JP2532093B2 - Image recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image recording apparatus that performs image recording with one pixel in a multi-step tone.

(Prior Art) At present, in an image recording apparatus, for example, when performing image recording with a thermal head at 64 gradations, as shown in FIG. 3, the pulse of the thermal head for producing the second gradation is generated by the thermal head. At the timing when the energizing pulse width at the time of transferring the first gradation data to the resistor becomes 2 ms,
After that, the second to the heating resistors of the thermal head
A pulse is applied to the thermal head at a timing such that the width of each energizing pulse during the transfer of 63 gradation data is 0.2 ms. The heating resistor of the thermal head is divided into two blocks and driven by a power supply voltage of 6.3 to 7.8 V.
After the transfer of the heating resistor of the block is completed, the heating resistor of the second block is transferred to perform line feed.

However, in this image recording apparatus, even if all the 64 gradation data to be collectively transferred by the heating resistor of the first block is the 33rd gradation data or more and there is no 1st to 32nd gradation data. (2ms + 32 x 0.2ms) = 8.4ms, the heating resistor of the thermal head must be energized, and image recording is slow. Therefore, if the power supply voltage is raised to increase the energy applied to the thermal head, this 8.4ms can be made shorter. However, the power supply voltage is currently (6.3 to 7.8
V), the energization pulse width of 0.2ms (the energization pulse width depends on the data transfer speed specifications of the thermal head).
It can be shortened to 0.1ms, but there is a margin due to deterioration of the thermal head), and the gradation of the recorded image cannot be 64 gradations. In addition, there is a problem that wrinkles occur due to elongation of the base of the ink sheet.

(Object) It is an object of the present invention to provide an image recording apparatus which can improve the above-mentioned drawbacks, can speed up image recording, and does not cause wrinkling.

(Structure) The present invention relates to an image recording apparatus for sending data of a plurality of (N) gradations to a thermal head and controlling an energizing pulse width of a heating resistor in the thermal head to perform image recording with one pixel as multi-step gradation. As shown in FIG. 1, it has a minimum value gradation detection means 1 and a voltage control means 2, and the minimum value gradation detection means 1 detects the weight of the gradation data to detect the gradation data to be transferred at the same time. The minimum value Nmin (Nmin ≦ N) gradation is determined. Then, the voltage control unit 2 determines that the voltage applied to the heating resistor of the thermal head is high until the transfer density reaches the transfer density of the mth gradation (0 ≦ m ≦ Nmin) according to the determination result of the minimum value gradation detection unit 1. Set the level to low level after that.

Embodiments of the present invention will be described below with reference to the drawings.

 FIG. 2 shows an embodiment of the present invention.

This embodiment is a sublimation thermal transfer printer that performs image recording with one pixel in a multi-step tone. A thermal head 11 has a large number of heating resistors arranged in a line, which are divided into two blocks and driven. You. The thermal control unit 12 converts the input data transferred collectively into data suitable for thermal control, and this data is image data having a weight of N (64 in this example) gradations. The gradation data weight detection counter unit 13 detects the weight of the gradation data from the thermal control unit 12 for each block, and at the same time, among the 64 gradation data to be transferred by the heating resistor of each block of the thermal head 11. Determine whether the data of the minimum value Nmin gradation is data of 32 gradations or less,
The control unit 14 is notified of the result. Also heat control section
The data from 12 is stored in the line memory 15 and applied to the thermal head 11, and the power supply voltage supplied from the power supply 16 to the thermal head 11 is controlled to a high level or a low level by the power supply control unit 17. The thermal head 11 latches the data from the line memory 15 in response to the latch pulse from the control unit 14, and the control unit 14 responds to this data.
By transferring the heat from the heating sheet by applying a strobe signal from the ink sheet to generate heat, the ink sheet is transferred to the recording sheet. In this case, the control unit 14 divides the heating resistor of the thermal head 11 into two blocks and sequentially performs the transfer, that is, first, normally, a latch pulse is output to transfer to the heating resistor of the first block and the first block is output. Latch the data of the gradation and output the strobe signal to transfer the data of the first gradation with the energization pulse width of 2 ms.
Then, a latch pulse is output every 0.2 ms to sequentially latch and transfer the data of the second to 64th gradations, and then the transfer by the heating resistor of the second block is similarly performed. During this transfer, the control unit 14 continuously outputs a strobe signal for each block, and causes the power supply control unit 17 to set the power supply voltage of the thermal head 11 to a low level. Control part
Reference numeral 14 denotes the output signal of the gradation data weight detection counter unit 13 as shown in FIG. 4 when the 64 gradation data to be transferred by the heating resistor of the 1st block does not include the data of the 32nd gradation or less. In 3 ms until the transfer density of the thermal head 1 reaches the density of the 33rd gradation based on the judgment, the power supply control unit 17 is made to switch the power supply voltage of the thermal head 11 to 12 V higher than usual,
When transferring the data of the 33rd to 64th gradations, the power supply control unit 17 returns the power supply voltage of the thermal head 11 to the normal low voltage of 7V. The same applies to the transfer by the heating resistor of the second block. In these transfers, the transfer for one line is performed, and this is repeated to transfer the one frame.

If each 64 gradation data does not include the 1st to 32nd gradation data, in the case of 2000 line image recording, the conventional device has (2ms + 31 x 0.2ms + 31 x 0.2ms) x 2 blocks x 2000 lines = 57.6S (line The feed time is excluded), and in this embodiment, (3 ms + 30 × 0.2 ms) × 2 blocks × 2000 lines = 36S. The difference between the two is 20.6 S, and when this is for three colors in full-color image recording, it is 61.8 S, and this embodiment greatly speeds up.

 FIG. 5 shows the configuration of the power control unit 17.

The power supply control unit 17 includes transistors 18 to 21, zener diodes 22, 23, resistors 24, 25, diodes 26, 27, and a buffer 28.
And a voltage Vcc is supplied from the power supply 16. One of the transistors 18 and 19 is turned on by a signal from the controller unit 14 to short-circuit one of the Zener diodes 22 and 23. When the Zener diodes 22 and 23 are not short-circuited by the transistors 18 and 19, the power supply voltage Vcc is applied through the resistors 24 and 25 to generate constant voltages different from each other, which voltage is the diode 26 or 27, the buffer 28 and the transistor. It is output as a power supply voltage to the thermal head 11 via 20, 21.

FIG. 8 shows the configuration of the gradation data weight detection counter unit 13. The gradation data weight detection counter unit 13 is a comparison circuit.
In 29, the weight of each gradation data from the heat control unit 12 is compared with the setting data of the 6-bit data setting switch 30, and when the weight of the gradation data is smaller than the setting data, the signal output from the comparison circuit 29 is output to the inverter 31. 12-bit counter via
Input to 32, and output each bit of this counter 32 to OR circuit
Output to the controller unit 14 via 33.

FIG. 7 shows the configuration of the controller unit 14. The controller unit 14 includes a central processing unit CPU and a read-only memory R.
It consists of OM, random access memory RAM, and I / O port I / O.

 FIG. 6 shows a processing flow of this embodiment.

This embodiment has a well-known mechanism (not shown). First, a recording sheet is inserted into a recording position, and a full-color transfer is performed by transferring yellow, magenta, and cyan to the recording sheet. And eject the recording paper. In the transfer of yellow, magenta, and cyan, one frame is transferred by transferring one line at a time on recording paper. In the transfer of one line, the line feed is performed after the transfer by the heating resistor of the first block and the transfer by the heating resistor of the second block. In the transfer by the heating resistor of each block, the control unit 14 transfers the gradation data from the thermal control unit 12 to the line memory 15 and checks the output signal of the gradation data weight detection counter unit 13 to determine the minimum value Nmin of the gradation data. Gradation data
If the data has 32 gradations or less, normal 64 gradation data is transferred. However, if the minimum value Nmin gradation data is data of 33 gradations or more, the power supply controller 17 switches the power supply voltage of the thermal head 11 to a high level, and the transfer density of the thermal head 11 reaches the density of the 33rd gradation. At that time, the power supply controller 17 returns the power supply voltage of the thermal head 11 to the low level to transfer the data of the 33rd gradation or higher. Then, the controller unit 14 outputs a latch pulse corresponding to each gradation data in the transfer of the normal 64 gradation data, and corresponds to each gradation data of the 33rd gradation or higher in the transfer of the data of the 33rd gradation or higher. Output a latch pulse.

(Effect) As described above, according to the present invention, data of a plurality of (N) gradations is sent to the thermal head, and the energizing pulse width of the heating resistor in the thermal head is controlled to form one pixel as a multi-step image. In the image recording device for recording,
The minimum value Nmin (Nmin ≦ N) of the gradation data to be transferred at the same time is determined by detecting the weight of the gradation data, and the voltage at the heating resistor of the thermal head is transferred at a transfer density of m (0 ≦ m).
≦ Nmin) High level until the transfer density of the gradation is reached and low level after that, so that the image recording can be speeded up and at the same time, the gradation of the image recording can be sufficiently taken.
No wrinkling problem occurs.

[Brief description of drawings]

FIG. 1 is a block diagram showing the present invention, FIG. 2 is a diagram showing an embodiment of the present invention, FIG. 3 is a diagram showing a thermal head applied pulse of a conventional apparatus, and FIG. 4 is a timing chart of the above embodiment. FIG. 5 is a circuit diagram showing the power supply control unit of the above embodiment, FIG. 6 is a flow chart showing the processing flow of the above embodiment, FIG. 7 is a block diagram showing the control unit of the above embodiment, and FIG. It is a block diagram showing a gradation data weight detection counter unit of the above embodiment. 1... Minimum value gradation detection means, 2... Voltage control means.

Continuation of the front page (56) Reference JP 61-276479 (JP, A) JP 61-157063 (JP, A) JP 59-216374 (JP, A) JP 63-306769 (JP , A) JP-A-58-138668 (JP, A) JP-A-63-41162 (JP, A) JP-A-63-242658 (JP, A) JP-A-61-205152 (JP, A) Actual development 49-72135 (JP, U) Actually opened Sho-57-136750 (JP, U)

Claims (1)

(57) [Claims] 1. An image recording apparatus for sending image data of a plurality of (N) gradations to a thermal head and controlling an energizing pulse width of a heating resistor in the thermal head to perform image recording with one pixel as multi-step gradation. The minimum value Nmin (Nm (Nm
in ≦ N) The minimum value gradation detecting means for judging the gradation and the judgment result of the minimum value gradation detecting means determines that the voltage applied to the heating resistor of the thermal head is m (0 ≦ m ≦ Nmi).
n) An image recording apparatus provided with a voltage control unit that keeps a high level until the transfer density of a gradation is reached and then sets a low level thereafter.