JPH0343990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal transfer recording device using a sheet-like or ribbon-like thermal transfer medium that can be used repeatedly.

Conventional Structures and Problems There are two types of thermal transfer media: those coated with ink that melts when heated, and those coated with a reactive agent that performs a coloring reaction with the color developer on the recording paper side. Conventionally, with the ink or reactive agent of such thermal transfer media, the entire amount of heated and melted ink or reactive agent is transferred to the recording paper during recording, so the same area cannot be used repeatedly for recording, making it uneconomical. There was a problem. In contrast, thermal transfer media have recently been developed in which only a portion of the heated and melted ink or reactive agent is transferred to recording paper. Since this thermal transfer medium can be used repeatedly for recording, it is more economical than conventional media.

However, conventional thermal transfer recording devices using this type of heat-sensitive recording medium that can be used repeatedly are configured to perform recording with the same amount of recording power each time, so as the number of times the thermal recording medium is used increases, There was a problem that the recording density gradually decreased. Although this is a heat-sensitive recording medium that can be used repeatedly, if the same part is used for recording over and over again,
This is because the amount of transferred ink or reactant decreases sequentially from the first transfer to the second transfer, from the second transfer to the third transfer, and so on. Furthermore, due to the above-mentioned change in recording density, there was a problem in that the number of times the heat-sensitive recording medium could not be used repeatedly was increased.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
It is an object of the present invention to provide a thermal transfer recording device that can reduce changes in recording density due to repeated recording and increase the number of times a thermal transfer medium can be used repeatedly.

Structure of the Invention The present invention detects the number of times the same portion of the thermal transfer medium is used for each pixel recording position in a thermal transfer recording device that performs recording operations multiple times using the same portion of a thermal transfer medium that can be used repeatedly. means and
The above object is achieved by providing means for changing the amount of recording power during each recording operation for each pixel recording position according to the number of uses of the corresponding pixel recording position detected by the above means. be.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic side view showing the configuration of a thermal head and its peripheral parts in a thermal transfer recording apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram showing the overall configuration of the thermal transfer recording apparatus. be.

In FIG. 1, 1 is a reusable ink sheet (thermal transfer medium), 2 is a recording paper,
These are conveyed between a line type thermal head 3 and a platen roller 4 as shown in the figure. 5 is a take-up roller for the ink sheet 1, and 6 is a feed roller for the recording paper 2. Note that the recording paper 2 may have a color developer layer on its surface, and a reusable heat-sensitive transfer medium coated with a reactant that performs a color reaction with the color developer may be used instead of the ink sheet 1. .

In FIG. 2, 7 is a number storage section having the same number of words as the number of pixels in one line, and 8 is an addition section. The number of times each pixel recording position in the same portion of the ink sheet 1 has been used is determined by the number of times storage section 7 and the addition section 8, and is stored in the number of times storage section 7. Reference numeral 9 denotes a maximum value detecting section that detects and holds the maximum value of the values output from the adding section 7 during a period when recording is performed using the same portion of the ink sheet 1. 10 is a counting section, 11 is a comparison section that compares the outputs of the counting section 10 and the number storage section 7, and 12 is an AND gate. 1
3 is an image information storage section that stores image information for one line, and 14 is a recording pulse generation section that generates recording pulses. 15 is a thermal head driving section for driving the thermal head 3; The thermal head driving section 15 includes a shift register capable of storing one line of image information and a switching circuit for controlling the energization of the heating elements arranged in the thermal head 3. 16 is a recording paper feed control unit that controls the operation of the rotation drive means (not shown) of the feed roller 6;
Reference numeral 17 denotes an ink sheet feed control section that controls the operation of a rotation drive means (not shown) for the take-up roller 5. Reference numeral 18 denotes a control section that controls the device section. 19 is an output terminal for a signal a requesting an external circuit (not shown) to transfer image information for one line;
20 is an input terminal for an image information signal b transferred from an external circuit, and 21 is an input terminal for a signal c indicating a valid section of the image information signal.

Next, the operation will be explained with reference to FIGS. 1 and 2.

Before starting the recording operation, the control section 18 clears the number storage section 7, the maximum value detection section 9, and the counting section 10, and sets the apparatus to the initial state.

Thereafter, the control section 18 turns on the signal a and requests the external circuit to transfer image information for the first line. When the external circuit detects that the signal a is turned on, it turns on the signal c and serially transfers one line of image information signal b pixel by pixel. This image information is
8 is stored in the image information storage section 13.
Further, under the control of the control section 18, the number of times storage section 7 performs a read/write operation in synchronization with the transfer of the image information signal b. That is, when transferring the image information signal of the i-th pixel, reading and writing of the i-th word in the number of times storage section 7 is performed. When the image information signal b is '1' (black pixel), the adding unit 8 stores the number of times in the number storage unit 7.
When the image information signal b is '0' (white pixel), the number storage unit 7 outputs data obtained by adding 1 to the output data of
Output the output data as is. Therefore, if the i-th pixel is a white pixel, the data stored in the i-th word of the number storage unit 7 does not change, but if the pixel is a black pixel, the data stored in the i-th word of the number storage unit 7 changes. increases by 1. Here, since the data stored in all words in the number storage unit 7 has been cleared to 0, when the transfer of image information for one line is completed, the stored data in each word corresponding to the white pixel in the number storage unit 7 is 0. , the stored data of each word corresponding to a black pixel is 1. The maximum value detection section 9 compares the value of the output data of the addition section 8 with the value held internally, and if the former is larger than the held value,
The value is retained internally again. Here, the maximum value detection section 9 is cleared in advance and the internally held value is 0. Therefore, the current line has 1 black pixel.
If no black pixel is included, the value held by the maximum value detection unit 9 remains 0, and if one black pixel is included, the value held by the maximum value detection unit 9 is 1.

Note that when the control unit 18 detects that the signal c is on, it turns off the signal a.

When the transfer of image information for one line is completed in this way, the external circuit turns off the signal c. When the control unit 18 detects that the signal c is off, it starts the actual recording operation. Note that in this apparatus, the recording operation for one line is performed in N cycles.

First, the control section 18 synchronizes the number storage section 7 and the image information storage section 13 to perform a read operation, and outputs the image information of each pixel and the corresponding storage data of each word of the number storage section 7 at the same time. The comparator 11 sets the signal d to the '1' level when the output data of the number of times storage unit 7 is larger than the value of the counter 10. Here, since the value of the counting section 10 is 0, the signal d becomes the '1' level at the time when the image information of the black pixel is output from the image information storage section 13. The AND gate 12 gates the image information signal e outputted from the image information storage section 13 according to the signal d, and here, the image information signal e outputted from the image information storage section 13 is thermally output as is as a signal f. The signals are input to the head driving section 15, and are sequentially taken in and stored in a shift register provided inside the thermal head driving section 15.

When the reading of one line of image information from the image information storage section 13 is completed, the control section 18 stops the reading operations of the number of times storage section 7 and the image information storage section 13 and turns on the signal g. When the signal g is turned on, the recording pulse generator 14 sends out a recording pulse h of a constant width. When the control unit 18 detects that the recording pulse h is turned on, it turns off the signal g. Thermal head drive section 15
During the ON period of the recording pulse h, the internal switch circuit is selectively turned on according to the image information stored in the shift register, and among the heating elements arranged in the thermal head 3, the one corresponding to the black pixel is activated. energize only. Thereafter, when the recording pulse h is turned off, the power supply to the heating element is cut off, and the first cycle of the recording operation is completed.

When the control section 18 detects that the recording pulse h is turned off, the control section 18 causes the calculation section 10 to count up by 1, and then restarts the reading operation of the number storage section 7 and the image information storage section 13. At this time, the signal d is always '
Since it is at 0' level, the image information signal e output from the image information storage section 13 is suppressed by the AND gate 12, and the signal f is always at the '0' level. When the reading of image information for one line is completed, the control section 18 stops the reading operations of the number of times storage section 7 and the image information storage section 13, and turns on the signal g. As a result, the recording pulse generator 13 again sends out the recording pulse h for a certain period of time. When the control unit 18 detects that the recording pulse h is turned on, it turns off the signal g. The thermal head driving section 15 drives the thermal head 3 during the ON period of the recording pulse h, but in this line, none of the heating elements is energized. Thereafter, when the recording pulse h is turned off, the second cycle of the recording operation is completed.

When the control unit 18 detects that the recording pulse h is off, it starts the third cycle of the recording operation. Thereafter, the process is similarly executed up to the Nth cycle. Note that this is the recording of the first line, so the second recording operation is performed.
From the cycle onwards, the signal d is always at the '0' level, and the signal f is always at the '0' level. Therefore, 2
From the th cycle to the Nth cycle, the heating element of the thermal head 3 is not energized.

When the Nth cycle is completed, that is, when the recording operation for one line is completed, the control section 18 clears the counting section 10 and then sends out the pulse i. When the recording paper feed control unit 16 receives the pulse i, it operates the rotation drive means of the feed roller 6 to transport the recording paper 2 by one line. At the same time, the control unit 18 compares the value held by the maximum value detection unit 9 with a preset value N (for example, 15).

If the value held by the maximum value detection section 9 is less than N, the control section 18 turns on the signal a and requests the external circuit to transfer the image information of the next line.

When the value held by the maximum value detection unit 9 matches N,
The control section 18 sends out the pulse j and clears the number storage section 7 and the maximum value detection section 9. When the ink sheet feed control section 17 receives the pulse j, it operates the rotation drive means of the take-up roller 5 to convey the ink sheet 1 by one line. After that, the control section 18 turns on the signal a and requests the external circuit to transfer the image information of the next line.

Here, since recording of the first line has been completed, the value held by the maximum value detection section 9 is less than N.

Therefore, the control section 18 does not clear the number of times storage section 7 and the maximum value detection section 9, and also does not clear the ink sheet 1.
Requests the transfer of image information for the next line without transporting the line. When the image information of the second line is transferred, it is stored in the image information storage section 13, and the stored data in the number of times storage section 7 is updated. After that, the same recording operation as the first time is performed. however,
Among the words in the number storage unit 7, the value of the stored data of the word corresponding to the pixel that becomes a black pixel on both the first line and the second line is 2. Therefore, the heating element corresponding to such a pixel is used for one part of the recording operation.
It is energized in the 1st cycle and the 2nd cycle. In other words, the heating element that is energized for both the 1st line and the 2nd line will receive the recording pulse 1 when recording the 1st line.
The current is applied for the duration of one recording pulse, but in the second line, the current is applied for the duration of two recording pulses. In other words,
The amount of recording power for the pixel recording position of the ink sheet 1 corresponding to the heating element is twice as much when recording the second line as when recording the first line.

In summary, with the ink sheet 1 stopped, the recording operation is repeatedly performed using the same portion. At this time, the number of times the ink sheet 1 has been used for recording is determined for each pixel recording position and stored in the number storage section 7. Then, control is performed for each pixel recording position so that the amount of recording power is increased as the pixel recording position is used more frequently. In this embodiment, since the number of times the ink sheet 1 is used is determined immediately before starting the recording operation for each line, the number of times the ink sheet 1 is used is calculated just before starting the recording operation for each line. The number of uses is one more than the actual number of uses, but from the second cycle onwards it matches the actual number of uses. Therefore, the number of times of use stored in the number of times storage section 7 can be considered as the actual number of times of use.

In this way, since the amount of recording power is increased as the number of times of use increases, the amount of ink transferred from the ink sheet 1 can be kept approximately constant, and the recording density can be made uniform. Furthermore, since the recording density can be made uniform, the number of times the ink sheet can be used can be increased, and the efficiency of using the ink sheet 1 can be increased accordingly.

In the above embodiment, the ink sheet is fed when the number of times a certain pixel recording position is used reaches a predetermined number of times, but regardless of the actual number of times a pixel recording position is used, a certain number of lines are recorded. The ink sheet 1 may be conveyed each time. In this case, although the usage efficiency of the ink sheet 1 is slightly lowered, the configuration of the recording apparatus can be simplified.

Further, in the above embodiment, the pulse width of the recording pulse is constant, but the pulse width of the recording pulse may be changed depending on the value of the counting section 10, that is, the cycle number.

Effects of the Invention As described above, according to the present invention, the number of times the thermal recording medium is used is detected for each pixel recording position, and the amount of recording power is changed for each pixel recording position according to the number of times of use. It is possible to compensate for the decrease in the amount of ink or reactive agent transferred due to repeated use, and to make the recording density uniform, thereby achieving the effect that the number of times the thermal transfer medium can be repeatedly used can be increased.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing the structure of a thermal head and its peripheral parts in a thermal transfer recording apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of the same thermal transfer recording apparatus. 1... Ink sheet (thermal transfer medium), 2...
Recording paper, 3...Thermal head, 4...Platen roller, 5...Take-up roller, 6...Feed roller, 7...Number of times storage section, 8...Addition section, 9...Maximum value detection section, 10 ...Counting section, 11...Comparison section,
13... Image information storage unit, 14... Recording pulse generation unit, 15... Thermal head drive unit, 16... Recording paper feed control unit, 17... Ink sheet feed control unit.

Claims (1)

[Claims] 1. A thermal transfer recording device that performs recording operations multiple times using the same portion of a reusable thermal transfer medium, comprising means for detecting the number of times the same portion of the thermal transfer medium is used for each pixel recording position, and A thermal transfer recording apparatus comprising: means for changing the amount of recording power during a recording operation for each pixel recording position according to the number of uses of the corresponding pixel recording position detected by the above means.