JP2000238308A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain a uniform printing density without image variation irrespective of a manufacturing condition of an ink ribbon without wasting the ink ribbon and a photographic paper. SOLUTION: There is disclosed a thermal printer that performs printing by outputting image data (d) to a thermal head 12 and heating an ink ribbon 20 containing a thermal transfer layer formed thereon. The thermal printer comprises a layer thickness measuring section 15 that measures a layer thickness distribution of a thermal transfer layer on the ink ribbon 20 as a transmittance, an image data processing section 17 for correcting image data so as to make a printing density uniform, a switch for instructing the start of the measuring of the layer thickness measuring section 15 and a conveying section 14 for conveying the ink ribbon 20. The thermal printer further comprises a control section 18 that executes positioning of a top edge of one unit of the thermal transfer layer by the conveying section 14 and reverses the conveying section 14, then executes the positioning of the top edge again after a layer thickness of the thermal transfer layer is measured by each color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal (thermal transfer) printer using a thermal head,
The present invention relates to a thermal printer having a correction function for print density unevenness.

Heretofore, in this type of thermal printer, print density unevenness has occurred mainly due to the following various factors. (1) Variations in the resistance value of the thermal head, irregularities in the surface shape of the thermal head, irregularities in the platen shape, etc. caused by the printer. (2) Due to the recording medium such as unevenness of dye application of the ink ribbon.

In order to correct the printing density unevenness in the main scanning direction caused by the above-mentioned factors, a conventional thermal printer prepares correction data to make the printing density uniform before shipping. Is stored, and the print density is corrected based on the stored correction data.

The following method is known as a known technique for creating correction data. (A) A method of creating correction data to make the heating value uniform from the resistance value of the thermal head. (B) A method of optically measuring the density of each dot actually printed and creating correction data for uniform density.

[0005]

However, in the above-mentioned method (a), a uniform density cannot be obtained because the printing density non-uniformity is not always caused by the variation in the resistance value of the thermal head.

On the other hand, in the method (b), if printing is performed using the ink ribbon used for the adjustment, it is possible to realize a uniform density, but the application of the dye ink generated at the time of dye printing on the ink ribbon is possible. The unevenness changes the application distribution of the dye depending on the conditions at the time of printing of the ink ribbon, and therefore, it is not always possible to obtain a uniform print density without unevenness regardless of which ink ribbon is used. Further, a printer having a function of correcting (b) every time the ink ribbon is replaced may be considered. However, it is necessary to actually print, and both the ink ribbon and the printing paper become useless.
There is a disadvantage that.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to obtain a uniform print density without printing unevenness regardless of the manufacturing conditions of the ink ribbon without wasting both the ink ribbon and the printing paper. It is to provide a thermal printer which can be obtained.

[0008]

According to a first aspect of the present invention, there is provided a thermal head for printing image data by outputting image data to a thermal head and heating an ink ribbon having a thermal transfer layer formed thereon. In the printer, a layer thickness measuring means (1) for measuring a layer thickness distribution of the thermal transfer layer of the ink ribbon.
5) and image data correcting means (17, S203) for correcting the image data so as to make the print density uniform based on the measurement value of the layer thickness measuring means. It is a thermal printer.

According to a second aspect of the present invention, there is provided a thermal printer which outputs image data to a thermal head and prints by heating the ink ribbon having the thermal transfer layer formed thereon. A layer thickness measuring means for measuring (15), a measurement start instructing means (SW) for instructing a start of measurement by the layer thickness measuring means, a conveying means (14) for conveying the ink ribbon, and the measurement start instructing means When instructed by the controller, the transfer unit performs cueing of one unit of the thermal transfer layer, and the layer thickness measuring unit measures the layer thickness of each color of the thermal transfer layer. And a control means (18) for reversing and performing the cueing again.

[0010] The invention of claim 3 is claim 1 or claim 2.
In the thermal printer described in (1), a layer thickness storage means (16a) for storing a measurement value of the layer thickness measurement means,
A thermal printer comprising:

[0011] The invention of claim 4 is the invention of claims 1 to 3.
In the thermal printer described in any one of the above, the layer thickness measuring means measures the transmittance of light transmitted through the ink ribbon (15a, 15b), and the image data correcting means measures the transmittance of the light. The thermal printer is characterized in that the ratio is converted into print density (16b).

The invention of claim 5 is the invention of claims 1 to 4.
In the thermal printer described in any one of the above, the image data correction means performs a second correction (S204) for correcting density unevenness caused only by the printer not including the factor of the ink ribbon. This is a thermal printer.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in more detail.
FIG. 1 is a block diagram showing an embodiment of a thermal printer according to the present invention. Figure 2 shows the amount of paint applied and CC
FIG. 4 is a diagram showing a relationship between output values of D. FIG. 3 is a diagram showing the results of measuring the distribution of the amount of dye applied to the ink ribbon with a CCD array unit. FIG. 4 is a diagram showing the relationship between the CCD output value and the print density at a certain gradation.

The thermal printer 10 of this embodiment
Are a platen 11, a thermal head 12, a guide roller 13, a transport unit 14, and a dye application distribution measuring unit 15
, A memory unit 16, an image data processing unit 17, a control unit 18, and the like.

The thermal printer 10 includes an ink ribbon 20 between a platen 11 and a thermal head 12.
Are guided by guide rollers 13, 13, and the like, and the ink ribbon 20 is transported by a transport unit 14 including a take-up roller 14a and a rewind roller 14b.

Here, although not shown, the ink ribbon 20 has a transfer layer formed of one unit of sublimable dye or the like, which is coated with a Ye (yellow) dye-coated portion and a Mg (magenta) dye-coated portion. It is formed side by side in the transport direction (plane direction) like a portion and a portion to which Cy (cyan) dye is applied. In addition, you may form the application | coating part of the dye of Bk (black) as needed. Further, the transfer layer may be coated with a solid ink or the like.

The dye application distribution measuring section 15 is a section for measuring the distribution of the application area (layer thickness of the transfer layer) of the dye on the entire width of the ink ribbon 20, and includes a light source 15a, a color CCD array unit 15b, It is composed of The ink ribbon 20 passes between the light source 15a and the color CCD array unit 15b, and the CCD array unit 15b is disposed upstream of the printing area (the portion of the thermal head 12). The full width transmittance is measured. Since the output of the CCD array unit 15b is proportional to the amount of dye applied as shown in FIG. 2, the amount of dye applied can be measured from this output value.

The storage unit 16 includes a first correction data storage unit 16
a, a CCD output value-print density conversion table storage unit (hereinafter referred to as a conversion table storage unit) 16b, a second correction data storage unit 16c, and the like.

The first correction data a is, as shown in FIG.
Ink ribbon 2 measured by color CCD unit 15b
It is measurement data based on the dye application distribution of 0. The CCD output value-print density conversion table b is, as shown in FIG.
This is a table in which CCD output values of respective colors of Ye, Mg, and Cy are associated with print densities at all gradations. The second correction data c is data for correcting density unevenness caused only by the printer 10 without including the factor of the ink ribbon 20, and is stored in advance in the second correction data storage unit 16c of the printer 10.

The image data processing unit 17 stores the image data (gradation value) d1 and the ink ribbon 2 at the corresponding pixel position.
0 and the CC as shown in FIG.
From the D output value-print density conversion table b, a first correction is performed so as to make print density uniform, and a second correction is performed.
The second correction is performed by the correction data c.
The corrected image data d2 is output to the thermal head 12.

The control section 18 controls each section of the printer 10. Here, the control section 18 is based on a signal from the power switch SW and a signal from the sensor S for detecting the thermal transfer layer of the ink ribbon 20. , The transport unit 14 is controlled. Note that the image data processing unit 17 and the control unit 18 are configured by one CPU 19.

FIG. 5 is a flowchart showing a dye application distribution measuring operation of the thermal printer according to the present embodiment. When the power switch SW is turned on (S10
1) The ink ribbon 20 is moved by the winding roller 14a.
Is wound up (S102), cueing detection is performed using the sensor S (S103), and after one screen is conveyed (S102).
104), the distribution of the Ye (yellow) dye applied portion is measured (S105). Similarly, one screen transfer (S106,
108), and the distribution of the coating portions of the Mg (magenta) and Cy (cyan) dyes is measured (S107, S109). After the measurement of the dye application distribution of each color is completed, the measured data is stored in the first correction data storage unit 16b (S11).
0).

Finally, the ink ribbon 20 is rewound using the rewind roller 14b (S111), and cueing detection (S112) is performed using the sensor S, thereby winding the ink ribbon 20 spent for measurement. return. Therefore, the ink ribbon 20 and the printing paper are not wasted.

As described above, in this embodiment, the timing for starting the measurement of the dye application distribution is when the power switch SW of the printer 10 is turned on. Then, when the power switch SW is turned on, the ink ribbon 20
The first correction data b is stored in the first correction data storage unit 16b until the power switch SW is turned on next time.

FIG. 6 is a flowchart showing the correction processing operation of the thermal printer according to the present embodiment. Upon input of the image data (gradation value) d1 (S201), the image data processing unit 17 reads the application distribution measurement data a of the ink ribbon 20 at the corresponding pixel position from the first measurement data storage unit 16a (S202). ), A first correction is performed based on the CCD output value-print density conversion table b of the conversion table storage unit 16b so as to make the print density uniform (S203). Next, a second correction is performed based on the second correction data c (S204), and the corrected image data d2 is output to the thermal head 12 (S20).
5).

As described above, according to the present embodiment, the thickness of the thermal transfer layer of the ink ribbon 20 is measured and the first correction is performed on the image data so that the printing density becomes uniform. Printing density unevenness resulting from unevenness in the formation of the thermal transfer layer of the ribbon 20 can be corrected. Therefore, a uniform print density without unevenness can be always obtained regardless of the manufacturing conditions of the ink ribbon.

Since the ink ribbon 20 used for the measurement is rewound, the ink ribbon 20 and the printing paper are not wasted.

(Modifications) Various modifications and changes are possible without being limited to the above-described embodiments, and these are also within the equivalent scope of the present invention. For example, the timing of starting the measurement of the dye application distribution has been described in the case where the power switch of the printer is turned on. However, regardless of whether the power switch is on or off, a predetermined button (switch) is pressed. Then, the dye application distribution measurement of the ribbon may be performed, and the first correction data may be stored in the storage unit until the button (switch) is pressed next time.

[0029]

As described above in detail, according to the present invention, the thickness distribution of the thermal transfer layer of the ink ribbon is measured,
Since the image data is corrected so that the print density becomes uniform, the print density unevenness caused by the unevenness of the formation of the thermal transfer layer of the ink ribbon can be corrected. There is an effect that no uniform print density can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a thermal printer according to the present invention.

FIG. 2 is a diagram showing a relationship between a coating amount of a paint and an output value of a CCD.

FIG. 3 is a diagram showing a result of measuring a dye application amount distribution of an ink ribbon by a CCD array unit.

FIG. 4 is a diagram showing a relationship between a CCD output value and a print density at a certain gradation.

FIG. 5 is a flowchart illustrating a dye application distribution measurement processing operation of the thermal printer according to the present embodiment.

FIG. 6 is a flowchart illustrating a correction processing operation of the thermal printer according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Thermal printer 11 Platen 12 Thermal head 13 Guide roller 14 Transport part 15 Application distribution measuring part 16 Memory part 17 Image data processing part 18 Control part

Claims (5)

[Claims] 1. A thermal printer which outputs image data to a thermal head and prints by heating an ink ribbon having a thermal transfer layer formed thereon, wherein a layer thickness measurement for measuring a layer thickness distribution of the thermal transfer layer of the ink ribbon is provided. And a means for correcting the image data so as to make the print density uniform based on the measurement value of the layer thickness measuring means. 2. A thermal printer which outputs image data to a thermal head and prints by heating an ink ribbon on which a thermal transfer layer is formed, wherein a layer thickness distribution of the thermal transfer layer of the ink ribbon is measured. Means, measurement start instructing means for instructing start of measurement by the layer thickness measuring means, conveying means for conveying the ink ribbon, and when there is an instruction from the measurement start instructing means, the conveying means Control means for performing cueing of one unit of the thermal transfer layer, measuring the layer thickness of each color of the thermal transfer layer by the layer thickness measuring means, inverting the transport means, and performing cueing again. And a thermal printer. 3. The thermal printer according to claim 1, wherein: a layer thickness storage unit that stores a measurement value of the layer thickness measurement unit;
A thermal printer comprising: 4. One of claims 1 to 3
In the thermal printer described in the paragraph, the layer thickness measuring means measures the transmittance of light transmitted through the ink ribbon, and the image data correcting means converts the transmittance into a print density. And a thermal printer. 5. The method according to claim 1, wherein:
2. The thermal printer according to claim 1, wherein the image data correction unit performs a second correction for correcting density unevenness caused only by the printer that does not include the factor of the ink ribbon.