JPH05238079A - Printing apparatus - Google Patents

Abstract

PURPOSE:To make printing without losing the printing quality even when a medium of the uneven thickness having a stamp seal or tone like attached thereto is to be printed. CONSTITUTION:In a platen unit 1, a platen 2 is supported to a platen base 4 by a spring 3 and a collar 5 restricts the movement of the platen 2 to the platen base 4. The platen unit 1 is moved by a motor of a platen driving part 11 corresponding to the thickness of the medium detected by a thickness detecting mechanism 14. Accordingly, while the appropriate gap is secured between a printing head 6 and the platen 2, printing is carried out,. When a part of a seal 10 of a transferred medium 9 comes to the printing position, the platen 2 is retreated in the opposite direction to that urged by the spring 3 because the thickness of the part is larger than the gap between a card holder 7 and the platen 2. Thus, printing is conducted without causing the improper transfer of the medium or making the printed medium dirty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, and more particularly to a printer for printing on a medium having a non-uniform thickness.

[0002]

2. Description of the Related Art In a conventional printing apparatus, a medium thickness detecting mechanism is provided to adjust a printing gap to detect the medium thickness, and an appropriate gap is secured by moving a platen with an actuator or the platen is fixed. The print head is biased to the platen side by a spring, and the print head is retracted according to the medium thickness.

[0003]

In the conventional print gap adjusting method, in the case of adjusting the platen by moving the platen with an actuator or the like, since the adjustment is performed at a predetermined position at a predetermined time, the adjustment is performed once. Printing will be performed with a constant print gap until the next adjustment time.
For example, in areas other than the thickness detection area of media with non-uniform thickness, such as media with a seal stamp attached, printing will be performed with an improper print gap, resulting in print fading, print smear, etc. There is a drawback that the printing quality is degraded.

On the other hand, in the mechanism in which the platen is fixed and the print head is biased toward the platen side by the spring, the print head is always pressed against the medium for printing, which has a drawback that resistance is large and high-speed printing cannot be performed.

[0005]

A printer according to the present invention is a printer provided with a print head, a peripheral portion of the print head, and a card holder that moves with a printing operation, and a platen. In addition, the platen is configured to be biased toward the print head side by a spring and retract according to the thickness of the print medium.

[0006]

The platen mechanism is displaced by the actuator according to the thickness of the print medium whose thickness is detected by the medium thickness detection mechanism, and in the case of a medium having a non-uniform thickness, the platen is moved according to the thickness. Retract in the direction opposite to the print head side.

[0007]

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

FIG. 1 is a side view showing an impact type printing apparatus showing the construction of an embodiment of the present invention.

In the figure, 1 is a platen unit,
It is composed of a platen 2, a spring 3, a platen base 4 and a collar 5. The platen 2 is mounted on the platen base 4 by a spring 3 so that the collar 5 guides the operation of the platen 2 with respect to the platen base 4 and the spring 3 restricts the maximum biasing position of the platen 2 from the platen base 4. Has been.

The print head 6 is attached so as to face the platen 2 and prints by printing an ink ribbon 8. The card holder 7 guides the medium 9 and
The print head 6 is attached at a position slightly closer to the platen 2 so that the ink ribbon 8 and the medium 9 do not come into contact with each other.

The platen drive unit 11 displaces the platen unit 1 according to the thickness of the medium 9 detected by the medium thickness detection mechanism unit 14 to change the distance between the print head 6 and the platen 2. The medium thickness detection roller 2 is elastically contacted with a fixed roller 13 by a spring (not shown),
It is displaced according to the thickness of the print medium 9 passing between the rollers 1 and 5, and forms a part of the medium thickness detection mechanism portion 14.

Therefore, according to the printing apparatus of the present embodiment, when the medium 9 is conveyed and placed at the printing position, the thickness is detected by the medium thickness detecting mechanism 14, and the platen unit is detected in accordance with the medium thickness. 1 operates by a motor (not shown) of the platen driving unit 11, and the print head 6 and the platen 2
Secure the proper gap with and print.

Here, for example, when the seal 10 thicker than the proper gap is pasted on the back surface of the medium 9, the medium thickness is detected when the medium 9 is conveyed and the seal 10 is placed at the printing position as shown in the figure. Since the printing position is different from that of the roller 12, the thickness of the seal 10 is larger than the distance between the card holder 7 and the platen 2, and the print gap corresponding to the thickness of the seal 10 is not secured. Further, not only the transport direction but also the spacing direction, that is, the medium thickness not only in the transport direction and in the direction perpendicular to the transport direction may also become non-uniform, so that it is also difficult to secure an appropriate print gap.

However, since the platen 2 compresses the spring 3 and retracts in the direction opposite to the urging force toward the print head, it is possible to perform printing without causing conveyance failure or print stain. Become.

[0015]

As described above, in the printing apparatus of the present invention, the distance between the platen and the card holder is displaced by the actuator or the like according to the thickness of the printing medium, and the spring is biased toward the printing head. By providing a retractable platen on the opposite side, a predetermined gap can be secured even when printing a medium with a non-uniform thickness such as a seal stamp, so printing can be performed without impairing print quality. effective.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of an embodiment of the present invention.

[Explanation of symbols]

 1 Platen Unit 2 Platen 3 Spring 4 Platen Base 5 Color 6 Print Head 7 Card Holder 8 Ink Ribbon 9 Medium 10 Seal 11 Platen Drive 12 Medium Thickness Detecting Roller 13 Roller 14 Medium Thickness Detecting Mechanism

Claims (1)

[Claims] 1. A printing apparatus comprising a print head, a card holder provided in the periphery of the print head and moving along with a printing operation, and a platen, which is displaced by an actuator and attached to the print head side by a spring. Energized,
A printing apparatus comprising a platen that retracts according to the thickness of a printing medium.