JPS6358704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a serial printer that, when printing on a plurality of print media of different thicknesses, requires that the gap between the print surface of the medium and the tip of the print head always be maintained at a predetermined amount.

Since this type of serial printer prints on a plurality of print media of different thicknesses, it is necessary to print while always maintaining a predetermined gap between the print surface of the print medium and the tip of the print head.

In a platen retraction type serial printer, a contact element (roller, etc.) is installed on the carrier unit equipped with the print head, and by sandwiching the print medium between the contacts and pressing it against the platen, the gap between the print surface of the medium and the tip of the print head is maintained at all times. Printing was performed while maintaining the specified amount.

On the other hand, in a print head retractable type serial printer, a contact is provided on the carrier unit on which the print head is mounted, and the contact is connected to the print medium via a guide member provided parallel to the reciprocating direction of the carrier unit. By pressing the media against the platen, printing is performed while always maintaining a predetermined gap between the printing surface of the medium and the tip of the printing head.

Therefore, the above-mentioned mechanism has disadvantages in printing quality, such as damage to the print medium by the contactor, and stains, transfer, and impressions caused by the contactor on multiple sheets of copy paper. In addition, since the print medium is sandwiched between the contact and the platen, the contact or the platen must be retracted each time a line feed occurs.
There were disadvantages such as long processing time.

When printing on a plurality of print media of different thicknesses, the present invention provides a contactor included in a carrier unit and a platen that can be moved up and down, and a step motor that is the power source for the up and down movement of the platen. The space between the printing surface of the medium and the tip of the printing head is always maintained at a predetermined amount by controlling rotation and reversal, and the printing head is moved back and forth without the contactor contacting the printing medium, resulting in a simple structure. The present invention provides a printing medium thickness detection mechanism that enables higher printing quality to be obtained at lower cost and to shorten processing time.

The present invention will be described in detail with reference to the drawings showing embodiments of the invention.

Referring to FIG. 1, in one embodiment of the present invention, a carrier unit 1 carries a printing head 2, a ribbon cartridge 3, a contactor 4, etc., and is supported by support guide shafts 5a and 5b. The platen 6 is attached to a support plate 7, and the support plate 7 is attached to a support shaft 8.
It is supported by a and 8b and is movable up and down, and is further urged in the direction of the print head 2 by the tension of a spring 9. On the other hand, a lever 11 attached to a rotatable support shaft 12 is engaged with a retraction pin 10 embedded in the support plate 7. Furthermore, a gear 13 with a built-in one-way clutch 14 (a bearing that connects to the shaft only when rotating in one direction) is mounted on one end of the support shaft 12, and a gear 13 that is a power source for vertical movement of the platen 6 is mounted. It is connected to a gear 15 attached to the shaft. 17 is a print medium.

Next, the operation will be explained with reference to FIGS. 1 and 2. The carrier unit 1 is connected to a power source such as a servo motor via a wire rope (the wire rope and servo motor are not shown), and prints on the print medium 17 while reciprocating on support guide shafts 5a and 5b. .

Since the position of the platen 6 relative to the print head 2 is initially unknown, an initializing operation is performed. When the step motor 16 is rotated counterclockwise, the gear 13 is rotated clockwise via the gear 15 mounted on the shaft of the step motor 16. At this time, a one-way clutch 14 built into the gear 13
Since the platen 6 is not connected to the support shaft 12, the platen 6 rises due to the tension of the spring 9 until it collides with the contact 4. The lever 11 and the support shaft 12 also rotate at the same time. The step motor 16 is connected to the platen 6
Even after colliding with the contactor 4, the rotation continues in the counterclockwise direction, and after the collision has occurred, the rotation is stopped.
The step motor 16 rotates by N steps + α steps (state shown in FIG. 2B). Next, when the step motor 16 is rotated clockwise N steps from this state, the gear 13 is rotated counterclockwise via the gear 15. At this time, the one-way clutch 14 built into the gear 13 is connected to the support shaft 12 and
also rotates counterclockwise. Since the lever 11 attached to the support shaft 12 also rotates counterclockwise, the support plate 7 is lowered against the tension of the spring 9 via the retraction pin 10 engaged with the lever 11. The platen 6 attached to the support plate 7 also descends in the same manner. This position is the home position (FIG. 2A), and in this state the print medium 17 is sucked in and discharged. This series of operations is an initialization operation.

When the initialization operation is completed, business processing is performed, and the series of operations for detecting the thickness of the printing medium as shown in FIG. 2 is repeatedly performed.

First, when the print medium 17 is sucked in, the step motor 16 is rotated counterclockwise by N steps + α steps in the same way as the initialization operation, the platen 6 is raised, and the print medium 17 is pressed against the contactor 4 by the platen 6 ( Figure 2B condition). Next, the step motor 16 is rotated clockwise n steps to lower the platen 6 by a small amount (the state shown in FIG. 2C). In this state, the gap between the print surface of the print medium 17 and the tip of the print head 2 becomes a predetermined amount d, and printing becomes possible. In addition, since the print medium 17 and the contact 4 are separated, printing operations and line feeds can be repeated and repeated, making it possible to significantly shorten processing time. problems can be solved at the same time. Even in the case of a print medium whose thickness changes midway, such as a passbook used in a bank, etc., the thickness detection operation may be performed once each for the previous and subsequent pages.

When the printing operation is completed, the step motor 16 is rotated clockwise N steps to lower the platen 6 (the state shown in FIG. 2A), and the print medium 17 is ejected. The position of the platen 6 at this time is the home position.

By repeating the operations described above, it is possible to print on any print medium of different thickness.

As explained above, the present invention has a contactor provided in the carrier unit and a platen that can move up and down, and controls the step motor as the power source in forward and reverse directions, thereby achieving a simple structure, low cost, and high quality printing. A print medium thickness detection mechanism that provides high quality and shortens processing time can be created.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, and FIG. 2 is an operational flow for detecting the thickness of a printing medium. 1...Carrier unit, 2...Print head,
3... Ribbon cartridge, 4... Contact, 5
a, 5b... Support guide shaft, 6... Platen, 7...
... Support plate, 8a, 8b ... Support shaft, 9 ... Spring, 10 ... Retraction pin, 11 ... Lever, 12 ... Support shaft, 13 ... Gear, 14 ...
One-way clutch, 15...gear, 16...step motor, 17...printing medium.

Claims (1)

[Scope of Claims] 1. A serial printer in which a carrier unit equipped with a print head prints on a print medium while reciprocating along a print line on a support guide shaft, comprising: a contactor provided on the carrier unit; A first member facing the contact and approaching the contact.
a platen that is free to move in the direction of the contact and in a second direction away from the contact and into which the print medium is inserted between the platen and the contact, and urging means that constantly urges the platen in the first direction. , having a support shaft and moving the platen in the first direction and the second direction by rotating the support shaft in a third direction and in a fourth direction opposite to the third direction; a link mechanism, during a positioning operation, the support shaft is free to rotate and the platen is moved in the first direction by the urging means to press the print medium against the contact, and then engaged with the support shaft; positioning means having a one-way clutch for forcibly rotating the support shaft by a predetermined amount in the fourth direction, moving the platen by a predetermined distance in the second direction, and maintaining this state; A serial printer, characterized in that after the positioning operation is completed, the carrier unit is moved on the support guide shaft to perform a printing operation.