JPH0930014A - Image recording method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply double-color recording capable of suppressing the blur of colors and good in the separation capacity of a pluraity of colors to a double- color thermal recording medium changed in its developed color state by heating temp. SOLUTION: Red and black recording images are read from an image memory 9 and recording image data are synthesized according to a predetermined rule and fundamental recording energy is calculated corresponding to whether the noticeable pixel within the reference region extracted in a reference region extraction part 14 is a red or black recording image by a recording energy control part 15. Further, in a heat control part 16, the fundamental recording energy of the noticeable pixel is corrected on reference to the heat control data stored in a heat control data ROM 17 to form recording data. In a recording drive part 18, a drive current supply pulse signal for controlling the driving of a recording part 19 is formed on the basis of the recording data to drive the recording part 19 to perform the simultaneous printing of red and black colors.

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 and an image recording apparatus for heating and recording an image on a multicolor thermosensitive recording medium which develops different colors by heating at different temperatures. .

[0002]

2. Description of the Related Art At present, thermal recording papers are used in various fields such as recording papers for word processors, recording papers for facsimiles, transportation tickets, bar code labels and the like.

The advantages of using thermal recording paper are:
The configuration of the recording device is simple, no replenishment items other than paper are required,
The maintenance costs are low and the running costs are low.

Regarding color recording, for example, Japanese Patent Laid-Open No. Sho 6
As disclosed in Japanese Laid-Open Patent Publication No. 1-175055, by using a thermal paper whose color is changed depending on the amount of applied heat, the heat generation energy of each heat generation element of a thermal head including a plurality of heat generation elements is independent. There is a thermal printer that records a multicolored recording image by changing the color of the thermal printer.

Further, as disclosed in Japanese Patent Laid-Open No. 52-093348, the first color is printed when basic information is printed on a two-color color thermosensitive recording medium used for a ticket for transportation. When printing special information at the color reaction temperature, there is a recording method in which heat recording is performed at the second color reaction temperature.

In both cases, the heating temperature of the heating element of the thermal head for performing multicolor color recording is controlled on the thermosensitive recording medium whose color-forming state changes depending on the heating temperature.

[0007]

The conventional image recording method and image recording apparatus for performing multi-color color recording on such a multi-color thermosensitive recording medium have the following problems. (1) It is difficult to separate a plurality of colors. (2) Color bleeding occurs at a lower temperature around the recorded image. (3) When high temperature color development is performed to obtain durability of a recorded image that is colored on the low temperature side, the energy of the recorded image that is colored on the high temperature side is increased, and the life of the thermal head is shortened.
The heat accumulated in the thermal head becomes large, and it becomes difficult to stabilize the two-color coloring.

In order to prevent color bleeding, a recording medium including an erasing layer for erasing a low temperature color recorded image which acts at the time of recording a high temperature recorded image has been devised. There is a problem that the stability of the recorded image is deteriorated and the recorded image density is lowered in a relatively short time.

Therefore, according to the present invention, an image capable of suppressing color bleeding on a multicolor thermosensitive recording medium whose color development state changes depending on the heating temperature and performing multicolor color recording with good separation performance of a plurality of colors. An object of the present invention is to provide a recording method and an image recording device.

[0010]

According to the image recording method of the present invention, a first color is developed by being heated at a first temperature and is heated at a second temperature lower than the first temperature. An image recording method for driving an image on a recording medium that develops a second color different from the first color by heating the image, and recording the image by heating the image on the recording medium. When recording a color image, the first
When the thermal recording unit is driven to record the image of the second color in each of the period and the second period following the first period, the thermal recording is performed in the second period within the one-pixel recording cycle. The image is heated and recorded on the recording medium by driving the means, and red or black can be selectively recorded within one pixel recording period.

Further, the image recording method of the present invention is an image recording method in which an image is thermally recorded on a recording medium which develops different colors by heating at different temperatures, by using the thermal recording means. The one-pixel recording cycle for recording each color-developing pixel of the image of the drive pulse signal for driving the control unit controls the temperature of each heating element of the thermal recording means to develop each color of the recording medium corresponding to the color of the color-developing pixel. When the color-developing pixel is recorded in the first color, the temperature of the heating element is set to the temperature for developing the first color. When the first energizing pulse, the second energizing pulse, or the third energizing pulse to be controlled is selected and the color-developing pixel is recorded in the second color, the temperature of the heating element is set to the second color. The second passage for controlling the temperature at which the Pulse, the third energizing pulse is selected, and the thermal recording means is driven by the drive pulse signal that makes the selected pulse effective, and the image is heated and recorded on the recording medium. , The drive pulse signal is a third energization pulse train (thermal control) used for correcting the temperature of the heating element so as to make the density of the first color or the second color uniform when the first color or the second color is developed within one pixel recording cycle. Since the energization pulse train) is continuous with the energization pulses of both the first and second colors, for example, when black and red are continuously recorded, the pause time before the energization pulse of red recording can be long. , The initial temperature of the heating element tends to be constant,
It becomes easy to obtain a red record with no color mixture at the maximum density.

Further, since the first and second energizing pulses are composed of a single pulse and the third energizing pulse is composed of a plurality of pulses, the temperature of the heating element during black pixel recording The rising of the rising speed becomes faster, and as a result, it is possible to suppress the red coloration at the recording start end portion of the black image, that is, to eliminate the red blurring of the black image which is likely to occur at the recording scan upstream end portion.

Further, since the first energizing pulse is composed of a single pulse and the second and third energizing pulses are composed of a plurality of pulses, in the black pixel recording, a black recording image It is possible to record black on the recording medium even at the upstream end of the relative movement direction of the recording medium and the thermal head, and it is possible to record a black image without red bleeding. In red pixel recording, there is little color mixing with black and red recording with high color density. Images can be obtained.

Further, the image recording apparatus of the present invention is an image recording apparatus for heating and recording an image on a recording medium that develops different colors by heating at different temperatures, and conveying means for conveying the recording medium. Thermal recording means for heating and recording an image on the recording medium conveyed by the conveying means using a heating element, and images for respectively storing a first color image and a second color image to be recorded on the recording medium. From the storage means, the image synthesizing means for reading out the first color image and the second color image stored in the image storing means and synthesizing them according to a predetermined rule, and the images synthesized by the image synthesizing means. Based on the extraction means for extracting the reference area including the target pixel to be recorded and the color information of the target pixel included in the reference area extracted by the extraction means, the temperature of the heating element of the thermal recording means is determined. Setting means for setting the temperature of the heating element set by the setting means, based on color information of pixels in the reference region extracted by the extracting means, the temperature of the heating element set by the setting means By including a correction unit that corrects the temperature and a control unit that controls the heating element of the thermal recording unit to heat to the temperature corrected by the correction unit,
Separation performance of a plurality of colors is improved, and multicolor recording with suppressed color bleeding is possible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment will be described. FIG. 1 schematically shows the structure of a multicolor thermosensitive recording medium used in this embodiment. That is, the recording medium 1
Is formed by laminating a first recording layer 4, a second recording layer 3, and a protective layer 2 on a base material 5 in this order.

In the recording medium 1 of the present embodiment, the first recording layer 4 is black with the first recording energy and the second recording layer 3 is
Develops red with a second recording energy lower than the first recording energy.

The second recording layer 3 and the first recording layer 4 are
It is composed of a heat-sensitive recording layer containing a leuco dye and a developer as main components. Examples of leuco dyes include triphenylmethane-based, fluorane-based, phenothiazine-based, auramine-based,
Leuco compounds of dyes such as spiropyran-based and indolinophtalide-based dyes are preferable. As the developer, various electron-accepting compounds that cause the leuco dye to develop color upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, are preferable.

The color forming temperature of the first recording layer 4 is preferably equal to or higher than the color forming temperature of the second recording layer 3. Here, the color development temperatures of the first and second recording layers were adjusted so that color development started at about 80 ° C. and reached maximum density at about 95 ° C.

The recording medium 1 shown in FIG. 1 uses a polyethylene terephthalate sheet having a thickness of 188 μm as the base material 5, for example. The thickness of the first recording layer 4 that develops black is about 3 μm, and the thickness of the second recording layer 3 that develops red is about 3 μm. The protective layer 2 is made of an ultraviolet curable resin having a thickness of about 2 μm.

FIG. 2 shows a recording medium 1 used in this embodiment.
On the other hand, the results of measuring the energy-density characteristics when recording is performed using a thermal head having a heating element density of 8 elements / mm using a black measurement filter for both red and black are shown.

As is clear from FIG. 2, energy of about 0.4 mJ / dot gives rise to red color, and about 0.7 mJ / dot.
When the number of dots is more than a dot, black color begins to be generated, and red and black are mixed. When the energy is further increased to about 1.1 mJ / dot or more, black becomes dominant and becomes reddish black.

FIG. 3 shows a waveform of an energizing pulse signal (also called a driving energizing pulse signal or a recording pulse signal) for driving the thermal head for realizing the image recording method of this embodiment. .

The energizing pulse signal shown in FIG. 3 is an active low signal (enable signal) effective for driving the thermal head at a low level. In FIG. 3, there are seven energizing pulses within one pixel recording period, and these energizing pulses are divided into three groups of energizing pulses. The pulse train consisting of the first two energizing pulses is called a first energizing pulse, the pulse train consisting of the third to fourth energizing pulses is a second energizing pulse, and the pulse train consisting of the fifth to seventh energizing pulses is called a third energizing pulse. .

Both the first energizing pulse and the second energizing pulse are made effective in order to heat up to the coloring temperature of black. The second energizing pulse is activated in order to heat up to the red color development temperature.

The energizing pulse used to heat the recording layers 3 and 4 of the recording medium 1 to the respective coloring temperatures of red and black is called a coloring energizing pulse. The third energizing pulse is used for correction to make their density uniform when black or red is colored, and this pulse train is called a heat control energizing pulse. A recording pulse signal for recording one pixel on the recording medium 1 is composed of the color forming energizing pulse and the heat control energizing pulse.

In the present embodiment, the on-time of each energizing pulse (the time when each energizing pulse is at the low level) and the off time (the time when each energizing pulse is at the high level) are the same.
0.2 ms and 0.04 ms. The recording cycle for one pixel is 3 ms.

The characteristic of this recording pulse is that the coloring energization pulse and the heat control energization pulse are continuous with both the black and red recording pulses, and that the coloring development energization pulse and the heat control energization pulse are continuous. is there.

FIG. 4 shows a block diagram of an image recording apparatus for realizing the image recording method of this embodiment. In FIG. 4, the CPU 6 controls the entire apparatus. ROM8 is C
A control program for operating the PU 6 is stored. The RAM 7 is used as a work area for the CPU 6 and temporarily stores various settings.

The image memory 9 stores image information data for recording, and the inside thereof is divided into a red image information storage area 9a and a black image information storage area 9b. The transport control unit 10 controls the entire transport system and drives the drive motor of the transport unit 11 that transports the recording medium 1. The sensor 12 detects the conveyed recording medium 1, and the detection signal is used for conveying control of the recording medium 1 and the like.

The recording controller 13 controls the timing relationship and sequence of the entire recording operation. Reference area extraction unit 14
Is the reference area portion for thermal control from the recorded image data composed of the red image information stored in the red image information storage area 9a and the black image information stored in the black image information storage area 9b. Extract.

The recording energy control unit 15 records the basic recording energy before the thermal control, that is, the target pixel, according to the recording image data of the target pixel in the reference region extracted by the reference region extracting unit 14. At this time, ON / OFF of each color energization pulse within one pixel recording cycle is selected and is output as basic recording data.

The thermal control section 16 uses the recorded image data of each pixel in the reference area extracted by the reference area extraction section 14 and the thermal control data stored in advance in the thermal control data ROM 17 as the pixel of interest. In recording, the basic recording energy of red / black is corrected so that the color of red / black becomes uniform. That is, the ON / OFF of the thermal control energizing pulse within one pixel recording cycle when recording the pixel of interest is selected, and the basic recording data output from the recording energy control unit 15 is corrected based on that. The corrected basic print data, that is, the print data is output to the print drive unit 18.

The recording drive unit 18 uses the recording data output from the heat control unit 16 to generate a thermal head (recording unit).
A drive energization pulse signal for driving and controlling 19 is generated. That is, the drive drive pulse signal for each pixel as shown in FIG. 3 is output from the recording drive unit 18 to the recording unit 19.

The recording section 19 performs the actual recording operation on the recording medium 1 according to the drive energization pulse signal output from the recording drive section 18. The recording operation of the image recording apparatus having such a configuration will be described and described with reference to the flowchart shown in FIG.

When the apparatus is started and the recording operation is started, the CPU 6 first executes the control program stored in the ROM 8. The CPU 6 operates the transport control unit 10 and drives the transport unit 11 to transport the recording medium 1 to the recording position.

Next, the CPU 6 causes the red color recorded image information storage section 9a and the black color recorded image information storage section 9 in the image memory 9.
Each data is read from b (step S1). Next, the recorded image information is synthesized according to a predetermined rule to generate recorded image data, and the recorded image data is temporarily stored in the RAM.
7 (step S2).

Here, the synthesis of the recorded image information in step S2 will be described with reference to FIG. The present embodiment is characterized in that the basic information of the black image and the red image is combined with information to be actually recorded (recorded image data) according to a predetermined rule to generate.

The red recorded image information storage section 9a in the image memory 9 stores pixels (red image) to be recorded in red among the pixels constituting the recorded image, and the black recorded image information storage section 9b records them. Pixels to be recorded in black (black image) among the pixels forming the image are stored. By separately storing the red image and the black image in this manner, there is an advantage that the storage capacity in the image memory 9 can be reduced.

In FIG. 6, the case where the red image is stored as a red image in the red recorded image information storage section 9a corresponding to each pixel forming the recorded image is represented by "1" and is stored as a red image. The case where there is not is represented by "0" (Fig. 6)
Leftmost column). Similarly, corresponding to each pixel forming the recorded image, "1" indicates that the image is stored as a black image in the black recorded image information storage unit 9b, and "1" indicates that the image is not stored as a black image. It is represented by “0” (center column in FIG. 6).

As is apparent from FIG. 6, the recorded image data is red in the pixels set to "1" in both the red recorded image information storage section 9a and the black recorded image information storage section 9b. Pixels set to "0" in the red recorded image information storage 9a and "0" in the black recorded image information storage 9b are not heat-recorded. The recorded image data is black for the pixels for which "0" is stored in the red recorded image information storage unit 9a and "1" is stored in the black recorded image information storage unit 9b. Red recorded image information storage section 9a
The recorded image data is red in the pixels which are set to "1" in the above and "0" in the black recorded image information storage unit 9b (the rightmost column in FIG. 6).

Returning to the explanation of FIG. Next, in step S3, the recording control unit 13 reads the recording image data from the RAM 7 and sends it to the reference area extracting unit 14. The reference area extraction unit 14 extracts a reference area from the sent recording image data and sends it to the recording energy control unit 15.

The recording energy control unit 15 obtains the basic recording energy according to whether the pixel of interest in the reference area is the red recording image or the black recording image (the basic recording energy of the red recording image is E1, the basic recording energy of the black recording image is E1). Energy is E2),
Selection is made to enable (turn on) the first energization pulse train, the second energization pulse train, or both, basic recording data is generated for the pixel of interest, and the basic recording data is sent to the thermal controller 16 (steps S4 to S6). .

In the heat control section 16, the heat control data ROM 1
7 for correcting the basic recording energy of the pixel of interest in accordance with the combination of the pixel of interest and the recording image data of other pixels in the reference region with reference to the thermal control data stored in FIG. Which of the three energizing pulse trains is to be enabled (turned on) is selected, basic recording data corrected based on the selection, that is, recording data is generated and output to the recording driving unit 18 (step S7). .

The recording drive unit 18 uses a thermal head (recording unit) based on the recording data output from the heat control unit 16.
A drive energization pulse signal (enable signal) for driving and controlling 19 and other signals (data transfer clock, latch signal, etc.) necessary for driving the thermal head 19 are generated and sent to the recording unit 19. The thermal head of the recording unit 19 selectively applies to each heating element of the corresponding thermal head in accordance with the red recording pixel / black recording pixel on a pixel-by-pixel basis of the recorded image, and at the same time, black recording energization corresponding to the recording energies EB and EK. A pulse and a red recording energizing pulse are applied, and the recording image recording for one line is completed (step S8 to step S8).
9). Next, returning to step S3, the same operation as described above is performed on all the recorded image data, and the recording operation for one screen is completed.

Next, referring to FIG. 7, step S of FIG.
The procedure from 3 to step S7, that is, the setting and correction of the basic recording energy will be described in more detail. Figure 7
FIG. 7A shows a specific example of a reference area necessary for correcting the basic recording energy, and FIGS. 7B and 7C show patterns of recorded image data of each pixel in the reference area. Here is an example:

The reference area shown in FIG. 7A is a 1 × 4 matrix, which is vertically long in the recording direction (the direction of the arrow in FIG. 7A), and the pixel of interest is "0". "-
The coordinates "1" to "2" are defined. The pixel recorded by the third pixel from the top of this reference area, that is, the pixel of interest, the two pixels above it are referred to in order to remove the effect of heat accumulation, and the pixel at the bottom is Reference is made to preheating.

In the pattern of the recorded image data in the reference area shown in FIG. 7B, the target pixel is a black pixel, the red pixel is recorded immediately before, and the black pixel is recorded before that. The pixel next to is a non-recording pixel. The recording image data of each pixel in the area thus extracted is sent to the recording energy control unit 15.

In the recording energy control unit 15, in this case,
Since the pixel of interest is black recorded image information, the basic recording energy E
E2 (corresponding to the case where all of the first energization pulse train + the second energization pulse train is turned on) is set in o. Also,
If the pixel of interest is red recording image information, the basic recording energy E
E1 (corresponding to the case where only the second energizing pulse train is turned on) is set to o.

In the relationship between the recording energy and the coloring density shown in FIG. 2, the basic recording energy is the energy corresponding to the coloring start recording energy, that is, the basic recording energy of red recording is 0.4 mJ / dot (energization time 0.4 m
s), the basic recording energy of black recording was set to 0.8 mJ / dot (energization time 0.8 ms).

The set basic recording energy data (basic recording data) and the cut-out reference area data are sent to the heat control section 16 and are corrected according to the heat history (heat storage etc.) of the heating element of the thermal head. .

In the example shown in FIG. 7B, the heating element of the thermal head corresponding to the pixel of interest has been driven and generated heat twice consecutively, so that the heating element has a higher temperature than in the normal state. It is expected that the recording density is lower than the basic recording energy, and a predetermined black color density can be obtained. Therefore, by using the heat control data stored in the heat control data ROM 17 and the recorded image data in the reference area, the correction amount due to the accumulated heat due to the continuous heat generation is obtained, and the third energization pulse train is effective corresponding to the correction amount. Corrected basic print data to be turned on (that is, print data is generated).

As described above, the recording data corresponds to the actual recording energies EK and ER of the black recording and the red recording, respectively.
Energization pulse train (first energization pulse train + second energization pulse train) corresponding to the basic recording energy of black recording, or
This is for designating an energization pulse train (second energization pulse train) corresponding to the basic recording energy of red recording and a third energization pulse train for correcting the basic recording energy.

The correction of the basic recording data is not limited to the case where the target pixel is black or red recording information. Figure 7
The pixel of interest in (c) is non-recorded information. The recording medium 1 used in the present embodiment develops black at the first recording energy and red at the smaller second recording energy. If the red recording layer is required to have the same heat resistance as conventional thermal recording,
Black color requires more recording energy than conventional thermal recording. Therefore, if there is data to be recorded in the next (future) pixel even if the pixel of interest is unrecorded information as shown in FIG. To preheat so that the color development temperature will be smooth during real black recording.

In this embodiment, the drive energizing pulse signal of the thermal head 19 is divided into three groups within one pixel recording cycle, the first energizing pulse train + the second energizing pulse train is colored black, the second energizing pulse train is colored red, and the second energizing pulse train is colored red. The three energizing pulse trains are assigned for thermal control, but their order has important meaning. The reason will be described with reference to FIG.

FIG. 8A shows the case where the drive energizing pulse signals are generated in the order of energizing pulse trains in this embodiment.
(B) shows a case where the recording energizing pulse is generated by allocating the energizing pulse train in the reverse order of the energizing pulse train in this embodiment. That is, in FIG. 8A, the first energization pulse train P1
+ The second energizing pulse train P2 is a black coloring energizing pulse, the second
The energizing pulse train P2 is a red colored energizing pulse, and the third energizing pulse train P3 is a heat control pulse. In FIG. 8B, the first energizing pulse train is the thermal control pulse train (P3 in FIG. 8A).
The second energizing pulse train, the second energizing pulse train is the red energizing pulse (corresponding to P2 in FIG. 8A), the second energizing pulse train + the third energizing pulse train.
The energizing pulse train is a black colored energizing pulse (P in FIG. 8A).
1 and P2).

In the case of the order of this embodiment, when the recording images of black, red and black are continuously recorded, a relatively long pause time I1 occurs before the recording energizing pulse train of red recording. However, in the reverse order of this embodiment, there is no pause time like I1 before the recording energization pulse train for red recording, and there is an interruption time I2 before the recording energization pulse for black recording.

As shown in FIG. 2, the recording medium 1 used in the present embodiment has a mixed color area of red and black between the color development of red color and the color development of black color. If this area is not used as much as possible, there is no color mixture. It is important to get a red image. Generally, in a binary recording image such as characters, recording is performed at the maximum density of the recording layer or a density close to the maximum density. For that purpose, it is sufficient that the temperature of the recording layer does not fall below the temperature giving the maximum density due to the recording energy giving the maximum density, and fluctuations may occur at temperatures above that.

In red recording of two-color recording, there is no saturation region in the maximum density as shown in FIG. 2, so it is necessary to strictly control the temperature of the recording layer. For this purpose, it is easier to keep the temperature of the red recording layer constant when the recording energy for red recording is applied, if the temperature of the heating element is constant before energization for red recording.

As shown in FIG. 2, black recording with a large recording energy has a large heat storage ratio, and has a great influence on the color development of the recording pixel next. Therefore, in the case of continuously recording black and red, as shown in FIG. 8A, when the pause time I1 before the recording energizing pulse train for red recording is longer, the initial temperature of the heating element is more likely to be constant. As compared with the case where there is no long pause time as in (b), it becomes easier to obtain red recording with no color mixture at maximum density.

Further, since high recording energy is required at the time of black recording as compared with that at the time of red recording, in a reverse order as shown in FIG. 8B, a long pause time I2 is provided between the red and black recording energizing pulses. Occurs, and the heating element is cooled, so that the rate of saving the applied energy is reduced. The fact that the thermal head can be driven with smaller recording energy enables the life of the thermal head to be extended.

FIG. 9 shows a specific example of image recording by the image recording apparatus of this embodiment. Here, it is assumed that some trouble is detected and a black character string is recorded on the recording medium 1 and a red invalid pattern that invalidates the character string is simultaneously recorded.

The character string "AB" shown in FIG.
"CD" and "12345" are recorded in black. If it is normal, only this printing is performed. This black image information is stored in the black image information storage area 9b of the image memory 9 of the device configuration shown in FIG.
Is stored in

FIG. 9B shows an invalid pattern recorded in red. This red image information is stored in the red image information storage area 9a of the image memory 9 of the device configuration shown in FIG.

A line type thermal head 18 having a width corresponding to the width of the recording medium 1 is used for recording, and recording is performed in line units from left to right. As described with reference to FIG.
The recorded image data is read from the same address of the red image information storage area 9a and the black image information storage area 9b, and the recorded information is combined according to the rule described with reference to FIG. That is, when the red image and the black image are the record information, the red image is prioritized and is combined as the red record information. The operation of combining recording information and simultaneous red / black recording is the same as described above.

The recorded image generated according to the composition rule is recorded on the recording medium 1 as shown in FIG. 9C. FIG.
As is clear from (c), the red invalid pattern having a high priority is preferentially recorded.

As described above, according to the first embodiment, the red recording image information storage unit 9 in the image memory 9 is used.
a and black, each data is read from the recorded image information storage unit 9b, the recorded image information is synthesized according to a predetermined rule to generate the recorded image data, and the reference area extraction unit 14 extracts the recorded image data. Based on the extracted reference area, the recording energy control unit 15 obtains the basic recording energy according to whether the pixel of interest in the reference area is the red recording image or the black recording image, and makes it correspond to the basic recording energy. Basic recording data is generated for the pixel of interest by selecting whether the first energization pulse train and the second energization pulse train of the drive energization pulse signal are valid (ON) or the second energization pulse train is valid (ON). Further, the thermal control unit 16 refers to the thermal control data stored in the thermal control data ROM 17 to refer to the target pixel and other pixels in the reference area. Third to the combination of recorded image data to determine the presence or absence of impact and preheating of the heat storage of the original to the heating element, to correct the basic recording energy of the pixel of interest
It is selected which one of the energizing pulse trains is to be made effective (ON), basic recording data corrected based on the selection, that is, recording data is generated and output to the recording driving unit 18, and the recording driving unit 18 In 18, a drive energization pulse signal for driving and controlling the thermal head (recording unit) 19 is generated based on the recording data, and the thermal head (recording unit) is generated.
By driving 19 to perform simultaneous printing of red and black, the separation performance of a plurality of colors is improved, and multicolor recording in which color bleeding is suppressed becomes possible.

The drive energizing pulse signal (recording pulse signal) for driving the thermal head (recording unit) 19 created based on the recording data is the first energizing pulse and the second energizing pulse within one pixel recording cycle. It is composed of three groups of pulse trains such as energizing pulse and third energizing pulse. When recording black,
By enabling the first energization pulse and the second energization pulse, and enabling the second energization pulse when recording red,
Red or black can be selectively recorded within one pixel recording cycle.

In the drive energizing pulse signal, the third energizing pulse train (heat control energizing pulse train) used for correction for equalizing the densities of black or red during one pixel recording period is black or red. Since any of the color energizing pulses are continuous, a long pause time can be taken before the recording energizing pulse for red recording when continuously recording black and red, so that the initial temperature of the heating element of the thermal head 19 is constant. And it is easy to obtain a red record with no color mixture at the maximum density.

When the red pixel and the black pixel are recorded information at the same position, the red pixel recording information is preferentially recorded to improve the visibility of a red image having a low density.

Next, a second embodiment will be described with reference to the drawings. FIG. 10 shows a waveform of an energizing pulse signal (also referred to as a driving energizing pulse signal or a recording pulse signal) for driving the thermal head for realizing the image recording method of the present embodiment.

The energizing pulse signal shown in FIG. 10 is an active-low signal (enable signal) effective for driving the thermal head at a low level. FIG.
In one pixel recording period, there are five energizing pulses, the first energizing pulse is the first energizing pulse, the second energizing pulse is the second energizing pulse, and the third to fifth energizing pulses are the third energizing pulses. It is called an energizing pulse.

In this embodiment, the first and second energizing pulses are one pulse, and the third energizing pulse is a pulse train consisting of three energizing pulses. Both the first energizing pulse and the second energizing pulse are enabled in order to heat up to the color development temperature of black. The second energizing pulse is activated in order to heat up to the red color development temperature.

The energizing pulse train used to heat the recording layer of the recording medium 1 to the respective coloring temperatures of red and black is called a coloring energizing pulse. The third energizing pulse is used for correction to make their density uniform when black or red is colored, and this pulse train is called a heat control energizing pulse. A recording pulse signal for recording one pixel on the recording medium 1 is composed of the color forming energizing pulse and the heat control energizing pulse.

In the present embodiment, the ON time / OFF time of the first energizing pulse is, for example, 0.4 ms / 0.04 ms,
The on time / off time of the second energizing pulse is, for example, 0.
35 ms / 0.04 ms, each ON time / OFF time of the energizing pulse of the third energizing pulse is, for example, 0.2
ms and 0.04 ms. Recording period for 1 pixel is 3 ms
It is.

Similar to the case of the first embodiment, this recording pulse is characterized in that the recording energizing pulse and the thermal control energizing pulse are continuous in both the black and red recording pulses, and the coloring energizing pulse and the thermal control pulse are continuous. The energizing pulse and the pulse are continuous.

The configuration and operation of the image recording apparatus in this embodiment are the same as those in the first embodiment. Next, the advantages of the recording method according to the present embodiment will be described with reference to FIGS.
This will be described with reference to FIG. Using the recording medium 1 of FIG. 1 and the image recording apparatus of FIG. 4, under the following recording pulse conditions,
The pattern shown in FIG. 9 was recorded.

The basic recording energy of red recording is about 0.35
mJ / dot (energization time 0.35 ms), the basic recording energy for black recording is 0.75 mJ / dot (energization time 0.
75 ms). The recording operation is similar to that described with reference to FIG.

FIG. 11 shows FIG. 3 described in the first embodiment.
Of the temperature change of the heating element of the thermal head when recording one black pixel by the recording method using the recording pulse signal as shown in FIG. 10 and the recording method using the recording pulse signal as shown in FIG. The situation is schematically shown.

The recording pulse signal of this embodiment compared in FIG. 11 is the first one of the recording pulse signals shown in FIG.
The recording pulse signal of the first embodiment is composed of the energization pulse + second energization pulse + leading pulse of the third energization pulse train. The recording pulse signal of the first embodiment is the first energization pulse train + second energization of the recording pulse signals shown in FIG. It is composed of two pulses from the beginning of the pulse train + third energizing pulse train.

The temperature of the heating element of the thermal head 19 driven by the recording method of the first embodiment rises in a sawtooth shape as shown in FIG. With respect to the temperature change of the heating element driven by the recording method of the present embodiment, the rise of temperature rises faster than in the case of the first embodiment. While the heating element is being driven to record one pixel, the heating element and the recording medium 1 move relatively. Therefore, the relative movement direction of the portion of the recording medium 1 (one pixel forming portion) heated by the heating element,
Heating overlaps in the central part and heating time becomes long, but heating time becomes short in both ends. In particular, the temperature of the heating element is low, because the heating time is short at the upstream end portion in the relative movement direction, which comes into contact when the temperature of the heating element starts to rise.

FIG. 12 is a schematic view of a part of the horizontal line of the recorded character when the character of black recording is recorded by scanning the thermal head 19 from left to right of FIG. 12 (direction of the arrow in FIG. 12). 12A shows the case of recording by the recording method of the present embodiment, and FIG. 12B shows the case of recording by the recording method of the first embodiment.

In the case of the recording method of the present embodiment, FIG.
Since the temperature of the heating element rises well as shown in Fig. 12, black color can be developed on the recording medium even at the upstream end in the relative movement direction of the recording medium and the thermal head, and black recording can be performed over the entire energization time (Fig. 12 ( See a)). On the other hand, in the recording by the recording method of the first embodiment, as shown in FIG. 11, since the temperature of the heating element rises relatively slowly, sufficient heat for black color development at the upstream end is not given, and Red that develops at a low temperature develops (see FIG. 12B).

As described above, according to the second embodiment, by making the first energizing pulse within the one pixel recording cycle of the driving energizing pulse signal of the thermal head 19 a monopulse, the driving energizing pulse signal is obtained. When the thermal head 19 is driven by, the temperature rise of the heating element during the black pixel recording rises faster, and as a result, the red coloration at the recording start end portion of the black image is suppressed, that is, it easily occurs at the recording scan upstream end portion. It is possible to eliminate red blur of a black image.

Next, a third embodiment will be described with reference to the drawings. FIG. 13 shows a waveform of an energization pulse signal (also referred to as a driving energization pulse signal or a recording pulse signal) for driving the thermal head for realizing the image recording method of the present embodiment.

The energizing pulse signal shown in FIG. 13 is an active low signal (enable signal) which is effective for driving the thermal head at a low level. FIG.
In 1 pixel recording cycle, there are 6 energizing pulses, the first energizing pulse is the first energizing pulse, the second to the third energizing pulses are the second energizing pulses, and the fourth to the sixth energizing pulses. The pulse is called a third energizing pulse. In the present embodiment, the first energizing pulse is one pulse, the second energizing pulse is a pulse train consisting of two energizing pulses, and the third energizing pulse is a pulse train consisting of three energizing pulses.

Both the first energizing pulse and the second energizing pulse are enabled (turned on) in order to heat up to the coloring temperature of black. The second energizing pulse is enabled (ON) in order to heat up to the red color development temperature.

The energizing pulse train used to heat the recording layer of the recording medium to the respective coloring temperatures of red and black is referred to as a coloring energizing pulse. The third energizing pulse is used for correction to make their densities uniform when black or red is colored. This pulse train is called a heat control energizing pulse. A recording pulse is composed of the color-forming energizing pulse and the thermal control energizing pulse. In this embodiment, the on / off time of the first energizing pulse is 0.4.
ms / 0.04 ms, the on-time / off-time of the energizing pulses of the second energizing pulse and the third energizing pulse are the same and are 0.2 ms and 0.04 ms, respectively. The recording cycle for one pixel is 3 ms.

Similar to the first embodiment, this recording pulse is characterized in that both the recording pulse for black and the recording pulse for red are continuous with the coloring energizing pulse and the heat control energizing pulse, and the coloring energizing pulse and the heat control energizing pulse are also present. And are in sequence.

The configuration and operation of the image recording apparatus in this embodiment are the same as those in the first embodiment. Next, the advantages of the recording method in this embodiment will be described with reference to FIGS. 14, 15 and 16.

FIG. 14 shows how the temperature of each heating element changes when the heating element of the thermal head is driven to record each of the black pixel and the red pixel by the recording pulse signal as shown in FIG. Is schematically shown.

The recording pulse signal for recording a black pixel is shown in FIG.
Of the recording pulse signal shown in FIG. 3, the first energizing pulse + the second energizing pulse + the leading pulse of the third energizing pulse train. The recording pulse signal for recording the red pixel is shown in FIG.
In the recording pulse signal shown in FIG. 3, it is composed of the first energization pulse + the second energization pulse of the third energization pulse train.

Using the recording medium 1 of FIG. 1 and the image recording apparatus of FIG. 4, simultaneous recording of two colors of red and black was performed. Also,
As recording pulse conditions, the basic recording energy for red recording was set to about 0.4 mJ / dot (energization time 0.4 ms), and the basic recording energy for black recording was set to 0.8 mJ / dot (energization time 0.8 ms).

When the thermal head is driven by the recording method of the present embodiment, the rise of the temperature of the heating element at the time of black pixel recording becomes as steep as in the second embodiment shown in FIG. This rapid rise of the temperature of the heating element can obtain the same advantages as the black image recording in the second embodiment in this embodiment. That is, in the black image recording of this embodiment,
The black recording of the recording medium was possible even at the upstream end in the relative movement direction of the recording medium and the thermal head, and the black image recording without red bleeding was possible. The recording state at this time is the same as that described in the second embodiment with reference to FIG.

The temperature rise of the heating element during red pixel recording is gentler than that during black pixel recording.
The advantages of red pixel recording according to this embodiment will be described with reference to FIGS.

FIG. 15 schematically shows how the temperature of the heating element of the thermal head changes when recording one pixel of red in the recording method of the second embodiment and the recording method of the present embodiment.

The recording pulse signal of the present embodiment compared in FIG. 15 is the second one of the recording pulse signals shown in FIG.
The recording pulse signal of the second embodiment is composed of the energizing pulse + the first two pulses of the third energizing pulse train. The recording pulse signal of the second embodiment is the second energizing pulse (energizing time: 0. 35 ms) + two pulses (energization time; 0.2 ms) from the head of the third energization pulse train.

FIG. 16 schematically shows the color development state in the red recording layer of the recording medium at the time of recording red pixels, with respect to the recording layer cross section (upper part) and the red recording layer surface (lower part).
6A shows the case of FIG. 1 when recording is performed by the recording method of the present embodiment.
6 (b) shows the case of recording by the recording method of the second embodiment.

16A and 16B show the temperature distribution in the cross section of the recording medium due to the heat applied from the heating element. The maximum recording energy that can be applied to the heating element for red color development is the energy at which the temperature of the black recording layer does not reach the black color development temperature and is maximum, as shown in FIG.
(B) In each of the upper diagrams, the black color development temperature range reaches near the boundary between the red recording layer and the black recording layer.

As shown in FIG. 14, the temperature of the heating element driven by the recording method of the present embodiment rises relatively slowly in a sawtooth shape. On the other hand, the temperature change of the heating element driven by the recording method of the second embodiment rises faster than in the present embodiment. The steeper the temperature change with respect to the heat transfer rate, the larger the temperature difference in the recording layer. Therefore, the gradual temperature rise in the recording method of the present embodiment causes a smaller temperature difference between the cross-sectional direction and the plane direction of the recording layer of the recording medium, as compared with the case where the temperature rises sharply. As a result, in the red recording of the present embodiment, FIG.
As shown in FIG. 16, immediately before the black color development temperature region reaches the black recording layer, the black color development temperature region is relatively widened to an area corresponding to the size of the heating element, and corresponds to the heating element area as shown in the lower part of FIG. A large color is obtained.

On the other hand, when the temperature of the heating element rises quickly, the red coloring temperature range is greater than the heating element size even when the black coloring temperature range reaches the black recording layer as shown in the upper part of FIG. 16 (b). small. Therefore, the colored portion is smaller than that of the present embodiment. Image density is the unit pixel area
The higher the ratio of the colored portion and the higher the density of the colored portion, the higher the value.

Comparing two-color simultaneous recording images recorded by the recording method of this embodiment and the recording method of the second embodiment, the red recording image density is higher in the recording method of this embodiment. The concentration was obtained.

As described above, according to the third embodiment, the first energizing pulse within the one pixel recording period of the driving energizing pulse signal of the thermal head 19 is a monopulse, and the second energizing pulse is a multipulse. (For example, two pulses), when the thermal head 19 is driven by the drive energization pulse signal, the temperature rise of the heating element during red pixel recording rises when the temperature of the heating element rises during black pixel recording. The temperature rise of the heating element at the time of red pixel recording becomes gentle compared to the case where the second energizing pulse is a mono pulse, and as a result, the red color is increased with respect to the unit pixel area. The proportion of the color-developed portion becomes large, and a red recorded image with high density can be obtained. Therefore, according to the third embodiment, in the black pixel recording, black color can be developed on the recording medium even at the upstream end in the relative movement direction of the recording medium of the black recording image and the thermal head, and black image recording without red blur can be performed. As a result, it is possible to obtain a red-recorded image with little color mixing with black and high color density in red pixel recording.

[0103]

As described above, according to the present invention,
An image recording method and an image recording apparatus capable of suppressing color bleeding and performing multi-color color recording with good separation performance of a plurality of colors on a multi-color thermosensitive recording medium whose coloring state changes depending on heating temperature can be provided. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a layer structure of a recording medium according to a first embodiment of the invention.

FIG. 2 is a diagram showing the coloring characteristics of a recording medium by a thermal head.

FIG. 3 is a waveform diagram of a drive energization pulse signal that drives a thermal head.

FIG. 4 is a block diagram showing a configuration of an image recording apparatus for realizing the image recording method according to the first embodiment.

FIG. 5 is a control flowchart of the image recording method according to the first embodiment.

FIG. 6 is a diagram for explaining composition of recorded image information.

FIG. 7 is a diagram for explaining setting of basic recording energy and correction thereof.

FIG. 8 is a diagram for explaining characteristics of a drive energization pulse signal according to the first embodiment.

FIG. 9 is a diagram for explaining a specific example of image recording by the image recording apparatus according to the first embodiment.

FIG. 10 is a waveform diagram of a drive energization pulse signal for driving the thermal head for realizing the image recording method according to the second embodiment of the present invention.

FIG. 11 is a diagram schematically showing how the temperature of a heating element of a thermal head changes in order to explain the features of the image recording method according to the second embodiment.

FIG. 12 is a diagram for explaining the characteristics of the image recording method according to the second embodiment.

FIG. 13 is a waveform diagram of a drive energization pulse signal for driving a thermal head for realizing the image recording method according to the third embodiment of the present invention.

FIG. 14 is a diagram for explaining the features of the image recording method in the third embodiment, and schematically shows the temperature change of the heating element of the thermal head during black pixel recording and red pixel recording. .

FIG. 15 is a diagram for explaining the characteristics of the image recording method according to the third embodiment, in which one pixel of red is recorded by the recording method of the second embodiment and the recording method of the third embodiment. 3 schematically shows how the temperature of the heating element of the thermal head changes.

FIG. 16 is a diagram for explaining the characteristics of the image recording method in the third embodiment, and schematically shows the color-developed state in the red recording layer of the recording medium.

[Explanation of symbols]

1 ... Recording medium, 3 ... Second recording layer (red recording layer), 4 ...
First recording device (black recording layer), 9a ... Red image information storage area, 9b ... Black image information storage area, 14 ... Reference area extraction section, 16 ... Thermal control section, 18 ... Recording drive section, 19 ... Recording section .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Ito 70 Yanagimachi, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Yanagimachi Factory

Claims (10)

[Claims] Claim: What is claimed is:
Image is formed by driving the thermal recording unit on a recording medium that develops a second color different from the first color by being heated at a second temperature lower than the first temperature. Is an image recording method for recording by heating, wherein when recording the image of the first color on the recording medium, a first period within a one-pixel recording cycle, and a second period subsequent to the first period. In each of the above, when the thermal recording means is driven to record the image of the second color, the thermal recording means is driven in the second period within the one pixel recording cycle to display the image on the recording medium. An image recording method characterized by heating and recording. 2. An image recording method for thermally recording an image on a recording medium, which develops different colors by heating at different temperatures, by using a thermal recording means, wherein the drive pulse signal for driving the thermal recording means is used. A one-pixel recording cycle for recording each color-developing pixel of an image is a color-developing pulse for controlling each heating element of the thermal recording unit to a temperature at which each color of the recording medium is colored, and the heating element continuous to the coloring pulse. And a thermal control pulse for correcting control of the temperature of the heating element, wherein the temperature of the heating element is selected to be a coloring temperature corresponding to the color of the coloring pixel and the thermal control pulse is enabled. An image recording method, wherein the thermal recording means is driven by a drive pulse signal to heat-record the image on the recording medium. 3. An image recording method for thermally recording an image on a recording medium that develops different colors by heating at different temperatures, the image recording method comprising the step of driving pulse signals for driving the thermal recording means. A one-pixel recording cycle for recording each color-developing pixel of the image is a first continuous cycle for controlling each heating element of the thermal recording unit to a temperature at which each color of the recording medium corresponding to the color of the color-developing pixel is colored. The first energizing pulse, which is composed of second and third energizing pulses, controls the temperature of the heating element to a temperature for developing the first color when the color-developing pixel is recorded in the first color. When selecting the second energizing pulse or the third energizing pulse and recording the color-developing pixel in the second color, the temperature of the heating element is controlled to a temperature for developing the second color. The second energizing pulse, the third energizing pulse Select a scan, image recording method, characterized in that the said heat recording means drives the selected pulse in the drive pulse signal to be effective to heat recording the image to the recording medium. 4. An image recording method for thermally recording an image on a recording medium which develops different colors by heating at different temperatures, wherein the image is heat-recorded by the thermal recording means. The one-pixel recording cycle for recording each color-developing pixel of the image is a series of first and second energizing pulses for controlling the temperature at which each heating element of the thermal recording means develops each color of the recording medium, and A third energizing pulse for correction control of the temperature of the heating element, which is continuous with the second energizing pulse,
When recording the color-developing pixels in the first color, the first energizing pulse, the second energizing pulse, and the third energizing pulse for controlling the temperature of the heating element to a temperature at which the color is developed in the first color. When the energizing pulse is selected and the color-developing pixel is recorded in the second color, the second energizing pulse and the third energizing pulse for controlling the temperature of the heating element to a temperature for developing the second color. An image recording method, wherein a pulse is selected, and the thermal recording unit is driven by the drive pulse signal that makes the selected pulse effective, and the image is thermally recorded on the recording medium. 5. The third to fifth energizing pulses are composed of a single pulse, and the third energizing pulse is composed of a plurality of pulses.
The image recording method described in the above. 6. The method according to claim 3, wherein the first energizing pulse is composed of a single pulse, and the second and third energizing pulses are composed of a plurality of pulses.
The image recording method described in the above. 7. The recording medium is configured by laminating a first recording layer that emits a first color and a second recording layer that emits a second color in this order toward the heating surface. When recording the color-developing pixel in the first color, the selected first,
When the thermal recording means is driven by the drive pulse signal that enables the second and third energizing pulses to perform thermal recording on the first recording layer and the color-developing pixel is recorded in the second color, 5. The thermal recording means is driven by the drive pulse signal for validating the selected second and third energizing pulses to perform thermal recording on the second recording layer. Image recording method described. 8. The temperature of the heating element corresponds to the second color when the recording positions of the pixels that develop the first color and the pixels that develop the second color of the image to be recorded are the same. The second energizing pulse for controlling the color development temperature of the recording medium,
A pixel of the second color is selected on the recording medium by selecting the third energizing pulse and driving the thermal recording means with the drive pulse signal that enables the selected second and third energizing pulses. The image recording method according to claim 3, wherein the image is recorded by heating. 9. An image recording apparatus for heating and recording an image on a recording medium that develops different colors by heating at different temperatures, the conveying means conveying the recording medium, and the conveying means conveyed by the conveying means. Thermal recording means for heating and recording an image on a recording medium by using a heating element, image storage means for respectively storing a first color image and a second color image to be recorded on the recording medium, and this image storage means The first color image and the second color image stored in
Image synthesizing means for reading out the respective color images and synthesizing them according to a predetermined rule, extracting means for extracting a reference area including a target pixel to be recorded from the image synthesized by the image synthesizing means, and this extracting means Setting means for setting the temperature of the heating element of the thermal recording means based on the color information of the target pixel included in the extracted reference area, and the temperature of the heating element set by the setting means Based on the color information of the pixels in the reference area extracted in
A correction unit for correcting the temperature of the heating element set by the setting unit; and a control unit for controlling the heating element of the thermal recording unit to heat it to the temperature corrected by the correction unit. Image recording device. 10. An image recording apparatus for heating and recording an image on a recording medium that develops different colors by heating at different temperatures, the conveying means conveying the recording medium, and the conveying means conveyed by the conveying means. Thermal recording means for heating and recording an image on a recording medium by using a heating element, image storage means for respectively storing a first color image and a second color image to be recorded on the recording medium, and this image storage means The first color image and the second color image stored in
Image synthesizing means for reading out the respective color images and synthesizing them according to a predetermined rule, extracting means for extracting a reference area including a target pixel to be recorded from the image synthesized by the image synthesizing means, and this extracting means The setting means for setting the temperature of the heating element of the thermal recording means based on the color information of the target pixel included in the extracted reference area, and the temperature of the heating element set by this setting means are extracted by the extraction means. Based on the color information of the pixels in the reference area extracted by means, the effect of heat accumulation of the heating element and the presence or absence of preheating are determined, and the temperature of the heating element set by the setting means is set to the target pixel. Correction means for correcting the color development temperature of the recording medium corresponding to the color information of 1., and control means for controlling the heating element of the thermal recording means to heat to the temperature corrected by the correction means. Special The image recording apparatus according to.