JP3305087B2 - Thermal head density characteristics measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation printer used for hard copy of an image such as a television and a video system, and relates to the relationship between the energy applied to a recording element and the density or reflectance recorded on a receiving paper. The present invention relates to a concentration characteristic measuring method that can be easily obtained.

[0002]

2. Description of the Related Art The thermal transfer method can perform gradation recording by modulating the energy applied to a heating resistor, and is easy to colorize and has excellent quietness and maintainability. It is expected to be used as a gradation printer for hard copy of halftone images such as video and video systems. Generally, when color recording is performed using a thermal transfer method, as shown in FIG.
A thermal surface in which a plurality of heating resistors 3a are linearly arranged in the main scanning direction with the recording surface of the ink sheet 2 and the ink-coated surface of the ink sheet 2 in which the ink sheet is sequentially applied in each of yellow, magenta, and cyan color surfaces facing each other. Head 3 to ink sheet 2
Then, the recording paper 1 is pressed against the platen roller 4 via the image receiving paper 1, and energy corresponding to the density information of the color to be recorded first is applied to each heating resistor to generate heat, thereby recording one line by thermal transfer. At the same time, the image receiving paper 1 and the ink sheet 2 are conveyed in the direction of the arrow a to complete the recording of one page with the first color ink.

[0003] Next, the pressing by the platen roller 4 is released, and the image receiving paper 1 is pulled back in the direction of the arrow b so that the recording start position is located at the heating resistor position. The ink sheet 2 is conveyed in the direction of the arrow a, and one page of recording is performed with the second color ink. Similarly, one page of recording is performed with the third color ink, and the color image is formed by the subtractive color mixing method. Complete the recording on However, in order to obtain a desired recording density, it is necessary to obtain a relationship between the recording density and the applied energy.

Therefore, the plurality of heating resistors 3a are divided into a plurality of groups in the main scanning direction, and first, recording is performed for a predetermined length in the sub-scanning direction with the same applied energy for each group. This will be referred to as a first recording step.
Subsequently, printing is performed for a predetermined length in the sub-scanning direction at a different applied energy for each group. This will be referred to as a second recording step. When this pattern is recorded for each color, a pattern including a plurality of different density blocks as shown in FIG. Next, each density of each pattern recorded in the second recording step of each color of this pattern is measured using a densitometer. At this time, the relationship between the applied energy and the recording density as shown in FIG. 7 is obtained for each color by making the measurement larger on the lower side in the main scanning direction.

[0005]

However, in the case of the thermal transfer method, the heat generation of the thermal head differs for each heating resistor even if the same energy is applied due to the variation of the heating efficiency of each heating resistor. Also varies in the main scanning direction (the recording density also varies in the main scanning direction due to variations in the pressing force between the thermal head, the ink sheet, and the image receiving paper). Therefore, in the case of the pattern as described above, the heating conditions for each heating resistor during recording of each color are different, and the recording density is different in the main scanning direction even when recording is performed with the same applied energy. There is a disadvantage that the relationship between the recording density and the applied energy cannot be obtained with high accuracy under a constant heat generation condition.

An object of the present invention is to solve the above problem and to provide a method of measuring density characteristics in a gradation printer which can obtain a highly accurate relationship between recording density and applied energy. .

[0007]

According to a first aspect of the present invention, there is provided a thermal head density characteristic measuring method, comprising: a plurality of heating resistors formed on a thermal head in a main scanning direction; Is divided into multiple groups,
Applying different energy for each loop to the receiving paper for the first time
A first recording step of performing thermal recording of the eyes;
A density characteristic measuring method for a thermal head and a measurement step of measuring a concentration or reflectivity of the corresponding each section of paper image receiving that is thermally recorded by each group, further
The first thermal recording is performed for each group of the heating resistors.
Thermal recording on the receiving paper by applying energy different from the recording
A second recording step of performing at least once,
And recording on the image receiving paper by the second recording step.
Measurement of the density or reflectance of images with different density arrangements
It is characterized by measuring and averaging in each process . Ma
The density characteristic of the thermal head according to claim 2 of the present invention.
The measuring method is the density characteristic of the thermal head according to claim 1.
In the measurement method, the first and second recording steps
And each of the groups of the heating resistors has n different
Energy in a combination of
n times and obtained for each group of the heating resistors
It is characterized by averaging n measurement results.

[0008]

According to the density characteristic measuring method in the gradation printer of the present invention, in the recording process, different energy is applied stepwise to each group of the heating resistors in different n combinations, and n different density arrangements are applied. And the measurement process is executed n times, and the n sets of reflection densities obtained are averaged, thereby averaging the fluctuations in the recording density in the main scanning direction due to the heat generation variations of the heating resistors of the thermal head. And obtains effective data for obtaining a highly accurate relationship between the recording density and the applied energy.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 3 is a basic configuration diagram of the gradation printer. In FIG. 3, reference numeral 1 denotes an image receiving paper, 2 denotes an ink sheet in which ink to be transferred onto the image receiving paper 1 by heat is sequentially applied in yellow, magenta, and cyan by one page for each color;
Reference numeral 3 denotes a line-type thermal head in which the heating resistors 3a are linearly arranged in the main scanning direction. Reference numeral 4 denotes a platen roller for holding the image receiving paper 1 and the ink sheet 2 between the thermal head 3 and the platen roller.

Next, the operation of the gradation printer will be described with reference to FIG. Before the start of recording, the recording start position of the image receiving paper 1 and the recording start position of the first color yellow ink of the ink sheet 2 are located at positions facing the heating resistor 3a. It is in a state separated from the platen roller 4. At the start of recording, the thermal head 3 is moved in the direction of arrow c by means (not shown) so that the heating resistor 3a is pressed against the platen roller 4 via the ink sheet 2 and the image receiving paper 1. Next, energy corresponding to the density information for one line of yellow is applied to each heating resistor 3a to generate heat, and the yellow ink is heated to transfer the image onto the image receiving paper 1. at the same time,
The image receiving paper 1 is driven by a driving unit (not shown) in synchronization with the density information.
Are moved line by line in the direction of arrow d. At this time, the ink sheet 2 is conveyed in the direction of the arrow e by the frictional force between the thermal head 3 and the platen roller 4 due to the frictional force between the image receiving paper 1 and wound up while applying tension by means (not shown).

When the printing of one page is completed with the yellow ink in this way, once the conveyance of the image receiving paper is stopped, the thermal head 3 is moved in the direction of arrow f to move the thermal head 3 and the ink sheet 2 to the platen. Move away from the roller 4. Thereafter, the ink sheet 2 moves in the direction indicated by the arrow e until the recording start position comes to a position facing the heating resistor 3a.
The image receiving paper 1 is transported in the direction opposite to the direction of the arrow d until the recording start position comes to a position facing the heating resistor 3a, and the recording of the second color magenta ink is started. Thereafter, the thermal head 3 and the ink sheet 2 are pressed against the platen roller 4 to record one page of the magenta ink on the recording image of the yellow ink. In the same manner, printing with the third color cyan ink is performed in the same manner, and printing of a color image by the subtractive color mixing method is completed.

FIGS. 1 and 2 are schematic structural diagrams of density characteristic measurement images in this embodiment recorded by a gradation printer having the structure of FIG. In the first pattern of FIG. 1, S0 divides the heating resistor 3a into m groups,
FIG. 3 is a recorded image obtained by a first recording step, in which an applied energy of one half of the maximum energy is uniformly applied to each group and recorded, wherein S ₁ to S _m correspond to the m-th group of each heating resistor group; FIG. 9 is a recorded image in a second recording step in which energy of one-mth of the maximum energy is applied, and energy that is sequentially increased by one-mth of the maximum energy is applied to the first group, and then recorded. Incidentally, m-th of the m respective groups from the first heat generating resistor corresponds to m each concentration block S _m from S ₁ on the pattern. The pattern in FIG. 1 is similar to the pattern in FIG. 6 shown in the conventional example.

The second pattern shown in FIG. 2 is the same as the first pattern, except that the energies of m density blocks from S ₁ to S _m are sequentially shifted by one block in the main scanning direction, and are recorded. , and the following Similarly, the pattern of the m-th order, respectively blocks of m density block S _m from S ₁ in the first pattern (m-
1) The data is rotated and shifted in the main scanning direction by the number of pieces, and recorded.

As described above, in the present embodiment, the heaters shown in FIGS. 1 and 2 which are applied and recorded with different combinations of m different energies applied stepwise to each group are used. 1 and 2 record the same pattern for each color.

FIG. 4A shows one half of the maximum energy.
FIG. 6 is a diagram showing an example of a recording density distribution when recording is performed by uniformly applying the applied energy over the entire length in the main scanning direction. FIG. 4B is a diagram showing one example of the result of measuring the reflection density of each density block in the density characteristic measurement image of FIG. 1 with a Macbeth densitometer. When performing gradation recording with an actual image, a table of applied energy corresponding to the density information is created in advance from this figure, and the applied energy is controlled based on this table to obtain a desired density. In FIG. 4A, the recording density distribution is not uniform due to variations in heat generation due to variations in the heat generation efficiency of the heating resistor (or variations in the pressing force between the thermal head and the ink sheet and the image receiving paper in the main scanning direction). Has become. Accordingly, data indicating the relationship between the recording density and the applied energy obtained in FIG.
Is not valid. Similarly, no effective data can be obtained due to the variation in heat generation from the second pattern of FIG. 2 to the m-th pattern. However, since m blocks are sequentially shifted in the main scanning direction and are recorded, the m-th block is shifted from the first pattern. Averaging the variation of the recording density distribution in the main scanning direction by averaging m reflection density values corresponding to m density blocks S ₁ to S _m obtained from the m-th pattern. This makes it possible to obtain highly accurate data indicating the relationship between the recording density and the applied energy. Note that the same result is obtained for each color.

As described above, according to this embodiment, the same energy is applied to each of the plurality of heating resistors 3a formed on the thermal head in the main scanning direction, and
A plurality of heating resistors 3a are divided into m groups, and different energy is applied stepwise to each group of the heating resistors 3a to perform a first recording process. A second recording step in which thermal recording is performed once on the image receiving paper 1 subsequent to the step, and a density of an image recorded on the image receiving paper 1 in the second recording step for each portion corresponding to each group of the heating resistor 3a. In the second recording step, different energies are applied stepwise to each group of the heating resistors 3a in different m combinations, and the recording is performed on the image receiving paper in the second recording step. Forming m images with different density arrangements, and executing the measurement process m times, and averaging the obtained m reflection density values corresponding to each group of the m heating resistors 3a. Resistance of the thermal head 3 Since the variation in recording density due to heating variations in 3a can be averaged in the main scanning direction, it is possible to provide a density characteristic measuring method in the gradation printer to obtain a highly accurate relationship between the recording density and the applied energy.

In this embodiment, the thermal transfer type gradation printer has been described. However, if the type of the printer is such that heat generation varies in the main scanning direction of the head during recording, a thermal type or an energized thermal type may be used. Similar effects can be obtained.

Although the arrangement of the density blocks having different applied energies used in the present embodiment is sequentially shifted in the main scanning direction and rotated, the same applies to other arrangements or completely random arrangements. The effect of can be obtained.

In this embodiment, the arrangement of m density blocks having different applied energies is changed to record m images having different density arrangements. The number m does not necessarily have to match.

Further, in the present embodiment, in the first recording step in which recording is performed with uniform applied energy, half of the maximum energy is applied, but the recording speed, the magnitude of the maximum energy, and the thermal head Energy of other magnitudes may be used depending on thermal characteristics and the like.

[0021]

As described above, according to the present invention, a plurality of heating resistors formed on the thermal head in the main scanning direction are divided into m groups, and each heating resistor group is divided in steps. Applying different energies to the recording paper to perform thermal recording at least once, and measuring the density or reflectance of each part corresponding to each group of the heating resistors of the image recorded on the receiving paper in the recording process In the recording step, different energy is applied stepwise to each group of the heating resistors in different n combinations, and n different density arrangements recorded on the image receiving paper by the recording step are applied. While forming an image, the measurement process is executed n times, and the obtained reflection density values corresponding to the respective groups of the n heating resistors are averaged to obtain the heating variation of the heating resistor of the thermal head. The variation of the recording density in the main scanning direction due can be averaged. This makes it possible to provide a density characteristic measuring method in a gradation printer that obtains a highly accurate relationship between the recording density and the applied energy, and has a great practical effect.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image of a first pattern in a density characteristic measuring method according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image after a second pattern in the density characteristic measuring method according to one embodiment of the present invention.

FIG. 3 is a basic configuration diagram of a gradation printer according to an embodiment of the present invention.

FIG. 4A is a diagram showing a recording density distribution in a case where recording is performed by applying an energy of の of the maximum energy uniformly over the entire length in the main scanning direction. FIG. 2B is a diagram showing the result of measuring the reflection density of each density block in the density characteristic measurement image of FIG. 1 using a densitometer.

FIG. 5 is a basic configuration diagram of a conventional gradation printer.

FIG. 6 is a schematic configuration diagram of an image in a density characteristic measuring method in a conventional gradation printer.

FIG. 7 is a diagram showing the result of measuring the reflection density of each density block of each color in the density characteristic measurement image of FIG. 6 with a densitometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image receiving paper 2 Ink sheet 3 Thermal head 3a Heating resistor 4 Platen roller

Continuing on the front page (72) Inventor Taiichi Koyama 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-4-147870 (JP, A) JP-A-63-283974 (JP, A) JP-A-3-141794 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) B41J 2/36

Claims (2)

(57) [Claims] 1. A dividing a plurality of heating resistors formed in the main scanning direction in the thermal head into a plurality of groups, the receiving sheet by applying different energy for each of the groups
A first recording step of performing a first thermal recording, and the thermal recording performed by each group of the heating resistors.
A density characteristic measuring method for a thermal head and a measurement step of measuring a concentration or reflectance for each corresponding portion of the receiver sheet, further of the first round for each group of said heating resistor
Applying energy different from that of thermal recording
A second recording step of performing recording at least once, and the first and second recording steps are performed on the image receiving paper.
The density or reflectance of images with different recorded density
A method for measuring the density characteristics of a thermal head, wherein the density is measured and averaged in the measuring step . 2. The method according to claim 1, wherein the first and second recording steps are performed at the same
N sets of steps which differ in steps for each group of heating resistors
The energy is applied in combination, the measurement process is performed n times, and the n measurement results obtained for each group of the heating resistors are obtained.
2. The thermistor according to claim 1, wherein the fruits are averaged.
The method for measuring the density characteristics of heads.