JPH03275361A - Laser thermal transfer recorder - Google Patents

Abstract

PURPOSE:To prevent the occurrence of scumming and density irregularities in a high-speed transfer recording to obtain a high-resolution, high-quality transfer image by a method wherein a preheating means consists of a heating body and a heat accumulating body. CONSTITUTION:A heating body 26d is previously heated based on the action of a temperature control circuit to heat a belt 26a. The belt 26a consisting of a heat accumulation material or containing a heat accumulation material stops its temperature increase when reaching a predetermined temperature and initiates a heat accumulation. When the belt 26a completes the accumulation of a predetermined heating value, it again initiates a temperature increase. A temperature is so controlled that the belt 26a can be heated by the heating body 26d until the temperature increase is again initiated after completion of the heat accumulation. Therefore, a payed-out ink ribbon R and receiving paper P are fed along with the belt 26a while being heated by the heating body 26d.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser thermal transfer recording device that converts laser light into heat to melt or sublimate ink and transfer it to receiving paper to form an image. It is.

[Prior Art] Conventionally, a laser thermal transfer recording method has been known as a method of converting light into heat to melt ink and transfer the ink onto a receiving paper. FIG. 4 shows an explanatory view of the head section of the laser thermal transfer recording device, and shows a condenser lens l disposed on the same optical axis as a laser light source (not shown), a conveyance mechanism 2 provided at both ends of the condenser lens l, and a condenser lens l disposed on the same optical axis as a laser light source (not shown). 1 and a platen 3 provided facing each other. At the time of transfer, the ink ribbon R and the receiving paper P are overlapped by the transport mechanism 2 and sent between the condenser lens 1 and the platen roller 3,
It is transported in the direction of arrow X. The ink ribbon R consists of an ink layer Ra and a light-transmissive base layer Rb.
b is on the condensing lens 1 side, and the ink layer Ra is overlapped with the receiving paper P. The ink ribbon R and the receiving paper P are tightly pressed by the platen roller 3. On the other hand, a light beam emitted from a light source (not shown) passes through the condenser lens 1, passes through the base layer Rb of the ink ribbon R, and passes through the ink layer Ra.
The light is focused on the top. The light absorbed by the ink layer Ra is converted into thermal energy and melts the ink. The molten ink is cooled and solidified while being conveyed, and is transferred to the receiving paper P.

In such a laser thermal transfer recording method, light passes through the base layer Rb of the ink ribbon R and is converted into thermal energy only in the ink layer Ra, so the spread of heat in the lateral direction is smaller than that of normal thermal transfer recording. And very few. Also,
The laser beam can be narrowed down to about 10 μm by the condenser lens 1. Therefore, it is possible to obtain transferred images of very high resolution and optical quality.

However, since the conversion efficiency from light to heat is not good, it is not possible to increase the recording speed by using a laser diode of about 40 mW. For example, if the beam diameter is about 10 μm, the conveyance speed will be about 60 mm per second, and it will take several hours to transfer the image to the entire receiving paper P of A4 size.

Therefore, although the resolution is high, the recording speed is extremely slow. Furthermore, since high-output laser diodes are expensive, there is also the drawback that it is difficult to reduce the cost of the device.

Therefore, in recent years, a proposal has been made to provide a heating element 4 as shown in FIG. 5 to heat the ink ribbon R and receiving paper P in advance to around the melting point of the ink. It is true that if the ink ribbon R and receiving paper P are preheated, the ink can be melted with less light output, so the recording speed can be increased, and the laser diode can also be used with low output and cheap. becomes possible.

[Problem H to be solved by the invention] However, if such a preheating means is simply provided, the ink ribbon R and the receiving paper P have a considerable area, so the heat will be diffused laterally within the surface. Therefore, when writing is performed using a laser beam, the temperature has already fallen and the preheating effect cannot be obtained. Furthermore, even if the temperature does not drop and is maintained near the melting point, it is difficult to create a uniform temperature field in the in-plane direction of the ink ribbon R and receiving paper P, and temperature distribution will inevitably occur. . If there is a temperature distribution in the in-plane direction, it will cause background stains and density unevenness when recording with laser beam flux.
The problem is that it is not possible to achieve high resolution and high image quality, which are the advantages of the laser thermal transfer recording method.

In view of the above-mentioned current situation, it is an object of the present invention to provide a laser thermal transfer recording device that is capable of obtaining high-resolution, high-quality transferred images without causing scumming or density unevenness, while having a high transfer recording speed. purpose.

[Means for Solving the Problems] The present invention provides a laser thermal transfer system comprising a preheating means for heating an ink ribbon and a receiving paper to around the melting point of the ink, and a laser light source and an imaging optical system for illuminating the ink ribbon. The recording apparatus is a laser thermal transfer recording apparatus characterized in that the preheating means comprises a heating element and a heat storage element.

[Function] When the ink ribbon and the receiving paper are preheated by a heating means consisting of a heating element and a heat storage element, the heat storage effect of the heat storage element suppresses the flow of heat in the in-plane direction of the ink ribbon and the receiving paper.
Since a uniform temperature field can be created, preheating can be performed without temperature unevenness. Therefore, it is not only possible to melt the ink with a small amount of light irradiation energy, but also to obtain a high-resolution, high-quality transferred image with little printing unevenness or scumming.

[Embodiment] The present invention will be explained in detail based on the embodiment illustrated in FIGS. 1 to 3.

FIG. 1 is a block diagram of a first embodiment of a laser thermal transfer recording apparatus according to the present invention. The optical system includes an aperture 12 along the optical axis of a light source 10 such as a laser diode,
A collimator lens 14, a beam splinter 16, and a condensing lens 18 are arranged in this order. Further, a photodetector 20 is arranged on the reflection optical axis direction of the beam splitter 16, and a drive circuit 22 is connected to the light source 10.

A transport mechanism 24 is provided at both left and right ends of the above optical system,
Further, a preheating means 26 and a platen roll 28 are provided opposite the condenser lens and the transport mechanism 24. The preheating means 26 consists of a belt 26a made of a heat storage body and belt conveyance rollers 26b and 26c.
An electric heating element 26d is housed inside 6b. In addition,
A temperature control circuit (not shown) is connected to the heating element 26d.

When performing transfer in the recording apparatus configured as described above, first, the ink layer Ra of the ink ribbon R and the receiving paper P are overlapped and sent between the transport mechanism 24 and the heald 26a. The base layer Rb of the ink ribbon R is in contact with the transport mechanism 24, and the receiving paper P is pressed by the platen call 28 while contacting the heald 26a and is transported in the direction of arrow X. On the other hand, the heating element 26d generates heat in advance based on the operation of a temperature control circuit (not shown) to heat the bell 26a. Since the belt 26a is made of a heat storage material or contains a heat storage material, when a predetermined temperature is reached, the temperature stops rising and starts accumulating heat. Then, when a predetermined amount of heat is accumulated, the temperature starts to rise again. Here, by the heating element 26d, the bell)
The temperature is controlled so that the ink ribbon R and receiving paper P are heated until the heat storage in the belt 26a is completed and the temperature starts to rise again.Therefore, the ink ribbon R and receiving paper P that have been fed are conveyed together with the belt 26a while being heated by the heating element 26d. Ru.

At this time, the ink ribbon R1 receiving paper P1 heald 26a is
The heald 26a is at a temperature somewhat higher than the temperature at which the heat storage effect occurs, and the platen roll 28 is separated from the heating element 26d.
Heat dissipation occurs as the temperature approaches . When the heat is radiated to a predetermined temperature, the bell 26a releases the accumulated heat, but the temperature remains constant without dropping. The emitted heat suppresses the temperature of the ink ribbon R and the receiving paper P from decreasing, and particularly prevents temperature distribution from occurring in the in-plane direction. On the other hand, since the heald 26a is kept at a constant temperature until the accumulated heat is released, the ink ribbon R and the receiving paper P can be uniformly preheated. Therefore, since the ink ribbon R and the receiving paper P are heated by the laser beam in a state where a uniform temperature field is formed, the ink layer Ra is evenly and uniformly melted, and a high-resolution and high-quality transferred image is formed on the receiving paper. can be formed into The preheating temperature is set 10 to 30°C lower than the temperature at which the ink layer Ra melts.

Note that the heat storage material constituting the bell) 26a is the ink layer Ra.
It is desirable to use a material that produces a heat storage effect at a temperature approximately 10'C lower than the melting point temperature of the material.

Further, the approximate amount of heat storage required is determined by the thermal properties of the ink ribbon R and the receiving paper P, but since the recording speed is fast, it does not need to be that large. Specifically, they include salt hydrates of alkali metals and alkaline earth metals, and high-density polyethylene.

The second part is a block diagram of the second embodiment, and the same reference numerals as in FIG. 1 indicate the same members. In this case, the heating element 3° is provided outside the belt conveyance roller 26b.

With this configuration, when the heating element 30 is close to the platen roll 28 side H<0:)T:, the amount of heat dissipated is reduced.
It is efficient because the amount of heat stored in the bell) 26a is small.

FIG. 3 is a block diagram of the third embodiment, in which the same reference numerals as in FIG. 1 indicate the same members, and a heat storage layer 32 and a heat generation layer 34 are provided on the outer surface of the platen roll 28. , it has the advantage of requiring fewer parts.

[Effects of the Invention] As explained above, the laser thermal transfer recording device according to the present invention uniformly and effectively heats the ink ribbon and receiving paper near the melting point of the ink by configuring the preheating means from a heating element and a heat storage element. Because it can be heated up to 100%, it is possible to obtain high-resolution, high-quality transferred images without background smudges or density unevenness when printing with a laser beam.

[Brief explanation of drawings]

Drawings 1 to 3 show embodiments of the laser thermal transfer recording apparatus according to the present invention, in which FIG. 1 is an explanatory diagram of the first embodiment, FIG. 2 is an explanatory diagram of the second embodiment, and FIG. 3 is an explanatory diagram of the second embodiment. The figure is an explanatory diagram of the third embodiment. Further, FIGS. 4 and 5 are cross-sectional views showing an example of a head portion of a conventional laser thermal transfer recording device. R... Ink ribbon Ra... Ink layer Rb... Base layer P... Receiving paper 10... Light a 12... ...Aperture 1
4...Collimator lens 16...Beam splitter 18...Condensing lens 2...Photodetector 22...Drive circuit 24...・・・・・・
Transport mechanism 26... Preheating means 26a...
...Belts 26b, 26c...Belt transport rollers 26d...Heating element 28...Platen roll 30...Heating element 32...
・Heat storage body 34... Heating element patent application Person Toppan Printing Co., Ltd. Representative Kazuo Suzuki Figure 4

Claims (1)

[Claims] (1) In a laser thermal transfer recording device comprising a preheating means for heating an ink ribbon and a receiving paper to around the melting point of the ink, and a laser light source and an imaging optical system for illuminating the ink ribbon, the preheating means is a heating element. A laser thermal transfer recording device comprising: and a heat storage body.