JP2000062222A - Thermal recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve brightness rising characteristics of a light source for optical fixing in a thermal recorder recording a color image on a color thermal recording material through thermal recording and optical fixing. SOLUTION: A heat conduction plate 7 fixed with a thermal head 3 and an optical fixing unit 5 is fixed to a supporting plate 8. When the heating element 10 in a thermal head 3 is driven to be heated at the time of thermal recording onto the thermal coloring layer of a recording sheet P, excess heat generated from the heating element 10 is conducted to the optical fixing unit 5 through the heat conduction plate 7. At the time of subsequent optical fixing to the thermal coloring layer of the recording sheet P, the optical fixing unit 5 is preheated and the brightness rising characteristics of light sources 12, 13 for the optical fixing unit 5 are improved through ambient temperature rise.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium which forms a full-color image on a thermosensitive light-responsive recording paper whose color is developed by heat energy and whose color development is stopped by irradiation of ultraviolet rays. It relates to a recording device. 2. Description of the Related Art Conventionally, a thermal recording system for recording a full-color image using a recording paper having three thermosensitive coloring layers of yellow, magenta and cyan formed on a sheet substrate (Japanese Patent Publication No. Hei 4-10879). No. 6-51425) has been proposed and put into practical use. In the recording paper, as shown in FIG. 4, a cyan thermosensitive coloring layer 27, a magenta thermosensitive coloring layer 28, a yellow thermosensitive coloring layer 29, and a protective layer 30 are sequentially provided on a support 26. The thermosensitive coloring layer has coloring properties as shown in FIG. That is, the thermal energy on the horizontal axis represents the thermal energy generated by the heating element of the thermal head, the thermal energy of the yellow thermal coloring layer (Y) is the lowest, and the magenta thermal coloring layer (M) and the cyan thermal coloring layer ( The heat energy increases in the order of C). Further, these heat-sensitive coloring layers lose their coloring ability by irradiation with light (ultraviolet light) of a specific wavelength and are fixed by light. In the thermal recording method, after a yellow image is thermally recorded on the yellow thermosensitive coloring layer 29 by a thermal head of the thermosensitive recording device, a light having a predetermined wavelength corresponding to the yellow thermosensitive coloring layer 29 is applied from the light source of the thermosensitive recording device. This operation is performed by irradiating light to fix the light, and this operation is repeated for the magenta thermosensitive coloring layer 28 and the cyan thermosensitive coloring layer 27 to develop each color to obtain a color image. A cold cathode tube is often used as a light source for light fixing of the thermal recording apparatus. In the above-described thermal recording method, optical fixing is performed after thermal recording of each thermosensitive coloring layer. The light source for performing the optical fixing is turned on and then required for optical fixing. It takes a certain amount of time until the luminance becomes sufficient, which slows down the recording speed. In addition, when light fixing is started without the required illuminance on the recording paper, fixing failure may occur. [0006] In the optical fixing device, the time until the required brightness is obtained after the light source is turned on depends on the ambient temperature of the light source.
It takes more time when the ambient temperature during lighting is low. In particular, when the light source is a cold-cathode tube, there is a problem that the rise to the required luminance is poor. That is, FIG.
Indicates the luminance rise characteristic of the cold cathode tube, and indicates the time required until the luminance required for light fixing is obtained when the ambient temperature changes. It can be seen that there is a difference in the rise of luminance depending on the ambient temperature. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a simple structure and can generate a predetermined luminance in a short time after a light source for light fixing is turned on, thereby shortening a recording time. It is an object to provide a thermal recording device. That is, in the thermal recording apparatus of the present invention, a color thermal recording material having a plurality of thermal coloring layers formed on a support is used. The thermal recording performed by driving the heating element of the thermal head while generating heat while being relatively moved with respect to the optical fixing device, and the subsequent optical fixing performed by turning on the light source of the optical fixing device are performed on each thermosensitive coloring layer. A thermal recording apparatus in which a color image is repeatedly recorded, wherein the thermal head and the optical fixing device are connected by a connecting member having thermal conductivity. In this thermal recording apparatus, the heating element of the thermal head generates heat during thermal recording on the thermal coloring layer of the color thermal recording material, and the temperature of the thermal head rises. The heat generated by the thermal head is transmitted to the optical fixing device via the connecting member, and raises the temperature of the optical fixing device. Therefore, during the optical fixing performed after the thermal recording by the thermal head, since the temperature of the optical fixing device has risen, the time required for the light source of the optical fixing device to reach the required brightness after the light is turned on. Can be shortened. Embodiments of the present invention will be described below with reference to the drawings. As the recording paper (color thermal recording material) used in the thermal recording apparatus according to the present invention, the conventionally known recording paper described with reference to FIGS. 4 and 5 is used. FIGS. 1 and 2 are side views showing the structure of a recording section which is a main part of a thermal recording apparatus according to an embodiment of the present invention. FIG. 1 shows a state during thermal recording, and FIG. 2 shows a state during light fixing. As shown in FIGS. 1 and 2, a pair of first and second transport rollers 1 and 2 for transporting a recording paper P are provided on a paper transport path of the thermal recording apparatus. A thermal head 3 for performing thermal recording and a platen roller 4 are provided on the road, and an optical fixing device 5 for performing optical fixing after thermal recording is provided. Reference numeral 6 denotes an entrance of the recording paper P. The transport rollers 1 and 2 transport the recording paper P back and forth along the paper transport path. At the time of thermal recording, the recording paper P is transported from the inside of the apparatus toward the paper entrance 6, and at the time of optical fixing, the recording paper P is transported from the paper entrance 6 toward the inside of the apparatus. The thermal head 3 is arranged in parallel with the axial direction of the platen roller 4 and is mounted on a heat conductive plate 7 made of a metal material having thermal conductivity such as aluminum. The heat conductive plate 7 is further attached to one end of a support plate 8 made of a metal material together with a thermal head 3 by a coupling member such as a screw. The support plate 8 is swingably disposed on a machine frame in the apparatus by a mounting shaft 9. The support plate 8 is configured to swing up and down around a mounting shaft 9 by a head moving mechanism (not shown), so that the thermal head 3 is pressed against and separated from the platen roller 4. The platen roller 4 of the thermal head 3
A heating element 10 is provided to extend in the longitudinal direction at the end of the opposite surface. The heating elements 10 are formed by arranging a number of heating elements corresponding to the maximum number of pixels in the main scanning direction of image recording (the longitudinal direction of the thermal head 3) in a row. The optical fixing device 5 includes a light source 12 for yellow fixing, which emits ultraviolet light of a predetermined wavelength for optically fixing the yellow coloring layer of the recording paper P, inside a housing 11 formed of a light shielding member. And a light source 13 for magenta fixing, which emits ultraviolet light of a predetermined wavelength for optically fixing the magenta coloring layer of the recording paper P. The yellow fixing light source 12 and the magenta fixing light source 13 are formed by cold cathode tubes such as fluorescent tubes.
The casing 11 is made of a metal material having good heat conductivity. The optical fixing device 5 is connected to the heat conductive plate 7.
, For example, by a coupling member such as a screw. Therefore, the optical fixing device 5 is connected to the thermal head 3 via the heat conductive plate 7. Reference numeral 14 denotes a sensor provided in the paper transport path for detecting the recording paper P. FIG. 3 shows a block diagram of an electronic circuit of the thermal recording apparatus. The thermal recording device has a control unit (CP
U) 15, and a control unit (CPU) 15 includes a head drive circuit 16 that drives the thermal head 3 to generate heat, and a head moving motor 17 of a head moving mechanism that moves the thermal head 3 with respect to the platen roller 4. Motor drive circuit 18, transport motor 1 that rotationally drives transport rollers 1 and 2
9; a light source control circuit 21 for controlling the yellow fixing light source 12 and the magenta fixing light source 13 of the optical fixing device 5; an interface 22 for connecting to an external device such as a personal computer; Image memory 2 for storing the transferred image data
3. ROM 24 in which a control program for a printing process executed by the control unit 15 is stored, and RAM 2 in which yellow image data, magenta image data, cyan image data, and the like for printing created from the image data are stored.
5 are connected. Next, the operation of the thermal recording apparatus will be described. When the recording paper P is inserted from the paper entrance 6 and the leading end thereof is detected by the sensor 14, the transport motor 19 is driven by the motor drive circuit 20, and the recording paper P is transported into the apparatus by the transport rollers 1 and 2. . When the leading end of the recording area of the recording paper P reaches the thermal recording position, the head driving motor 17 is driven by the motor driving circuit 18, and the head moving mechanism (not shown) is operated to press the thermal head 3 against the platen roller 4. Hereinafter, thermal recording of the yellow image is started. First, the control unit 15 reads an image signal for the first line of the yellow image data stored in the RAM 25. The image signal for one line is converted into a drive signal in consideration of the coloring characteristics shown in FIG. The drive signal for one line is sent to the thermal head 3 and supplied to the corresponding heating elements 10. Each heating element 10 is driven by the head drive circuit 16 to generate heat at a temperature corresponding to the density to be recorded. As a result, the first yellow image is printed on the recording paper P.
The line is thermorecorded. When the recording of the first line is completed, the transport motor (step motor) 19 rotates the transport rollers 1 and 2 by one line, and transports the recording paper P by that amount. In the same procedure, the drive signal of the second line of the yellow image data is sent to the thermal head 3, and the second line is thermally recorded on the recording paper P. Hereinafter, a yellow image is recorded line by line in a similar manner. When the thermal recording of the yellow image is completed, the head moving motor 17 is driven by the motor driving circuit 18 to separate the thermal head 3 from the platen roller 4. At the same time, the transport motor 19 is reversed to pull the recording paper P back to the recording start position. In the process of pulling back the recording paper P, the yellow fixing light source 12 of the optical fixing device 5 is turned on, and light of a predetermined wavelength is irradiated on the portion of the recording paper P on which the yellow image is thermally recorded. As a result, the coloring ability of the yellow thermosensitive coloring layer 29 disappears, and light fixing is performed. As described above, the recording of the yellow image is performed in the order of thermal recording and light fixing. When the heating element 10 of the thermal head 3 is driven to generate heat during thermal recording, part of the heat generated therefrom is conducted from the heat conducting plate 7 to the optical fixing device 5. When the thermal recording of the yellow image is completed and the optical fixing is started, the yellow fixing light source 12 of the optical fixing device 5 is preheated by the heat supplied from the thermal head 3 during the preceding thermal recording. . When the light fixing of the yellow thermosensitive coloring layer 29 is completed, the light source 12 for yellow fixing is turned off, the thermal head 3 is pressed against the platen roller 4, and the transport motor 19 is rotated forward to move the recording paper P to the paper entrance 6 The image signal of the magenta image data stored in the RAM 25 is sequentially read out from the first line while being conveyed toward the magenta thermosensitive coloring layer 28 by the thermal head 3.
Heat record line by line. When the thermal recording of the magenta image is completed, the thermal head 3 is separated from the platen roller 4, and the transport motor 19 is again rotated reversely to pull the recording paper P back to the recording start position, while the magenta fixing of the optical fixing device 5 is performed. The light source 13 is turned on, and the light generated from the light source is irradiated to fix the magenta thermosensitive coloring layer 28 with light. When the light fixing of the magenta thermosensitive coloring layer 28 starts, the light source 13 for magenta fixing of the light fixing device 5
It is preheated by the heat supplied from the thermal head 3 during the previous thermal recording of the magenta image. After the light fixing of the magenta image, the transport motor 19 is rotated forward again to thermally record the cyan image on the cyan thermosensitive coloring layer 27 of the recording paper P from the recording start position. Since the cyan thermosensitive coloring layer 27 has a high coloring temperature and does not develop color in a normal storage state, light fixing is omitted. The thermal conduction plate 7 for connecting the thermal head 3 and the optical fixing device 5 is not directly attached to the support plate 8 for supporting the heat conduction plate 7 but is attached with a heat insulating material interposed therebetween. The heat generated from the head 3 may not escape to the support plate 8 so that the efficiency of heat conduction to the optical fixing device 5 may be increased. In the above embodiment, the optical fixing device 5 is attached to the heat conducting plate 7 together with the thermal head 3.
The heat conductive plate 7 mechanically supports the optical fixing device 5 and the thermal head 3 together with the support plate 8.
And the optical fixing device 5 may be fixedly supported in the thermal recording apparatus by a support member separate from the support plate 8. In that case, the movable thermal head 3 and the immobile optical fixing device 5 may be connected by a flexible and excellent heat conductive member such as an aluminum film or sheet. Further, a temperature sensor is provided at or near the optical fixing device 5, and at the time of starting the optical fixing, the time until the required luminance is reached is estimated based on the temperature measured by the temperature sensor. After waiting for the time, light fixing may be started. Alternatively, the luminance and illuminance may be measured at or near the optical fixing device 5 and the optical fixing may be started when the measured value becomes a value suitable for the optical fixing process. According to the thermal recording apparatus of the present invention, the heat generated by the thermal head during the thermal recording is transmitted to the optical fixing device through the connecting member to preheat the light source, so that the thermal recording is continued during the thermal recording. At the time of light fixing, the brightness of the light source for light fixing is quickly raised, and the performance required for light fixing can be obtained in a short time.
Therefore, with a simple configuration, it is possible to improve the luminance rise characteristics with respect to the ambient temperature of the optical fixing device, and it is possible to shorten the recording time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a configuration of a thermal recording apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a configuration of a thermal recording apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of an electronic circuit of the thermal recording apparatus. FIG. 4 is an explanatory view showing a structure of a recording paper used in the thermal recording apparatus. FIG. 5 is a view showing the coloring characteristics of recording paper used in the thermal recording apparatus. FIG. 6 is a diagram illustrating a luminance rising characteristic of a light source. [Description of Signs] 1 ... Conveying roller 2 ... Conveying roller 3 ... Thermal head, 4 ... Platen roller, 5 ... Optical fixing device, 6 ... Paper entrance / exit, 7 ... Heat conductive plate, 8 ... Support plate, 9 ... Mounting shaft, DESCRIPTION OF SYMBOLS 10 ... Heating element, 11 ... Case, 12 ... Yellow fixing light source, 13 ... Magenta fixing light source, 14 ... Sensor, 15 ... Control part, 16 ... Head drive circuit, 17 ... Head moving motor, 18 ... Motor drive circuit , 19 ... Convey motor, 20 ... Motor drive circuit, 21 ... Light source control circuit, 22 ... Interface, 23 ... Image memory, 24 ... ROM, 25 ... RAM, 26 ... Support body, 27 ... Cyan thermosensitive coloring layer, 28 ... Magenta Thermosensitive coloring layer, 29: yellow thermosensitive coloring layer, 30: protective layer, P: recording paper.

Claims (1)

Claims: 1. A color thermosensitive recording material having a plurality of thermosensitive coloring layers formed on a support, and the color thermosensitive recording material is moved relative to a thermal head and an optical fixing device. A thermal recording apparatus for recording a color image by repeating a thermal recording performed by driving a heating element of the thermal head to generate heat and a subsequent optical fixing performed by turning on a light source of the optical fixing device for each thermosensitive coloring layer. A thermal recording apparatus, wherein the thermal head and the optical fixing device are connected by a connecting member having thermal conductivity.