JPS58148777A - Heat-sensitive printer using laser diode - Google Patents

Abstract

PURPOSE:To obtain a laser heat-sensitive printer using a non-contact type head by providing plural optical fibers to transmit laser to a heat-sensitive recording paper and a laser diode to select the optical fibers. CONSTITUTION:Optical fibers 4 in plural numbers corresponding to the number of picture elements in the widthwise direction of a recording paper 3 are provided, and the tip faces of them are arranged in the widthwise direction of the paper 3 on a drive drum 5 in the face of the face of the paper 3. The read ends of the optical fibers 4 are connected with corresponding lasers diodes D1, D2...Dn, and they are selectively energized by a switching and energizing circuit 6 according to a desired print pattern. The optical fiber used is the one composed of a mixture of both TlI and Tl Br compounds, and the laser diode is a PbS or SbSe compound semiconductor for the infrared rays region.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printer having an improved thermal recording head.

In printers using heat-sensitive recording paper, the conventional heat-sensitive recording head consists of a diode array combined with a heat-generating resistor such as a Ta-8i thin film or a RuO□ thick film. By controlling the applied voltage (pixel), the heat-sensitive recording paper pressed against this head was made to be sensitive to heat and develop color in a desired pattern.

A major problem with such conventional thermal recording heads is that the end surface of the head and the surface of the thermal paper are under strong pressure (approximately 190g).
/α) - This is something that you are directly touching on. That is, the end face of the head is coated with a coating (for example, SiO□) to protect the heating element.
), and the heat-sensitive layer material scraped from the heat-sensitive paper or melted thereon tends to adhere to it. Such foreign matter adhering to the end face of the head prevents heat dissipation from the heating resistor, causing an abnormal temperature rise σ, which causes hair cracks in the protective coating, disconnection, and deterioration of the resistor itself.

The second problem with the heating resistor as a recording head is
In the manufacturing process, there are large variations in quality and low yields.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal printer equipped with a non-contact head using a laser beam in order to solve the above-mentioned problems with a contact head using a heating resistor.

In order to achieve the above object, the present invention includes a mechanism for feeding thermal recording paper along a predetermined transport path, and a mechanism arranged in the width direction of the thermal recording paper in the feeding path, with the leading end facing the paper. a plurality of optical fibers suitable for infrared rays, and a plurality of laser diodes for making infrared laser beams incident on the other ends of the plurality of optical fibers, and selectively exciting the plurality of laser diodes. The present invention constitutes a thermal printer capable of producing a desired print pattern on the thermal recording paper.

The laser diode in the above configuration is not one in the tITl viewing region used in conventional laser printers, but one in the infrared region that can directly apply thermal energy to the heat-sensitive sheet.
Laser diodes based on Pb5e and Pb5se compound semiconductors have a wavelength of 4.3-8.5 pm, and Pb5nS
In the case of e, since the wavelength is 8.5 to 26 μm, it is well suited for this purpose.

The optical fiber that constitutes the so-called thermal recording head, which transmits the laser beam from the laser diode to the thermal recording paper, is inconvenient because visible light fibers made of quartz or other glass materials absorb strongly. The present invention has TI! which has favorable transparency in the infrared region! It was decided to use a fiber made of both I and TiBr compounds. In addition, KBr, Ag
C/, AgBr, CdTe, etc. are also transparent in the infrared region, but presently have problems with moisture resistance or fiber formation.

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, (1) is a paper feeding mechanism that pulls out thermal recording paper (3) from a supply roll (2) along a predetermined feeding path. It is. A plurality of optical fibers +41 are provided corresponding to the number of pixels in the width direction of the paper 13), and are arranged so that each tip end faces the paper surface on the drive drum 15+ and crosses the paper surface in the width direction. The rear end of each optical fiber (41) is connected to a corresponding laser diode D, , I) 2 ---Dn such that each laser beam is incident on the rear end 1]11]. As mentioned above, the laser diodes D, D2---Dn are made of PbS or 5bSe thread compound semiconductors that emit laser beams in the infrared region, and the optical fibers (4) are 'I' t I, 'r/Br2H composite semiconductors. It is made up of fibers. The plurality of laser diodes are selectively activated according to the desired printed pattern by a switching activation circuit (6).

In the above embodiment, the laser diodes D1, D2-
--Dn used was one with a light emitting frame of 6jlIIIψ, a light emitting wave boundary of 4°3 to 8.5 μm, and an output of 2.5 rnW. Therefore, the diameter of the optical fiber (41 is 611 at the receiving end (laser diode II)
IIψ, and the diameter at the tip (head side) is 100 to 250 μmψ depending on the desired print dot height, thereby producing sufficiently clear print dots! ! I was able to obtain an I image.

Note that the full width of A-4 size recording paper is, for example, 4 dots/I.
III++ coverage requires more than 800 laser diodes, and the diode arrangement is the same as A-4 above.
If you want to fit it within the width of , you have to divide it into multiple tiers and stack them on top of each other.

The present invention is as follows, and the following effects could be obtained.

(1) Since it is a non-contact head, the drawbacks of conventional contact heads (adhesion of melted recording paper to the head protection surface, wear of the protection surface, etc.) can be completely eliminated.

(2) In relation to the previous item, even if the thermal paper has cut-out perforations in the width direction, those perforations do not pose any obstacle to the tip (head) of the optical fiber placed in place.

(3) The laser beam from the laser diode blinks in an extremely short period of time, passes through the cut optical fiber several times, and becomes thermal energy only after it hits the thermosensitive recording paper.

Therefore, the spatula l' itself (one end of the fiber) generates almost no heat, and like a conventional resistance heating element head, the outer crystal heats up from the ON signal to the coloring temperature, and from the OF' signal to the dead temperature, depending on its heat capacity meter. There is almost no delay required for the reduction of In other words, high-speed printing is possible as the speed of temperature rise and fall is greater.

(4) An advantage of a semiconductor laser is that it performs direct modulation (direct ON-OF'F), so it is possible to downsize the entire device, such as a gas laser system consisting of a laser oscillator and an external modulator. ,

[Brief explanation of drawings]

The figures are a block and perspective view showing the configuration of the present invention. (1) - - - - i > Q recording paper feed mechanism 131 - - - Ikkankun recording paper + 41 - - Optical fiber (61 - -
- Switch energizing circuit IJI, D2---Dn-
--Tarf-Taioh) --Patent applicant: Kanzaki Paper Co., Ltd. Agent: Niimi Namazube (1 other person)

Claims (2)

[Claims] (1) A mechanism for feeding thermal recording paper along a predetermined feeding path, and a plurality of sheets arranged in the width direction of the thermal recording paper in the feeding path, with their tips facing the surface of the paper. An optical fiber suitable for infrared rays and a plurality of laser diodes for respectively injecting infrared laser beams into the other end of the optical fiber are provided, and by selectively exciting the plurality of laser diodes, the thermal recording paper is heated. A thermal printer characterized in that it is adapted to express a desired print pattern. (2) Laser diode is PBS thread or Pb5e
A thermal printer according to claim 1, characterized in that it is made of a thread semiconductor. +31 The thermal printer according to claim 11 or claim 21, wherein the optical fiber is made of a fiber molded body containing a thallium thread compound.