JP2000326537A - Print apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically adjust a print density by sharing members to be used for normally processing photoprint images without setting a special measuring device such as a densitometer or the like in a print apparatus of a TA system. SOLUTION: A test pattern of a predetermined photoprint gradation value (gray) is printed to a print paper 50 similarly to a normal image. Then, the test pattern of the print paper is supplied between a home position(HP) sensor 40 and a fixing lamp (fluorescent lamp 42 for Y fixing). Light irradiated from the lamp 42 and reflected by the test pattern is received by a light receiving sensor of the HP sensor 40. A density of the test pattern is detected from a quantity of the received light. A quantity of heat to be added to the print paper 50 by a thermal head 36 is adjusted to turn the density to a reference density. A variation in print density because of dispersion in characteristics of the print paper 50 or the like is prevented accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, and more particularly to a printing apparatus having a function of automatically adjusting print density.

[0002]

2. Description of the Related Art A printing apparatus which prints an image photographed by a digital still camera or the like on a printing paper and adopts a TA (Thermo-Autochrome) method as a printing method is currently on the market. In the TA system, the photographic paper itself develops color by heat and is fixed by irradiation of ultraviolet rays, and has a feature that an ink ribbon and a toner are unnecessary.

Conventionally, when it is attempted to print colors of the same density on different printing papers with such a TA type printing apparatus, the density (printing density) of the colors printed on these printing papers depends on various conditions. There was a problem that it was different depending on the difference. Similar problems also occur in printing apparatuses of other printing systems such as a sublimation type thermal transfer system, for example, manufacturing variations and changes over time of the characteristics of various devices mounted on the printing apparatus, ink used for printing, and the like. The difference in the characteristics of photographic paper is the cause. In particular, when the photographic paper itself develops color, such as photographic paper used in a TA-type printing apparatus, there is a variation in the color development sensitivity characteristics of each photographic paper, and the characteristics of the photographic paper change with time. This has a great influence on the print density fluctuation.

In order to prevent such fluctuations in print density, some conventional print apparatuses use a densitometer (calibrator) installed inside or outside the print apparatus to adjust the print density. . As a general method, for example, a test pattern serving as a reference is printed on printing paper in the same manner as a normal image, and the print density of the test pattern is measured by a densitometer. It is known that the difference between the print density of a test pattern to be originally printed and the print density is fed back to a control amount for controlling the print density as a correction amount to eliminate the difference.

[0005] Further, in a TA printing apparatus, since several tens of photographic papers are usually stored in one paper cartridge and sold, the color development sensitivity characteristics are examined for each production lot of photographic paper, and each paper cartridge is examined. In some printers, barcodes with sensitivity rankings are printed or the like, so that the printing apparatus can read the barcode of the paper and automatically adjust the print density according to the sensitivity of each manufacturing lot.

[0006]

However, in the case of adjusting the print density in a TA-type printing apparatus, if the above-described densitometer is mounted on the printing apparatus, the cost of the entire printing apparatus is high. Disadvantage. Further, even if barcodes whose sensitivity is classified at the manufacturing stage are provided for each production lot of TA paper as described above, the characteristics of the photographic paper change with the lapse of time after the production, and the placement of the photographic paper is changed. Even if the print density is adjusted according to the sensitivity characteristics at the time of photographic paper manufacture, the adjustment is not always performed correctly in accordance with the sensitivity characteristics at the time of use of the photographic paper, because it varies greatly depending on the environment in which the photographic paper is manufactured. Absent.

[0007] The present invention has been made in view of such circumstances, and uses a sensor, a light source, and the like, which are used when printing a normal image, without mounting a special measuring device such as a densitometer. A printing device that can directly prevent the change in print density due to changes in the characteristics over time of photographic paper and various mounted devices and variations in the characteristics at the time of manufacture without directly increasing the cost by directly measuring the sensitivity characteristics of the paper. The purpose is to provide.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, colors having different densities are developed according to the amount of heat applied, and light of a predetermined wavelength is irradiated. A printing means for printing a required image on a printing paper for fixing a color developing state, a light receiving means for detecting the printing paper, and a light source for irradiating fixing light to the printing paper. And a test pattern printing means for printing a test pattern of a predetermined shape having a color of a predetermined printing gradation value on the printing paper by the printing means, and printing on the printing paper by the test pattern printing means. Irradiating the test pattern with light from the light source, receiving light reflected by the test pattern by the light receiving means, and printing the test pattern on the printing paper. Density detection means for detecting the color density, and the density of the color of the test pattern detected by the density detection means, so that the density of the color of the test pattern coincides with the target density corresponding to the print gradation value of the color Density correction means for correcting the amount of heat to be added to the printing paper with respect to the printing gradation value based on the image data of the image to be printed by the printing means.

According to a second aspect of the present invention, there is provided a photographic paper which develops colors having different densities in accordance with the amount of heat to be applied and fixes the color development state when irradiated with light of a predetermined wavelength. In a printing apparatus including a printing unit for printing a required image, a light receiving unit and a light source for detecting the printing paper, a test pattern having a predetermined shape formed of a color of a predetermined printing gradation value may be used. Test pattern printing means for printing on the printing paper by printing means, and irradiating light from the light source to the test pattern printed on the printing paper by the test pattern printing means, and light reflected by the test pattern Density detecting means for receiving the light by the light receiving means and detecting the density of the color of the test pattern printed on the printing paper; The concentration of the color of the test pattern,
The amount of heat to be applied to the printing paper with respect to a printing gradation value based on image data of an image to be printed by the printing means so as to match a target density corresponding to a printing gradation value of a color of the test pattern. Density correction means for correcting
It is characterized by having.

According to a third aspect of the present invention, the density correction means corrects the amount of heat to be applied to the photographic paper and changes the voltage at which the photographic means generates the amount of heat to be applied to the photographic paper. It is characterized by performing by doing. According to a fourth aspect of the present invention, the density correction unit corrects the amount of heat to be added to the photographic paper, and changes the energization time of a voltage that generates the amount of heat to be applied to the photographic paper in the printing unit. It is characterized by performing by doing.

According to a fifth aspect of the present invention, the density correction means corrects the amount of heat to be added to the printing paper by changing a print gradation value based on image data of an image printed by the printing means. It is characterized by performing by doing. According to a sixth aspect of the present invention, the density detecting means detects the density of the color of the test pattern printed on the photographic paper by the light incident on the test pattern printed on the photographic paper from the light source. Assuming that the light amount of light is Lw and the light amount of the reflected light reflected by the test pattern and detected by the light receiving means is Lp,

[0012]

It is characterized in that calculated by Equation 1] _{Dp = -log 10 (Lp / Lw} ) ... (1). Further, the invention according to claim 7 is characterized in that the density detecting means sets the light quantity Lw of the incident light in the above equation (1) to a fixed value.

According to an eighth aspect of the present invention, the density detecting means irradiates light from the light source to a reference paper of a predetermined color and receives light reflected by the reference paper by the light receiving means. The amount of light received when
(1) The amount of incident light Lw in (1) is set. According to a ninth aspect of the present invention, when the density detecting means irradiates light from the light source to a reference paper made of a predetermined color and receives light reflected by the reference paper by the light receiving means. The sensitivity of the light receiving means is calibrated so that the amount of received light is constant.

According to the first to ninth aspects of the present invention, a test pattern of a predetermined shape composed of a color of a predetermined print gradation value is printed on a printing paper in the same manner as printing a normal image. Then, the density of the test pattern was measured using a light receiving unit and a light source used during normal image printing, and the print density was corrected based on this.
No special measuring equipment such as a densitometer is required, and there is no cost increase.
It is possible to automatically adjust the print density, and it is possible to appropriately prevent a change in the characteristics over time of the photographic paper or the printing apparatus, and a change in the density due to a variation in the characteristics at the time of manufacture.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a printing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of a printing apparatus according to the present invention. The printing apparatus according to the present invention employs a printing method called a TA (thermo auto chrome) method. In this printing apparatus, a printing paper (which has a property of developing a color by applying heat and fixing by applying ultraviolet rays). TA paper) is being used. The print paper will be described later.

The printing apparatus includes a card type IC.
SSF for loading an SSFDC (State Floppy Disk Card (also called smart media)) 12 as a memory
A DC slot 14 is provided so that an image recorded on the SSFDC 12 by a digital still camera or the like can be directly read into a printing apparatus without passing through another apparatus such as a personal computer and printed on the print paper. ing.

Further, the printing apparatus is provided with a function for automatically adjusting the print density.
Fluctuations in print density are suppressed irrespective of variations in the characteristics of the print paper, etc., and the density of the print image printed on the print paper is determined based on the image data when the print image is to be printed. The tone is adjusted to a density appropriately corresponding to a tone value (hereinafter referred to as a print tone value).

Hereinafter, the configuration and operation relating to the printing process generally performed in the TA type printing apparatus will be described first, and then the configuration and operation relating to the automatic adjustment of the print density will be described. A system controller 10 illustrated in FIG. 1 is a processing unit that controls the entire system as a whole. The system controller 10 performs various processing such as processing of image data, transfer of image data to each control block described later, execution of printing, and the like. Instructions are given. Instructions for various processes to the system controller 10 are given from the operation unit 16 based on a user's operation, and an operation program of the system controller 10 is recorded in the EEPROM 18.

The SSFDC slot 14 into which the SSFDC 12 is inserted reads out image data of an image file recorded in the SSFDC 12 and inputs the image data to the system controller 10. The reading of the image data is performed by the system controller 10. Performed according to instructions. In the SSFDC 12, the image data is recorded in a compressed state in a predetermined format. When the system controller 10 instructs the SSFDC slot 14 to read the image data and obtains the required image data from the SSFDC 12, The data is decompressed and restored to the original image data, and further subjected to required image processing, and the image data is transferred to the memory 22 via the memory controller 20.
To memorize.

An example of a procedure for obtaining image data of an image to be printed (print image) from the SSFDC 12 will be described.
When the C12 is loaded in the SSFDC slot 14, first, the image data of the thumbnail image of the reduced size recorded in the SSFDC 12 is read for all frames. And
Image data for a print image selection screen in which a plurality of the thumbnail images are arranged in one screen is generated, and the image data is stored in the memory 22. As a result, the image data for the print image selection screen stored in the memory 22 is transmitted to the memory 26 (and the D / A converter 4) by the monitor connected to the LCD 26 and the video output terminal 46 described later.
7), and the print image selection screen is
It is displayed on a CD 26 or the like. When the user operates the operation unit 16 to select an image to be printed on the displayed print image selection screen, the system controller 10 stores the image data of the selected print image in the SSFDC slot 14 as described above. Via SSF
The image data is read from the DC 12, subjected to necessary processing on the image data, and stored in the memory 22. Through the above procedure, the image data of the required print image is acquired in the memory 22.

The memory controller 20 is a processing unit that controls writing and reading of data to and from the memory 22. By the processing of the memory controller 20, image data such as a print image read from the SSFDC 12 as described above. Is stored in the memory 22, and the image data such as the print image stored in the memory 22 according to the instruction from the system controller 10 is stored in the LC 22.
The data is output to the D control unit 24, the print controller 28, and the like.

The LCD control unit 24 is a processing unit that controls display on a liquid crystal display (LCD) 26 mounted on the printing apparatus. The system controller 10 instructs the LCD control unit 24 to display a screen. Then, the image data of the image to be displayed is obtained from the memory controller 20 and the image is displayed on the LCD 26. The LCD 26 displays a print image selection screen (index screen) for selecting a print image as described above, a print image being printed, and the like.

The print controller 28 shown in FIG.
The head drive circuit 30, the paper transport control unit 32, and the fixing control unit 34 are control blocks for executing printing, and these control blocks are synchronized with each other by a print execution instruction from the system controller 10 to perform various operations. Execute control. Here, the print paper used in the present printing apparatus will be described. As shown in FIG. 2, the print paper 50 has a cyan (C) coloring layer 54, a magenta (M) coloring layer 56,
Three layers of the yellow (Y) color-forming layer 58 are sequentially stacked. In each of the C-color forming layer 54, the M-color forming layer 56, and the Y-color forming layer 58, when a heat amount corresponding to each is given, C, M, and Y colors of density (gradation) corresponding to the heat amount are obtained. Color develops. In addition, ultraviolet rays having wavelengths corresponding to each of the M color forming layer 56 and the Y color forming layer 58 except for the C color forming layer 54 (the M color forming layer 56 is about 365 nm, and the Y color forming layer 58
(Ultraviolet light of about 425 nm) is applied to fix the state of color development.

When a print execution instruction is given from the system controller 10, the print controller 28 acquires the image data of the print image recorded in the memory 22 through the memory controller 20, and converts the image data into the image data of the print image. Based on this, the gradation (print gradation value) of each color of Y, M, and C in each pixel of the print image is set within a range of, for example, an 8-bit resolution (0 to 255). Then, the data of the print gradation values of each color of Y, M, and C in each pixel of the print image is synchronized with the travel of the print paper in one direction (main scan direction) perpendicular to the travel direction (sub-scan direction). The data is output to the head drive circuit 30 line by line.

The head drive circuit 30 is arranged in the main scanning direction based on the print gradation values of the Y, M, and C colors when data of the print gradation values are given from the print controller 28 as described above. Voltage applied to the heating element of each dot of the thermal head 36 and its energizing time (pulse width)
Is controlled in synchronization with the travel of the print paper. As a result, the amount of heat given to each point of the print paper from the heating element of each dot of the thermal head 36 is Y, M, C.
Control is performed in accordance with the print gradation value of each color, and a color having a density corresponding to the print gradation value specified by the print controller 28 is generated for each color forming layer of the print paper.

When a print execution instruction is given from the system controller 10, the paper transport control unit 32 shown in FIG. 1 feeds print paper from the print paper storage unit to the print processing unit. It is to be noted that a commercially available paper cartridge containing several tens (for example, 20) print papers is directly loaded in the print paper storage section. The paper transport control unit 32
When the print paper is fed to the print processing unit, the capstan roller 38 is driven by a motor to run the print paper in synchronization with the print processing of coloring and fixing. At this time, the system controller 10 uses the home position (HP) sensor 40 to detect that the print paper is at the home position, and causes the paper transport control unit 32 to reciprocate the print paper based on the home position. Let it run. The specific contents of the print paper conveyance control will be described later.

The fixing control unit 34 controls the turning on and off of the Y fixing fluorescent lamp 42 and the M fixing fluorescent lamp 44 in synchronization with the processing of the coloring of the Y and M color layers of the print paper by the thermal head 36. I do. The Y-fixing fluorescent lamp 42 is a lamp that emits ultraviolet light having a wavelength of about 425 nm. When the Y-fixing fluorescent lamp 42 is turned on and the print paper is irradiated with ultraviolet light from the lamp, the Y of the print paper is irradiated. The coloring layer is fixed. On the other hand, the M fixing fluorescent lamp 44 is a lamp that emits an ultraviolet ray having a wavelength of about 365 nm. When the M fixing fluorescent lamp 44 is turned on and the print paper is irradiated with the ultraviolet light, the print paper is printed. Are fixed.

FIG. 3 is an arrangement diagram showing an embodiment of the arrangement of members of a printing processing section in which printing processing of color development and fixing on print paper is performed in the printing apparatus. As shown in the figure, the print processing unit includes the above-described thermal head 36, capstan rollers 38, and 3 from the upstream side of the conveyance path 60 to which the print paper 50 is fed.
8, an HP sensor 40, a Y fixing fluorescent lamp 42, and an M fixing fluorescent lamp 44 are sequentially arranged. The print paper 50 fed from the upstream side of the transport path 60 is nipped by the thermal head 36 and the platen roller 62 and nipped by the capstan rollers 38, 38.
When the printing process is performed, the capstan rollers 38, 3
When the motor 8 is rotated by the motor, the print paper 50 reciprocates in the sub-scanning direction shown by arrows A and A 'in FIG. In the thermal head 36, a plurality of heating elements are arranged in a line in a main scanning direction perpendicular to the sub-scanning direction which is a conveyance direction of the print paper 50.
In synchronization with the printing paper 50 being conveyed in the printing direction indicated by the arrow A in the drawing, a predetermined heat is applied to the printing paper 50 line by line in the main scanning direction to cause each color forming layer to develop a color. As shown in FIG. 4, the HP sensor 40 disposed downstream of the capstan roller 38 includes a light emitting LED 40A and a light receiving sensor 40B, and emits light from the light emitting LED 40A onto the conveyance path of the print paper 50. Thus, the reflected light can be detected by the light receiving sensor 40B. The detection signal output from the light receiving sensor 40B is input to the system controller 10 shown in FIG. 1 via an A / D converter (not shown). The system controller 10 determines whether the print paper 50 is located at the position of the HP sensor 40 by detecting whether or not the reflected light of the light emitted from the light emitting LED 40A is received by the light receiving sensor 40B. I do. Then, by detecting a switch between when the print paper 50 is positioned at the position of the HP sensor 40 and when the print paper 50 is not positioned, it is detected whether or not the leading end of the print paper 50 has been transported to the position of the HP sensor 40. Thereby, the position of the print paper 50 is adjusted using the time when the leading end of the print paper 50 is conveyed to the position of the HP sensor 40 as the home position of the print paper 50. The fixing printing process is performed synchronously.

An outline of a processing procedure for printing a required print image on the print paper 50 in the printing apparatus configured as described above will be described with reference to a flowchart of FIG. First, the system controller 10 shown in FIG.
When a print execution instruction is given from the operation unit 16, the printing sequence starts, and the paper transport control unit 32
Then, the print paper 50 is fed from the paper storage unit to the print processing unit in FIG. 3 (step S10). Then, the print paper 50 is fed at a constant speed from the predetermined time in the printing direction indicated by the arrow A in FIG. 3 (start of paper feeding) (step S12). System controller 10
Starts paper feed at a constant speed, counts the number of pulses of a synchronization signal synchronized with the paper feed operation,
The leading edge of the print paper 50 is detected by the HP sensor 40. First, the print paper 50 is detected within a prescribed pulse.
It is determined whether the tip of is detected by the HP sensor 40 (step S14). At this time, if NO,
It is determined that the print paper 50 is not loaded in the paper storage unit or an error such as a paper jam has occurred, and error processing such as stop of the printing process is performed (step S16).

On the other hand, if YES, then the system controller 10 turns on the Y fixing fluorescent lamp 42 by the fixing control unit 34 of FIG. 1 (step S18), and as shown in FIG. , The portion of the print paper 50 conveyed to the position of the Y fixing fluorescent lamp 42 is sequentially irradiated with ultraviolet light having a wavelength of about 425 nm.

The system controller 10 instructs the print controller 28 to execute the printing process for the Y color, and calculates the amount of heat to be added to the print paper 50 by the heating elements of each dot of the thermal head 36 to the image data of the print image. Is controlled based on the Y-color printing gradation value determined by the above. Then, the print paper 5 is sent to the print controller 28 and the head drive circuit 30.
A synchronization signal synchronized with the paper feed speed of the print paper 50 is given based on the time when 0 has passed the home position. Thus, first, when the print paper 50 passes through the thermal head 36, the print paper 5
A low-energy heat is applied by the thermal head 36 to a point where color is to be formed on the uppermost layer of 0 (Y color forming layer), and Y color is formed. The amount of heat applied to each point of the print paper 50 by the thermal head 36 is adjusted according to the density of the Y color to be colored, and the density of the Y color to be colored is
The print controller 28 of FIG. 1 sets the print gradation value of Y color based on the image data of the print image.

The portion where the print paper 50 has passed through the thermal head 36 as described above and has passed through the thermal head 36 and has undergone color development for the Y color is then irradiated with ultraviolet light by the Y fixing fluorescent lamp 42. The Y-fixing fluorescent lamp 42 irradiates ultraviolet rays to perform fixing. Thus, the printing process for the Y color of the print paper 50 ends (step S).
20).

When the printing process for the Y color is completed, the system controller 10 causes the paper transport control unit 32 to transport the print paper 50 in the return direction shown by the arrow A 'in FIG. 3 (start paper return). (Step S2
2) As in step S14, the leading edge of the print paper 50 is detected by the HP sensor 40, and it is determined whether the leading edge of the print paper 50 is detected by the HP sensor 40 within a prescribed pulse (step S2).
4). At this time, if NO, an error process such as canceling the print process is performed (step S26).

On the other hand, if YES, the paper return operation of the print paper 50 is stopped at the home position, and the print paper
0 is fed at a constant speed in the printing direction indicated by arrow A in FIG. Then, the system controller 10 causes the fixing control unit 34 shown in FIG.
Is turned off (step S28), the M fixing fluorescent lamp 44 is turned on (step S30), and the portion of the print paper 50 that has passed through the thermal head 36 and conveyed to the position of the M fixing fluorescent lamp 44 is turned on. The ultraviolet rays having a wavelength of about 365 nm are sequentially irradiated.

Further, the system controller 10 instructs the print controller 28 to execute the printing process for the M color, as in the case of coloring the Y color layer of the print paper 50, and generates heat of each dot of the thermal head 36. The amount of heat applied to the print paper 50 by the element is controlled based on the print gradation value of M color determined by the image data of the print image. Then, the print paper 50 is sent to the print controller 28 and the head drive circuit 30.
Supplies a synchronization signal synchronized with the paper feed speed of the print paper 50 based on the point at which the paper feed operation is started from the home position. As a result, heat of medium energy is applied by the thermal head 36 to the point at which the intermediate layer (M color-forming layer) of the print paper 50 is to be colored, and M color is developed (step S32). The amount of heat applied to each point of the print paper 50 is adjusted in accordance with the density of the M color to be developed in the same manner as in the case of the Y color, and the density is determined by the printing gradation of the M color based on the image data of the print image. Set by value.

The portion where the print paper 50 has passed through the thermal head 36 as described above, and has passed through the thermal head 36 and has undergone M color development, is then irradiated with ultraviolet light by the M fixing fluorescent lamp 44. The fixing is performed by irradiating ultraviolet rays from the M fixing fluorescent lamp 44 to the position where the fixing is performed. Thus, the printing process for the M color of the print paper 50 ends (Step S).
32).

When the printing process for the M color is completed, the system controller 10 then sends the print paper 50 to the paper transport control unit 32 in the same manner as when the printing process for the Y color is completed, as indicated by an arrow A in FIG. ′ (Start paper return) (step S34),
The leading edge of the print paper 50 is detected by the HP sensor 40, and it is determined whether the leading edge of the print paper 50 is detected by the HP sensor 40 within a prescribed pulse (step S36). At this time, if NO, an error process such as canceling the print process is performed (step S38).

On the other hand, if YES, the paper return operation of the print paper 50 is stopped at the home position, and the print paper
0 is fed at a constant speed in the printing direction indicated by arrow A in FIG. Then, the system controller 10
The fixing fluorescent lamp 44 is turned off (step S4).
0).

Further, the system controller 10 instructs the print controller 28 to execute the printing process for the C color similarly to the case of coloring the Y color layer and the M color layer of the print paper 50, and The amount of heat applied to the print paper 50 by the heating element of each dot is controlled based on the C-image printing gradation value determined by the image data of the print image. Then, a synchronization signal synchronized with the paper feed speed of the print paper 50 is given to the print controller 28 and the head drive circuit 30 based on the time when the print paper 50 starts the paper feed operation from the home position. As a result, high-energy heat is applied by the thermal head 36 to the point at which the lowermost layer (the C color-forming layer) of the print paper 50 is to be colored, and the C color is developed (step S42). still,
The amount of heat given to each point of the print paper 50 is Y
Adjustment is made in accordance with the density of C color to be developed in the same manner as in the case of the color and M color, and the density is set by the print gradation value of M color based on the image data of the print image.

As described above, the Y, M, and C colors are formed and fixed, the print paper on which a predetermined print image is printed is discharged from the printing apparatus, and the print processing ends. Next, the function of the print density automatic adjustment in the above-described printer will be described. Print density automatic adjustment is based on the image data of the print image, when you try to print a color of a certain print gradation value on print paper,
The density of the color actually printed on the print paper is made to appropriately correspond to the print gradation value. Due to this automatic adjustment of the print density, the characteristics of the print paper and the thermal head 36 over time can be changed. Irrespective of the above, images of the same density are printed on print paper for images of the same image data.

In the above-described printing apparatus, before a desired print image is printed, a print paper used for the print or a print paper regarded as having the same characteristics as the print paper (print paper contained in the same paper cartridge is substantially Sensitivity characteristics (actually, not only the characteristics of the print paper but also the characteristics of the equipment mounted on the printing apparatus such as the thermal head 36) are detected because the characteristics can be regarded as the same characteristics. The print density is corrected based on this. However, the printing apparatus does not have a special light source or detector for detecting the sensitivity characteristics of the print paper, and is not equipped with a light source or detector (HP sensor 40 or Y fixing The fluorescent lamp 42) is also used. Therefore, there is no problem such as an increase in cost for mounting the automatic print density adjustment function and a sufficient space.

First, the detection of the sensitivity characteristics of the print paper in the printing apparatus will be described. FIG.
FIG. 3 is a diagram illustrating a configuration of a detection unit that detects a sensitivity characteristic of print paper. This detection unit is the same as the print processing unit shown in FIG. 3 as it is, and the members shown in FIG. 6 with the same reference numerals as those in FIG. 3 are exactly the same members as those in FIG. The ultraviolet light emitted from the Y fixing fluorescent lamp 42 is
The stray light other than the reflected light from the print paper 50 does not reach the light receiving sensor 40B of the HP sensor 40. For example, the Y fixing fluorescent lamp 42 and the HP
Between the sensors 40, there is provided a light shielding plate 70 for preventing ultraviolet rays emitted from the Y fixing fluorescent lamp 42 from directly entering the light receiving sensor 40B of the HP sensor 40.
However, even if the light shielding plate 70 is not provided, the Y fixing fluorescent lamp 4
In the case where the ultraviolet light emitted from 2 does not directly enter the light receiving sensor 40B of the HP sensor 40 (or in the case of such a configuration), it is not necessary to provide the light shielding plate 70. When detecting the sensitivity characteristic of the print paper 50, as described later, a predetermined test pattern is printed on the print paper 50, and the test pattern is irradiated with light from the Y fixing fluorescent lamp 42 to reflect the reflected light. HP
The light reception is performed by the light receiving sensor 40B of the sensor 40.

On the other hand, in the system controller 10 shown in FIG. 1, a program for detecting the sensitivity characteristic of the print paper is added to the printing processing program. When the system controller 10 executes the program, first, in order to detect the sensitivity characteristics of the print paper used for printing, the system controller 10 prints a predetermined test pattern on the print paper in the same procedure as the print image printing process described above. . Various methods can be adopted for the timing of detecting the sensitivity characteristic and the print paper used for the same. For example, print papers stored in the same paper cartridge can be determined according to the date of manufacture and storage conditions. Since the conditions are substantially the same and these sensitivity characteristics are considered to be substantially the same, with respect to the print paper of the same paper cartridge, a test pattern is printed for only one of the sheets, and the sensitivity characteristics are detected by the processing described later. Can be treated as having the same sensitivity characteristic.

As for the print paper on which the test pattern is printed as described above, if the test pattern is printed on the print portion of the print image, it cannot be used for printing the print image and the print paper stored in the paper cartridge is not used. Since one sheet of paper is wasted, the portion on which the test pattern is printed is a blank portion of the print paper not used for printing the print image, and the print paper on which the test pattern is printed can be effectively used for printing the print image. You may do so. When the print paper on which the test pattern is printed can be used for printing a print image, the test pattern can be printed on all the print papers, and the sensitivity characteristics can be detected for each print paper.

Furthermore, since it takes a certain amount of time to detect the sensitivity characteristics of the print paper, the user does not have to detect the sensitivity characteristics for each paper cartridge or each print paper, but for the user to detect the sensitivity characteristics of the print paper. Specify whether to perform printing, print a test pattern on print paper only when the specification is made, detect the sensitivity characteristics, correct the print density based on this, and do not specify In this case, the print density may be corrected on the assumption that the print paper has the same characteristics as the print paper used in the previous printing. The user may also be able to select whether or not to automatically perform the print density adjustment itself.

The shape and color of the test pattern to be printed on the print paper are determined in advance, and the print gradation value of each of the Y, M, and C colors at each point of the image to be printed is 8 bits (0 to 255). ), The test pattern is set, for example, as a gray rectangle or band with the print gradation values for all the colors of Y, M, and C being 128, which is the intermediate value. The test pattern data may be generated by the system controller 10, the print controller 28, or the like when printing the test pattern, or may be stored in advance in a memory such as the EEPROM 18 built in the main body. Good. The process of printing the test pattern is performed in the same manner as the printing of the print image described above.

After the test pattern is printed on the print paper as described above, the system controller 10 measures the density of the test pattern printed on the print paper in order to detect the sensitivity characteristics of the print paper. To measure the density of this test pattern,
The Y fixing fluorescent lamp 42 and the HP sensor 40 shown in FIG.
Is used. Here, an example of the emission spectrum of the Y fixing fluorescent lamp 42 is shown in FIG. 7, and an example of the spectral sensitivity characteristic of the light receiving sensor 40B is shown in FIG. As shown in these figures, the emission spectrum of the Y fixing fluorescent lamp 42 and the spectral sensitivity of the light receiving sensor 40B are multiplied by 400 nm to 500 nm and about 550 nm.
It can be seen that there is a wavelength region common to the emission spectrum and the spectral sensitivity in the wavelength region of. Therefore, it is possible to irradiate the test pattern of the print paper with the Y fixing fluorescent lamp 42 and detect the reflected light with the light receiving sensor 40B. In order to improve the accuracy, a Y-fixing fluorescent lamp 42 having a fluorescent material that emits light of a longer wavelength side may be used, or the light receiving sensor 40 may be used.
As B, an element sensitive to the shorter wavelength side can be selected.

Therefore, the system controller 10 first causes the paper transport control unit 32 to control the position of the print paper, and moves the test pattern printed on the print paper to an intermediate position between the HP sensor 40 and the Y fixing fluorescent lamp 42. Let it. Then, an instruction is given to turn on the Y fixing fluorescent lamp 42 of the fixing control unit 34, the test pattern is irradiated with light from the Y fixing fluorescent lamp 42, and the amount of reflected light is detected by the light receiving sensor 40B of the HP sensor 40. To detect.

The amount of light reflected by the test pattern printed on the print paper in this manner is determined by the light receiving sensor 40.
When detected by B, the system controller 10
The density of the test pattern is calculated based on the detected amount of the reflected light. The density of the test pattern is represented by the following formula, where Lw is the amount of light incident on the print paper from the Y fixing fluorescent lamp 42 and Lp is the amount of light reflected by the test pattern on the print paper.

[0050]

[Number 2] is quantified by _{Dp = -log 10 (Lp / Lw} ) ... (1). The above equation (1) is generally used as an equation for quantifying the density of an image printed on photographic paper,
Dp is called the optical density. The density Dp of the test pattern is calculated by substituting the quantity of reflected light of the test pattern detected by the light receiving sensor 40B into the quantity of reflected light Lp using the equation (1). Note that the amount of incident light L
The value of w will be described later.

When the system controller 10 calculates the density Dp of the test pattern printed on the print paper using the above equation (1), the system controller 10 then calculates the density Dp and the print gradation value of each color of the test pattern. Density of the test pattern to be printed (target target density Dt)
Is calculated, and the density difference ΔD is stored. The target density Dt is a predetermined value, and the target density Dt when the print gradation value of each of the Y, M, and C colors of the test pattern is 128 is, for example, 0.52 (the reflectance is 0.3). Is set. In this case, the light receiving sensor 4 detects the reflected light of the test pattern with respect to the reference white paper.
It is assumed that the signal strength of 0B is 30%.

Here, the value of the light quantity Lw of the incident light when calculating the density Dp using the above equation (1) will be described. The light quantity Lw of the incident light is assumed when determining the target density Dt. It is determined by the relationship with the value of the light quantity Lw of the incident light. That is, the finally required information is the density difference ΔD. If the target density Dt is determined and the light quantity Lp of the reflected light of the test pattern is detected, the light quantity Lw of the incident light is constant. If the amount of light emitted from the fluorescent lamp 42 is constant, the value of ΔD is equal to the amount Lw of incident light.
Is not affected, the value of the light quantity Lw of the incident light may be an arbitrary value. Alternatively, the light quantity Lw of the incident light may be deleted from the calculation formula of ΔD so as to be unnecessary from the beginning. The same applies to the case where the fluctuation of the light quantity Lw of the incident light is set as the error range regardless of whether the light quantity Lw of the incident light is constant or not.

On the other hand, the fluctuation of the light quantity Lw of the incident light,
That is, when the fluctuation of the light amount of the light emitted from the Y fixing fluorescent lamp 42 is taken into consideration, the incident light at each time when the target density Dt is determined and when the light amount Lp of the reflected light of the test pattern is detected. It is necessary to know the light amount Lw of the incident light, but when calculating ΔD, it is sufficient to know their ratio, and instead of the light amount Lw of the incident light, the reflected light when the incident light is reflected by the same color paper is used. Light quantity can be substituted. Therefore, for example, immediately before or immediately after detecting the amount of light Lp of the reflected light of the test pattern, the Y fixing fluorescent lamp 42 and the HP sensor 40 are applied to the reference paper of a certain color similarly to the case of detecting the reflected light of the test pattern. And the amount of reflected light emitted from the Y fixing fluorescent lamp 42 and reflected by the reference paper is detected by the light receiving sensor 40B of the HP sensor 40, and the amount of reflected light obtained by this is detected. The light quantity Lw of the incident light of the above equation (1) can be used. However, the target density Dt must be determined on the assumption that the density Dp of the test pattern is substituted for the quantity of light reflected by the reference paper into the value of the quantity of light Lw of the incident light in the above equation (1). is there.

The color of the reference paper may be, for example, white or a color that reflects a wavelength that can be detected by the light receiving sensor 40B among the wavelengths of the light output from the Y fixing fluorescent lamp 42. In this case, for example, a white background portion of the print paper on which the test pattern is printed, on which the test pattern is not printed, can be used. Further, if a reference paper of a different color from the reference paper assumed when determining the target density Dt is used for the measurement when detecting the density Dp of the test pattern, the user can intentionally adjust the print density. it can.

Also, as described above, the variation of the Y fixing fluorescent lamp 42 is not taken into account by substituting the quantity of the reflected light reflected by the reference paper into the quantity of the incident light Lw of the above equation (1). Alternatively, the sensitivity of the light receiving sensor 40B may be calibrated so that the amount of light reflected by the reference paper is always constant. That is, when light is emitted from the Y fixing fluorescent lamp 42 and reflected light reflected by the reference paper is detected by the light receiving sensor 40B, the light receiving sensor 40B
A predetermined reference value S ₀ is determined in advance for the value of the detection signal output from. When calibrating the sensitivity of the light receiving sensor 40B, the reference paper is fed between the HP sensor 40 and the Y fixing fluorescent lamp 42 of the reflected light, and the reflected light reflected by the reference paper is sent from the light receiving sensor 40B. obtaining a value S ₁ of the detection signal output. Then, a ratio S ₁ / S ₀ between the value S ₁ obtained at this time and the above-mentioned reference value S ₀ is obtained, and the ratio S ₁ / S ₀ is subsequently added to the detection signal output from the light receiving sensor 40B.
₁ / S ₀ and multiply this value by the light receiving sensor 40
The light amount detected in B is assumed. Thus, when calculating the density of the test pattern, the reference value S ₀ is substituted into the value of the light quantity Lw of the incident light of the above equation (1) regardless of the fluctuation of the light quantity emitted from the Y fixing fluorescent lamp 42. You can do it. The calibration of the sensitivity of the light receiving sensor 40B may be performed in the sensor calibration mode irrespective of the detection of the sensitivity characteristic of the print paper, or may be performed whenever the density of the test pattern is obtained. Good.

When calibration of the light amount Lw of the incident light or the sensitivity of the sensor is performed using the reference paper as described above, a predetermined determination mark is provided on the reference paper, and the determination mark is determined. Alternatively, the system controller 10 may automatically recognize that the reference paper has been fed. When it is recognized that the reference paper has been fed, the mode is automatically switched to the detection mode of the sensitivity characteristic of the print paper or the sensor calibration mode, so that the user does not need to set the mode, which is convenient.

When the fluctuation of the light amount Lw of the incident light is considered, the absolute light amount change of the light amount emitted from the Y fixing fluorescent lamp 42 can be detected in real time. The value of the light amount Lw of light may be corrected. The density difference ΔD between the density Dp of the test pattern and the target density Dt obtained as described above indicates the sensitivity characteristics of the print paper on which the test pattern is printed (and the characteristics of the thermal head 36 and the like). When a normal print image is printed, a control amount affecting the print density is corrected by a method described later so that the density difference ΔD becomes 0, and the print density is corrected.

An example of the procedure for detecting the sensitivity characteristics of the print paper described above will be described with reference to the flowchart of FIG. In this detection procedure, the method using the above-described reference paper is adopted, and a white background portion of the print paper is used as the reference paper. When the start of the sensitivity correction is instructed by a predetermined operation button of the operation unit 16 shown in FIG. 1, the system controller 10 sets the fixed gradation value, that is, the printing gradation value of each of Y, M, and C to 128. The generated test pattern is generated, and the test pattern is stored in the memory 22 of FIG. Then, the test pattern stored in the memory 22 is printed on print paper by a normal printing sequence (step S50). When the printing of the test pattern is completed, the density measurement sequence starts without discharging the print paper.

When entering the density measurement sequence, the system controller 10 turns on the Y fixing fluorescent lamp 42 (step S52).
The white background portion of the print paper on which the test pattern is not printed is transported between the Y fixing fluorescent lamp 42 and the HP sensor 40 (step S54). Then, the reflected light emitted from the Y fixing fluorescent lamp 42 and reflected on the white background portion of the print paper is reflected by the light receiving sensor 4 of the HP sensor 40.
0B, and the signal value at this time is set as Lw in the above equation (1) (step S56). When the light amount Lw of the incident light is set to a fixed value as described above, this step S
Steps S54 and S56 are unnecessary.

Next, the printed portion of the test pattern is transported between the Y fixing fluorescent lamp 42 and the HP sensor 40 (step S58). The reflected light emitted from the Y fixing fluorescent lamp 42 and reflected by the test pattern of the print paper is detected by the light receiving sensor 40B of the HP sensor 40, and the signal value at this time is defined as Lp in the above equation (1). (Step S60).

Lw and Lp obtained as described above are calculated by the above equation (1).
And the density Dp is calculated. And its density Dp
A density difference ΔD = Dp−Dt between the target density Dt and the target density Dt is obtained and stored in a memory in the system controller 10 (step S62). As described above, the detection of the sensitivity characteristic of the print paper is completed, the fact that the normal print operation is enabled is displayed on the LCD 26 and the like in FIG. 1, and the input of the next print instruction is awaited.

In the detection of the density Dp, the light receiving sensor 40B of the HP sensor 40 for detecting the presence or absence of print paper is also used, but other light receiving means (for example, a type for determining the type of print paper) is provided to the printing apparatus. In the case where an object or a bar code is read, the light receiving means may be used for detecting the density Dp.

Next, a method of correcting the print density based on the density difference ΔD when printing a normal print image will be described. First, as a first embodiment, a case where the print density is corrected by correcting the drive reference voltage of the thermal head 36 shown in FIG.
This will be described with reference to the system diagram of FIG. When detecting the density difference ΔD based on the test pattern, the system controller 10 gives the density difference ΔD (block 100 in the figure) to the correction voltage conversion unit 102. Correction voltage converter 102
Calculates the correction value (correction voltage) of the drive reference voltage of the thermal head 36 for setting the density difference ΔD to 0 when the density difference ΔD is given, and calculates the correction voltage (block 10 in the figure).
4) is output. The drive reference voltage of the thermal head 36 is a reference voltage applied to each heating element. By changing the drive reference voltage, the amount of heat applied to the print paper increases or decreases. The correction value of the drive reference voltage is associated in advance with the density difference ΔD input as shown in FIG. 11. For example, when the density difference ΔD is 0.1, the density Dp of the test pattern is the target density. D
Since it is larger than t, the drive reference voltage of the thermal head 36 is reduced by 0.5V. Note that the correction voltage converter 102
May be performed by any of the system controller 10, the print controller 28, the head drive circuit 30, and the like, or may be performed by another arithmetic circuit. Further, the correction value may be obtained by calculation or by a look-up table.

The correction voltage (block 104 in the figure) output from the correction voltage converter 102 is added to the drive reference voltage (block 106 in the figure) of the thermal head 36 in the head drive circuit 30 in FIG. The corrected drive reference voltage of the thermal head 36 (block 10 in the figure)
8) controls the thermal head 36. As a result, the amount of heat applied to the print paper from each heating element of the thermal head 36 is corrected according to the sensitivity characteristics of the print paper, and the density appropriately corresponding to the print gradation values of each of the colors Y, M, and C based on the image data. Is printed on print paper.

Next, as a second embodiment of the method for correcting the print density based on the density difference ΔD, a case in which the print density is corrected by correcting the energizing time of the thermal head 36 as shown in FIG. This will be described with reference to the drawings. When the system controller 10 detects the density difference ΔD from the test pattern, it provides the density difference ΔD (block 120 in the figure) to the correction energization time conversion unit 122. When the density difference ΔD is given, the correction energization time conversion unit 122 corrects the energization time (pulse width) of the voltage applied to each heating element of the thermal head 36 to make the density difference ΔD zero (correction energization). ), And outputs the corrected energization time (block 124 in the figure). The energization time of the thermal head 36 is a control amount when controlling the amount of heat applied to the print paper by each heating element of the thermal head 36 according to the printing gradation value, and the correction amount is as shown in FIG. The input density difference ΔD is associated in advance. Note that the processing in the correction energization time conversion unit 122 may be performed by any of the system controller 10, the print controller 28, the head drive circuit 30, and the like, or may be performed by another arithmetic circuit. Further, the correction value may be obtained by calculation or by a look-up table.

The correction energization time (block 124 in the figure) output from the correction energization time converter 122 is determined by the heat generation of the thermal head 36 determined by the head drive circuit 30 in FIG. It is added to the energizing time of the element, and the corrected energizing time after this addition (block 12
By 8), each heating element of the thermal head 36 is controlled. Thereby, the amount of heat given to the print paper from each heating element of the thermal head 36 is corrected according to the sensitivity characteristics of the print paper, and Y,
An image having a density appropriately corresponding to the print gradation value of each of the colors M and C is printed on print paper.

Next, as a third embodiment of the method of correcting the print density based on the density difference ΔD, the print density is corrected by correcting the gradation value based on the image data of the image to be printed. Will be described with reference to the system diagram of FIG. When the system controller 10 detects the density difference ΔD based on the test pattern, the system controller 10 converts the density difference ΔD (block 140 in the figure) into the corrected gradation value conversion unit 14.
Give to 2. Given the density difference ΔD, the correction gradation value conversion unit 142 obtains a correction value (correction gradation value) of the print gradation value for setting the density difference ΔD to 0, and obtains the correction gradation value (FIG. The middle block 144) is output. The print gradation value is a control amount for controlling the amount of heat applied to the print paper, and is generated by the print controller 28 of FIG. 1 for each of the colors Y, M, and C based on the image data of the image to be printed. The correction value of the print gradation value is associated in advance with the input density difference ΔD as shown in FIG. The processing in the correction gradation conversion unit 142 may be performed by any of the system controller 10, the print controller 28, and the like, or may be performed by another arithmetic circuit. Further, the correction value may be obtained by calculation or by a look-up table.

The corrected tone value (block 144 in the figure) output from the corrected tone value conversion unit 142 is added to the print tone value (block 146 in the figure) generated by the print controller 28. The thermal head 3 based on the corrected print gradation value (block 148 in the figure)
6 are controlled (however, if the corrected print gradation value exceeds the range of 0 to 255, the negative value is 0).
And 256 or more are clipped to 255). As a result, the amount of heat applied to the print paper from each heating element of the thermal head 36 is corrected according to the sensitivity characteristics of the print paper, and the density appropriately corresponding to the print gradation values of each of the colors Y, M, and C based on the image data. Is printed on print paper.

As described above, in the above-described embodiment, in the density detection of the test pattern printed on the print paper,
The fixing fluorescent lamp 42 is used as a light source, and the reflected light of the test pattern is detected by the light receiving sensor 40B of the HP sensor 40. Instead of using the Y fixing fluorescent lamp 42 as a light source, an M fixing fluorescent lamp 44 is used. The light source may be used, or the light emitting LED 40A of the HP sensor 40 may be used as the light source. When the light emitting LED 40A of the HP sensor 40 is used as a light source, the wavelength range of the light emitted from the light emitting LED 40A and the wavelength range of the light that can be received by the light receiving sensor 40B are the density of the test pattern of the print paper. A light-emitting LED and a light-receiving sensor having characteristics suitable for detection may be used. In this case, the configuration is as shown in FIG. 3 and no special configuration change is required.

In the above-described embodiment, gray is used as the test pattern with the print gradation value of each color of Y, M, and C being 128. However, the present invention is not limited to this. Any color may be used as long as the ratio (reflectance) of the reflected light reflected by the test pattern changes depending on the density of the test pattern. For example, since the main component of the wavelength of the light emitted from the Y fixing fluorescent lamp 42 is blue, a Y-color test pattern having a predetermined gradation value may be printed.

Further, in the above-described embodiment, the description has been made assuming that the print density is corrected for variations in the sensitivity and the like of the print paper used for printing. However, the present invention is applied to a mechanical adjustment step in the manufacture of a printing apparatus. Can also be applied. In particular, if the print density is corrected once and then the sequence is repeated again to repeat the same process, automatic convergence can be achieved, and the number of man-hours can be reduced.

[0072]

As described above, according to the printing apparatus of the present invention, a test pattern of a predetermined shape composed of colors of a predetermined print gradation value is printed on photographic paper in the same manner as a print of a normal image. Since the density of the test pattern is measured using the light receiving means and light source used for normal image printing, and the print density is corrected based on this, special measuring equipment such as a densitometer is not required. This makes it possible to automatically adjust the print density without increasing the cost, and it is possible to appropriately prevent a change in the density due to a change in characteristics over time of the photographic paper or the printing apparatus or a variation in the characteristics at the time of manufacture.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a printing apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a print paper used in the printing apparatus according to the present invention.

FIG. 3 shows a printing apparatus according to the present invention;
FIG. 4 is a layout diagram illustrating an embodiment of a member layout of a print processing unit in which a process of coloring and fixing a print paper is executed.

FIG. 4 is a diagram showing a configuration of a home position sensor.

FIG. 5 is a flowchart illustrating an outline of a processing procedure when printing a required print image on print paper;

FIG. 6 is a layout diagram illustrating a configuration of a detection unit that detects a sensitivity characteristic of print paper.

FIG. 7 is a diagram illustrating an example of an emission spectrum of a Y fixing fluorescent lamp.

FIG. 8 is a diagram illustrating an example of a spectral sensitivity characteristic of a light receiving sensor.

FIG. 9 is a flowchart illustrating an example of a procedure for detecting the sensitivity characteristic of print paper.

FIG. 10 is a system diagram showing a system in which print density is corrected by correcting a drive reference voltage of a thermal head.

FIG. 11 is a diagram illustrating a correction amount of a thermal head driving reference voltage with respect to a density difference ΔD.

FIG. 12 is a system diagram illustrating a system in a case where correction of print density is performed by correcting a power-on time of a thermal head.

FIG. 13 is a diagram illustrating a correction amount of a thermal head energizing time with respect to a density difference ΔD.

FIG. 14 is a system diagram illustrating a system in which a print density is corrected by correcting a print gradation value based on image data of an image to be printed;

FIG. 15 is a diagram illustrating a correction value of a print gradation value with respect to a density difference ΔD.

[Explanation of symbols]

10 system controller, 20 memory controller, 22 memory, 28 print controller, 30
... Head drive circuit, 32 ... Paper transport controller, 34 ...
Fixing controller, 36: thermal head, 38: capstan roller, 40: home position (HP) sensor, 4
2 ... Y fixing fluorescent lamp, 44 ... M fixing fluorescent lamp

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Fukuda 3-11-46 Izumi, Asaka-shi, Saitama Prefecture Inside Fujisha Shin Film Co., Ltd. (72) Hiroyuki Matsukawa 3-11-46 Izumi, Asaka-shi, Saitama Prefecture Inside Fujisha Shin Film Co., Ltd. (72) Inventor Satoshi Ikeya 3-1-146 Izumi, Asaka-shi, Saitama Prefecture Inside Fujisha Shin Film Co., Ltd. (72) Hiroyuki Iwasaki 3-1-146 Izumi, Asaka-shi, Saitama Prefecture F-term in Fujisha Shin Film Co., Ltd. (reference) 2C061 AQ04 AS14 HK11 KK03 KK25 KK32 2C066 AA03 AD03 CD03 CD06 CD14 CD16 CZ06

Claims (9)

[Claims] And a printing means for printing a desired image on a printing paper which develops colors of different densities in accordance with the amount of heat applied thereto and fixes the color development state when irradiated with light of a predetermined wavelength. A printing apparatus comprising: a light receiving unit for detecting the printing paper; and a light source for irradiating the printing paper with light for fixing, wherein a test of a predetermined shape including a color having a predetermined printing gradation value is performed. A test pattern printing means for printing a pattern on the printing paper by the printing means, and irradiating light from the light source to the test pattern printed on the printing paper by the test pattern printing means, and being reflected by the test pattern. Density detecting means for receiving the light received by the light receiving means and detecting the density of the color of the test pattern printed on the printing paper; and detecting the density by the density detecting means. The print gradation value based on the image data of the image to be printed by the printing means, so that the density of the color of the test pattern matches the target density corresponding to the print gradation value of the color of the test pattern. And a density correcting means for correcting the amount of heat to be added to the photographic paper. 2. A printing means for printing a desired image on a printing paper which develops colors of different densities in accordance with the amount of heat applied and which fixes the color development state when irradiated with light of a predetermined wavelength. A light receiving unit and a light source for detecting the photographic paper,
A test pattern printing means for printing a test pattern of a predetermined shape comprising a color of a predetermined printing gradation value on the printing paper by the printing means; and a printing paper by the test pattern printing means. A density that irradiates the test pattern printed on the light source with light from the light source, receives the light reflected by the test pattern by the light receiving unit, and detects the color density of the test pattern printed on the printing paper. Detecting means, and printing by the printing means so that the density of the color of the test pattern detected by the density detecting means matches the target density corresponding to the printing gradation value of the color of the test pattern. Density correction for correcting the amount of heat to be added to the photographic paper with respect to the print gradation value based on the image data of the image Printing apparatus characterized by comprising: a stage, a. 3. The method according to claim 2, wherein the density correction unit corrects the amount of heat to be applied to the photographic paper by changing a voltage at which the photographic unit generates the amount of heat to be applied to the photographic paper. Item 1. The printing device according to Item 1 or 2. 4. The method according to claim 1, wherein the density correction means corrects the amount of heat to be applied to the photographic paper by changing the energization time of a voltage for generating the amount of heat to be applied to the photographic paper in the photographic means. 3. The printing apparatus according to claim 1, wherein: 5. The method according to claim 1, wherein the density correction unit corrects the amount of heat to be added to the printing paper by changing a printing gradation value based on image data of an image to be printed by the printing unit. The printing apparatus according to claim 1. 6. The density detecting means sets a color density of the test pattern printed on the photographic paper to a light amount Lw of light incident on the test pattern printed on the photographic paper from the light source. The light amount of reflected light reflected by the test pattern and detected by the light receiving means is defined as Lp, and is calculated by the following equation: Dp = −log ₁₀ (Lp / Lw). Printing equipment. 7. The printing apparatus according to claim 6, wherein said density detecting means sets a light amount Lw of said incident light to a fixed value. 8. The density detecting means irradiates light from the light source to a reference paper of a predetermined color and receives the light reflected by the reference paper by the light receiving means to determine a light receiving amount. 7. The printing apparatus according to claim 6, wherein the amount of emitted light is Lw. 9. The density detecting unit irradiates light from the light source to a reference paper of a predetermined color and receives a light reflected by the reference paper by the light receiving unit, and a light receiving amount is constant. 3. The printing apparatus according to claim 1, wherein the sensitivity of said light receiving means is calibrated.