JPH0516399A - Method and device for recording image - Google Patents

Abstract

PURPOSE:To provide a method and a device for recording an image wherein influence of irregular density, which occurs at recording by superposing a plurality of images, is reduced as much as possible. CONSTITUTION:Image data of colors Y, M, C stored in frame memories 34 are inputted to a correction circuit 35. By the correction circuit 35, an influence on an image data of a color to be recorded is corrected in the case that the image data of the color to be recorded and an image which has been already recorded are superposed. Recording energy corresponding to the corrected data is outputted to a line buffer 42 by corresponding LUTs 36. Based on this recording energy, a thermal head 46 heats and an image of a color corresponding to this heating is formed on a thermal recording material 12. Images of the three colors Y, M, C are recorded in sequence on the thermal recording material 12. Thus, an image having less change in density at a superposed part of images can be formed.

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 apparatus, and more particularly to an image recording method and apparatus for recording an image on a thermosensitive recording material.

[0002]

2. Description of the Related Art At present, there is a heat-sensitive recording method as a method of recording an image on a recording sheet using a heating element. In this heat-sensitive recording method, a heat-sensitive recording material in which a color former and a developer are applied to a support such as paper or synthetic paper is used, and the heat-sensitive recording material is heat-treated by a thermal head for recording. For example, a thermosensitive recording material in which a plurality of electron-donating dye precursors and an electron-accepting compound coexist is prepared, and different temperatures are applied by utilizing the fact that each electron-donating dye precursor has a different color initiation temperature. Therefore, it has been proposed to obtain images of different hues (Japanese Patent Publication No. 49-69).

In such a recording field, along with the rapid development of the information industry, there is a demand for easily obtaining a color hard copy from a terminal of an information device such as a computer or facsimile.

There is a digital color printer as a printer that meets this demand. In this digital color printer, a color image is separated into Y (yellow), M (magenta), C (cyan), and K (black) color image data for each color component, and the color image is processed based on the image data of each color. An image is recorded on the heat sensitive layer.

There is also a light-sensitive type recording material which records an image by irradiating light beams of different ultraviolet wavelength ranges. The light-sensitive recording material as such a recording material is
A two-component thermosensitive coloring medium in which two components are separated and arranged with a microcapsule containing a photocurable composition (JP-A-52-89915), a vinyl monomer having an acidic group and a photopolymerizable composition. Which contains a layer containing a compound, an isolation layer, and a layer composed of an electron-donating colorless dye (Japanese Patent Laid-Open No. 61-123838), and is provided with a plurality of photosensitive layers that emit different colors, each photosensitive layer having a central wavelength. Those which have (Japanese Patent Laid-Open Nos. 1-224930 and 2-19710) have been proposed. According to this, for example, by irradiating the recording material with a light beam in a different ultraviolet wavelength range according to a recorded image, color development of a hue corresponding to the irradiated light beam area and the light beam wavelength range is suppressed. It
Then, by heating the recording material, the recording material in the region not irradiated with the light beam is colored to form an image.

[0006]

As described above, when an image is recorded on a multicolor thermosensitive recording material by thermal energy,
Recording is performed by sequentially supplying different thermal energies according to the images of three colors of Y, M and C. Here, for example, when an image is recorded on a heat-sensitive recording material in which three color developing layers of Y, M and C are sequentially stacked, if an image is recorded on one heat-sensitive layer, thermal energy is transferred to an adjacent heat-sensitive layer. To be done. For example,
When a Y-color image is being recorded, the heat energy during this recording is conducted to the adjacent heat-sensitive layer, that is, the M-color heat-sensitive layer. Therefore, when recording an M-color image at a portion where the Y-color image and the M-color image overlap, the thermal energy of the M-color heat-sensitive layer slightly changes due to the thermal energy when the Y-color image is recorded. In addition, heat energy for recording an M-color image is further supplied. Therefore, the obtained image density may not be appropriate. Therefore, there is a problem that the color balance of the overlapping portion of the images is not proper.

When a photo-sensitive recording material is used as the recording material, for example, the composition of the medium irradiated with the light beam is changed and the layer having the changed composition serves as a filter for suppressing the transmission of the light beam. May act. When the medium is successively exposed to the light beam, the light intensity of the light beam transmitted through the layer acting as the filter is attenuated. For this reason, in the case of a photo-sensitive recording material having a color density corresponding to direct light beam irradiation, the color density is low. On the other hand, when the color density is suppressed by the light beam irradiation,
Higher color density. As described above, the composition of the layer irradiated with the light beam changes, and the light intensity of the light beam irradiated on the recording layer changes as the recording moves to the lowermost layer. Therefore, the color density changes after development. Therefore, there is a problem that the density of the overlapping portion on the light-sensitive recording material changes, and the image density becomes uneven.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image recording method in which the influence of density unevenness that occurs when recording a plurality of images in a superimposed manner is reduced as much as possible. .

In addition to the above-mentioned object, it is another object of the image recording apparatus to obtain an image recording apparatus capable of properly recording the image density of an overlapping portion of images.

[0010]

To achieve the above object, a first aspect of the present invention provides a plurality of recording materials in which a plurality of color forming layers that develop different colors when recording energy is supplied are laminated. When recording the images of
Is an integer greater than or equal to 1, and when the pixel of the image to be recorded N times overlaps the pixel of the image to be recorded N + 1 times, the pixel of the image to be recorded N times and the pixel N +
It is characterized in that the recording energy of at least one of the pixels of the image on which the first recording is performed is changed.

According to a second aspect of the invention, there is provided the image recording method according to the first aspect, wherein a portion of a portion where the pixel of the image for which the Nth recording is performed and the pixel of the image for which the N + 1th recording is performed overlap each other. If it is predicted that the image density will increase, the pixels of the image to be recorded for the Nth time and the Nth image are recorded.
It is characterized in that the recording energy of at least one of the pixels of the image on which the + 1st recording is performed is lowered.

According to a third aspect of the invention, there is provided the image recording method according to the first aspect, wherein a portion of a portion where the pixel of the image for which the Nth recording is performed and the pixel of the image for which the N + 1th recording is performed overlap each other. When it is predicted that the image density will be low, the pixel of the image to be recorded for the Nth time and the Nth image are recorded.
The feature is that the recording energy of at least one of the pixels of the image on which the + 1st recording is performed is increased.

According to a fourth aspect of the present invention, there is provided an image recording apparatus,
In an image recording apparatus for recording a plurality of images on a recording material in which a plurality of color forming layers, which are colored in different colors when recording energy is supplied, are recorded, an energy supplying means for supplying the recording energy to the recording material. , N is an integer of 1 or more, and when the pixel of the image to be recorded N times and the pixel of the image to be recorded N + 1 times overlap, the N
The control means controls the energy supply means so that the recording energy of at least one of the pixel of the image to be recorded for the first time and the pixel of the image to be recorded for the (N + 1) th time is changed.

[0014]

According to the invention described in claim 1, a plurality of images are superposed and recorded on a recording material in which a plurality of coloring layers which are colored in different colors when recording energy is supplied are laminated. Therefore, the pixels of the image on which the Nth recording is performed and the pixels of the image on which the (N + 1) th recording is performed may overlap, and a density change occurs in that portion. Therefore, in the case where the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times overlap, at least one of the pixel of the image to be recorded N + 1 times and the pixel of the image to be recorded N times Change the recording energy of. That is, the recording energy of the pixel of the image to be recorded N times is changed or N + 1.
The recording energies of the pixels of the image to be recorded for the first time are changed, or the recording energies of both the pixels of the image to be recorded at the Nth time and the pixels of the image to be recorded at the (N + 1) th time are changed. As described above, it is possible to form an image in which the density change is small in the overlapping portion of the images.

According to the second aspect of the invention, it is predicted that the density of the portion where the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times are overlapped on the recording material is high. In this case, the recording energy of at least one of the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times is lowered. As a result, the density of the portion of the recording material where the pixels of the Nth recorded image and the pixels of the N + 1th recorded image overlap becomes low, and an image with little change in density can be formed.

According to the third aspect of the invention, when it is predicted that the image density of the portion where the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times overlap are predicted to be low. Causes the recording energy of at least one of the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times to be high. As a result, the image density of the portion where the pixels of the image of the Nth recording and the pixels of the image of the N + 1th recording overlap on the recording material is high, and an image with a small density change can be formed.

According to the image recording apparatus of the invention described in claim 4, a plurality of images are superposed and recorded on a recording material in which a plurality of color forming layers which emit different colors when recording energy is supplied are laminated. At this time, the recording energy is supplied to the recording material by the energy supply means. Here, when N is an integer of 1 or more, and the pixel of the image to be recorded N times overlaps the pixel of the image to be recorded N + 1 times, the control unit controls the image of the image to be recorded N times. The energy supply unit is controlled so that the recording energy of at least one of the pixel and the pixel of the image on which the (N + 1) th recording is performed changes. Thus, the above-described image recording method can be realized, and an image having a small density change can be formed on the recording material in the overlapping portion of the images in which a plurality of images are overlapped and recorded.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. This embodiment is a digital color printer 10.
The present invention is applied to.

First, a thermal recording material 12 as a recording material used in the embodiment of the present invention will be described.

As shown in FIG. 3, the heat-sensitive recording material 12 used in this embodiment has the first, second and third recording materials on the support 22.
The thermosensitive coloring layers comprising the thermosensitive recording layers 20, 18 and 16 are sequentially laminated. A protective layer 14 is coated on the surface of the third thermosensitive recording layer 16 in order to protect the color developing layer from scratches and the like. Similarly, a back coat layer 24 is applied to the surface of the support 22. The first thermosensitive coloring layer 20 contains an electron-donating dye precursor and an electron-accepting compound as main components. The second heat-sensitive layer 18 contains a diazonium salt compound having a maximum absorption wavelength of 360 ± 20 nm, and a coupler that reacts with the diazonium salt compound to produce a color when heated. The third heat-sensitive layer 16 has a maximum absorption wavelength of 4
It contains a diazonium salt compound having a wavelength of 20 ± 20 nm and a coupler that reacts with the diazonium salt compound under heat to develop a color.

The procedure for recording an image on the heat-sensitive recording material 12 is as follows. First, heat 1 sufficient for recording on the third heat-sensitive recording layer 16 is applied, and the diazonium salt contained in the third heat-sensitive recording layer 16 is added. Color the coupler. Then 420 ± 20 nm
Of light UV1 to irradiate the heat-sensitive recording material 12 to decompose the diazonium salt contained in the third heat-sensitive recording layer 16 and give heat 2 sufficient for the second heat-sensitive recording layer 18 to record,
The coupler and the diazonium salt contained in the heat-sensitive recording layer 18 are developed. At this time, strong thermal energy is applied to the third heat-sensitive recording layer 16, but no color is developed because the diazonium salt has already been decomposed and the color-forming ability has been lost. Then, the heat-sensitive recording material 12 is irradiated with light UV2 of 360 ± 20 nm to decompose the diazonium salt contained in the second heat-sensitive recording layer 18 and generate sufficient heat 3 for recording the first heat-sensitive recording layer 20. Then, the coupler and the diazonium salt contained in the first thermosensitive recording layer 20 are colored. At this time, strong thermal energy is applied to the third thermosensitive recording layer 16 and the second thermosensitive recording layer 18, but no color is developed because the diazonium salt is already decomposed and the color forming ability is lost.

Here, in this embodiment, the first, second and third
The coloring hues of the respective heat-sensitive recording layers are selected so as to be the three primary colors in the subtractive color mixture, cyan, magenta and yellow. That is, each of the first thermosensitive recording layers has a cyan coloring hue of the C layer 20, the second thermosensitive recording layers have a magenta coloring hue of the M layer 18, and the third thermosensitive recording layers have a yellow coloring hue. Which is the Y layer 16. Therefore, full-color image recording can be performed on the heat-sensitive recording material 12 by recording according to the above procedure.

Further, the thermal recording material 12 used in this embodiment.
Is a Y layer 16, an M layer 18, and a C layer 2 as shown in FIG.
0 develops a color with a color density corresponding to different heat energy. That is, the Y layer 16 is colored according to the thermal energy in the thermal energy region Py, and the thermal energy region Pm is generated.
The M layer 18 is colored in accordance with the heat energy in the inside, and the C layer 20 is colored in accordance with the heat energy in the heat energy region Pc.

Next, a digital color printer 10 applicable to the embodiment of the present invention will be described with reference to the schematic structure shown in FIG.

A table 52 of the heat-sensitive recording material 12 is projected from the right side surface of the casing 50 in FIG. The thermosensitive recording material 12 is conveyed to the table 52 in the direction of arrow A in FIG. 2 by inserting the thermosensitive recording material 12 with the recording layer facing upward and inserting the tip of the thermosensitive recording material 12 into the casing 50.

A pair of conveying rollers 54 are arranged on the downstream side of the table 52 so as to sandwich and convey the thermosensitive recording material 12. A plurality of guide plates 56 are sequentially arranged on the downstream side of the transport roller 54 so that the heat-sensitive recording material 12 is guided. Therefore, the thermal recording material 12 is substantially C by the plurality of guide plates 56.
It is conveyed in a letter shape.

The carrying roller 54 is connected to a rotating shaft of a motor (not shown). The motor is connected to the control device 26, and the rotation of the motor in the forward and reverse directions is controlled by the control device 26 according to the insertion or unloading of the thermosensitive recording material 12.

A pair of conveying rollers 58 is arranged between each of the plurality of guide plates 56. These transport rollers 58 are connected by a belt, and this belt is connected to the rotating shaft of a motor 66. The motor 66 is connected to the control device 26, and a signal from the control device 26 causes 1
It is designed to be rotated in the direction (counterclockwise in FIG. 2).

On one side of the conveying path of the heat-sensitive recording material 12, corresponding to the side where the color-forming layer of the heat-sensitive recording material 12 is not formed,
A platen roller 60 is arranged. The platen roller 60 is connected to the rotating shaft of the motor 68 via a drive belt. The motor 68 is rotated in one direction by a signal from the control device 26.

A line-type thermal head 46 as a recording head is arranged on the other side of the conveying path of the thermal recording material 12. A heating element 62 is attached to one end of the thermal head 46, and when an image signal is supplied from the control device 26, heat is generated in accordance with the image signal to heat the thermal recording material 12. . The amount of heat generated by the heating element 62 can be changed depending on the heating time.

The controller 26 also outputs a positioning signal to the thermal head 46.
A positioning signal is output at the time of heat recording of the first dye layer (Y dye layer in this embodiment), and bar-shaped positioning marks are recorded. It should be noted that this positioning mark is recorded after a lapse of a predetermined time from the time when the tip portion of the thermosensitive recording material 12 is detected by the first photoelectric sensor 70. Based on this positioning mark, the recording time for recording the other dye layers (M layer, C layer) is determined.

A pair of conveying rollers 64 are arranged on the downstream side of the platen roller 60 so that the heat-sensitive recording material 12 is nipped by the conveying rollers 64. A second photoelectric sensor 72 is attached between the platen roller 60 and the transport roller 64. This second photoelectric sensor 72
Is connected to the control device 26 so as to detect the positioning mark and output the detected signal.

The two sets of conveying rollers 64 are connected via a drive belt. The transport roller 64 is connected to a rotary shaft of a motor (not shown), and rotates in one direction in response to a signal from the control device 26.

Two light sources 78 for irradiating the surface (coloring layer side) of the thermosensitive recording material 12 with a light beam are provided between the two sets of conveying rollers 64. The light source 78 is turned on and off according to a signal from the control device 26.

The wavelength of the light emitted from the light source 78 is
It can be switched to about 365 nm and 420 nm, and is used for fixing the Y dye layer and the M dye layer of the thermal recording material 12, respectively.

On the downstream side of the conveying roller 64, a conveying path switching means 74 having a cam 76 is provided, and the cam 76 rotates in response to a signal from the control device 26 to convey the thermosensitive recording material 12. The discharge direction is the route (right side in Fig. 2)
Alternatively, the loop direction (upper side in FIG. 2) is switched.

Thermal recording material 12 guided in the discharge direction
Are transported to the vicinity of the transport roller 54. Here, by rotating the conveyance roller 54 in the reverse direction, the heat-sensitive recording material 12 guided and conveyed by the guide plate is nipped and conveyed onto the table 52.

On the other hand, the heat-sensitive recording material 12 guided in the loop direction passes through the hole provided in the guide plate 56, is pinched again by the transport roller 58, and reaches the loop-shaped transport path. That is, in the present embodiment, since the same surface is scanned (heated) three times, the table 52
The thermosensitive recording material 12 inserted from above is guided to the loop-shaped conveyance path by the cam 76, and after the third scanning,
The thermosensitive recording material 12 is taken out to the table 52 with the cam 76 in the ejecting direction.

Next, the control device 26 will be described with reference to FIG. The control device 26 includes a host computer 30.
Are connected.

Image data is stored in the host computer 30 as a digital image signal, and the digital image signal supplied from the host computer 30 is input to the conversion circuit 32.

Here, the handling of the image density data in the conversion circuit 32 of the present embodiment will be described. First,
In the case of subtractive color mixing, it is known that Y, M, and C colors are mixed at a predetermined mixing ratio to produce black. That is, the black (character) data can be converted and output by outputting the black (character) data as the same density for each of Y, M, and C.

Further, in this embodiment, when an image is recorded on the thermosensitive recording material, the maximum density of each color of the image may be lower than the maximum color density of each color forming layer. Further, when recording an image so that it becomes black (character), it is possible to record so that each color forming layer has a higher density than the maximum density of each color of the image. This relationship is: Dmr (i) <Dmk (i) ≦ Dm (i) where i = 1, 2, 3 (corresponding to Y, M, C) Dmr (i): maximum density Dmk (i of image in each color ): It can be expressed as the maximum density of each color after black color separation.

At this time, for example, when the change area of the image density is a linear area, Dr (i) = ki · D (i) + si · Dk (i), where i = 1, 2, 3 (Y , M, C) Dr (i): Density D (i) during recording: Density Dk (i) of each color of input image data: Density ki of each color after black color separation ki <1, si ≦ It can be expressed as 1. Therefore, it is possible to easily convert a plurality of input image data into three colors of Y, M, and C. In this way, in the conversion circuit 32, the input digital image signal is converted into signals for the respective colors of Y, M and C, and then the converted signals of the respective colors of Y, M and C are stored in the corresponding frame memory 34. It is outputting.

Each frame memory 34a, 34b, 34c
An image signal for one image of a color corresponding to each frame memory 34 is stored in the memory. Also, the host computer 3
0 is connected to the controller 40, and the horizontal sync signal and the vertical sync signal from the host computer 30 are input to the controller 40. The horizontal synchronizing signal and the vertical synchronizing signal are output to the conversion circuit 32 and the frame memory 34 for synchronization.

Each frame memory 34a, 34b, 34c
The YMC signal output from, that is, the image density data is input to the correction circuit 35. The image data input to the correction circuit 35 is corrected according to the number of recordings.

YMC signal output from the correction circuit 35,
That is, the print data is converted into a YMC color drive value corresponding to the color density by a look-up table (LUT) 36, and then output to the line buffer 42 via the switch 38 for each line. Here, the switch 38 is connected to the controller 40, and the controller 40
It is connectable so that the recording data of the color at the time of recording is supplied to the line buffer 42 according to the signal from.

This lookup table (LUT) is
The table is different depending on the characteristics of the thermal recording material 12. That is, in the heat-sensitive recording material 12 used in this embodiment, the characteristic of the color density D with respect to the printing energy E according to the image density data is not linear as shown in FIG. As a result, even if recording is performed in order to obtain a desired color density, the color density of the thermosensitive recording material 12 is different and an image having the desired density cannot be obtained. Therefore, the color density D with respect to the printing energy (heat energy) E
Create a table so that the characteristics of are linear. For example, with the printing energy Ea, the thermosensitive recording material 12 has the color density Da. Since the desired color density D at this printing energy Ea is the density Da ', the printing energy E
a'is required. Therefore, in the printing energy Ea, the printing energy E in which the color density D corresponds to the density Da '
Prepare a table for taking out a '. That is, as shown in FIG. 6, a characteristic of the driving value (thermal energy) of the thermal head that can obtain a linear color density according to the image density data is prepared, and this characteristic is used as the LUT. Also,
In the present embodiment, in order to develop different colors, different heat energies are supplied to the heat-sensitive recording material while being shifted by a predetermined heat energy for each color. Therefore, this shifting thermal energy is also taken into account. Note that a separate circuit may be added for this thermal energy shift.

The line buffer 42 includes a controller 4
A vertical sync signal is input from 0, and a signal is output to the thermal head 46 via the driver 44 based on the vertical sync signal, and the thermal head 46 is heated. An image is recorded on the heat-sensitive recording material 12 by this heat.

The controller 40 is connected to the motor 68 via the driver 69 and sends a signal to rotate the platen roller 60. Also, the controller 4
0 is connected to the light source 78 via the driver 79,
A control signal is sent according to the image of the color recorded on the thermosensitive recording material 12. As a result, the light source 78 emits light of 365 nm and 4
The thermal recording material 12 is irradiated by switching to a light beam having a wavelength of 20 nm.

Here, the correction circuit 35 in the present embodiment.
The image data corrected in 1 will be described in detail. First, in the case where Y, M, and C colors are sequentially overlapped and recorded by the conventional recording method, the following formula (1), P (i) = α · D (i) ----- (1) i = 1, 2, 3 (corresponding to Y, M, C) P (i): recording data when recording each color D (i): image data (gradation) α: can be expressed by a constant. According to this equation (1), for example,
When the image data of each color is input with 256 gradations,
The print data (recording data) corresponds to the input data.

Here, in the present embodiment, when recording a plurality of images in an overlapping manner, when recording an image on a specific color layer, the degree of influence of the already recorded image on the image to be recorded from now on. Is calculated, and the image data to be recorded is corrected based on the influence degree, and then the recording is performed. This can be expressed by the following equation 1,

[0052]

[Equation 1] However, when i = 1, 2, 3 j = i−1 A (n): degree of influence of recorded image β: constant (256, same as the number of gradations) P (n) = 0 (unrecorded) , A (n) * {1 / β * P (n)} = 1 and, when j = 0 when the total product Π is calculated, it can be expressed by Π = 1.

The inventor conducted a recording experiment by using the thermal recording material 12 used in this embodiment and converting image data for each thermal recording of each color based on the data shown in Table 1 below. It has been confirmed by experiments that good results were obtained that images with good color balance were obtained.

[0054]

[Table 1] The operation of this embodiment will be described below with reference to the flow chart of the control circuit with reference to FIGS.

First, when the main routine shown in FIG. 7 is executed, in step 102, the input image data (Y, M, C, K, characters) is data (Y, M) corresponding to the color at the time of recording. Coefficients ki and si when converting to M, C)
Is captured.

At step 104, one pixel data D
(I) is taken in and the process proceeds to step 106. Step 1
In 06, Y when recording the input image data,
The data is converted into data for each of the three colors M and C, and stored in the frame memory 34 in step 108. Step 1
In step 10, it is determined whether or not reading of all pixel data has been completed. If not completed, the process returns to step 104, and pixel data for one screen is repeatedly converted. Therefore, in each of the frame memories 34, Y,
Pixel data for one screen of each color of M and C is stored.
When the pixel data conversion for one screen is completed, the process proceeds to step 112, and an image recording subroutine described later is executed. In this subroutine, images are sequentially recorded on the thermosensitive recording material 12. When the recording of the image ends, this main routine ends.

Next, the image recording subroutine will be described with reference to FIG. In this subroutine, when the image data in the frame memory 34 described above is overprinted and recorded, the image data is corrected according to the number of recordings, that is, the color at the time of recording, and the corrected recording data is obtained. The control for recording the image of each color on the thermosensitive recording material 12 is performed based on the image data.

When this subroutine is executed, the routine proceeds to step 150, where the counter value i is set to 1. Also,
The values of the coefficients A (i), α, and β used when correcting the image data are captured. As the counter value i,
1 corresponds to the Y color, 2 corresponds to the M color, and 3 corresponds to the C color at the time of recording. Further, A (i) is a value of the degree of influence according to the number of times the image is recorded, α is a coefficient for normalizing image data (gradation data) into recording data, and β is image data (level). It is a constant determined according to the number of steps of the key data). In step 152, the image data of one pixel is read, and the value of the recording data P (i) is calculated based on the above-mentioned formula 1.

For example, when i = 1, the Y color is recorded, and the Y color is the first recording and is not affected by the recording of other colors. The value of the recording data P (Y) is output without correcting the data as it is. When i = 2, the recording of M color is performed, and the Y color may be already recorded. Therefore, the value of the recording data P (M) based on the above equation (1) is output. In the case of i = 3, the recording is C color, and at least one of the Y color and the M color may be already recorded. Therefore, the value of the recording data P (C) based on the above equation (1) is output.

That is, when recording one line,
There is an overlapping portion of YMC recording. For example, as shown in FIG. 9 (A), combinations of Y, M, C, Y + M, M + C, Y + C, and Y + are available when the three colors are developed with the same density D.
There are M + C types. In Y-color recording, as shown in FIG. 9B, since the recording is the first recording, the value of the recording data P1 is output so that the color density D is obtained.

When recording M colors, it may or may not overlap with Y color recording. If they do not overlap,
Since the recording of the M color is the first recording, the value of the recording data P1 is output so that the color density D is obtained. On the other hand, when the recording of the Y color and the M color overlap, the state of the recording of the Y color is affected during the recording of the M color. Therefore, the value of the recording data P3 is set so that the coloring density becomes the density D. Output (Fig. 9
(See (C)).

At the time of recording the C color, there are cases where it overlaps with at least one of the recording of the Y color and the M color, and there is a case where it does not overlap with any of the colors. If they do not overlap each other, the value of the recording data P1 is output so that the color density D is obtained because the recording of C color is the first recording. On the other hand, when the recording of Y color and the recording of C color overlap, the value of the recording data P2 is output so that the color density is D because the state at the time of recording of the Y color is affected when recording the C color. To be done. When the recording of the M color and the recording of the C color overlap, the state of the recording of the M color is affected during the recording of the C color, and thus the value of the recording data P3 is output so that the coloring density becomes D. . When the recording of the Y color and the M color overlaps with the recording of the C color, the state of the recording of the Y color and the M color is affected when the recording of the C color is performed, so that the recording data P4 is set so that the coloring density becomes D. Is output (Fig. 9 (D))
reference).

When the calculation of the recording data P (i) is completed, the process proceeds to step 154. In step 154, the operation value of the thermal head 46 corresponding to the print data in which the image data is corrected by referring to the LUT is stored in the line buffer 42. In step 156, it is determined whether or not the image recording for one line is completed, and if it is not completed, step 1
It returns to 52 and is repeated until the storage of the image data for one line is completed. Therefore, the line buffer 42 stores the operation value of the thermal head 46 corresponding to the image data for one line. In step 158, image recording for one line is performed according to the operation value stored in the line buffer 42. When the image recording for one line is completed, the process proceeds to step 160, and it is judged whether or not the recording of one screen for one color is completed. If not completed, the process returns to step 152 and the recording of one screen is completed. The recording is repeated until it is done. When recording with the thermal head 46, the controller 40 outputs a control signal to the switch 38 so that the LUT 36 of the color used for recording and the line buffer 42 are electrically connected.

When the recording of one screen for one color is completed, the process proceeds to step 162, and it is judged whether i = 3 or not, so that the image data for all colors (Y, M, C) is obtained. It is determined whether or not the recording of is completed. If the recording has not been completed, the process proceeds to step 164, and it is determined whether or not the recording-completed color is the Y color by determining whether or not i = 1. Step 1 after Y color recording is completed
At 66, ultraviolet light UV1 having a wavelength of 420 nm is irradiated for a predetermined time, and the process proceeds to step 170. By irradiating the UV light UV1 having a wavelength of 420 nm, the area where the Y-color image is not recorded is the thermal energy at the time of the next recording, that is, M,
Color development due to thermal energy during recording of C color is suppressed. After the M color recording is completed, step 168
In step 3, UV light UV2 having a wavelength of 365 nm is irradiated for a predetermined time, and the process proceeds to step 170. By irradiating the UV light UV2 having the wavelength of 365 nm, it is possible to prevent the portion where the M color image is not recorded from being colored by the thermal energy at the time of the next C color recording. In step 170, the counter value i
Is incremented by 1, and the process returns to step 152. When the recording of images for all colors (Y, M, C) is completed, this subroutine is completed.

Therefore, a Y-color image is recorded,
When the recording of the Y-color image is completed, ultraviolet light UV1 having a wavelength of 420 nm is irradiated for a predetermined time so as to prevent the unrecorded portion of the Y-color from being colored, and then the M-color image is recorded.
When the recording of the M-color image is completed, ultraviolet light UV2 having a wavelength of 365 nm is irradiated for a predetermined time so as to prevent the unrecorded portion of the M-color from being colored, and finally the C-color image is recorded.

Here, as described above, when recording M colors, the thermal energy for recording M colors is changed according to the recording state of the Y color image. That is, when the Y-color image and the M-color image overlap, the M-color image data is recorded based on the degree of influence on the M-color when the Y-color image is recorded. On the other hand, in a portion where the above two images do not overlap, recording is performed according to the M color image data. Furthermore, C
At the time of color recording, the thermal energy at the time of recording C color is changed according to the recording state of the Y color image and the M color image. That is, if any one of the Y-color image and the M-color image and the C-color image overlap, based on the degree of influence on the C-color when the Y-color image and the M-color image are recorded. The image data of C color is recorded. On the other hand, in the portion where the C color images do not overlap with any of the colors, recording is performed according to the C color image data.

As described above, in the present embodiment, when the Y, M, and C color images are sequentially recorded on the thermosensitive recording material, the thermal energy at the time of recording is changed when the images overlap each other. It is possible to reduce density unevenness in the overlapping portion where the images of (1) and (2) are recorded in an overlapping manner. Therefore, it is possible to record an image without color unevenness.

In the above-described embodiment, an example in which different colors are formed by applying different heat energy to the thermal recording material 12 using the thermal head 46 has been described, but the present invention is not limited to this. Instead, for example, it can be used when recording is performed so that thermal energy generated by irradiation with a light beam is supplied to a recording material so that different colors are developed. In this case, the same effect as in the above-described embodiment can be obtained by replacing the thermal head 46 of the above-described embodiment with an optical head that emits a light beam and controlling the irradiation energy of the light beam, that is, thermal energy.

Recording materials that emit different colors by irradiating light beams with different wavelengths in the order of image recording,
For example, it can be easily applied to the case of using a recording material that emits each color of YMC by irradiating light beams of different wavelengths λ1, λ2, and λ3. For example, it is assumed that this recording material has the same structure as that shown in FIG. 3 and is provided with coloring layers 16, 18, and 20 for coloring each color of YMC. The recording material is irradiated with a light beam corresponding to each color of YMC to make each color ready for color development, and then color is developed by heat development to form an image. At this time, when the Y-color can be developed by irradiating the light beam of the wavelength λ1, the composition of the coloring medium or the like irradiated with the light beam of the wavelength λ1 in the Y layer 16 changes, and the Y layer 16 having the changed composition. Is the transmission of the light beam, that is, the wavelengths λ2 and λ3 during recording of the M layer 18 and the C layer 20.
May act as a filter that suppresses the transmission of the light beam. Similarly, when the light beam of wavelength λ2 is irradiated to make it possible to develop M color, the composition of the coloring medium or the like irradiated with the light beam of wavelength λ2 in the M layer 18 changes, and the M layer 18 having the changed composition Is the transmission of the light beam, ie
It may act as a filter that suppresses the transmission of the light beam having the wavelength λ3 during recording of the C layer 20. In this case,
Instead of correcting the thermal energy in the above-described embodiment, specific wavelengths (wavelengths λ1, λ2, λ3) corresponding to the color to be developed are used.
By controlling the exposure amount of any one of the light beams according to the irradiation order, the same effect as in the above embodiment can be obtained.

Furthermore, when the above recording material is used for a recording medium such as an optical memory and a plurality of information is recorded at the same location,
Information values can be recorded in correspondence with color or density. Even in this case, since recording can be performed without density unevenness and color unevenness according to the value of the information to be recorded, it is possible to prevent defective recording or defective reproduction of information.

In the above embodiment, the recording material provided with a plurality of coloring layers for coloring different colors was described, but the present invention is not limited to this, and the recording provided with a coloring layer of a single color. It is also applicable to a material and a recording material in which a plurality of coloring layers that develop the same color are laminated. For example, when the present invention is applied to a line drawing device such as a plotter as an apparatus, it is possible to perform recording without density unevenness and color unevenness in an image, that is, an overlapping portion of line images. It is possible to prevent the line from becoming thick. This enables precise drawing.

In the above embodiment, an example in which the correction of the YMC three-color image data according to the number of recordings is calculated is described, but a digital-analog conversion circuit and an amplification circuit are combined. You may comprise with an electric circuit.

Further, in the above-mentioned embodiment, an example in which the conversion for converting a plurality of image data into the data of three colors of YMC is obtained by calculation has been described. However, it is an electrical combination of a digital-analog conversion circuit and an amplifier circuit. It may be configured by a circuit.

In the above embodiment, an example in which digital data is input for each pixel as image data has been described, but the present invention is not limited to the type of data, and the density of an image is directly read. Use a scanner, etc.
The present invention can be applied to analog data output from a scanner or the like.

[0075]

As described above, according to the present invention, when a plurality of images are recorded in an overlapping manner, the pixels of the image to be recorded N times and the pixels of the image to be recorded N + 1 times are overlapped. It is possible to reduce the effect of uneven density that occurs in a part as much as possible, and when developing images of different colors, reduce the effect of uneven color in the overlapping layers of the images due to uneven density in each coloring layer. The effect is that proper color balance can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a control device for a digital color printer according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a schematic configuration of a digital color printer.

FIG. 3 is a cross-sectional view showing a recording material used in an example of the present invention.

FIG. 4 is a diagram showing a relationship between printing energy and color density on a recording material.

FIG. 5 is a diagram showing a relationship between printing energy (image density data) and color density for a specific color of a recording material.

FIG. 6 is a diagram showing a relationship between printing energy (image density data) and a driving value in a specific color of a recording material.

FIG. 7 is a flowchart showing a control main routine according to the embodiment of the present invention.

FIG. 8 is a flowchart showing a subroutine for controlling image recording.

9A is an image diagram showing an overlapping state of recorded images of YMC colors on a thermal recording material, and FIG. 9B is Y.
A diagram showing the relationship between the recording position in the layer and the recording data (recording energy), (C) is a diagram showing the relationship between the recording position in the M layer and the recording data (recording energy), (D)
FIG. 4 is a diagram showing a relationship between a recording position and recording data (recording energy) on the C layer.

[Explanation of symbols]

10 Digital color printer (image recording device) 12 Thermal recording material (recording material) 26 Control device (control means) 32 conversion circuit 35 Correction circuit 46 thermal head (energy supply means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9113-2C B41J 3/20 115 C

Claims (4)

[Claims] 1. When superposing a plurality of images on a recording material in which a plurality of coloring layers that emit different colors by supplying recording energy are stacked, N is an integer of 1 or more, and N When the pixel of the image to be recorded and the pixel of the image to be recorded N + 1 times overlap, the pixel of the image to be recorded N times and the pixel N +
An image recording method, characterized in that the recording energy of at least one of the pixels of the image to be recorded for the first time is changed. 2. The N-th recording is performed when it is predicted that the image density of a portion where the pixel of the N-th recording image and the pixel of the N + 1-th recording image overlap becomes high. 2. The image recording method according to claim 1, wherein the recording energy of at least one of the pixel of the image for which the recording is performed and the pixel of the image for which the N + 1th recording is performed is lowered. 3. The N-th recording is performed when it is predicted that the image density of a portion where the pixel of the N-th recording image and the pixel of the N + 1-th recording image overlap becomes low. 2. The image recording method according to claim 1, wherein the recording energy of at least one of the pixel of the image for which the recording is performed and the pixel of the image for which the N + 1th recording is performed is increased. 4. An image recording apparatus for recording a plurality of images on a recording material in which a plurality of color forming layers, which emit different colors when recording energy is supplied, are superposed and recorded, wherein the recording energy is supplied to the recording material. If the energy supply means for performing the recording and the pixel of the image for which the Nth recording is performed overlap with the pixel of the image for which the Nth recording is performed and N is an integer of 1 or more, the pixel of the image for which the Nth recording is performed. And said N +
An image recording apparatus comprising: a control unit that controls the energy supply unit so that the recording energy of at least one of the pixels of the image on which the first recording is performed changes.