JPH11277796A - Printer using special printing paper coated with photosensitive microcapsules - Google Patents

Abstract

(57) Abstract: To improve the quality of printing by generating irradiation data for controlling a light emitting element so that the input / output characteristics of the printer are made closer to linear. The 8-bit input image data is converted into 9-bit irradiation data in accordance with the color development characteristics and stored in the RAM 53 of the printer. When the irradiation data is supplied to the other input of the comparator 66c via the register 66b, the PWM circuit 66 receives the output of the counter 66a.
Outputs a pulse width-modulated pulse with irradiation data.
Then, based on the pulse width-modulated with the irradiation data, the controller 5 sets the red LED 23R and the green L
The drive current is selectively supplied to the ED 23G and the blue LED 23B by controlling the opening and closing of the electronic switch 67.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a latent image by scanning a special print paper coated with photosensitive microcapsules with a print head having three types of light emitting elements of red, green and blue. The present invention relates to a printer that performs printing by applying a mechanical pressure to the special print paper on which an image is formed and developing the same, and particularly to an improvement in input / output characteristics thereof.

[0002]

2. Description of the Related Art The applicant of the present invention has previously filed Japanese Patent Application No. 9-1.
At 52719, the special print paper coated with the photosensitive microcapsules is scanned by a print head having three types of light-emitting elements of red, green, and blue to form a latent image, and the special print on which the latent image is formed is formed. It discloses in detail the specific configuration and operation and effect of a printer that develops paper by applying mechanical pressure with a print roller. This printer is a device particularly suitable for a handy type printer for a digital camera that stores image data in a storage medium such as a floppy disk. The special printing paper is obtained by uniformly coating photosensitive microcapsules having a diameter of about 4 microns on a base paper, coating an image receiving layer containing a color developing agent thereon, and further laminating a polyester film thereon. The microcapsules themselves are merely transparent gelatin microvessels that are light-transmissive and strong enough to be broken by the mechanical pressure of the print roller.

[0003] The color-forming substance encapsulated in the microcapsules is a colorless leuco dye, which is a substance that forms a color upon contact with an image receiving layer containing a color developer. The color-forming substances correspond to the three primary colors of light, that is, red (R), green (G), and blue (B).
That is, three types of magenta (M), yellow (Y), and cyan (C) are prepared. The photo-curing material that is encapsulated in the microcapsule in combination with the color-forming substance is a light of a color that is complementary to the color presented by the color-forming substance coming into contact with the image receiving layer,
That is, a substance that is cured by light having a specific wavelength is selected. That is, a photo-curable substance that cures when irradiated with green light (G) is selected as the magenta (M) color-forming substance that absorbs green and exhibits reddish purple. Similarly, a color-forming substance for yellow (Y) that absorbs blue-violet is a photo-curing substance that cures when irradiated with blue light (B), and a cyan (C) that absorbs red and exhibits blue-violet. As the color-forming substance, a photo-curable substance that cures when irradiated with red light (R) is selected.
Therefore, there are three types of photosensitive microcapsules, M, Y, and C. Therefore, there are two types of special printing paper: mono-color for only one type of photosensitive microcapsule and 256-color full-color for three types of photosensitive microcapsules. There is for sensitivity. The principle of coloring of such special print paper is as follows.

For example, when one type of light of R, G, and B, that is, monochromatic light is selected and irradiated on a special printing paper for full color coated with three types of photosensitive microcapsules,
Of the three types of photosensitive microcapsules of M, Y, and C, only the photosensitive microcapsules enclosing a photocurable substance having a complementary color relationship with the selected monochromatic light are cured in response to light, and the other two are cured. The type does not cure. That is, when the light of R is irradiated, the photosensitive microcapsule of C hardens in response to the red light of the photocurable substance, and the other two types, that is, the photosensitive microcapsules of M and Y do not harden. When the pressure of the print roller is applied to the special printing paper in this state, the photosensitive microcapsules of M and Y are completely destroyed, but the photosensitive microcapsules of C are not destroyed or are incomplete depending on the degree of curing. Destroyed. For this reason, the M and Y coloring substances come into contact with the image receiving layer of the special printing paper, and the area develops red mixed with M and Y. The color of the red color obtained by mixing M and Y changes depending on the degree of curing of the photosensitive microcapsule C. This is because, although incomplete, the photosensitive microcapsules of C are destroyed, and the color-forming substance for C comes into contact with the image receiving layer. Similarly, when the light of G is irradiated, the color develops green mixed with Y and C, and when the light of B is irradiated, the color develops blue mixed with M and C.

[0005] In short, special printing paper for full color coated with three types of photosensitive microcapsules, R, G,
When one type of light in B is selected and irradiated, the region irradiated with the selected light is M and Y, Y and C or C and M
Is developed into a mixed color. Further, when two types of light of R, G, and B are selected and irradiated on the full-color special print paper, an area irradiated with the selected two types of light is one of M, Y, or C. It develops into a color corresponding to one. Areas that were not irradiated with any type of light were M,
Since color development corresponding to all of Y and C is performed, black is exhibited. The color tone, saturation, and brightness of the print are adjusted by adjusting the intensity of irradiation light and the irradiation time.

[0006] By the way, the special print paper coated with the photosensitive microcapsules is scanned by a print head having three kinds of light emitting elements of red, green and blue to form a latent image, and the latent image is formed. The color development characteristic of a printer that develops a special print sheet by applying a mechanical pressure is not linear, but has a non-linear relationship as shown in FIG. That is, the irradiation amount of light from the print head to the special print paper (light amount ×
In FIG. 3 in which the irradiation time) is plotted on the horizontal axis and the color density is plotted on the vertical axis, the photosensitive microcapsules increase in the degree of curing as the irradiation amount is increased from t0 when the irradiation amount is zero to t1 and t2. The color density is 100%, that is, 0 from the full color intensity.
%, I.e., the colorless intensity, but the degree of the transition gradually changes when the irradiation amount is small and when the irradiation amount is large, but sharply decreases in the middle. Another factor that determines the color developing characteristics of the printer is the non-linearity of the light emitting characteristics of the LED, which is a light emitting element. That is, the intensity of light emission with respect to the drive current does not change linearly.

In a conventional printer using special print paper coated with photosensitive microcapsules, the light emitting element of the head is driven at a constant drive current and the supply time is made to correspond to the input image data. That is, the control of the irradiation amount has been performed by controlling the supply time of the drive current of the light emitting element based on the pulse signal pulse width modulated with the 8-bit irradiation data corresponding to the 8-bit input image data. For this reason, the color development characteristics of the printer using the special print paper coated with the photosensitive microcapsules, that is, the input / output characteristic curve of the printer of FIG. 3 shows that the input image and the output image are non-linear relations, There were problems with print density reproducibility, and therefore print quality.

[0008]

A latent image is formed by scanning a special print paper coated with photosensitive microcapsules with a print head having three types of light emitting elements of red, green and blue. In a printer that applies mechanical pressure to the formed special printing paper and develops the printing paper, it is an object of the present invention to improve the quality of printing by correcting the irradiation data for controlling the light emitting elements so that the input / output characteristics of the printer are made closer to linear. .

[0009]

A latent image is formed by scanning a special print paper coated with photosensitive microcapsules with a print head having three types of light emitting elements of red, green and blue. In a printer that applies mechanical pressure to the formed special printing paper and develops the input printing data, the input image data is converted into irradiation data that is at least one bit larger in accordance with the color development characteristics of the printer, and stored in a printer memory. The light emitting element of the print head is driven based on a pulse width-modulated with data. Specifically, when the input image data is an 8-bit digital signal, the irradiation data is a 9-bit digital signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a printer using special printing paper coated with photosensitive microcapsules according to the present invention.
As shown in the block diagram of FIG. 1, a print head 2, a print roller 3, a paper feed mechanism 4, a controller 5, a drive unit 6, a setting unit 7 for setting various parameters, and a digital signal given by an FD or a transmission signal. And input means 8 for inputting image data of an image device such as a camera. The controller 5 includes a CPU 51, a ROM 52 storing programs for performing various processes in accordance with predetermined procedures, a RAM 53 storing image data to be printed and related data such as various parameters, an input / output circuit I / O 54, and a bus 55. It is configured. The paper feed drive unit 61 and the head drive unit 63 of the drive unit 6 form an optical scanning mechanism of the print head 2. That is, the paper feed drive unit 61 drives the paper feed mechanism 4 to drive the special print paper 1
Is moved in one direction at a predetermined speed, and at the same time, the head driving unit 63 reciprocates a carriage (not shown) at a predetermined speed at right angles to the moving direction of the special print paper 1. The print head 2 can scan a special print sheet with light to form a latent image.

The photosensitive control circuit 64 of the drive unit 6 performs printing based on print data obtained by performing various types of correction processing on input image data input via the input means 8 and stored in the RAM 53 of the controller 5. The light irradiation amount of the light emitting element 23 provided in the head 2 is controlled to form a latent image corresponding to the input image data on the special print paper 1.
The special print paper 1 on which the latent image is formed is subjected to mechanical pressure by the print roller 3 driven by the roller drive unit 62 of the drive unit 6, and the photosensitive capsule is selectively destroyed. Done. A heater (not shown) is used to promote development and fixing.

FIG. 2 shows an embodiment of the photosensitive control circuit 64, which includes an irradiation data generating circuit 65, a PWM circuit 66, an electronic switch 67, and a constant current source 68. The constant current source 68 supplies light emitting elements, ie, a red LED 23R and a green LED 23G. And blue L
The supply of the drive current to the ED 23B is controlled by selectively opening and closing the electronic switch 67. Note that the electronic switch 67 includes three switches S1, S2, and S3. R1, r2 and r3 are resistors.

The irradiation data generation circuit 65 is a circuit for converting 8-bit input image data into 9-bit irradiation data in accordance with the color development characteristics of the printer and storing the converted data in the RAM 53 of the printer. The irradiation data generation circuit 65 is actually a part of the function of the controller 5. That is, the input image data provided via the input means 8 is subjected to processing corresponding to the color development characteristics of the printer in accordance with a program stored in the ROM 52, and is converted into irradiation data.
Stored in AM53. For example, a data conversion table for converting input image data into irradiation data is stored in the RAM 53, and by using this data conversion table, generation of irradiation data and storage in the RAM 53 can be easily performed.

FIG. 3 shows the correspondence with the color development characteristics of the printer.
The color characteristic curve in the density range (a% to b%) desired to be used, that is, the color characteristic curve connecting the points (t1, a) and (t2, b) should be close to a straight line connecting these two points. It is. When the conversion table between the input image data and the irradiation data is used, if the input image data is an 8-bit digital signal, the irradiation data is a 9-bit digital signal. By the way, a pulse width-modulated with 8-bit irradiation data using the input image data of 256 gradations as it is, that is, from a pulse width corresponding to 0 gradation to a pulse width corresponding to 255th gradation FIG. 3 shows the coloring characteristics of the printer obtained by driving the light emitting elements of the print head 2 using 256 pulses having different pulse widths. In FIG. 3, the pulses used for controlling the supply of the drive current in the concentration range to be used (a% to b%) are 256 pulses of different pulse widths used in the entire range of the irradiation amount 0 to t3. A pulse used in part, that is, from the irradiation dose t1 to t2,
About half of the total. Regardless of how this approximately half of the pulses are used, the print result is represented by points (t1, a) and (t).
It is impossible to approach the straight line connecting 2, b).

Therefore, when a data conversion table for converting input image data into irradiation data is used for generating irradiation data, if the input image data is an 8-bit digital signal, the irradiation data is a 9-bit digital signal. . That is, if the irradiation data has 9 bits, the pulse width-modulated pulse is a pulse whose pulse width is changed in 512 ways from the pulse width corresponding to the irradiation data 0 to the pulse width corresponding to the irradiation data 511. As a matter of course, the pulse width corresponding to the irradiation data 511 in the case of 9 bits is adjusted to be the same as the pulse width corresponding to the input image data of the 255th gradation, that is, the irradiation data 255 in the case of 8 bits. I have. This adjustment is performed, for example, by changing the clock pulse frequency of the pulse width modulation circuit.

In one embodiment of the present invention, converting the input image data of 8 bits into the irradiation data of 9 bits in correspondence with the color development characteristics of the printer and storing the data in the RAM 53 of the printer is performed by converting the input image data into the irradiation data. Is to rewrite the data conversion table to be converted to. If the irradiation data is set to 9 bits as described above, the pulse width-modulated pulse is a pulse that changes the pulse width in 512 ways from the pulse width corresponding to the irradiation data 0 to the pulse width corresponding to the irradiation data 511. . Therefore, if the irradiation data is set to 9 bits, the number of pulses that can be used to drive the light emitting element of the print head is twice that of the case where the irradiation data is 8 bits.

A 9-bit irradiation data in a printer, that is, irradiation data 0 to irradiation data 511 is set on the horizontal axis.
Referring to FIG. 4, which is an input / output characteristic diagram of the printer with the color density on the vertical axis, an example of converting 8-bit input image data into 9-bit irradiation data in accordance with the color characteristics of the printer will be described below. . In FIG. 4, the density range (a
% To b%), and this density range corresponds to the range from the irradiation data 80 to the irradiation data 430. Therefore, the irradiation data 430 is obtained from the irradiation data 80.
If the irradiation data in the range of is used, in other words, if 351 pulses having different pulse widths are used, the density of the print image which is the output image of the printer can be changed substantially linearly with respect to the input image data. . Therefore, the input image data 0 (0 gradation) and the input image data 255
(255th gradation) is made to correspond to the irradiation data 80 and the irradiation data 430 of 9 bits, respectively. During this time, 254 pieces of input image data are made to correspond to 349 pieces of irradiation data as linearly as possible. By performing such association, the data conversion table for converting 8-bit input image data into 9-bit irradiation data is rewritten, and accordingly, irradiation data is generated.

In the above example, the input image data of 8 bits 0
And 255 correspond to the irradiation data 80 and 430 of 9 bits, respectively. However, such a correspondence is not always required. That is, the 8-bit input image data 0 is not the 9-bit irradiation data 80 but, for example, 85
Or 91. At the same time, the 8-bit input image data 255 is not irradiated data 430 but 426 or 422.
Corresponds to During this time, the irradiation data is changed by two or three in response to one change of the input image data in an area where the change of the characteristic curve is gradual so that the density of the print image is as linear as possible, and in an area where the change is sharp. The input image data is associated with the irradiation data in such a manner that one change is made for one change. By performing such association, the data conversion table for converting 8-bit input image data into 9-bit irradiation data is rewritten, and accordingly, irradiation data is generated. According to this latter method, it is also possible to associate 8-bit input image data 0 to 255 with 9-bit irradiation data 0 to 511.

By the way, the slope of the straight line portion of the characteristic curve in FIG. 4 is steep, and the range of the irradiation data corresponding to the density range (a% to b%) to be used becomes narrow. There is a case where irradiation data in a wide range from the data 80 to the irradiation data 430 cannot be used. There is a case where input image data can be associated only with one-to-one or close to the irradiation data. In such a case, it is difficult to change the print density linearly with respect to the input image data. The problem is that the irradiation data is 10 bits instead of 9 bits.
It will be clear that this can be solved by using bits.

The PWM circuit 66 is a pulse width modulation circuit for generating a pulse having a pulse width corresponding to the irradiation data stored in the RAM 53. For example, a counter 66a for counting clock pulses φ, the irradiation data stored in the RAM 53 66b and the output of the counter 66a as one input and the register 6b
The comparator 66c detects the coincidence between the output of the comparator 6c and the output of the comparator 6c. The comparator 66c is reset when the counter 66a overflows.

In the PWM circuit 66 having such a configuration, when the irradiation data is supplied via the register 66b to the other input of the comparator 66c to which the output of the counter 66a is supplied to one input, the PWM circuit 66 performs the irradiation. Outputs a pulse width-modulated pulse with data. Then, based on the pulse width-modulated with the irradiation data, the controller 5 controls the red LED 23R and the green LED 23R.
The drive current is selectively supplied to the 23G and blue LEDs 23B by controlling the opening and closing of the electronic switch 67. As described above, the irradiation data in the present invention is obtained by converting the input image data in association with the color development characteristics of the printer so that the input / output characteristics are close to linear. Therefore,
A printer equipped with a print head controlled based on a pulse width-modulated pulse with this irradiation data has an input / output characteristic, in particular, a change in density of an output image with respect to input image data in a half tone approaches a linear, and a print quality is reduced. Improved.

In the above embodiment, the input image data is an 8-bit digital signal, and the irradiation data is a 9-bit digital signal. However, the illumination data only needs to be at least one bit larger than the input image signal,
Therefore, a 10-bit digital signal may be used. Although the conversion table between the input image data and the irradiation data is used for generating the irradiation data, it is needless to say that the present invention is not limited to this.

[0023]

According to the present invention, a latent image is formed by scanning a special print paper coated with photosensitive microcapsules with a print head having three types of light emitting elements of red, green and blue. In a printer that applies mechanical pressure to the formed special print paper and develops the input print data, the input image data is converted into irradiation data of at least one bit more digital signal corresponding to the color development characteristics of the printer and stored in a memory of the printer. A light emitting element of the print head is driven based on a pulse width-modulated by the irradiation data. Therefore, the input / output characteristics of the printer could be made closer to the desired linear relationship, so that the reproducibility of the input image data was improved and the quality of printing was improved. The irradiation data is generated using, for example, a conversion table between the input image data and the irradiation data, and a conventional PWM circuit can be used, so that there is almost no increase in cost due to improvement of the apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a printer using special print paper coated with photosensitive microcapsules of the present invention.

FIG. 2 is a block diagram illustrating an embodiment of a photosensitive control circuit.

FIG. 3 is a diagram illustrating an example of a color developing characteristic of a printer using special print paper coated with photosensitive microcapsules.

FIG. 4 is a diagram illustrating another example of the color development characteristics of a printer using special print paper coated with photosensitive microcapsules.

[Explanation of symbols]

 Reference Signs List 1 special print paper 2 print head 3 print roller 4 paper feed mechanism 5 controller 6 drive unit 7 setting means 8 input means 23R red LED 23G green LED 23B blue LED 51 CPU 52 ROM 53 RAM 54 I / O 55 bus 61 paper feed drive Unit 62 roller driving unit 63 head driving unit 64 photosensitive control circuit 65 irradiation data generation circuit 66 PWM circuit 66a counter 66b register 66c comparator 67 electronic switch 68 constant current source S1 switch S2 switch S3 switch r1 resistance r2 resistance r3 resistance φ clock pulse

Claims (2)

[Claims] 1. A special print sheet coated with photosensitive microcapsules is scanned by a print head having three kinds of light emitting elements of red, green and blue to form a latent image, and the latent image is formed. In a printer that applies mechanical pressure to a special print paper to develop it, the input image data is converted into irradiation data that is at least one bit larger in accordance with the color development characteristics of the printer and stored in a memory of the printer. A printer using special print paper coated with photosensitive microcapsules, wherein the light emitting element of the print head is driven based on the modulated pulse. 2. The printer according to claim 1, wherein the input image data is an 8-bit digital signal, and the irradiation data is a 9-bit digital signal.