JP2001260406A - Method of correcting sensitivity or density of printer and thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of correcting a sensitivity or a density of a printer wherein a sensitivity change with time and by a moisture content is corrected thereby preventing a density from changing and a color balance from worsening, and a thermal printer. SOLUTION: When a paper feed cassette is mounted, a production date of the year, month and day of a recording paper and sensitivity information of each color are read out from a bar code of a recording paper package by a bar code scanner 40. A controller 72 calculates the number of days having passed after the package was opened based on a date when the paper feed cassette was set and the present date, and reads out a sensitivity correction coefficient for each of Y, M and C corresponding to the number of days, season information and region information from a sensitivity correction LUT 82 for the change by the moisture content. Moreover, the controller calculates the number of days having passed after the recording paper was produced on the basis of the present date and the production date of the recording paper, and reads out a sensitivity correction coefficient for each of Y, M and C corresponding to the number of days from a sensitivity correction LUT 81 for the change with time. The controller 72 adds both sensitivity correction coefficients for each of Y, M and C, obtains a synthetic sensitivity correction coefficient, multiplies the synthetic sensitivity correction coefficient by a sensitivity of the read recording paper and obtains an actual sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the sensitivity or density of a printer for recording an image having no density fluctuation even if the sensitivity of recording paper fluctuates with time or moisture content, and to a thermal printer.

[0002]

2. Description of the Related Art For example, a color thermal printer uses a color thermal recording material in which a magenta coloring layer, a cyan coloring layer, and a yellow coloring layer are sequentially formed on a support. This color thermosensitive recording material develops a color when heated by a thermal head. In order to selectively color each thermosensitive coloring layer, its coloring heat energy is different,
A deeper thermosensitive coloring layer requires higher coloring heat energy. Also, when the next heat-sensitive coloring layer is thermally recorded, the heat-fixed heat-sensitive coloring layer is irradiated with a specific electromagnetic wave so as to prevent the heat-sensitive coloring layer therefrom from being recorded again. Is performed.

On the other hand, thermosensitive recording paper records color sensitivity information in a bar code. The barcode sensor installed in the printer controls the driving of the thermal head by reading the sensitivity information, and applies heat energy according to the sensitivity to the thermal recording paper, so that the same color density is obtained even if the sensitivity changes. Thermal printers are known (Japanese Unexamined Patent Application Publication No.
-286160).

[0004]

The heat-sensitive recording paper has a uniform coloring sensitivity at the time of shipment, but the coloring sensitivity changes with the lapse of time and fluctuations in the water content from the time of manufacture. Therefore, even if the thermal energy applied to the thermosensitive recording paper is controlled in accordance with the read color development sensitivity, there is a problem that a color density faithful to image data cannot be obtained. In particular, in the color thermosensitive recording paper, since the change in the color development sensitivity differs depending on the color thermosensitive layer, there is a disadvantage that the color balance of the recorded image is lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sensitivity or density correction method for a printer and a thermal printer, which correct the sensitivity fluctuation due to aging or moisture content to prevent the density fluctuation and color balance deterioration.

[0006]

In order to achieve the above object, a sensitivity correction method according to the present invention is directed to a method for correcting an image on a recording sheet on which at least date information and sensitivity information at the time of manufacture are recorded on a storage member or a core. In the printer which records the date, the date information and the sensitivity information at the time of manufacture are read, the elapsed time from the time of manufacture of the recording paper is calculated by the date information at the time of manufacture and the current date, and the sensitivity changed by the elapsed time is calculated. It is to be corrected.

[0007] Sensitivity information is recorded on a storage section for accommodating the recording paper of the cut sheet in a removable manner or on a winding core on which a long recording paper is wound. In a printer that sets this cassette in a printer and records images on recording paper,
It measures the elapsed time since the cassette in which the new recording paper has been transferred is set in the printer, and corrects the change in sensitivity due to the fluctuation in the water content of the recording paper with respect to this elapsed time.

Further, in a printer for recording an image on a recording sheet having at least date information and sensitivity information at the time of manufacture recorded on a storage member or a winding core, the date information and sensitivity information at the time of manufacture are read, The elapsed time from the time of production of the recording paper is calculated based on the date information of the time and the current date, and the sensitivity is corrected using a comparison table indicating a change in sensitivity with respect to the elapsed time.

In addition, sensitivity information is recorded on a storage portion for accommodating a cut sheet of recording paper so as to be taken out or on a winding core on which a long recording sheet is wound. In a printer that sets this cassette in a printer and records images on recording paper,
The elapsed time from setting the cassette in which the new recording paper was transferred to the printer was measured, and the read sensitivity was measured using a control table showing the change in sensitivity due to fluctuations in the water content of the recording paper with respect to this elapsed time. It is to be corrected.

The comparison table is provided for each region and season in which the printer is used. Further, the recording paper is a color thermosensitive recording paper formed with a plurality of thermosensitive coloring layers, each of which has a different color, and the control table is provided for each thermosensitive coloring layer.

[0011] The thermal printer of the present invention is a thermal printer for thermally recording an image with a thermal head on a thermal recording paper on which at least date information and color sensitivity information at the time of manufacture are recorded on a storage member or a core. A reading means for reading date information and color sensitivity information at the time, a calendar for generating date information at the time of printing, and a comparison table representing a relationship between an elapsed time from manufacturing to printing and a change in color sensitivity are stored. The storage means, the elapsed time from the time of manufacture to the time of printing is obtained from the date information at the time of manufacture and the date information at the time of printing, a change in color sensitivity corresponding to the elapsed time is obtained from a comparison table, and the color sensitivity is calculated. And control means for controlling the voltage applied to the thermal head or the energizing time according to the change.

In addition, sensitivity information is recorded on a storage section for removably storing the thermal recording paper of the cut sheet or on a winding core on which a long thermal recording paper is wound, and the moisture-proof bag is opened to open the recording paper. Is transferred to a cassette, the cassette is set, and an image is thermally recorded on a thermal recording paper by a thermal head. In the thermal printer, reading means for reading the color sensitivity information and a cassette containing new recording paper are set in the printer. Measurement means for measuring the elapsed time from the current time to the present, and a comparison table showing the relationship between the elapsed time with the recording paper stored in the cassette and the change in color sensitivity caused by fluctuations in the moisture content of the thermal recording paper. Based on the elapsed time measured by the measuring means, a corresponding change in color sensitivity is obtained from a reference table, and a mark on the thermal head is printed in accordance with the change. It is made of a control means for controlling the voltage or current time.

The reference table is provided for each printer use condition such as region, season, etc., and is selected by the printer use condition input means. Further, the thermosensitive recording paper is composed of a plurality of thermosensitive coloring layers, each of which has a different color, and the reference table is provided for each thermosensitive coloring layer.

Further, sensitivity information is recorded on a storage section for accommodating the thermal recording paper of the cut sheet in a removable manner or on a core for winding a long thermal recording paper, and the moisture-proof bag is opened to open the recording paper. In a thermal printer for setting the cassette and thermally recording an image on a thermal recording paper with a thermal head, reading means for reading the date information at the time of manufacture and the color development sensitivity information, and date information at the time of printing. , A measuring means for measuring the elapsed time from the time when the cassette containing the new recording paper is set in the printer to the present, and a first means representing the relationship between the elapsed time from the time of manufacture and the change in color sensitivity. A control table, and a second table showing the relationship between the elapsed time when the moisture-proof bag is opened and kept in the cassette and the change in color sensitivity caused by a change in the moisture content of the thermal recording paper. The elapsed time from the time of manufacture to the time of printing is obtained from the control table and the date information at the time of manufacture and the date information at the time of printing, and the first change amount of the color sensitivity corresponding to the elapsed time is obtained from the first control table. At the same time, a second change amount corresponding to the elapsed time measured by the measuring means is obtained from the second control table, and a combined change amount of the coloring sensitivity is obtained from the first change amount and the second change amount. And control means for controlling the voltage applied to the thermal head or the energization time in accordance with

The second comparison table is provided for each printer use condition such as region, season, etc., and is used to select a comparison table by printer use condition input means. Further, the thermosensitive recording paper is composed of a plurality of thermosensitive coloring layers having different colors, and the first and second comparison tables are provided for each thermosensitive coloring layer.

According to the density correction method of the present invention, in a printer which is used by opening a moisture-proof bag and prints an image on a recording paper having date information of manufacture recorded on a storage member or a core, the date information is stored in a printer. It reads the current date and examines the number of days elapsed from the current date, uses a reference table showing the change in recording density with respect to the number of days elapsed, finds the change in recording density, and corrects this density change during image recording. is there.

[0017]

FIG. 2 is a bottom view of a recording paper package used in a color thermal printer (hereinafter referred to as a thermal printer). In FIG. 2, a recording paper package 10 includes a color thermal recording paper (paper) in a paper package 11. (Hereinafter referred to as recording paper) 12
A plurality of, for example, 20 sheets are stacked, and are commercially available in a state of being stored in a moisture-proof light-shielding bag (not shown). The recording paper 12
As is well known, a cyan thermosensitive coloring layer is provided on the recording surface side of the support,
A magenta thermosensitive coloring layer and a yellow thermosensitive coloring layer are sequentially provided. The yellow thermosensitive coloring layer, which is the uppermost layer, has a high thermal sensitivity and develops yellow with small heat energy. The cyan thermosensitive coloring layer, which is the lowermost layer, has the lowest thermal sensitivity and develops cyan when a large amount of thermal energy is applied. Further, the yellow thermosensitive coloring layer loses its coloring ability when irradiated with near-ultraviolet rays of 420 nm. The magenta thermosensitive coloring layer loses its coloring ability when irradiated with 365 nm ultraviolet rays.

The package 11 is composed of a thin rectangular tubular sheath 13 and a drawer 14 inserted therein. The drawer section 14 is provided with an upper piece 14a (see FIG. 4) and a bottom piece 14b, which are formed by bending a sheet. On the bottom side 14b, a plurality of recording papers 1
2 is placed with the recording side down and the top piece 14
a is superimposed on the uppermost recording paper 12. Sheath part 1
3, a roller insertion opening 13a is formed in the upper surface on the front side of the sheet feeding roller 42 (see FIG. 4), and a push-up plate 30 (FIG. 4) for lifting the bottom piece 14b is formed on the lower surface.
(See FIG. 3) is formed therein.

A bar code seal 16 on which a bar code 15 representing recording paper information is printed is attached to the outer surface of the sheath portion 13. The recording paper information includes the date of manufacture of the recording paper 12, the sensitivity of each thermosensitive coloring layer, the type of recording paper, the production lot number, and the like.

As shown in FIGS. 3 and 4, the paper feed cassette 20 into which the recording paper package 10 is loaded is composed of a cassette body 21 and a lid 22, and is formed in a thin box shape as a whole. . The lid 22 is rotatably attached to the cassette body 21 via an attachment shaft 23. Lid 22
In the closed position, the lid 22 is locked to the cassette body 21 by the locking claws 24 and 25 being locked. Further, when the operation plate 26 is pressed, the locking of the locking claws 24 and 25 is released, and the lid 22 can be opened.

The upper surface of the lid 22 also serves as a paper discharge tray.
For this reason, the lid 22 is provided with a pair of recording paper guides 27 and a stopper 28 protruding. The pair of recording paper guides 27 guides both sides of the recording paper 12,
The cover 22 is formed long along the long side. Stopper 2
Numeral 8 locks the leading end of the recording paper 12 to prevent the recording paper 12 from dropping off the lid 22.

A pair of roller openings 22a into which the paper feed roller 42 enters are formed near the end of the lid 22 on the side of the mounting shaft 23. With the lid 22 closed, a gap is formed between the cassette body 21 and the lid 22 near the mounting shaft 23. The gap forms a paper feed port 29.

A push-up plate 30 is arranged on the inner bottom of the cassette body 21. The push-up plate 30 is rotatably mounted via a mounting shaft 31 and is urged upward by a coil spring 32. The push-up plate 30 is formed such that the mounting shaft 23 side of the lid 22 is narrow, and
3b to push up the bottom piece 14b upward,
Is pressed against the feed roller 42.

A rectangular opening 33 is formed in the bottom of the cassette body 21 on the side wall 21a side at a position not blocked by the push-up plate 30, and a transparent resin plate 34 is fitted into the opening 33. Recording paper package 1 in paper cassette 20
When 0 is loaded, the barcode seal 16 faces the resin plate 34. When the paper cassette 20 is inserted into the cassette storage room 38 of the thermal printer, a barcode scanner 40 installed under the floor of the cassette storage room 38 reads the barcode 15 on the barcode seal 16 through the resin plate 34.

Above the cassette storage chamber 38, a pair of paper feed rollers 42 is rotatably mounted on a roller holding arm 43. The roller holding arm 43 is retracted upward by a rotation of the gear 44 fixed to one end of the roller holding arm 43 to a sheet feeding position (indicated by a two-dot chain line in FIG. 4) where the sheet feeding roller 41 contacts the uppermost recording sheet 12 Between the retracted positions. At the sheet feeding position, the sheet feeding roller 42 enters the roller opening 22 a of the lid 22. Recording paper 1 in paper cassette 20
2 is urged upward by the push-up plate 30, so that the uppermost recording paper 12 always contacts the paper feed roller 42. The paper feed roller 42 rotates in the paper feeding direction during printing, and sends out only the uppermost recording paper 12 from the recording paper package 10 and feeds it to the print position of the thermal printer.

At the back of the cassette storage space 38, when the paper feed cassette 20 is loaded into the cassette storage space 38, the cover 22 is closed.
A movable portion 45a of a cassette detection switch 45 (see FIG. 1) for detecting the presence or absence of the sheet cassette 20 is attached. Above the paper feed roller 42, a paper discharge roller 48 for discharging the recorded recording paper 12 from the discharge port 47 to the outside is provided.

In FIG. 5 showing the structure of the thermal printer,
A paper feed path 51 is provided at the back of the cassette storage chamber 38, and a print path 52 is provided to be connected to the paper feed path 51. A print path 52 is provided above the sheet supply path 51.
A paper discharge passage 53 extending from the printer to the discharge port 47 is provided.

The print path 52 is provided with a feed roller pair 55 for feeding the recording paper 12 fed by the paper feed roller 42 in a paper feed direction indicated by an arrow α or a print direction indicated by an arrow β. An optical fixing device 56 and a recording paper sensor 57 are arranged in this order upstream of the feed roller pair 55 in the paper feeding direction α. A thermal head 58 and a platen roller 59 are disposed downstream of the feed roller pair 55 in the paper feeding direction α. This platen roller 5
Reference numeral 9 denotes a displacement between a recording position where the recording paper 12 is pressed against the heating element array 60 of the thermal head 58 and a retracted position away from the heating element array 60.

The light fixing unit 56 emits near-ultraviolet rays of 420 nm to the recording paper 12 to fix the yellow thermosensitive coloring layer, and a yellow ultraviolet lamp 56a for radiating near-ultraviolet rays of 365 nm to the recording paper 12 to produce magenta thermosensitive coloring. It comprises a magenta ultraviolet lamp 56b for fixing the layer, and a reflector 56c provided behind these to increase the irradiation efficiency.

In FIG. 1 showing the electrical configuration of the thermal printer, one frame of image data is written in the frame memory 65 in a state where the image data is separated for each color. At the time of printing, the image data of the color to be printed is read line by line from the frame memory 65 and is read out from the line memory 6.
6 is written. The image data in the line memory 66 is read out for each pixel and sent to the comparator 67.

To the comparator 67, a gradation data generation circuit 68 is connected. The gradation data generating circuit 68 generates gradation data (comparison data) and sends it to the comparator 67. The comparator 67 compares the image data of each pixel with the gradation data, and outputs a signal of “1” when the image data is larger, and outputs a signal of “0” when the image data is smaller. As a result, drive data indicating whether active or non-active from the “0” gradation to the “N” gradation is sent to the thermal head 58.

The gradation data generation circuit 68 is, for example, 256
In the case of gradation, gradation data "0" to "FF" are generated in order in hexadecimal. When the gradation data of “0” is sent from the gradation data generation circuit 68, the comparator 67 sequentially compares the image data of each pixel with the gradation data. As a result, the comparison result for one line is output from the comparator 67 as a serial signal and sent to the shift register 71. When the comparison of the image data for one line is completed, the gradation data generation circuit 68 generates the gradation data of “1” and sends it to the comparator 67. Therefore,
By using the gradation data “0” to “FF”, the image data of each pixel is compared 256 times and converted into 256-bit drive data. The 256-bit drive data is sent to the shift register 71 in 256 times.

The serial drive data is sent to the controller 7
The data is shifted in the shift register 71 by the clock from the second and converted into a parallel signal. Shift register 7
The drive data converted into the parallel signal in 1 is latched by the latch array 73 in synchronization with the latch signal.

When a strobe signal is input from the controller 72, the AND gate array 74 outputs an "H" signal when the input drive signal is "1". These AND gate array 74 and latch array 7
3 is that a circuit element is provided for each pixel.

The transistors 75a to 75n are connected to the output terminals of the AND gate array 74, respectively. When the output signal is "H", the transistors are turned on. The heating elements 60a to 60n of the heating element array 60 are connected in series to these transistors 75a to 75n. Resistance elements are used as the heating elements 60a to 60n.

A voltage control circuit 78 is connected to the heating elements 60a to 60n via a selector 77. The voltage control circuit 78 includes a rectifier circuit, a voltage stabilizing circuit, and the like, outputs a voltage corresponding to each sensitivity value, and the selector 77 extracts a voltage corresponding to the sensitivity value. The controller 72 corrects the sensitivity based on the coefficient obtained from the time-dependent sensitivity correction LUT 81 and the moisture content variation sensitivity correction LUT 82, and generates the heating elements 60a to 60n via the selector 77 according to the corrected sensitivity. The applied voltage applied to is switched.

The controller 72 is connected to a calendar device 83 for referring to the date of use. The calendar device 83 has, for example, a backup battery so that the operation is continued even when the thermal printer is turned off. In the standby state where the AC outlet of the thermal printer is inserted, a small amount of current is always supplied to the calendar device 83 from the AC power supply of the thermal printer, regardless of whether the power switch of the thermal printer is on or off, instead of the backup battery power supply. May be performed.

The time-dependent sensitivity correction LUT 81 is based on the time elapsed from the time of manufacture (the number of days elapsed in this embodiment).
The sensitivity of each of the thermosensitive coloring layers of yellow (Y), magenta (M), and cyan (C) is determined by an experiment (see FIG. 6). As shown in Table 1 below, correction coefficients for correcting the sensitivities of Y, M, and C according to the number of days elapsed from the date of manufacture (hereinafter referred to as “number of days elapsed after manufacture”) are stored. FIG. 6 shows only the sensitivity correction coefficient of the yellow thermosensitive coloring layer as a representative.

[0039]

[Table 1]

As shown in FIG. 7, the sensitivity of the recording paper 12 also varies depending on the water content of the recording paper 12. The moisture content of the recording paper 12 changes according to the elapsed time (in the present embodiment, in days, hereinafter referred to as “open elapsed days”) after the recording paper 12 is taken out of the moisture-proof bag and placed in the paper feeding cassette 20. . Further, since it varies depending on the region and the season, as shown in the following Table 2, the sensitivity correction LUT for moisture content fluctuation Y, M, C according to the region information (prefecture name), the season information, and the number of days elapsed after opening. Are stored.
FIG. 7 shows only the sensitivity correction coefficient of the yellow thermosensitive coloring layer as a representative. The regional information is an example of a domestic region, but may be a northern or southern hemisphere, a foreign name, a city name, or the like.

The controller 72 is connected to an input operation section 84 for inputting area information to the thermal printer. The season information is automatically set from the date information from the calendar device 83. The area information and the season information are stored in the flash memory 85 connected to the controller 72, and are maintained until they are rewritten next. In addition to the flash memory 85, a work memory 86 used for various task processes is connected to the controller 72. For the work memory 86, an SRAM or the like having a high access speed is used.

[0042]

[Table 2]

The recording paper 12 is immediately put into the paper feed cassette 20 after the moisture-proof bag is opened and taken out. Immediately thereafter, the paper feed cassette 20 is set in the thermal printer. Therefore, in the present embodiment, the date and time when the sheet cassette 20 was loaded into the cassette storage chamber 38, that is, the date and time when the cassette detection switch 45 detected the sheet cassette 20 is the date and time when the recording paper 12 was removed from the moisture-proof bag.

The operation of the thus configured thermal printer will be described with reference to the flowchart of FIG. When the thermal printer is installed, power is supplied to the thermal printer, and then date setting of the thermal printer and input of regional information where the thermal printer is installed are performed. This area information is stored in the flash memory 85 and is maintained even if the power of the thermal printer is turned off unless changed. The season information is automatically set from the current date, and the flash memory 85
Is stored.

When the thermal printer is used for the first time, the moisture-proof bag is broken and the recording paper package 10 is placed in the paper feed cassette 20.
, And set the paper cassette 20 in the thermal printer. The cassette detection switch 45 controls the paper feed cassette 20
Is detected. The setting date and time of the paper cassette 20 is
It is stored in the flash memory 85. If the paper feed cassette 20 is not detected when the power is turned on, a warning that prompts the user to load the paper feed cassette 20 is issued, for example, by sound.

Subsequently, the bar code 15 is read by the bar code scanner 40 via the resin plate 34,
The date of manufacture of the recording paper 12 and the sensitivity information for each color recorded on the barcode 15 are input to the controller 72. The controller 72 temporarily stores the date of manufacture of the recording paper 12 and sensitivity information in the work memory 86. If the barcode 15 is not read, it is considered that the paper feed cassette 20 is empty, and therefore, for example, a warning display urging the loading of the recording paper package 10 is performed on the liquid crystal display panel.

When the print key is operated, the controller 72 calculates the number of days that has elapsed since the setting of the sheet cassette 20 and the current date obtained from the calendar device 83. The controller 72 reads out the sensitivity correction coefficient for each of Y, M, and C corresponding to the elapsed days of opening, the season information, and the regional information from the sensitivity correction LUT 82 for water content fluctuation.

The controller 72 calculates the number of elapsed days from the date of manufacture to the present date from the current date obtained from the calendar device 83 and the date of manufacture of the recording paper 12. This number of days of manufacture is stored in the work memory 86. The controller 72 determines Y,
The sensitivity correction coefficient for each of M and C is read from the sensitivity correction LUT 81 for aging.

The controller 72 has a sensitivity correction LU for aging.
The sensitivity correction coefficients read from the T81 and the moisture content variation sensitivity correction LUT 82 are added for each of Y, M, and C, and
A synthetic sensitivity correction coefficient resulting from both aging and fluctuations in water content is determined. For example, when 1.01 and 1.05, 1.0
6, and when it is 1.01 and 0.8, it becomes 0.81.
This is multiplied by the sensitivity read by the barcode sensor 40 to obtain the actual sensitivity. In accordance with this sensitivity, the controller 72 selects a selector 77 for each of Y, M, and C image recordings.
Switch. First, since a yellow image is recorded, the selector 77 is switched according to the actual sensitivity of the yellow thermosensitive coloring layer.

Next, after the paper feed roller 42 is set at the paper feed position, it is rotated in the paper feed direction. Due to the rotation of the paper feed roller 42, the uppermost recording paper 12 that is in contact with the paper feed roller 42 is pulled out of the paper feed cassette 20 and sent toward the recording position. When two seconds elapse after the leading edge of the fed recording paper 12 is detected by the recording paper sensor 57,
It is determined that the leading end of the recording paper 12 has reached the feed roller pair 55, and the paper feed roller 42 is displaced from the paper feed position to the retracted position. Thereafter, the recording paper 12 is fed in the paper feed direction α by the feed roller pair 55. When the rear end of the recording paper 12 passes through the recording paper sensor 57, the recording paper 12 is stopped at the recording start position.

The image data of the yellow image for one line is read from the frame memory 65 and once written to the line memory 66. Next, the image data of each pixel is read out from the line memory 66 in order, and
Where it is compared with the gradation data of the gradation level “0”. In the pixel for recording the yellow image, the comparator 6
7 is “1”, and is “0” for pixels that do not record a yellow image. The comparison result of each pixel is sent to the shift register 71 as serial drive data, and is shifted in the shift register 71 by a clock to be converted into parallel drive data. The parallel drive data is sent to the AND gate array 74 after being latched by the latch array 73.

Since the AND gate array 74 outputs the logical product of the strobe signal and the output signal of the latch array 73, the output terminal of the latch array 73 is "1" among the output terminals of the AND gate array 74. The thing outputs "1". For example, when the first output terminal of the AND gate array 74 is "1", the transistor 75a is turned on, and the heating element 60a is energized to generate heat. As a result, the heating element 60a causes the yellow thermosensitive coloring layer of the recording paper 12 to develop a color at the gradation level "1". Hereinafter, in order for the controller 72 to sequentially change the gradation level from “1” to “FF”, drive data corresponding to each gradation level is output from the comparator 67.
As a result, the heating elements 60a to 60n are energized in accordance with the image data, and apply the gradation expression heat energy to the recording paper 12 to develop the color to a desired density. At this time, the recording paper 12
The voltage for yellow image recording is controlled by each heating element 6 so as to correct the sensitivity change caused by both the aging and the moisture content fluctuation of the heating element 6.
0a to 60n.

When the first line of the yellow image is recorded, the recording paper 12 is fed by one pixel, and at the same time, the image data of the second line of the yellow image is read from the frame memory 65. The second line is thermally recorded on the recording paper 12 based on the image data of the second line of the yellow image. When the portion where the yellow image is thermally recorded reaches the optical fixing device 56, near ultraviolet rays of 420 nm are irradiated from the yellow ultraviolet lamp 56a to fix the yellow thermosensitive coloring layer. In this way, each line is sequentially thermally recorded.

When the yellow recording is completed, the recording paper 12 is pulled back by the feed roller pair 55 to the recording start position. Next, the selector 77 switches the applied voltage to the actual sensitivity of the next magenta thermosensitive coloring layer. After the adjustment of the applied voltage, the magenta image is thermally recorded on the recording area in the same manner as the thermal recording of the yellow image, and during this thermal recording, the magenta ultraviolet lamp 56b is turned on and the recording paper 12
The magenta thermosensitive coloring layer is fixed.

After magenta recording, the recording paper 12 is similarly returned to the recording start position. After the selector 77 switches the applied voltage according to the actual sensitivity of the cyan thermosensitive coloring layer,
A cyan image is thermally recorded on the recording area. Also during this thermal recording, the magenta ultraviolet lamp 56b is turned on,
Unrecorded areas are bleached. After thermal recording of the cyan image,
The recording paper 12 is moved by the paper discharge roller pair 48 to the paper feed cassette 20.
Is discharged to the upper surface of the

As described above, since the thermal head 58 heats each thermosensitive coloring layer with an applied voltage corresponding to the actual sensitivity,
Each of the thermosensitive coloring layers develops a color at an intended density, whereby an image having a good color balance is recorded on the recording paper 12.

In the embodiment described above, cut paper is used as the recording paper, but roll paper 91 as shown in FIG. 9 may be used. In this case, a bar code 93 is provided on the end surface of the winding core 92. The barcode 93 is a barcode sensor 9 provided in a magazine for storing the roll paper 91 or a magazine loading chamber in which the magazine for paper is loaded.
4 is read.

Further, in the above embodiment, the sensitivity correction is performed according to both the aging and the fluctuation of the water content. However, the sensitivity correction may be performed only for either the aging or the fluctuation of the water content. In this case, either one of the LUTs may be provided by the thermal printer, or both may be provided and selected as necessary.

In the above embodiment, the color density is corrected by controlling the voltage applied to the thermal head. In addition, the image data is corrected to change the time and pulse number of the strobe signal. May be performed.

Further, instead of the correction coefficient, the correction value is
And the actual sensitivity may be obtained by adding or subtracting the read sensitivity value.

If the recording paper has only one type of sensitivity, a sensitivity bar code is not required. In this case, a voltage value may be stored in the LUT, and the selector 77 may be switched according to the voltage value.

The sensitivity of the recording paper, the date of manufacture, and the like are automatically input to the printer by a bar code.
The input may be performed manually using input means of a printer, for example, a numeric keypad. Further, the sensitivity correction value that changes with time may be directly input by the input means of the printer.

Although the manufacturing process and the opening process are performed in units of days, they may be performed in units of hours. If an ID code is given to the recording paper and the ID code is compared with the ID code read so far, it is determined whether or not the recording paper is newly loaded, and the recording paper is stored in the cassette. You can see the number of days that are put. Further, when loading new recording paper, the user may directly input the date and time as the opening date and time into the printer. In this case, the opening date and time will not be reset unless the user changes next.

Although the above embodiment is directed to a thermal printer, the present invention can also be applied to a printer whose recording density changes with temperature, for example, a thermal transfer printer using an ink ribbon, an ink jet printer, an electrophotographic printer, and the like. Further, when the dye transfer rate of the ink ribbon changes due to humidity or aging, the transfer sensitivity is recorded on the ink ribbon.

[0065]

As described above, according to the present invention,
The elapsed time from the production of the recording paper is calculated based on the date information when the recording paper was manufactured and the current date, and the sensitivity that changed according to the elapsed time is corrected. Fluctuation and deterioration of color balance can be prevented.

In addition, the elapsed time since the cassette in which the new recording paper is transferred is set in the printer is measured, and the sensitivity changed due to the fluctuation of the moisture content of the recording paper with respect to the elapsed time is corrected. By correcting the sensitivity fluctuation of the recording paper due to the rate fluctuation, it is possible to prevent the density fluctuation and the deterioration of the color balance.

By providing a change in sensitivity to elapsed time for each region and season, an image can be recorded at a constant density regardless of the water content of the recording paper that changes depending on the environment in which it is used. When using a recording paper composed of a plurality of heat-sensitive coloring layers, each of which is different in color, a change in the sensitivity of the control table is provided for each heat-sensitive coloring layer, and the control of the thermal head is performed for each heat-sensitive coloring layer. Because of the change, an image with good color balance can be recorded.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an electrical configuration of a color thermal printer.

FIG. 2 is a perspective view showing a recording paper package from a lower surface side.

FIG. 3 is a perspective view showing a sheet feeding cassette.

FIG. 4 is a cross-sectional view showing a cassette storage chamber in which a paper feed cassette is set.

FIG. 5 is a schematic view showing an example of a color thermal printer.

FIG. 6 is a schematic graph showing a relationship between recording paper sensitivity and elapsed days.

FIG. 7 is a schematic graph showing a relationship between recording paper sensitivity and water content of the recording paper.

FIG. 8 is a flowchart showing a print sequence of the color thermal printer.

FIG. 9 is an explanatory diagram showing an embodiment in the case of using roll paper.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 recording paper package 12 recording paper 15 barcode 20 paper cassette 38 cassette storage chamber 40 barcode scanner 45 cassette detection switch 58 thermal head 72 controller 77 selector 81 sensitivity correction LUT for aging 82 sensitivity correction LUT 83 for water content fluctuation calendar device

Claims (14)

[Claims] 1. A printer for recording an image on a recording sheet having at least date information and sensitivity information at the time of manufacture recorded on a storage member or a core, and reads the date information and sensitivity information at the time of manufacture. A sensitivity correction method comprising calculating an elapsed time from the time of production of a recording sheet based on date information of a time and a current date, and correcting a sensitivity changed according to the elapsed time. 2. Sensitivity information is recorded in a storage section for removably storing recording paper of a cut sheet or in a winding core on which a long recording paper is wound. In a printer that sets this cassette in the printer and records an image on recording paper, measures the elapsed time since the new cassette is set in the printer and measures the elapsed time for this elapsed time. A sensitivity change method for correcting a change in sensitivity caused by a change in water content. 3. A printer for recording an image on a recording sheet having at least date information and sensitivity information at the time of manufacture recorded on a storage member or a core, and reads the date information and sensitivity information at the time of manufacture. A sensitivity correction method comprising calculating an elapsed time from the time of production of a recording sheet based on date information of a time and a current date, and correcting the sensitivity using a comparison table indicating a change in sensitivity with respect to the elapsed time. 4. Sensitivity information is recorded in a storage section for removably storing recording paper of a cut sheet or a core for winding a long recording paper, and the moisture-proof bag is opened to store the recording paper in a cassette. In a printer that sets this cassette in the printer and records an image on recording paper, measures the time elapsed since the new cassette was transferred and set it in the printer. A sensitivity correction method, wherein the read sensitivity is corrected using a control table indicating a change in sensitivity caused by a change in water content. 5. The sensitivity correction method according to claim 4, wherein the comparison table is provided for each region and season when the printer is used. 6. The recording paper is a color thermosensitive recording paper in which a plurality of thermosensitive coloring layers having different colors are formed, and the reference table is provided for each thermosensitive coloring layer. The sensitivity correction method according to any one of claims 3 to 5, wherein 7. A thermal printer for thermally recording an image with a thermal head on a thermal recording paper having at least manufacturing date information and coloring sensitivity information recorded on a storage member or a winding core, and the like. Reading means for reading the color sensitivity information, a calendar for generating date information at the time of printing, storage means for storing a comparison table representing a relationship between the elapsed time from the time of manufacture to the time of printing and a change in color sensitivity, The elapsed time from the time of manufacture to the time of printing is obtained from the date information at the time of manufacture and the date information at the time of printing, and the change in color sensitivity corresponding to the elapsed time is obtained from a comparison table. A thermal printer, comprising: control means for controlling a voltage applied to the head or an energizing time. 8. Sensitivity information is recorded in a storage section for removably storing the thermal recording paper of a cut sheet or in a core for winding a long thermal recording paper, and the moisture-proof bag is opened to open the recording paper. Is transferred to a cassette, the cassette is set, and the image is thermally recorded on the thermal recording paper by a thermal head. In the thermal printer, reading means for reading the color sensitivity information and a cassette containing new recording paper are set in the printer. Measurement means for measuring the elapsed time from the current time to the present, and a comparison table showing the relationship between the elapsed time with the recording paper stored in the cassette and the change in color sensitivity caused by fluctuations in the moisture content of the thermal recording paper. Based on the elapsed time measured by the measuring means, the corresponding change in the coloring sensitivity is obtained from the reference table, and in accordance with the change, the electric power applied to the thermal head is determined. Or thermal printer, characterized in that comprising a control means for controlling the energizing time. 9. The thermal printer according to claim 8, wherein the comparison table is provided for each printer use condition such as region and season, and the comparison table is selected by a printer use condition input unit. 10. The heat-sensitive recording paper comprises a plurality of heat-sensitive coloring layers, each of which has a different color, and the reference table is provided for each heat-sensitive coloring layer. Thermal printer according to any of the above. 11. Sensitivity information is recorded on a storage portion for accommodating the thermal recording paper of a cut sheet in a removable manner or on a winding core for winding a long thermal recording paper, and the moisture-proof bag is opened to open the recording paper. Is read into a cassette, the cassette is set, and a thermal head is used to thermally record an image on a thermal recording paper with a thermal head. And a measuring means for measuring the elapsed time from when the cassette containing the new recording paper is set in the printer to the present,
A first control table showing the relationship between the elapsed time from the time of manufacture and the change in the color sensitivity, and the elapsed time when the moisture-proof bag is opened and kept in the cassette and the fluctuation of the moisture content of the thermal recording paper. The elapsed time from the time of manufacture to the time of printing is obtained from the second comparison table indicating the relationship between the change in the color sensitivity and the date information at the time of manufacture and the date information at the time of printing, and the color sensitivity corresponding to the elapsed time is obtained. Is obtained from the first control table, a second change amount corresponding to the elapsed time measured by the measuring means is obtained from the second control table, and color development is performed based on the first change amount and the second change amount. A thermal printer comprising: control means for obtaining a combined change in sensitivity and controlling an applied voltage or an energizing time to the thermal head according to the combined change. 12. The thermal printer according to claim 11, wherein the second comparison table is provided for each printer use condition such as region and season, and the comparison table is selected by a printer use condition input unit. . 13. The thermosensitive recording paper comprises a plurality of thermosensitive coloring layers, each of which has a different color, and the first and second reference tables are provided for each thermosensitive coloring layer. The thermal printer according to claim 11. 14. A printer which is used by opening a moisture-proof bag and prints an image on a recording paper having date information of manufacture recorded on a storage member or a core. From the elapsed days, using a control table showing the change in the recording density with respect to the elapsed days, to determine the change in recording density, at the time of image recording,
A density correction method, wherein the density change is corrected.