JPS61106285A - Thermal printer - Google Patents

Abstract

PURPOSE:To enable a reduction in cost and size and accomplish reduction in noise, by a construction wherein a holding member for a thermal printing element can be oscillated relatively to a platen, and pressing and retraction of the element from the platen is effected through a cam member. CONSTITUTION:A shaft 16 is engaged with a lower hole of a thermal head support 17, which can be turned with the shaft 16 as a center and is energized by a coil spring. When a carriage base 15 approaches a left margin position, a movable plate 23 is stopped on contact with the inside surface of a left side plate 4L of a frame 4 of a main body of the printer, but the carriage base 15 is further moved, and a slant surface of a cam plate 27 pushes up a leaf spring 22. When the carriage base 15 reaches the left margin position, the top surface of the cam plate 27 pushes up the spring 22, whereby a tip pawl part 22A of the spring 22 is disengaged from a recessed part 15C of the base 15, the support 17 is tilted to the platen side with the shaft 16 as a center due to the elasticity of a coil spring 18 to be pressed against the platen, and an ink ribbon is pressed against a recording paper on the platen 1 by a thermal head 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is capable of applying a voltage to a plurality of printing elements provided in a thermal head as appropriate.
The present invention relates to a thermal printer that performs printing directly onto thermal recording paper or onto recording paper via a thermal transfer ink ribbon, and particularly to a serial type thermal printer that performs sequential printing.

[Conventional technology]

As general recording methods for thermal printers, there are known methods that use thermal recording paper and methods that use thermal transfer ribbon. In addition, there are two printing methods: a serial character printing method in which characters are separated into pixels and printed one by one, and the other is a serial character printing method in which characters are separated into pixels and printed one by one, and the other is a serial character printing method in which multiple heating elements are placed perpendicular to the recording paper feeding direction, as in facsimile printers. There is a dot line printing format in which dots are arranged and recorded along a straight line.

Thermal transfer type thermal printers have features such as good clarity of recorded images and the ability to form multicolor images.

In particular, serial type thermal printers have excellent features such as small size, light weight, low noise, ease of maintenance, and high reliability.

The thermal head of a serial ←+half+4 type thermal printer has a single ceramic substrate mounted on a thermal head holder made of a metal plate such as aluminum. A group of heating elements are arranged on the ceramic substrate. The heating element group is arranged in one or more rows along a direction perpendicular to the direction of movement of the thermal head.

When performing thermal recording, the heating element group of the thermal head is moved in the recording direction while being pressed against the thermal recording paper or thermal transfer ink ribbon, and a voltage is selectively applied to the heating element group to heat it, thereby printing characters. etc. are recorded sequentially.

- When the sequential recording of rows is completed, the thermal head is returned to its original position and the next row is sequentially recorded again, but during this return process, the heating elements of the thermal head are forcibly removed from the recording surface. [Problems to be Solved by the Invention] Conventionally, an electromagnetic solenoid was used to press the thermal head against the recording surface and to withdraw it from the recording surface, and the thermal head was driven by being suppressed or released from the back surface.

However, when electromagnetic solenoids are used, the cost of parts and drive circuits are high, and there are disadvantages such as shortened component life due to noise generation and impact.

[Means for solving the problem] The present invention has been made to improve the above problems, and its purpose is to reduce the number of component parts and provide a simple structure. The objective is to enable cost reduction and miniaturization, as well as to achieve further noise reduction.

A thermal printer of the present invention that achieves this object is a serial type thermal printer in which a holding member for a heat-generating printing element is swingable with respect to a platen, and the printing is performed at both ends of the carriage supporting the holding member. The device is characterized in that the suppressing operation and retracting operation of the element with respect to the platen are performed by cam members, respectively.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a specific example of a mechanical section of a thermal printer according to the present invention. FIG. 2 is a plan view of the apparatus, showing the carriage part on which the thermal head is mounted, with the thermal transfer ink ribbon cassette and supporting member removed. Third
The figure is an enlarged perspective view of the carriage section.

In the following specific example, a thermal transfer type thermal printer will be explained, but the present invention is of course applicable to a thermal printer using heat-sensitive recording paper.

The mechanical parts of a thermal printer include a recording paper feeding section, a carriage feeding section that carries a thermal head and runs it, a carriage unit that has a swinging section for the thermal head and a thermal transfer/ink ribbon winding section, and a thermal transfer ink ribbon cassette holding section. It consists of several departments.

The recording paper feeding section includes a cylindrical platen 1 that transports the recording paper P in a rolled-up manner, and a paper feed roller 2 that is located below the circumference of the platen 1 and that presses and clamps the recording paper P to feed it. , and a guide plate 3 that guides and introduces the recording paper P and guides it to the recording position.

Both ends of the center axis IA of the platen 1 are rotatably supported by bearings on the left side plate 4L1 and the right side plate 4R of the printer body frame 4. A toothed pulley 5 is fixed to one end of the central axis of the platen 1, and is driven via a toothed belt 8 by a toothed pulley 7 that is integrated with the drive shaft of a motor 6 such as a pulse motor or a servo motor. be done.

On the other hand, at the front lower part of the platen 1, one screw shaft 10 is rotatably supported by bearings on the left side plate 4L and the right side plate 4R. The screw shaft 10 is a feed screw having a spiral male thread, and a toothed boot IJII is fixed to one end thereof.

The toothed pulley 11 is a toothed pulley 13 that is integrated with a drive shaft of a drive motor 12 such as a pulse motor or a servo motor.
is rotationally driven via a toothed belt 14.

The screw shaft 10 fits into the female thread of the carriage base 15, and the protrusion 15A of the carriage base 15 slides on the rail surface 4A on the front upper surface of the main body frame 4, so that the rotation of the screw shaft 10 The carriage base 15 is capable of linear movement in the axial direction of the screw shaft 10.

Two arms 15B protrude from the side of the carriage base 15 closer to the platen 1, and a shaft 16 extends through the arms 15B. A lower hole of a thermal head support 17 is fitted into the shaft 16, and the support 17 is rotatable around the shaft 16. Further, the support body 17 is biased by a coil spring 18 and is brought into contact with the outer periphery of the platen 1 in a tilting manner.

A thermal head 20 is fixed to the upper front surface of the support 17. The thermal reflex head 20 has a plurality of heating elements 20B arranged in columns at equal intervals on a substrate 20A made of ceramic or the like, and is electrically connected to a flexible printed wiring board 21 and further connected to a drive circuit (not shown).

One end of a leaf spring 22 is fixedly supported on the back surface of the tiltable support 17. The other end of the leaf spring 22 is bent into a claw shape, and the thermal head 2° is attached to the platen l.
When it is separated or retracted from the outer circumferential surface of the carriage base body 15, it is engaged with and stopped in the recessed portion 15C of the carriage base body 15.

A movable plate 23 is attached to one end surface of the carriage base 15 so as to be movable in parallel. That is, rods 24 and 25 are implanted near both ends of the movable plate 23, and are fitted into holes in the carriage base 15. Further, a coil spring 26 is interposed between the base plate 15 and the movable plate 24 on the outer periphery of the rod 24, and constantly presses the movable plate 23 outward. Note that the protrusion stop position of the movable plate 23 is determined by the flange portion at the rear end of the rod 24 or 25. A cam plate 27 having an inclined surface 27A at its tip is integrally provided on the upper part of the movable plate 23.

When the movable plate 23 approaches the carriage base 15 by an external force, the inclined surface 2 of the cam plate 27 that is integral with the movable plate 23
7A pushes up the lower surface of the leaf spring 22 and
The engagement between the distal end claw and the recess 15C of the carriage base 15 is released.

Next, linear rack teeth 4B are formed on the inside of the rail surface 4A of the frame 4 of the printer body, and mesh with a gear 29 that fits on a fixed shaft 28 on the carriage base 15. The gear 29 meshes with a gear 32 coaxial with the ink ribbon take-up shaft 31 via an intermediate gear 30. When the carriage base 15 is linearly moved by the rotation of the screw shaft 10, driving force is transmitted from the gear 28 meshing with the rack teeth 4B, causing the ink ribbon take-up shaft 31 to rotate. A holding plate 34 that removably holds a thermal transfer ink ribbon cassette 33 is fixed. The thermal head 2o and the ink ribbon take-up shaft 31 pass through the cutout or opening of the holding plate 34 and extend upward to reach the cutout of the cassette 33 and the ink ribbon core.

On the other hand, a cam plate 35 having an inclined surface 35A is fixedly installed near the right side plate 4R of the frame 4 of the printer main body, which supports one person on the central axis of the platen 1. Incline ff of cam plate 35
135A, when the carriage base 15 reaches a predetermined position [1 (light margin) at the right end of the platen 1], it slides into contact with the surface of the extended flat plate portion 17A of the thermal head support 17, and rotates the support 17 toward the shaft 16. The thermal head 2o is forcibly swung around the center to retreat from the outer peripheral surface of the platen 1.

4 and 6 are a plan view and a side sectional view of the carriage base 15 reaching the write margin position and the thermal head 2o being in a retracted state. The cam plate 35 is the flat plate part 17
When the support body 17 is moved in the direction of sliding away from the platen 1 by slidingly contacting the support body 17, the tip claw portion 22A of the plate spring 22 fixed to the support body 17 also retreats, and the carriage base body 15 It engages with the recess 15C and stops.

In the process of inverting the carriage base 15 from the light margin position and moving to the left, the claw portion 22A and the recessed portion 15C
The ink ribbon returns with the surface of the heating element 20B of the thermal head 20 separated from the outer peripheral surface of the platen 1 while maintaining engagement with the ink ribbon.Of course, no printing is performed during this return process, and the ink ribbon 31 does not rotate.

5 and 7, the carriage base 15 is connected to the platen 1.
FIG. 3 is a plan view and a side sectional view showing a state in which a predetermined left end position (left margin) has been reached.

When the carriage base 15 approaches the left margin position, the movable plate 23 attached to the left end of the carriage base 15 is biased by a spring, and the movable plate 23 is attached to the left side plate 4L of the frame 4 of the printer body.
The carriage base 15 comes into contact with the inner surface I and stops.
As the cam plate 27 progresses further, the distance from the movable plate 23 becomes narrower, and the inclined surface 27A of the cam plate 27, which is integral with the movable plate 23, becomes closer to the leaf spring 2.
2 and pushes the leaf spring 22 upward.

When the carriage base 15 reaches the left margin position, the uppermost surface of the cam plate 27 pushes the leaf spring 22 upwardly, and at this time, the tip claw 22A of the leaf spring 22 is hardly released from the recess 15C of the carriage base 15 and is locked. is removed. &Here, due to the elasticity of the coil spring 18 that biases the support 17, the support 17 is tilted toward the platen 1 about the shaft 16 and pressed into contact with the platen 1. At this time, the thermal transfer ink ribbon stretched on the front surface of the thermal head 20 is pressed against the platen 1 by the thermal head 20 which is integrated with the support 17.
It is pressed against the upper recording paper P. If a charge is applied to the heating element 20B of the thermal head 20 in this state, an image is formed on the recording paper by thermal transfer due to the heat generated by the heating element 20B. This image formation is carried out in a direction perpendicular to the heating element 20B, that is, on the outer peripheral generatrix of the platen 1.
By sliding and selectively applying voltage, serial printing is achieved.

In the above embodiment, an example using an ink ribbon was explained, but yellow (to), magenta (to), and cyan ICs were used.
5. By using four ink ribbons each coated with black heat-melting ink, it is possible to perform multicolor recording or full-color graphic expression with multiple colors and gradations.Also, by using a thermal transfer ink ribbon First, the thermal head pressure bonding and retracting mechanism of the present invention can be easily applied to a thermal printer that applies a voltage by directly pressing a heating element to a thermal recording paper.

〔Effect of the invention〕

As explained above, according to the present invention, by reducing the number of component parts and having a simple structure, it is possible to reduce the cost and size of a thermal printer, and furthermore, to reduce noise and prevent breakdowns. It is possible to realize a thermal printer that requires less maintenance and has good properties.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a specific example of a mechanical part of a thermal printer according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is an enlarged perspective view of a carriage unit. 4 and 6 are a plan view and a side sectional view of the thermal printer mechanism when the carriage unit is at the right margin position. 5 and 7 are a plan view and a side sectional view when the carriage unit is at the left margin position. 1...Platen 4...Frame 4L of the printer body -Left side plate 10...Screw shaft 15...Carriage base 15C...Recessed portion 17.
thermal head support

Claims (1)

[Claims] In a serial type thermal printer, a holding member for a heat-generating printing element is swingable with respect to a platen, and a pressing operation and a retracting operation of the printing element against the platen are performed at both ends of travel of a carriage supporting the holding member. , a thermal printer characterized in that each of these is performed by a cam member.