JPH1016263A - Image recording method and image recording device - Google Patents

Abstract

(57) Abstract: An image recording method and an image capable of improving the separation state of a plurality of colors and suppressing the occurrence of color bleeding at a lower temperature around a recorded image. A recording device is provided. An image in which two-color images are simultaneously recorded by selectively driving each heating element of a thermal head including a plurality of heating elements on a recording medium that develops two different colors by heating at different temperatures. In the recording method, a plurality of energizing pulses including a color energizing pulse for heating to the color developing temperature of the recording medium and a thermal control pulse for performing correction so that the temperature of the heating element by the color energizing pulse always becomes a predetermined value are used. By driving the heating element of the thermal head, two color images are simultaneously recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method for heating and recording two-color images using a thermal head on a multicolor heat-sensitive recording medium which develops two different colors by heating at different temperatures. The present invention relates to an image recording device.

[0002]

2. Description of the Related Art At present, thermal recording paper is used in various fields, for example, recording paper for word processors, recording paper for facsimile, transportation tickets, bar code labels, and the like.

The advantages of using heat-sensitive recording paper are that the configuration of the image recording apparatus is simple, and no replenishment is required other than paper.
It requires little maintenance and low running costs. On the other hand, there is a disadvantage that the recording image is not suitable for recording a color image, and recording can be easily performed by applying heat at a temperature higher than the color development temperature, so that the security of the recorded image is low.

[0004] As a method for improving the disadvantages of such heat-sensitive recording, a method for recording a color image is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-175055.
By using a heat-sensitive recording paper whose color changes according to the magnitude of the applied heat, a heat-generating unit having a plurality of heat-generating elements is provided, and the heat-generating energy of each of the heat-generating elements is independently varied to achieve two colors. There is a thermal printer that records an image simultaneously.

[0005] When printing basic information using two-color heat-sensitive paper as the ticket paper, the first-color development reaction temperature is used.
When printing special information, there is a printing method of heating and recording at a second color development reaction temperature (for example, Japanese Patent Application Laid-Open No. 52-933).
No. 48).

[0006]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Sho 61-61
Japanese Patent Application Laid-Open No. 175055 and Japanese Patent Application Laid-Open No. 52-93348 disclose a method of controlling the heat generation temperature of a heating element of a thermal head for performing multicolor color printing using a heat-sensitive recording medium whose coloring state changes depending on a heating temperature. Although recorded, the specific description of the specific circuit configuration and the energizing pulse applied to the heating element of the thermal head is insufficient.

Further, when multi-color recording is performed using the above-described recording medium for recording a multi-color image, (1) it is difficult to separate a plurality of colors, and (2) color is formed around the recorded image at a lower temperature. (3) When high-temperature coloring is performed to obtain the durability of a recorded image that develops on the low-temperature side, the energy of the recorded image that develops on the high-temperature side increases, and the surface of the recording medium is heated by heat. There are problems such as destruction, a shortened life of the thermal head, an increase in heat storage of the thermal head, and difficulty in controlling stabilization of two-color development.

Accordingly, the present invention provides an image recording method and an image recording method capable of improving the separated state of a plurality of colors and suppressing the occurrence of color bleeding at a lower temperature around a recorded image. It is an object to provide a recording device.

[0009]

According to the image recording method of the present invention, each of the heating elements of the heating means comprising a plurality of heating elements is selectively applied to a recording medium which develops different colors by heating at different temperatures. An image recording method for recording an image by driving, wherein a color-forming energizing pulse for heating up to a color-forming temperature of the recording medium and a correction are performed so that the temperature of the heating element by the color-forming energizing pulse always becomes a predetermined value. An image is recorded by driving the heating element of the heating means with a plurality of energizing pulses including the heat control pulse.

Further, in the image recording method of the present invention, each of the heating elements of the heating means including a plurality of heating elements is selectively driven on a recording medium which develops two different colors by heating at different temperatures. Is an image recording method for simultaneously recording images of two colors by using a first pulse, a second pulse, and a first pulse within a one-pixel recording cycle of the image to be recorded.
A third pulse for continuously correcting the temperature of the heating element by the second pulse to a predetermined value is provided continuously, and the heating pulse of the heating means is generated by an energizing pulse including the first, second, and third pulses. A first color heating of the recording medium is performed by driving a heating element, and a heating element of the heating means is driven by an energizing pulse composed of the second and third pulses, thereby causing a second heating of the recording medium.
The first color image and the second color image are simultaneously recorded by performing the color heating.

Further, the image recording apparatus of the present invention comprises a conveying means for conveying a recording medium which develops a different color by heating at different temperatures, and a plurality of heating elements for the recording medium conveyed by the conveying means. A heating means for recording an image by selectively driving the recording medium, a coloring energizing pulse for heating to the coloring temperature of the recording medium, and a correction so that the temperature of the heating element by the coloring energizing pulse always becomes a predetermined value. Pulse generating means for generating a plurality of energizing pulses each comprising a heat control pulse for driving the heating means of the heating means with the energizing pulses generated from the pulse generating means.

Further, the image recording apparatus of the present invention has a conveying means for conveying a recording medium which emits two different colors by heating at different temperatures, and a plurality of heat generating means for the recording medium conveyed by the conveying means. Heating means for recording an image by selectively driving the body; a first pulse, a second pulse, and the heating element by the first and second pulses within one pixel recording cycle of the image to be recorded. A pulse generating means for generating a third pulse for performing correction so that the temperature always becomes a predetermined value; and an energizing pulse consisting of the first, second, and third pulses generated by the pulse generating means, A first driving means for performing the first color heating of the recording medium by driving the heating element of the first color; and an energizing pulse comprising the second and third pulses generated by the pulse generating means. And and a second driving means for the second color heating of the recording medium by driving the heating element means.

According to the present invention, it is possible to accurately control the energy of each color development temperature regardless of the pattern of a recorded image, so that the separation state of a plurality of colors can be improved.
It is possible to suppress the occurrence of color bleeding at a lower temperature around the recorded image. Therefore, a clear recorded image can always be obtained.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described.

FIG. 2 schematically shows the structure of a multicolor thermal recording medium used in the present embodiment. That is, the recording medium 1 is configured by sequentially laminating the first recording layer 3, the second recording layer 4, and the protective layer 5 on the base material 2 in this order. In the recording medium 1 of the present example, the first recording layer 3 is heated by the first recording energy (high temperature side) to be black, and the second recording layer 4 is heated.
Is heated by the second recording energy (lower temperature side) and develops a red color.

Here, the first recording layer 3 and the second recording layer 4 are composed of, for example, a thermosensitive recording layer mainly containing a leuco dye and a developer. As the leuco dye, for example, a leuco compound of a dye such as a triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, or indolinophthalide-based dye is preferable. As the developer, various electron-accepting compounds which cause the leuco dye to develop color upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof are preferred.

The coloring temperature of the first recording layer 3 is preferably equal to or higher than the coloring temperature of the second recording layer 4. Here, the color development temperature when the first and second recording layers 3 and 4 are formed as a single layer is adjusted so that the color development starts at about 90 ° C. and reaches a maximum density at about 100 ° C.
The recording medium 1 shown in FIG.
Using a polyethylene terephthalate sheet having a thickness of about 3 μm, a first recording layer 3 having a thickness of about 3 μm for forming a black color and a second recording layer 4 having a thickness of about 3 μm for forming a red color were formed from an ultraviolet curable resin. In this configuration, a protective layer 5 having a thickness of about 2 μm is sequentially laminated.

FIG. 3 shows the energy-density characteristics when an image is recorded on the recording medium 1 used in this embodiment using a thermal head (heating means) having a heating element density of 8 elements / mm. ing. The curve A indicating the characteristic of the black color density is measured using a cyan filter, and the curve B indicating the characteristic of the red color density is obtained by “measured value of magenta filter−measured value of cyan filter”.

As is apparent from FIG. 3, the energy is changed from about 0.5 mj / dot to red to about 0.7 mj / dot.
When the number of dots becomes equal to or more than the dot, black color starts to be formed, and a mixed color of red and black is obtained. Further, the energy is increased to about 1.
At 3 mj / dot or more, black becomes dominant and becomes reddish black.

FIG. 1 shows an energizing pulse (enable signal) for driving the thermal head for realizing the image recording method according to the present embodiment (the signal is low active). As is apparent from the figure, for example, six energizing pulses are included in one pixel recording cycle of an image to be recorded, and these energizing pulses are roughly divided into a recording pulse and a thermal control pulse. The recording pulse is composed of two pulses, and when recording a red image, the second pulse (E
When recording a black image using 1), the first and second pulses (E0, E1) are used, and the third and subsequent pulses are thermal control pulses used for thermal control.

Here, the six energizing pulses shown in FIG. 1 are numbered 0, 1,..., 5 in order from the top, and the effective time of each pulse is Ei (i = 0 to 5), The delay time from the first pulse is Di (i = 0 to 5). In this example, the values shown in Table 1 below were used as the values of Ei and Di. The recording cycle of one pixel is 3 ms.

The pulse width of the heat control pulse (E2 to E5) is set to E2: E3: E4: E5 = 1: 2: 4: 8 in the present embodiment. Energy control is possible.

[0024]

[Table 1]

When recording a two-color image of red / black on a two-color recording medium, it is important that the pixel to be recorded in black is heated to a black color development temperature so as not to mix red. . If black recording is performed by using only one pulse, which is different from this example, for the black color pulse used in black recording, the temperature of the heating element of the thermal head continues to rise while the enable signal is valid, When the central portion of the heating element of the head reaches the black color temperature, the peripheral portion of the heating element of the thermal head does not reach the black color temperature, but develops a red color, and an image in which the area around the black dot blurs red is recorded. In addition, if the temperature difference between the central part and the peripheral part of the image point is large, thermal stress occurs, and often damages the surface of the recording medium.

Therefore, as shown in this example, the black coloring pulse is set to 2
By using one or two or more pulses, the temperature rise of the heating element of the thermal head becomes slower than heating with one pulse, and the temperature difference between the central part and the peripheral part of the heating element. Is small, and the image points are colored to a uniform density. Since the temperature difference between the central part and the peripheral part of the image point is relatively small, thermal stress is small, and damage to the surface of the recording medium can be reduced.

In addition, as described above, by sharing a part of the recording pulse for black recording and red recording,
Since the recording period of one pixel can be shortened as compared with the case where the data is not shared, recording can be performed at a higher speed.

The width of the plurality of heat control pulses in this row is sequentially increased as described above (E2: E3: E
4: E5 = 1: 2: 4: 8). In the red recording by the two-color recording method of the present example, a lower limit can provide a sufficient red color development, but an upper limit requires accurate control in a temperature region where there is no color mixture with black.

In the two-color printing, since different temperatures are applied from the thermal head for printing, in the black printing of the present embodiment, in which the color is generated on the high temperature side, it is necessary to control the temperature of the heating element of the thermal head higher than in the prior art. There is a need.

In order to solve these problems, it is necessary to achieve both control in a fine temperature range and control for suppressing a rapid temperature drop from the high temperature side of the heating element of the thermal head. In the two-color recording method of the present embodiment, control with a fine temperature width and suppression of a rapid temperature drop are realized by the above-described pulse width control.

In the control using the heat control pulse having the same pulse width, if the pulse width is narrowed, it is difficult to suppress a rapid temperature drop. Conversely, if the pulse width is widened, it is difficult to perform control with a fine temperature width.

Next, a method of determining a thermal head drive pulse including the thermal control method in this embodiment will be described with reference to a flowchart shown in FIG. The procedure is as follows.

(1) Combining Two Types of Binary Images (Monochrome Red / Black) The red image and the black image are read from the image memory, and are synthesized according to the rules shown in Table 2 below. In this example, when the red image and the black image overlap,
Although the red image is prioritized, the black image can be prioritized by rewriting the data in Table 2 (for example, storing the data as table data in the ROM).

[0034]

[Table 2]

(2) Cut out the reference area from the synthesized image The size (range) of the reference area is changed depending on whether the target pixel is red or black. In this example, the sizes shown in Table 3 below are used.

[0036]

[Table 3]

For example, when an image as shown in FIG. 5A is recorded, FIG. 5B shows an example in which a target pixel and a reference area are cut out. In this case, the pixel to be recorded =
Since the target pixel is recorded in red, the reference area size is “3 × 5” from Table 3.

It is meaningful to switch the size (range) of the reference area depending on the pixel of interest. As shown in FIG. 3, the recording medium 1 used in the present example emits red at low energy (low temperature) and black at high energy (high temperature). At this time, the black color generated with high energy can be obtained by applying energy of about 1.5 mJ / dot or more to the recording medium 1, whereas the low-energy red color is obtained from about 0.6 to 0.7 mJ / dot.
The energy must be controlled in the range of / dot.

That is, black must be used in the saturated region, while red must be used in the transition region (non-saturated region). In the case of black color, if a slightly higher energy is applied in consideration of fluctuations and the like only at the lower limit of the energy, there is little need to perform accurate control. However, as described above, since the energy range of red is about 0.1 mJ, if fluctuation occurs due to a problem such as heat storage of the thermal head, black may be mixed with red.

Therefore, the range of the reference region is set narrow for high energy black recording (S1), and the range of the reference region is set wide for low energy red recording (S2). If the black reference area is set to be as wide as red, the black does not need to be set to a wide range from the beginning.
In addition, the smaller the reference area is, the more preferable in terms of hardware scale and calculation speed.

(3) Determining the basic recording pulse according to the target pixel The basic recording pulse is stored in advance as table data as shown in Table 4 below. In the case of FIG.
Since the pixel of interest is a red recording pixel (RP), the basic recording pulse is “010000” from Table 4.

[0042]

[Table 4]

(4) Calculating Total Weight Value in Reference Area The total weight value in the reference area is calculated by associating each image data in the reference area with a weight value. Tables 5 to 7 below show weight value tables corresponding to the image data in the reference area. Each value indicates the effect of heat storage on the pixel of interest. The value is a positive value, and the larger the absolute value, the larger the heat storage.

[0044]

[Table 5]

[0045]

[Table 6]

[0046]

[Table 7]

The weight values for each pixel in the reference area are obtained by associating Tables 5 to 7 with the cut-out images in FIG. 5B, and the total weight value is calculated by simply adding them. I do. In the case of this example, the weight value of each pixel is shown in Table 8 below.
And the total weight value is 10.9.

[0048]

[Table 8]

(5) Determining Correction Pulse A correction pulse is determined by referring to the total weight value-drive pulse table shown in Tables 9 to 11 based on the total weight value. In this example, since the pixel of interest is red (RP) and the total weight is 10.9, the correction pulse is “220,000” from Table 10.

[0050]

[Table 9]

[0051]

[Table 10]

[0052]

[Table 11]

(6) Combining Basic Recording Pulse and Correction Pulse The basic recording pulse and the correction pulse are combined according to the driving pulse synthesis rule shown in Table 12 below to generate a thermal head driving pulse. In this case, the pulse is
For example, corresponding pulses are synthesized such as E0 of the basic recording pulse and E0 of the correction pulse. In this case, So, Becomes

[0054]

[Table 12]

Next, an image recording apparatus for realizing the image recording method according to the present embodiment will be described with reference to FIG. A CPU (Central Processing Unit) 6 controls the entire apparatus. The ROM (read only memory) 7 stores a control program for operating the CPU 6 and the like. A RAM (random access memory) 8 is used as a work area of the CPU 6 and temporarily stores various setting data. The image memory 9 stores image information to be recorded, and is internally divided into a red image storage area 9a and a black image storage area 9b.

The thermal control parameter ROM 10 is shown in Table 1 above.
To Table 12 are stored. The transport control unit 11 controls a drive motor (not shown) of the transport unit 12 that transports the recording medium 1. The sensor 13 detects the recording medium 1 to be conveyed.
6, the CPU 6 controls the start and end timings of the operation of the apparatus.

The recording control section 14 controls the timing relationship and the sequence of the entire recording operation. The red / black image synthesizing unit 15 synthesizes a red image and a black image to generate a recorded image, and performs the process of the procedure (1).

The reference area extracting section 16 determines a target pixel from the recorded image synthesized from the red image and the black image, determines the range of the reference area based on the determination result, and further extracts the reference area portion. Then, the processing of the procedure (2) is performed.

The heat control unit 17 receives the image information in the reference area from the reference area extraction unit 16, calculates the total weight value in the reference area, and calculates the correction pulse. Perform the process of (5).

The recording energy control unit 18 receives the target pixel information from the reference area extracting unit 16, obtains a basic recording pulse, receives correction pulse information from the thermal control unit 17, and determines the basic recording pulse and the correction pulse. The information is synthesized, and the information for the thermal head drive pulse is obtained.

The recording drive unit 19 includes the recording energy control unit 1
Based on the information from 8, a drive energizing pulse for a thermal head (recording unit) 20 as a heating unit and a signal necessary for driving the thermal head 20 are generated. The thermal head 20 performs an actual recording operation.

Next, the recording operation of the image recording apparatus shown in FIG. 6 will be briefly described. When the recording operation starts, C
The PU 6 executes a control program stored in the ROM 7. That is, the CPU 6 operates the transport control unit 11 to drive the transport unit 12 such as a motor,
The recording medium 1 is transported to a recording position.

The recording drive unit 19 includes the recording energy control unit 1
In accordance with the thermal head drive pulse information generated in step 8, a signal (data transfer clock, latch, enable signal, etc.) necessary to drive the thermal head 20 is generated and sent to the thermal head 20.

In the thermal head 20, the heating elements of the corresponding thermal head 20 are selectively and simultaneously corresponding to the recording energies Ek and Er according to the red recording pixels / black recording pixels on a pixel basis of the recording image. The energized black recording pulse and the energized red recording pulse are applied, and image recording for one line is performed. These operations are performed for all the recorded images, and the recording operation for one screen is completed.

FIG. 7 shows an example of a sample in which two colors are recorded. FIG. 7A shows the result of red recording without performing the heat control as in the present invention, and FIG. 7B shows the result of red recording after performing the heat control of the present invention. The respective recording energies are shown in Table 13 below.

[0066]

[Table 13]

As is clear from FIG. 7A, it is understood that the density of "52" or "12" is different from the density of black when no thermal control is performed. In this example, since the thickness of the image pattern is relatively uniform, the unevenness is relatively inconspicuous, but the printing quality is very poor in a pattern in which one-dot characters are mixed, and the black and one-dot characters are used. It cannot be compatible with letters. If the energy is optimized for recording one-dot characters, the energy becomes excessive when recording black and white, and conversely, if the energy is optimized for recording black and white, the energy becomes insufficient when recording one-dot characters. become.

As shown in FIG. 7B, by using the recording method of the present invention, high-quality image recording can always be performed.

Next, a second embodiment will be described.

The procedure of generating the thermal head drive pulse information including the thermal control is basically the same as that of the first embodiment, and the procedure is as follows.

(1) Combining two types (red / black single color) of binary images (2) Cutting out a reference area portion from the combined image (3) Determining a basic recording pulse according to the pixel of interest (4) Calculate the total weight value in the reference area. (5) Find the correction pulse. (6) Combine the basic recording pulse and the correction pulse. In the second embodiment, (2) refer to from the combined image during red recording. The portion of (4) calculating the total weight value in the reference region (5) finding the correction pulse is different from the first embodiment. Hereinafter, the different procedures (2), (4), and (5) will be described.

(2) Extraction of Reference Area from Synthesized Image FIG. 8 shows an example of thermal control according to this embodiment. When recording the image shown in FIG. 8A, only when the pixel of interest is red,
A reference area as shown in FIG. For example, in the case of recording a pixel having the coordinate value (i, j), in the red recording, a rectangular area of “3 × 5” is used in the first embodiment, but “1” is used in the second embodiment. × j ”rectangular area. Therefore, when printing pixels on the 10th line, the range is “1 × 10”, and when printing pixels on the 100th line, the range is “1 × 100”.
Reference the variable length area. That is, the heat generation history of the thermal head 20 corresponding to the pixel in the recording medium unit is referred to.

(4) Calculating the Total Weight Value in the Reference Area The total weight value of the image in the reference area shown in FIG. 8B is calculated. Here, more global energy control, such as correcting a difference in color tone and density between the beginning and end of the recording medium, rather than a local pattern of the image to be recorded, is performed.

Here, the weight value of the non-recording pixel is Wn, the weight value of the black recording pixel is Wk, and the weight value of the red recording pixel is Wr.
Then, the total weight value Wt in the reference area is obtained by the following equation (1). If the total weight value Wt is a negative value, “0” is set.
And The reason why “0” or a negative weight is given when the pixel m = NP (non-recording) is that the amount of heat storage decreases when pixels that do not record continue.

[0075]

(Equation 1)

In this example, the weight values shown in Table 14 below were used. The energy ratio between red color development and black color development is 1:
2, Wr = 1.0, Wk = 2.0, and Wn was experimentally obtained.

[0077]

[Table 14]

(5) Determining Correction Pulse A correction pulse is determined by referring to the total weight value-drive pulse table shown in Table 15 below.

[0079]

[Table 15]

The subsequent procedure is the same as in the first embodiment. Although the description is omitted here,
At the time of black recording, recording can be performed in exactly the same manner as in the first embodiment described above.

Next, an image recording apparatus for realizing the image recording method according to the present embodiment will be described with reference to FIG. A CPU (Central Processing Unit) 21 controls the entire apparatus. The ROM (read only memory) 22 stores a control program for operating the CPU 21 and the like. RAM
The (random access memory) 23 is used as a work area of the CPU 21 and temporarily stores various setting data. The image memory 24 stores image information to be recorded, and is internally divided into a red image storage area 24a and a black image storage area 24b.

The heat control parameter ROM 25 is as shown in Table 1 above.
Table data of Table 4, Table 12, Table 14, and Table 15 are stored. The transport control unit 26 controls a drive motor (not shown) of the transport unit 27 that transports the recording medium 1. The sensor 28 detects the recording medium 1 to be conveyed. When the detection signal is sent to the CPU 21, the CPU 21 controls the start and end timings of the operation of the apparatus.

The recording control section 29 controls the timing relationship and sequence of the entire recording operation. The red / black image synthesizing unit 30 synthesizes a red image and a black image to generate a recorded image, and performs the process of the procedure (1).

The reference area extracting section 31 determines a target pixel from the recorded image synthesized from the red image and the black image, determines the range of the reference area based on the determination result, and further extracts the reference area portion. Then, the processing of the procedure (2) is performed.

The heat control unit 32 receives the image information in the reference region from the reference region extraction unit 31, calculates the total weight value in the reference region, and calculates the correction pulse. Perform the process of (5). At this time, the total weight in the reference area at the time of red recording is not recalculated every time, but the calculated lower value is stored in the RAM 23, and only the difference from the previous calculated value is newly calculated. The calculation time is shortened.

The recording energy control unit 33 receives the target pixel information from the reference area extracting unit 31, obtains a basic recording pulse, receives correction pulse information from the thermal control unit 32, and determines the basic recording pulse and the correction pulse. The information is synthesized, and the information for the thermal head drive pulse is obtained.

The recording drive unit 34 includes the recording energy control unit 3
Based on the information from 3, a drive energizing pulse for a thermal head (recording unit) 35 as a heating unit and a signal necessary for driving the thermal head 35 are generated. The thermal head 35 performs an actual recording operation.

Next, the recording operation of the image recording apparatus shown in FIG. 9 will be briefly described. When the recording operation starts, C
The PU 21 executes a control program stored in the ROM 22. That is, the CPU 21 controls the transport control unit 26
Is operated, and the transport unit 27 such as a motor is driven to transport the recording medium 1 to the recording position.

The recording driving unit 34 is provided with the recording energy control unit 3
In accordance with the thermal head drive pulse information generated in step 3, a signal (data transfer clock, latch, enable signal, etc.) required to drive the thermal head 35 is generated and sent to the thermal head 35.

In the thermal head 35, the heating elements of the corresponding thermal head 35 are selectively and simultaneously corresponding to the recording energies Ek and Er according to the red recording pixels / black recording pixels on a pixel basis of the recording image. The energized black recording pulse and the energized red recording pulse are applied, and image recording for one line is performed. These operations are performed for all the recorded images, and the recording operation for one screen is completed.

FIG. 10 shows an example of a sample recorded in red by performing the thermal control of this example. It can be seen that the recording was performed at a uniform density irrespective of the start and end of the recording, as compared with the recording performed in red without performing the thermal control shown in FIG.

As in the present embodiment, by switching the reference area for controlling the energy of the thermal head 35 (thermal control of the heating element) according to the type of information (red / black) of the target pixel, finer energy can be obtained. Control becomes possible.

[0093]

As described above in detail, according to the present invention, the separation state of a plurality of colors is improved, and the occurrence of color bleeding at a lower temperature around the recorded image is suppressed. It is possible to provide an image recording method and an image recording apparatus that can be used.

[Brief description of the drawings]

FIG. 1 is a diagram showing drive pulses for a thermal head according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a layer configuration of the recording medium according to the first embodiment.

FIG. 3 is a view showing the coloring characteristics of a recording medium by a thermal head according to the first embodiment.

FIG. 4 is a flowchart illustrating a two-color simultaneous printing operation in the first embodiment.

FIG. 5 is a diagram showing an example of a reference area according to the first embodiment.

FIG. 6 is a block diagram schematically showing a configuration of the image recording apparatus according to the first embodiment.

FIG. 7 is a diagram illustrating an example of a recording result according to the first embodiment.

FIG. 8 is a diagram illustrating an example of a reference area according to the second embodiment of the present invention.

FIG. 9 is a block diagram schematically showing a configuration of an image recording apparatus according to the second embodiment.

FIG. 10 is a diagram illustrating an example of a recording result according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... Base material, 3 ... First recording layer, 4
... Second recording layer, 5... Protective layer, 6, 21... CP
U, 7, 22 ... ROM, 8, 23 ... RAM, 9, 2
4 ... Image memory, 9a, 24a ... Red image storage area, 9b, 24b ... Black image storage area, 10, 25 ...
... thermal control parameter ROM, 11, 26 ... transport control unit, 12, 27 ... transport unit, 14, 29 ... recording control unit, 15, 30 ... red / black image synthesis unit, 16, 31 ...
Reference region extraction unit, 17, 32... Thermal control unit, 18, 33
... a recording energy control unit, 19, 34 ... a recording driving unit,
20, 35 ... thermal head (recording unit).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Ito 70 Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa

Claims (10)

[Claims] 1. An image recording method for recording an image by selectively driving each of said heating elements of a heating means comprising a plurality of heating elements on a recording medium which develops different colors by heating at different temperatures. A plurality of energizing pulses including a color energizing pulse for heating the recording medium to the color developing temperature and a thermal control pulse for performing correction so that the temperature of the heating element by the color energizing pulse always becomes a predetermined value. An image recording method, wherein an image is recorded by driving a heating element of the heating means. 2. The energy control by the heat control pulse is performed by referring to the heating history information of the pixel to be recorded and the heating element of the heating means corresponding to the pixel, and according to the color information of the pixel to be recorded. 2. The image recording method according to claim 1, wherein the range of the reference area is switched. 3. The image recording method according to claim 1, wherein the heat control pulse is composed of a plurality of pulses, and the widths of the plurality of heat control pulses are sequentially increased. 4. A two-color image is simultaneously recorded by selectively driving each of said heating elements of a heating means comprising a plurality of heating elements on a recording medium which develops two different colors by heating at different temperatures. A first pulse and a second pulse within one pixel recording cycle of an image to be recorded.
A pulse and a third pulse for correcting the temperature of the heating element by the first and second pulses so that the temperature always becomes a predetermined value. The pulse is composed of the first, second and third pulses. The heating element of the heating means is driven by an energizing pulse to perform the first color heating of the recording medium, and the heating element of the heating means is driven by the energizing pulse composed of the second and third pulses to drive the recording medium. An image recording method for simultaneously recording a first color image and a second color image by performing the second color heating. 5. The energy control by the third pulse is performed by referring to the heating history information of the heating element of the heating means corresponding to the pixel to be recorded and the pixel, and
5. The image recording method according to claim 4, wherein a range of the reference area is switched according to color information of a pixel to be recorded. 6. A range of a reference area for recording the lower recording energy between the first color image and the second color image is larger than a range of the reference area for recording the higher recording energy. The image recording method according to claim 5, wherein 7. A method of recording a first color image and a second color image, wherein when recording is performed with a lower recording energy, pixels of the recorded first color image and the second color image in the reference area are recorded. 6. The image recording method according to claim 5, wherein the numbers are added at a predetermined ratio, and the energy applied to the heating element of the heating means is controlled based on the addition. 8. The image recording method according to claim 4, wherein when the third pulse is composed of a plurality of pulses, the width of the plurality of third pulses increases in order. 9. A transport unit for transporting recording media that develops different colors by heating at different temperatures, and by selectively driving a plurality of heating elements with respect to the recording media transported by the transport unit. A heating unit for recording an image, a coloring power supply pulse for heating to a coloring temperature of the recording medium, and a heat control pulse for performing correction so that the temperature of the heating element by the coloring power supply pulse always becomes a predetermined value. An image recording apparatus, comprising: pulse generating means for generating a plurality of energizing pulses; and driving means for driving a heating element of the heating means with the energizing pulses generated from the pulse generating means. 10. A conveying means for conveying a recording medium which emits two different colors by heating at different temperatures, and selectively driving a plurality of heating elements with respect to the recording medium conveyed by the conveying means. Heating means for recording an image by means of a first pulse and a second pulse within one pixel recording cycle of the image to be recorded.
Pulse and pulse generating means for generating a third pulse for correcting the temperature of the heating element by the first and second pulses so that the temperature always becomes a predetermined value; and A first driving unit for performing first color heating of the recording medium by driving a heating element of the heating unit with an energizing pulse including first, second, and third pulses; and a pulse generating unit. And a second driving unit for performing a second color heating of the recording medium by driving a heating element of the heating unit with an energizing pulse including the second and third pulses. Recording device.