JPH03254953A - Recording device for laser thermal transfer - Google Patents

Abstract

PURPOSE:To obtain a transfer image with a high resolution and a high image quality under a stable condition at all times without regard to the surface state and the like of the base layer of a transfer paper by detecting reflected light from the transfer paper to adjust the output of a laser beam source according to the amount of the reflected light in an optical system for adjustment and heating the transfer paper to transfer an image to a recording paper in an optical system for recording. CONSTITUTION:A controlling circuit 60 fetches thereinto the reflectance and surface temperature of the base layer Ra of a transfer paper R, the condensed state of a light flux L2 for recording, etc., as the data. The controlling circuit 60 determines a light intensity modulation signal to be sent to a light modulation element 38 on the basis of these data and the image data to be printed and sends the signal thus determined to a drive circuit 62 through an interface circuit 66. The light modulation element 38 performs light modulation on the basis of the data of these kinds and projects light onto an ink layer Rb, whereby the ink layer Rb is melted by heating, and a transferred image can be obtained on a 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] A thermal transfer recording method is conventionally known as a method of transferring ink onto a receiving paper using thermal energy. FIG. 2 shows a cross-sectional view of the head portion of the thermal transfer recording apparatus, and a pulse power application circuit 12 is connected to a thermal head 10 composed of a thin film resistor or the like. Further, conveyance mechanisms 14 are provided at both left and right ends of the thermal head 10, and a platen roll 16 is provided opposite to these. When performing the transfer, the transfer paper R and the recording paper P are superimposed and sent between the thermal head 10 and the platen roll 16 by the transport mechanism 14 . Transfer paper R is base layer Ra
and an ink layer Rh, the base layer Ra is in contact with the thermal head 10, and the ink layer Rb is in contact with the recording paper P.

Transfer paper R and recording paper P are transferred by platen roll 16.
Arrow X while being pressed by the thermal head 10 with a predetermined pressure
conveyed in the direction. At the same time, the thermal head 10 generates heat due to the pulsed power supplied from the pulsed power application circuit 12. The generated heat reaches the ink layers R and b from the thermal head 10 via the base layer Ra of the transfer paper R, and melts the ink. The melted ink is cooled and solidified while being conveyed in the direction of the arrow X, and is transferred onto the recording paper P. In this way, a transferred image using ink is formed on the recording paper P. However, since the heat generated by the thermal head 1o is transmitted not only in the thickness direction of the transfer paper R but also in the lateral direction, the area of the image actually transferred is
The area will be larger than that of the heating element 0, and the outline will be unclear. Furthermore, the width of the heating element of the thermal head 10 is
Due to production limitations, the thickness cannot be reduced to at least about 40 μm. Therefore, it is difficult to obtain a high-resolution, high-quality transferred image using a normal thermal transfer recording method.

Therefore, in recent years, a laser thermal transfer recording apparatus as shown in FIG. 3 has been devised. The head section includes a condenser lens 2o arranged on the same optical axis as a laser light source (not shown), a transport mechanism 22 provided at both ends of the condenser lens 2o, and a condenser lens 2o.
and a platen roll 24 provided facing each other. At the time of transfer, the transfer paper R and the recording paper P are overlapped by the transport mechanism 22, sent between the condenser lens 2o and the platen roll 24, and transported in the direction of arrow X. The transfer paper R is composed of a light-transmissive base layer Ra and an ink layer Rb, the base layer Ra is on the condensing lens 20 side, and the ink layer Rb is overlapped with the recording paper P. The transfer paper R and the recording paper P are tightly pressed by the platen roll 24. On the other hand, a light beam emitted from a light source (not shown) passes through the base layer Ra of the transfer paper R through the condenser lens 20, and is focused on the ink layer Rb. The light absorbed by the ink layer Rb is converted into thermal energy and melts the ink. The molten 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.
Since the ink passes through the base NRa and is converted into thermal energy for the first time in the ink layer Rb, the spread of heat in the lateral direction is very small compared to normal thermal transfer recording. Further, the laser beam can be focused down to 10 μm or less by the condenser lens 20. Therefore, it is possible to obtain a transferred image with very high resolution and original quality.

[Problem B to be solved by the invention] However, in the case of the laser thermal transfer method, since light is used as a means for applying heat, the amount of heat applied to the ink layer Rb depends on the light reflectance and absorption of the surface of the base layer Ra. It depends greatly on the rate. Of course, it is desirable to suppress the light absorption and surface reflection of the base liRa to as small a quantity as possible, but in reality, it is difficult to suppress these variations within a narrow range for each transfer paper. In particular, laser thermal transfer involves high-density recording with a recording 1' of 10 μm or less, so there is a drawback that even minute stains or scratches on the surface of the base layer Ra have a large effect on the transferred image, making it impossible to obtain good image quality.

In light of the above-mentioned current situation, an object of the present invention is to provide a laser thermal transfer recording device that can always stably obtain high-resolution, high-quality transferred images regardless of the surface condition of the transfer paper base layer. shall be.

[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 flux 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 laser thermal transfer recording apparatus is characterized in that the imaging optical system includes a recording optical system that heats the transfer paper and an adjustment optical system that detects light reflected from the transfer paper.

[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. First, the adjustment optical system detects the reflected light from the transfer paper, and the laser is activated according to the amount of reflected light. The output of the light source is adjusted, and the recording optical system heats the transfer paper to transfer the image onto the recording paper.

In this way, by adjusting the intensity of the laser light,
Even if there are some variations in the characteristics of the transfer paper, it is possible to always obtain a good transferred image.

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

FIG. 1 is a block configuration diagram of a laser thermal transfer recording apparatus according to the present invention, and the optical system includes an aperture 32, a collimator lens 34, a half mirror 36, and a light modulation element 38 along the optical axis of a light source 30 such as a laser diode. , a beam splitter 40, and a condenser lens 42 are arranged in this order. A mirror 44, a beam splitter 46, and a condensing lens 48 are arranged in this order on the optical axis in the reflection direction of the half mirror 36, and a photodetector 50 is arranged on the other optical axis of the beam splitter 46. Further, an image sensor 52 is arranged on the other optical axis of the beam brick 40.
has been done. Next, the electricity and drive system will be explained. A transport mechanism 54 is installed at both left and right ends of the optical system, and a platen roll 56 is installed facing the optical system. A drive circuit 58 and a control circuit 60 are sequentially connected to the light source 30, and a drive circuit 62 is connected to the light modulation element 38. On the other hand, a temperature sensor 64 is provided near the surface of the base layer Ra of the transfer paper R. A photodetector 50, an image sensor 52, a drive circuit 62,
An interface circuit 66 is connected to the temperature sensor 64, and the interface circuit 66 is further connected to the control circuit 60.

When performing transfer using a device configured as above,
First, the ink layer Rb of the transfer paper R and the recording paper P are overlapped,
It is sent between the conveyance mechanism 54 and the platen roll 56. The base layer Ra of the transfer paper R faces the optical system, and the receiving paper P is conveyed in the direction of the arrow X while contacting the platen roll 56. At this time, the control circuit 60 sends a signal to the drive circuit 58 to turn on the light source 30 at the same time as the transport mechanism 54 is driven. When the light source 30 receives power from the drive circuit 58, it emits light. The laser beam passes through the aperture 32 and the collimator lens 34, and is partly reflected by the half mirror 36, while the other part is transmitted. The light beam L1 reflected by the half mirror 36 is reflected by the mirror 44 and sent to the beam splitter 4.
6 and is condensed onto the base layer Ra of the transfer paper R via the condenser lens 48. The light beam reflected by the surface of the base layer Ra is reflected by the beam splitter 46 and enters the photodetector 50. Since the amount of light reflected by the half mirror 36 is always constant, the reflectance of the base layer Ra of the transfer paper R can be determined from the amount of light incident on the photodetector 50. This reflected light amount data is converted into a digital signal via the interface circuit 66 and sent to the control circuit 60.
be taken in. At the same time, the temperature sensor 64 detects the temperature of the surface of the base layer Ra of the transfer paper R, and the interface circuit 6
6, the temperature data is sent to the control circuit 6o as a digital signal. On the other hand, the luminous flux L transmitted through the half mirror 36
2 passes through the light modulation element 38 and the beam splitter 40,
The light is focused onto the ink layer Rb of the transfer paper R via the focusing lens 42. At this time, the light modulation element 38 receives and receives a modulation signal corresponding to the image data from the control circuit 60 via the interface circuit 66 and the drive circuit 62, and modulates the light intensity of the light beam L2. Further, the reflected light from the ink layer Rh enters the image sensor 52. Therefore, from the data obtained from the image sensor 52, it is possible to know the condensation state of the light beam L2, the beam diameter, etc. These data are sent to control circuit 60 via interface circuit 66. As described above, the control circuit 60 controls the base layer Ra of the transfer paper R.
The reflectance, surface temperature, and condensation state of the recording light beam L2 are captured as data. The control circuit 60 determines the light intensity modulation signal to be sent to the light modulation element 38 based on these data and the image data to be printed, and sends it to the drive circuit 62 via the interface circuit 66. The light modulation element 38 performs light modulation in consideration of the above various data and irradiates the ink layer Rb with light. The ink layer Rb is heated and melted to obtain a transferred image on the recording paper P.

For example, as a method for adjusting the intensity of the luminous flux L2, when the signal from the photodetector 50 is large, that is, when there is a large amount of reflected light at the surface Jii Ra of the transfer paper P, the amount of light reaching the ink layer Rb is insufficient. The amount of light that the light beam L2 transmits through the light modulation element 38 is increased so that the transfer can be performed satisfactorily.

When the detection signal from the temperature sensor 64 is large, that is, when the surface temperature of the transfer paper R is high, it is considered that heat is spreading in the lateral direction as a whole. At the same time, the beam diameter is made smaller based on data obtained from the image sensor 52.

In this way, by adjusting the intensity, beam diameter, etc. of the laser beam used for recording, it is possible to obtain a transferred image with stable resolution and less density unevenness and background stains.

Note that in the above embodiment, one light source is used by dividing it into two beams, but the same effect can be obtained even if two light sources are used. Further, since a laser diode is used as a light source, it goes without saying that modulation can be performed by the drive circuit without using a light modulation element.

[Effects of the Invention] As explained above, the laser thermal transfer recording device according to the present invention detects the reflected light from the transfer paper and adjusts the laser light intensity during recording based on the amount of light. Even if the optical properties of each transfer paper are different, it is possible to always obtain a transfer image with good image quality. In particular, it is effective when performing gradation recording because density unevenness can be reduced. Further, since the optical properties of the transfer paper may vary to some extent, there is an advantage that the transfer paper can be produced at low cost and by an easy method.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a laser thermal transfer recording apparatus according to the present invention. Further, FIGS. 2 and 3 are for explaining the prior art. FIG. 2 is an explanatory diagram showing an example of a head section of a thermal transfer recording device, and FIG. 3 is an explanatory diagram showing an example of a head section of a laser thermal transfer recording device. FIG. 7 is an explanatory diagram showing another example. P...Recording paper R...Transfer paper Ra
...Base layer Rb...Ink layer 30...Light source 32...Shutter 34...Collimator lens -11- 36... ...Half mirror--38... Light modulation element 40... Beam splitter 42... Condensing lens 44... Mirror 46... Beam splitter 48...Condenser lens 50...Photodetector 52...Image sensor 54...Transportation mechanism 56...Platen roll 58... ...Drive circuit 60...
Control circuit 62...Drive circuit 64...Temperature sensor 66...Interface circuit 2- Patent application Representative of Toppan Printing Co., Ltd. Kazuo Suzuki

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 apparatus, the imaging optical system includes a recording optical system that heats the transfer paper, and an adjustment optical system that detects reflected light from the transfer paper. Recording device.