shown in Japanese Patent Publication No. 56-42472, there has been a technique to maintain a constant distance between the print head and the print medium by directly applying it to the paper surface of the print medium or by applying a thin film to the paper surface. There is a technique in which the gap between the print head and the paper surface is adjusted to a constant level by bringing the seal into contact with a guide arm attached to the print carrier and moving the carrier in a predetermined direction. When conveying the print medium, the entire carrier or a heavy portion such as the print head fixing part must be moved to retract the guide arm from the print medium. However, no particular consideration is given to the operating time required for this purpose, missing prints due to bounce of the print head, and generation of ghosts due to direct contact with the paper surface. On the other hand, in a printing device with a platen retraction mechanism, the distance between the paper guide and the print head, on which the platen presses the print medium, is kept constant by the parallelism of the paper guide and the support rail that supports the print carrier. There is. However, in this printing device, no particular consideration is given to the non-adjustment of the parallelism of the support rails.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art as described above, and to provide a printing device that has the effect of quickly keeping the gap between the printing head and the paper surface of printing media such as sheets of paper or forms of different thickness constant. It is about providing.

[Summary of the invention]

To achieve the above object, the printing device of the present invention includes a platen that is arranged parallel to the direction of movement of the print head and that is moved back and forth with respect to the print head.
a paper guide disposed between the print head and the platen, facing the platen and having a width corresponding to the movement range of the print head, and positioning the print medium pushed by the platen; and a paper guide with the platen shaft as the center of rotation. In a printing device equipped with a member that movably holds a platen and presses a print medium against a paper guide from below, the print head is attached to a print head or a print carrier to which it is attached, and the print head and paper guide are moved along the paper guide. It is characterized in that it is equipped with a guide arm section that maintains a constant spacing, and a pressure section that generates a force that presses the guide arm section against the paper guide from above, and that these members maintain a constant spacing between the print head and the print medium. There is.

[Embodiments of the invention]

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

FIG. 1 is a perspective view showing the configuration of a printing device according to an embodiment of the present invention. In the figure, the print carrier 3 on which the print head 2 is mounted is located on the sabo rail 9.
It is supported by a motor 13, and is configured to move in a printing direction B via a timing belt 14 by rotation of a motor 13. Further, the print carrier 3 receives force from the upper frame 12 in the direction of arrow X by means of a ball bearing 11 and a leaf spring 10, and is rotatable about the support rail 9. As a result, the guide arm section (double-dashed line section) 6 formed by the guide shaft 8 attached to the print carrier 3 and the ball bearing 7 always keeps the paper guide 4 and the print head 2 in contact with each other during printing. Keeps the gap within acceptable tolerances. Therefore, as shown in FIG. 3, the parallelism between the support rail 9 and the paper guide 4 does not need to be adjusted, and compared to the difference α between the positions of the left and right support rails 9, the difference β between the positions of the printing head 2 is Small and can be kept within acceptable tolerances. On the other hand, platen 5
When the left and right pair of platen solenoids 22 are sucked in the W direction, the platen link 23 moves the platen bracket 20 and the platen shaft 21 in the arrow Y direction, and the printing medium 1 is conveyed to the center of the printing head 2 with the printing center. It is configured to be pressed against the paper guide 4 and squeezed. Platen 5
It is made of light material such as aluminum so that it can complete its operation in a short time.

Note that 15, 16, and 17 are paper pans that guide the print medium 1, and 18 and 19 are side frames. Further, 24 is a ribbon guide that holds an ink ribbon 225.

As shown in FIG. 2, when processing print media 1 such as sheets of paper or forms of different thickness, the platen 5 and paper guide 4 control the paper surface from the C of the paper guide 4.
You can always keep a constant gap with the surface. Therefore, the gap between the print head 2 and the paper surface is kept within acceptable tolerances. As described above, according to this embodiment, printing media 1 of any thickness can be processed in a short time, and the number of adjustment factors for the apparatus can be reduced.

Although one embodiment has been described above, the present invention is not limited thereto. The paper guide 4 and print head 2 may face each other as in the embodiment, or may be in the same direction. The life of the guide arm part 6 can be set to be long by combining the guide shaft 8 and the ball bearing A7 as in the embodiment, but in relation to the life of the device, the guide shaft 8 should be coated or molded with nylon resin or the like. It is also possible to use it as an arm part. The guide arm 6 may be attached to the print carrier 3 or to the print head 2 in order to adjust the gap between the print head 2 and the paper surface and reduce the number of parts as in the embodiment. It is also possible to lower the rigidity of the guide arm 6 attached to the print carrier 3 and to engage a portion of the guide arm 6 with the print head 2 to maintain a constant gap with the paper surface. The printing carrier drive system also does not use a dedicated motor, but may be connected to the paper conveyance motor with a clutch, or the timing belt 14.
You can also use wire rope instead. The force for rotating the print carrier 3 in the direction of the arrow X may also be provided by a coil spring instead of the leaf spring 10, or by using a ball bearing B1 in relation to the life of the device.
It is also possible to use a nylon resin material instead of 1.
Regarding the method in which the print head 2 moves relative to the paper guide 4, the method in which the entire print carrier 3 is rotated around the support rail 9 as in the embodiment can reduce the number of parts; A method of sliding is also possible.

〔Effect of the invention〕

According to the present invention, since the gap between the paper guide and the print head is always kept constant by the guide arm, there is no need to adjust the parallelism between the paper guide and the support rail, so the number of adjustment steps during assembly can be reduced. . Furthermore, instead of moving the heavier print head up and down to conform to the paper surface, the print head is aligned with the paper guide in advance, and a light platen is moved to press the print medium against the paper guide, which allows the print head to be printed instantly and with low power. Printing can be performed on print media such as sheets of paper or forms of different thicknesses without causing dots on the print medium due to bounce of the print head or ghosts caused by rubbing the paper surface.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a printing device according to an embodiment of the present invention, FIG. 2 is a side view of the printing device showing the movement of the platen due to changes in the thickness of the printing medium, and FIG. 3 is a diagram showing the height of the support rail. A side view showing movement due to a change in height. DESCRIPTION OF SYMBOLS 1...Print medium, 2...Print head, 3...Print carrier, 4...Paper guide, 5...Platen, 6...Guide arm section, 7...Ball bearing, 8...Guide shaft, 9...Support rail, 10...Flat spring, 1
1...Ball bearing, 12...Upper frame, 13...Motor, 14...Timing belt.

Claims (1)

[Claims] 1 A platen arranged parallel to the direction of movement of the print head and moved back and forth with respect to the print head; A paper guide having a width and positioning the printing medium pushed by the platen, and a member movably holding the platen around a platen shaft as a rotation center and pressing the printing medium against the paper guide from below. The printing device includes a guide arm that is attached to the print head or a print carrier on which it is attached, and that follows the paper guide to maintain a constant distance between the print head and the paper guide; Equipped with a pressure section that generates a force that presses the paper guide from above,
A printing device characterized in that the spacing between the printing head and the printing medium is kept constant by these members.