JPH03281358A - Laser thermal transfer recorder - Google Patents

Abstract

PURPOSE:To enhance a speed, prevent the occurrence of scumming and density irregularities, and obtain a high-resolution and quality transfer image by a method wherein an image-forming optical system is provided with a beam splitter for dividing a luminous flux into two parts and first and second optical emitting system which respectively emit the luminous flux from a transfer paper side and a recording paper side. CONSTITUTION:When a transfer is conducted, an ink layer Rb of transfer paper R is overlapped with recording paper P, and this is fed between a feed mechanism 28 and a platen roll 30. The transfer paper R and the recording paper P are fed respectively while being pressed by the feed mechanism 28 and the platen roll 30. A part of a laser flux L emitted from a light source 10 is reflected at a half mirror 16, the other part is transmitted through the mirror. The luminous flux L1 transmitted through the half mirror 16 is condensed on the interface of a base layer Ra and the ink layer Rb of the transfer paper R through a condensing lens 18. The luminous flux L2 reflected at the half mirror 16 transmits through the platen roll 30 via a condensing lens 26 to reach the recording paper P. When the recording paper P is a light- transmittable film, the flux L2 is condensed on the interface of the ink layer Rb of the transfer paper R and the recording paper P.

Description

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

[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. 2 shows a cross-sectional view of the head section of the laser thermal transfer recording device, showing 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 roll 3 provided facing each other. During transfer, the transfer paper R and recording paper P are overlapped by the transport mechanism 2 and sent between the condenser lens 1 and the platen roll 3,
It is transported in the direction of arrow X. The transfer paper R is composed of an ink layer Ra and a light-transmissive base layer Rb, the base layer Rb is located in the direction of the condenser lens l, and the ink layer Ra is overlapped with the recording paper P. The transfer paper R and the recording paper P are tightly pressed by the platen roll 3. On the other hand, a beam of light emitted from a light source (not shown) passes through the base layer Rb of the transfer paper R through the condenser lens 1, and is focused on the ink layer Ra. The light absorbed by the ink layer Ra is converted into thermal energy and melts the ink. The fJ-melted ink is cooled and solidified while being conveyed, and is transferred onto the recording paper P.

In such a laser thermal transfer recording method, light is transmitted to the transfer paper R.
It passes through the base layer Rb and is converted into thermal energy for the first time in the ink layer Ra, so the spread of heat in the lateral direction is very small compared to normal thermal transfer recording. The optical lens 1 can narrow the field down to about 10 μm. Therefore, it is possible to obtain a transferred image with very high resolution and original 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 um, the scanning speed of the beam is 60r per second
nm, and it would take several hours to transfer the entire A4 size receiving paper P. 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, as shown in FIG. 3, a heating element 4 is provided to raise the temperature of the transfer paper R and recording paper P to around the melting point of the ink in advance! ! One proposal has been made. If fI transfer paper R and recording 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 a low output and cheap one. It becomes possible to use it.

The problem that this invention tries to solve! 9! ] However, if such a preheating means is simply provided, since the transfer paper R and the recording paper P have a considerable area, the heat will be diffused laterally within the plane, and the laser beam will By the time writing is started, the temperature has already fallen,
The disadvantage is that the preheating effect cannot be obtained. Furthermore, even if the temperature does not fall and is maintained near the melting point, it is difficult to create a uniform temperature field in the in-plane direction of the transfer paper R and the recording paper P, and it is inevitable that the temperature will be uneven. .

If there is a temperature distribution in the in-plane direction, it will cause background smudges and density unevenness when recording with laser beam flux, making it impossible to achieve the high resolution and high image quality that should be the advantage of laser thermal transfer recording. There is a problem.

In view of the above-mentioned current situation, the present invention provides a laser thermal transfer recording device that is capable of obtaining high-resolution, high-quality transferred images without background smudges or density unevenness, even though the transfer recording speed is high. The purpose is to

[Means for Solving the Problems] The present invention includes a laser light source, an imaging optical system for irradiating a transfer paper with a light beam emitted from the laser light source, and a laser light source that brings the transfer paper into close contact with a recording paper. In a laser thermal transfer recording device consisting of a conveyance mechanism that sends the image to an imaging optical system,
The imaging optical system includes a beam splitter that divides the light beam into two, a first illumination optical system that irradiates one of the divided light beams from the transfer paper side, and a first illumination optical system that irradiates the other divided light beam. This is a laser thermal transfer recording apparatus characterized by comprising a second illumination optical system for irradiating from the recording paper side.

[Operation] The transfer paper and the recording paper are brought into close contact with each other and sent into the imaging optical system by the transport mechanism, while the light beam emitted from the laser light source is split into two light beams by the beam splitter. One of the light beams is focused on the surface of the recording paper by the first illumination optical system, and the other light flux is focused on the surface of the recording paper by the second illumination optical system. Therefore, if the base layer of the transfer paper and the recording paper are transparent to laser light, the ink layer of the transfer paper is irradiated with light from both the front and back surfaces and is heated and melted. Therefore, the lateral diffusion of heat can be minimized and the heat transfer can be accelerated, resulting in improved image quality and increased recording speed.

[Example] The present invention will be explained in detail based on the example illustrated in FIG.

FIG. 1(a) is an explanatory diagram showing one embodiment of a laser thermal transfer recording apparatus according to the present invention, and FIG. A diaphragm 12, a collimator lens 14, a 1-f mirror 16, and a condensing lens 18 are sequentially arranged along the optical axis of a light source such as a diode. And half mirror
A nine-order electric and drive system in which mirrors 20, 22, and 24 and a condensing lens 26 are sequentially arranged on the optical axis in the reflection direction of 16 will be described. A conveyance mechanism 28 and a platen roll 30 made of a light-transmitting member are provided between the condenser lens 18 and the condenser lens 26 . Further, a drive circuit 32 is connected to the light source 10.

In the apparatus configured as described above, when performing transfer, first, the ink layer Rb of the transfer paper R and the recording paper P are overlapped and sent between the transport mechanism 28 and the platen roll 30.

The transfer paper R is held down by the conveyance mechanism 28, and the recording paper P is held down by the platen roll 30 and conveyed in the direction of arrow Y. At this time, the base layer Ra of the transfer paper R is
The recording paper P faces the condensing lens 26 .

On the other hand, the light source 10 emits light while changing its output according to the modulation signal from the drive circuit 32. The modulated signal is transferred to the drive circuit 32 through a D/A converter (not shown) or the like in correspondence with, for example, an image signal. The laser beam emitted from the light source 10 passes through the aperture 12 and the collimator lens 14, and is partly reflected by the half mirror 36, while the other part is transmitted. Luminous flux Li transmitted through the half mirror 16
is focused by the focusing lens 18 onto the boundary surface between the base layer Ra and the ink layer Rb of the transfer paper R. On the other hand, the light beam L□ reflected by the half mirror 16 is reflected by the mirrors 20, 22, .
24 and passes through the condensing lens 26 to the platen roll 3.
0 and reaches the recording paper P. Since the platen roll 30 is light-transmissive, if the recording paper P is a light-transmissive film, the light flux is focused on the boundary surface between the ink layer Rb of the transfer paper R and the recording paper P.

In this way, when the ink is heated by irradiating the light beam from both the upper and lower boundary surfaces of the ink layer Rb, a more uniform temperature field is formed in the thickness direction of the ink layer Rb compared to the case where the ink is heated only from one side. I can do it. Furthermore, the heat transfer time can be considered to be the same as when the apparent thickness of the ink layer Rb is halved, so it can be significantly shortened. Furthermore, since lateral diffusion of heat can be prevented, even if the light intensity is the same, heating from both sides can perform more efficient heating. Therefore, the recording speed is increased and the transferred image quality is improved compared to the conventional method.

In particular, when color transfer or gradation recording is performed on a single transfer paper R, it is inevitable that the ink layer Rb becomes thicker, so it is more advantageous to irradiate the light beam from both sides1. When performing modulated recording, the light intensity of the light beam L1 is kept constant and the light intensity of the light beam is adjusted, thereby melting and transferring an ink layer Rb having a thickness corresponding to the light intensity. As a method of adjusting the luminous flux and the intensity of s, half mirror 16
A light modulation element may be inserted into the optical path of the luminous flux L0 divided by .

Note that it is also possible to further improve the transfer image quality by slightly shifting the irradiation time of the luminous flux L3 depending on the optical path length, etc. 6 For example, by changing the timing at which the luminous flux L1 is irradiated, the luminous flux L2 is irradiated. If the timing is slightly delayed, the ink layer Rb will solidify from the side closer to the recording paper P, and then the side closer to the base layer Ra will solidify in order, making it possible to obtain a high-quality transferred image. can.

[Effect of the Invention 1] As explained above, in the laser thermal transfer recording device according to the present invention, the laser beam is divided into two parts, and the - side is irradiated from the transfer paper side, and the other side is irradiated from the recording paper side. The ink layer of the transfer paper is heated and melted from both the front and back sides. Therefore, the time required for heat to be transferred to the ink layer is shortened, and lateral diffusion can also be suppressed, making it possible to increase the recording speed and improve image quality.

[Brief explanation of drawings]

FIG. 1 (Al is an explanatory diagram showing an embodiment of a laser thermal transfer recording device according to the present invention, and FIG. 1 劽) is an explanatory diagram of a chrysanthemum seen from the χ direction. 2 and 3 are for explaining the conventional technology. FIG. 2 is a sectional view of the head section of a thermal transfer recording device, and FIG. 3 is a sectional view of the head section of a laser thermal transfer recording device. The diagram is: P...Recording paper, R...Transfer paper, Ra...
... Base layer, Rh ... Ink layer, 10
...Light source, 12...Aperture, 14...
... Collimator lens, 16 ... Half mirror 18, 26 ... Condenser lens, 20.22.24 ... Mirror 28 ... Transport mechanism, 30...Platen, 32...Drive circuit

Claims (1)

[Claims] (1) A laser light source, an imaging optical system for irradiating the transfer paper with the light beam emitted from the laser light source, and a conveyance mechanism that brings the transfer paper into close contact with the recording paper and sends it to the imaging optical system. In the laser thermal transfer recording device, the imaging optical system includes a beam splitter that divides the light beam into two, a first irradiation optical system that irradiates one of the divided light beams from the transfer paper side, and the A laser thermal transfer recording apparatus comprising: a second irradiation optical system for irradiating the other divided light beam from the recording paper side.