JP3002800B2 - Method and apparatus for correcting recording density of printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for correcting the recording density of a printer suitable for use in a thermal printer having a thermal head.

[0002]

2. Description of the Related Art In general, a thermal printer is provided with a thermal head having a large number of recording elements (heating elements) in dot units. Therefore, at the time of recording, a current having a time width corresponding to the gradation of the image signal (recording data) is supplied to each recording element of the thermal head to generate heat. For example, in the case of thermal paper, the density corresponding to the gradation is increased. Colors the thermal paper itself. However, in the thermal head, since the characteristics of the individual recording elements vary, the heat generation becomes non-uniform and the recording density becomes uneven in the line direction.

[0003] For this reason, in the prior art,
As in the method for correcting the recording density of a thermal head in Japanese Unexamined Patent Publication, the resistance value of a recording element in dot units is measured in advance,
Deviation data based on the deviation between the resistance value and the reference value is obtained, and the deviation data is stored. At the time of recording, the gradation of the corresponding image signal is corrected based on the deviation data to eliminate the recording density unevenness. I was

[0004]

The above-described conventional recording density correction method can effectively eliminate the variation in the line direction based on the characteristics of each recording element in the thermal head. Since there are variations in characteristics and the like in the recording system other than the head, it is not possible to completely eliminate unevenness in the recording density in the line direction, and usually, the thermal printer is constituted by an open loop recording system. In addition to variations in recording density between printers, there is a problem in that recording cannot be performed with accurate absolute density and recording quality cannot be improved, in addition to remaining recording density unevenness.

[0005] The present invention has solved the problems existing in such prior art, and almost completely eliminates recording density unevenness, and achieves recording with accurate absolute density, thereby improving recording quality. It is an object of the present invention to provide a method and apparatus for correcting recording density of a printer, which can dramatically increase the recording density.

[0006]

A recording density correction method for a printer according to the present invention records an image on recording paper P based on reference data Ds, and reads the recorded image to obtain read data Dr. The read data Dr is corrected by a read correction value Nr for correcting an error of the read unit 2 previously obtained and stored, and a specific correction corresponding to a position with respect to the recording data Dp from a deviation between the corrected read data Dr and the reference data Ds. The value Nf is calculated and stored, and at the time of recording,
The recording data Dp is corrected by the stored specific correction value Nf. In this case, a known unique correction value Ns is obtained and stored in advance, and the reference data Ds is corrected using the stored unique correction value Ns.
A read correction value Nr for correcting an error of the reading section is obtained and stored, and the read data Dr is read based on the stored read correction value Nr.
Is desirably corrected.

A recording density correcting apparatus 1 for a printer according to the present invention includes a reading section 2 for reading an image recorded on a recording sheet P, and a reading correction value Nr for correcting an error of the reading section 2.
And the read correction value N
r, and the read data Dr obtained from the reading unit 2 is corrected by the read correction value Nr stored in the third storage unit 14, and is used for recording the corrected read data Dr and the image. A calculation unit 3 for calculating a specific correction value Nf corresponding to the position with respect to the recording data Dp from the deviation of the reference data Ds, a storage unit (first storage unit) 4 for storing the calculated specific correction value Nf, It is characterized by including a correction unit 5 for correcting the recording data Dp with the correction value Nf. In this case, it is possible to provide a second storage unit 6 for storing a known unique correction value Ns for correcting the reference data Ds. Further, it can be configured to include a read correction value calculation unit 13 for obtaining a read correction value Nr for correcting an error of the reading unit 2 and a third storage unit 14 for storing the read correction value Nr.

[0008]

According to the recording density correction method and the recording density correction apparatus 1 of the printer according to the present invention, first, an image is recorded on the recording paper P based on the reference data Ds. The image recorded on the recording paper P is read by the reading unit 2, and read data Dr is obtained from the reading unit 2. In addition, a read correction value Nr for correcting an error of the reading unit 2 is calculated in advance by the read correction value calculation unit 13 by calculation, and the third storage unit 14
, The read data Dr is the read correction value N
It is corrected by r. Then, the corrected read data Dr is provided to the calculation unit 3 to calculate a deviation with respect to the reference data Ds, calculate a specific correction value Nf corresponding to the position with respect to the recording data Dp, and obtain the obtained specific correction value. Nf is stored in the first storage unit 4.

On the other hand, at the time of recording, the specific correction value Nf is read from the storage unit 4, and the recording data Dp actually recorded is corrected by the specific correction value Nf. As a result, errors in the entire recording system, such as variations in the recording elements of the thermal head, variations in the driver characteristics of the thermal head, uneven contact between the thermal head and the recording paper, heat accumulation in the thermal head, and variations in the characteristics of the recording paper Is eliminated, and recording with uniform and accurate recording density is performed.

A known intrinsic correction value Ns, for example, an intrinsic correction value Ns for eliminating an error or the like of the reading unit 2 is previously stored in the second storage unit 6, and the intrinsic correction value read from the second storage unit 6 is stored. If the reference data Ds is corrected by the value Ns, printing with more uniform and accurate printing density can be realized.

[0011]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of a recording density correction apparatus 1 for a printer according to the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 10 denotes a printer unit;
It is composed of a main circuit of a recording system, a thermal head, and the like. Therefore, the printer unit 10 has a function of performing recording based on the recording data by inputting the recording data (image signal).

On the other hand, reference numeral 1 denotes a recording density correction device attached to the printer unit 10, which is roughly divided into a reading unit 2, an arithmetic unit 3,
First storage unit 4, correction unit 5, second storage unit 6, position designation unit 1
1 and a reference data generator 12, a read correction value calculator 13 and a third storage 14.

The reading section 2 comprises a reading head, a reading circuit, and the like, so that read data Dr of a read image is obtained.
The output side is connected to the arithmetic unit 3. The calculation unit 3 has an input unit to which the reference data Ds is input, and has a function of calculating a specific correction value Nf corresponding to a position with respect to the recording data Dp from a deviation between the reference data Ds and the read data Dr. One storage unit 4 is connected. Note that the specific correction value Nf is set as a correction coefficient or a correction amount that makes the deviation of the strobe time or gradation between the reference data Ds and the read data Dr zero. First storage unit 4
Has a function of storing the specific correction value Nf, and its output side is connected to the correction unit 5. The correction unit 5 has a function of correcting the recording data Dp with the specific correction value Nf, and the output side is connected to the printer unit 10.

The second storage unit 6 stores a known intrinsic correction value N
s is stored in the first storage unit 4
In addition to the connection to the (correction unit 5), the position specification unit 11 connects to the reading unit 2, the calculation unit 3, the first storage unit 4, the second storage unit 6, and the correction unit 5 to specify the position. Furthermore, the reference data generator 12 has a function of generating the reference data Ds. In this case, the reference data Ds may be a single color, a specific pattern, or the like. The reference data Ds may be generated or stored as data, or an image displayed on paper or the like may be read. The reading correction value calculation unit 13 has a function of detecting a variation in characteristics of the reading head and the like in the reading unit 2 and calculating a reading correction value Nr for correcting the reading data Dr. A function for storing the value Nr is provided. In FIG. 1, P indicates a recording sheet.

Next, the operation of the recording density correction apparatus 1 including the recording density correction method according to the present invention will be described with reference to the flowcharts shown in FIGS. 1, 2 and 3.

First, a method of setting a correction value will be described with reference to FIG.

First, a unique correction value Ns that is known and has a small variation factor is obtained and stored in the second storage unit 6 (step 21). That is, a fixed error factor such as an error (variation) in the resistance value of the recording element of the thermal head is detected in advance, and a unique correction value Ns is calculated from this and stored in the second storage unit 6. The error of the resistance value of the recording element of the thermal head can be corrected by the specific correction value Nf. However, if the specific correction value Ns is set in advance, for example, the reading unit 2 to be used has a low capacity. Is enough.

The reading correction value calculating section 13 detects an error (variation) in the characteristics of the reading head and the like in the reading section 2 and reads the reading correction value N for correcting the reading data Dr.
r is calculated, and the obtained read correction value Nr is stored in the third storage unit 14 (step 22).

Next, reference data Ds is generated from the reference data generator 12 (step 23). As a result, the reference data Ds is provided to the input side of the correction unit 5, and the correction unit 5
Is corrected by the unique correction value Ns read from the second storage unit 6. Then, the corrected reference data Ds is provided to the printer unit 10, and an image based on the reference data Ds is recorded on the recording paper P (step 24). The reference data Ds generated from the reference data generator 12
Is also given to the input unit of the arithmetic unit 3.

On the other hand, the image recorded on the recording paper P is read by the reading section 2 (step 25). This allows
Reading data Dr is obtained from the reading unit 2 and is provided to the calculation unit 3. The arithmetic unit 3 corrects the read data Dr based on the read correction value Nr read from the third storage unit 14, calculates a deviation between the corrected read data Dr and the reference data Ds, and calculates a deviation between the read data Dr and the recording data Dp. A specific correction value Nf corresponding to the position is obtained by calculation (step 26). That is, the specific correction value Nf is the read data Dr.
And a correction coefficient or correction amount for making the deviation between the reference data Ds and the reference data Ds zero, and the obtained specific correction value Nf is stored in the first storage unit 4 (step 27).

Next, a correction method at the time of actual recording will be described with reference to FIG.

At the time of recording, the recording data D to be actually recorded
p is given to the input side of the correction unit 5, and the specific correction value Nf is read from the first storage unit 4 and given to the correction unit 5 (step 31). Then, the recording data Dp is corrected by the correction unit 5 using the specific correction value Nf (step 32). As a result, errors in the entire recording system, such as variations in the recording elements of the thermal head, variations in the driver characteristics of the thermal head, uneven contact between the thermal head and the recording paper, heat accumulation in the thermal head, and variations in the characteristics of the recording paper And the like.

Accordingly, the corrected recording data Dp is given to the printer unit 10 and the recording data Dp
Is recorded with a uniform and accurate recording density (step 33).

The position specifying section 11 gives position information to each section, sets correction values Nf and Ns corresponding to the position, and corrects the recording data Dp corresponding to the position. Accordingly, position information such as a position in the line direction (main scanning direction), a position in the feeding direction (sub-scanning direction), a roller rotation angle, the number of prints, and a printing time is given to each unit from the position designation unit 11, and the timing and the like are given. Controlled.

Incidentally, the recording density correction apparatus 1 may be built in a facsimile machine, a copying machine or the like together with the printer section 10, or may be configured as a separate correction dedicated apparatus. When incorporated integrally, a reading mechanism originally provided in a facsimile, a copying machine, or the like can be used, and calibration can be performed periodically. In the case where the correction unit 5 is configured separately,
The first storage unit 4 is built in the printer, and the reading unit 2, the operation unit 3, the position designation unit 11, the second storage unit 6, and the reference data generation unit 12 are built in the correction dedicated device. Therefore, in the case of a separate configuration, the setting operation may be performed at the time of shipment from a manufacturing factory or the like, and the determined correction value Nf may be stored in the first storage unit 4.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the second storage unit can be provided as needed.
In addition, it is possible to arbitrarily change the detailed circuit configuration, method, and the like without departing from the gist of the present invention.

[0029]

As described above, according to the recording density correction method for a printer according to the present invention, an image is recorded on recording paper based on reference data, and the recorded image is read to obtain read data. Is corrected by a read correction value for correcting an error of the reading unit previously obtained and stored, a specific correction value corresponding to the position with respect to the recording data is calculated from the deviation between the corrected read data and the reference data, and stored. In addition, at the time of recording, the recording data is corrected by the stored specific correction value, so that the recording density unevenness is almost completely eliminated, and the recording quality is dramatically improved by realizing the recording with the accurate absolute density. It has a remarkable effect that it can be performed.

The recording density correcting apparatus for a printer according to the present invention further comprises a reading unit for reading an image recorded on a recording sheet;
A read correction value calculation unit that calculates a read correction value for correcting an error of the reading unit, a third storage unit that stores the read correction value, and read data obtained from the read unit are stored by the third storage unit. A calculation unit that corrects with the reading correction value and calculates a specific correction value corresponding to the position with respect to the recording data from a deviation between the corrected read data and the reference data used for recording the image, and stores the calculated specific correction value And a correction unit that corrects the recording data based on the stored specific correction value, there is a remarkable effect that the correction method can be easily and reliably performed.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a recording density correction device according to the present invention,

FIG. 2 is a flowchart for setting a correction value of a recording density correction method according to the present invention;

FIG. 3 is a flowchart for correcting at the time of recording according to the recording density correction method,

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording density correction device 2 reading unit 3 calculation unit 4 storage unit (first storage unit) 5 correction unit 6 second storage unit 13 read correction value calculation unit 14 third storage unit Ds reference data Dr read data Dp record data P record Paper Nf Specific correction value Ns Known intrinsic correction value Nr Reading correction value

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-55262 (JP, A) JP-A-2-80264 (JP, A) JP-A-5-293996 (JP, A) 67051 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2 / 36,2 / 45 B41J 2 / 015,29 / 46

Claims (4)

(57) [Claims] 1. An image recording method for recording an image on a recording sheet based on reference data, reading the recorded image to obtain read data, and correcting the error of a reading unit which previously obtained and stored the read data. Correcting with a read correction value, calculating and storing a specific correction value corresponding to a position with respect to recording data from a deviation between the corrected read data and the reference data, and correcting recording data with the stored specific correction value during recording. And a recording density correcting method for a printer. 2. The method according to claim 1, wherein a known intrinsic correction value is obtained and stored in advance, and the reference data is corrected based on the stored intrinsic correction value. 3. A reading section for reading an image recorded on a recording sheet, a reading correction value calculating section for calculating a reading correction value for correcting an error of the reading section, and a third storage for storing the reading correction value. Unit, the read data obtained from the reading unit is corrected by the read correction value stored by the third storage unit, and a position between the corrected read data and the reference data used for recording the image is shifted to a position corresponding to recording data. It is characterized by comprising a calculation unit for calculating a corresponding specific correction value, a storage unit (first storage unit) for storing the calculated specific correction value, and a correction unit for correcting recording data using the stored specific correction value. Recording density correction device for printer. 4. The apparatus according to claim 3, further comprising a second storage unit for storing a known intrinsic correction value for correcting the reference data.