JPH03227259A - Heating photographic printing device - Google Patents

Abstract

PURPOSE:To perform control of suitable electrification time for each photographic printing means by a method wherein photographic printing is operated by controlling a power energized quantity of each photographic printing means based on a photographic printing data to be inputted for each heating element and a memory content of a memory means. CONSTITUTION:A control part 14 calculates each resistant value of heating element blocks B1-BM following a program in a ROM 15 based on a data from an analog/digital convertor 20 to be stored in a RAM 13. Electrification time control signal STB1-STMB controlling electrification time of heating element block B1-BM based on each photographic printing data from a photographic printing data input means 12 and each resistant value of the heating element block B1-BM is prepared, and is given to a drive circuit DR1-DRM. Further the photographic printing data is given to the drive circuit DR1-DRM via a serial transfer control circuit 16. Electrification time of each heating element R1-RN1 can be controlled by controlling a low level period of the control signal STB1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat-generating printing device that is suitably implemented in a printing device that uses thermal radiation.

BACKGROUND OF THE INVENTION FIG. 3 is a block diagram showing the basic configuration of a conventional thermal printer 1. When the control circuit 3 receives printing data from the printing data input means 2, it drives the drive circuit 4 to sequentially drive the plurality of printing means P1 to Pn, which are made up of a plurality of heating resistive elements provided in the thermal head 5. Then, perform the printing operation. Generally, there is variation in the resistance value of each heat generating resistor element of a thermal head, and even when printing images of the same density, it is necessary to correct the energization time and the like for each printing means. Therefore, conventionally, the thermal head 5 is ranked based on the average resistance value of all heat generating resistive elements constituting the thermal head 5, and the energization time is corrected based on this rank information.

In the thermal printer 1, rank information set by the setting means 6 is given to the control circuit 3 via the buffer 7. The control circuit 3 controls the energization time of each printing means based on the rank information from the setting means bIJ- et al. and the printing data from the printing data inputting means 2. Hardware switches Sa, Sb.

It is configured including Sc, and the ○N of these switches
10 FF Eight types of ranks can be set depending on the F status. Table 1 shows the correspondence between the resistance rank of the thermal head and the 0N10FF states of the switches Sa, Sb, and Sc.

Table 1 Thermal heads are ranked based on the average resistance value of all heat generating resistive elements in the thermal head. For example, when the average resistance value is small within a predetermined tolerance value, it is ranked as "1", and when the average resistance value is large, it is ranked as "8".

Problems to be Solved by the Invention As mentioned above, since the ranking of the thermal head is performed for the entire thermal head, the same correction is performed for all the heating resistive elements, and the individual printing means P1 to Pn When focusing on this, there were cases where the energization time was not properly controlled. Further, the above ranking is performed during the manufacture of the thermal held, which requires time and effort to measure the resistance values of all heat generating resistive elements, and in addition, the switch Sa.

Since the setting states of Sb and Sc are fixed, there is also the problem that if the resistance value of the heat generating resistor element changes due to changes over time, it becomes impossible to control the energization time appropriately.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned technical problems and to provide a heat-generating printing device that can appropriately control the energization time for each printing means based on the resistance value of each heat-generating resistor element.

Means for Solving the Problems The present invention provides: a power source that outputs a predetermined energizing power; a plurality of printing means comprising a plurality of heat generating resistive elements connected in parallel to the power source; and a combination of the power source and the heat generating resistive elements. a selective detection means provided between the heating resistor and the selective detection means for outputting the energizing power to each heat generating resistor element during printing operation and detecting the resistance value of each heat generating resistor element during measurement; A storage means for storing resistance value data for each heating resistor element, and control of the power energization amount for each printing means based on printing data input for each heating resistor element and the memory contents of the storage means. This is a heat-generating printing device characterized by including a driving means for performing a printing operation.

According to the present invention, when measuring the resistance value of a heat generating resistor element, the force resistance value of each heat generating resistor element is detected by the selective detection means provided between the power supply and the heat generating resistor element, and the resistance value of each heat generating resistor element is detected. The resistance value data for each is stored in the storage means. During the printing operation, the selective detection means outputs energizing power from the power supply to each heat generating resistor element, and the driving means outputs energizing power from the power supply to each heat generating resistor element, and the driving means outputs energizing power from the power supply to each heat generating resistor element, and the driving means outputs the printing data input for each heat generating resistor element and the storage contents of the storage means. Based on this, the amount of power energized for each printing means is controlled to perform a printing operation.

Therefore, the resistance value can be measured for each heating resistor element, and the amount of power energization, such as the energization time, can be controlled for each printing means based on this resistance value and printing data, so that uneven printing density can be avoided. You can make beautiful prints. Furthermore, if the resistance value of the heating resistor element changes due to changes over time, the resistance value can be measured again and the data stored again, and high-quality printing can always be performed. As a result, the printing quality of the heat-generating printing device is significantly improved.

Embodiment FIG. 1 shows a thermal printer 1 which is an embodiment of the present invention.
FIG. 1 is a block diagram showing the basic configuration of FIG.

Thermal 19 is the heating resistor block B1~
BM, and drive circuits DRI to DRM that drive heat generating resistive element blocks B1 to BM, respectively.

The heating resistance element block B1 includes heating resistance elements R1 to RN.
Similarly, the heating resistive element blocks B2 to BM are composed of N heating resistive elements.

The drive circuit DRI includes transistors TR1 to TRN connected in series to the heat generating resistive elements R1 to RN, respectively, gate circuits G1 to GN for energization control, a serial/parallel conversion circuit 17, and an inversion circuit 18. be done. The serial/parallel conversion circuit 17 converts the printing data given from the serial transfer control unit 16 into parallel data to create printing control signals S1 to SN, and outputs printing control signals S1 to SN.
1 to SN are given as one input to gate circuits 01 to GN. The inversion circuit 18 inverts the energization time control signal STB 1 given from the parallel boat control section 22 and supplies it as the other input to each of the gate circuits 01 to G and N. Therefore, it is possible to select the heat generating resistive element to generate heat using the print control signals 81 to SN based on the print data, and to control the energization time of the heat generating resistor element by the low level period of the energization time control signal STB1. Drive circuit DR2~
DRM also has the same configuration as the drive circuit DRI.

The print data from the print data input means 12 is stored in the RAM.
(random access memory) 13. Also R
AM1B stores data from the analog/digital converter 20 measured by a measurement operation described later. CPU (Central Processing)
The control unit 14, which is realized by an analog/
Based on the data from the digital converter 20, the ROM
(Read-only memory) Calculate each resistance value of the heating resistor blocks B1 to BM according to the program in 15, and
Store it in AM1B. Furthermore, the control unit 14 generates an energization time control signal that controls the energization time of the heat generating resistor blocks B1 to BM based on the print data from the print data input means 12 and the resistance values of the heat generating resistor blocks B1 to BM. Create STB 1 to STBM and drive circuit DF 1
~DRM, and print data is applied via the serial transfer control circuit 16 to drive circuits DR1~DRM.

Heat generating resistor element R1 forming heat generating resistor element block B1
~RN is supplied with voltage VDD from the power supply circuit 21. A high-level control signal is applied to the bases of the transistors TRI to TRN, and by setting the energization time control signal STB1 to a low level, the heating resistance elements R1 to R
A current is passed through N. Therefore, the control signal ST
By controlling the low level period of B1, the energization time of each heating resistor element R1 to RN can be controlled. The same applies to the heat generating resistive elements constituting the heat generating resistive element blocks B2 to BM.

Here, the operation of measuring the resistance values of the heat generating resistive elements R1 to RN in the heat generating resistive element block B1 will be explained. Control unit 1
4 controls the parallel boat control circuit 22 and supplies a high level switching signal SX to the base of the transistor TRX via the bell conversion circuit 24, thereby turning the transistors 1 to TRX into the OFF state. In this state,
Voltage VDD from power supply circuit 21 is applied to each heating resistance element R1 to RN via resistor RX. Next, the control unit 14 controls the drive circuit D via the serial transfer control circuit 16.
Drive R1. That is, by setting the printing control signal S1 to a high level and setting the energization time control signal 5TBI to a low level, the output of the gate circuit G1 is set to a high level and the transistor TRI is turned on. An equivalent circuit in this state is shown in FIG. Here, the resistance value rx of the resistor RX and the voltage VDD are predetermined values, so by detecting the potential V at the connection point 23 by the analog/digital converter 20, the resistance value rx of the resistor R1 is determined based on the following equation. The resistance value r1 can be calculated.

By repeating the above operations sequentially for the heating resistive elements R2 to RN, the respective resistance values r1 to rn of the heating resistive elements R1 to RN can be calculated, and the resistance value of the heating resistive element B1 can be calculated. Furthermore, the resistance values of the heating resistive element blocks B2 to BM can also be determined by a similar operation.

The resistance value rx of the resistor RX is the analog/digital converter 2
It can be set freely depending on the input voltage range of 0. In addition, by increasing the resistance value rx of the resistor RX, printing can be prevented when measuring the resistance value of the heating resistor element.During normal printing operation, the switching signal Sx is set to low level and the transistor TRX is turned on. As a result, the voltage VDD from the power supply circuit 21 is directly supplied to the thermal head 19, and the printing operation as described above is performed.

As described above, according to this embodiment, it is possible to measure the resistance value of each heat generating resistor element and control the energization time for each heat generating resistor element block based on the resistance value and print data. Therefore, uneven printing density due to variations in the resistance values of the heating resistive elements is prevented from occurring, making it possible to perform high-quality printing. In addition, the resistance value of the heating resistor element can be measured as needed, so even if the resistance value of the heating resistor element changes due to changes over time, etc.
Print quality will not deteriorate.

Effects of the Invention As described above, according to the present invention, the resistance value can be measured for each heating resistor element, and the power energization amount can be determined for each printing means, for example, based on the measured resistance value and printing data. Since the energization time is controlled, it is possible to print beautiful images with uniform print density. Furthermore, if the resistance value of the heating resistor element changes due to changes over time, the resistance value can be measured again and the data stored again, and high-quality printing can always be performed. As a result, the printing quality of the heat-generating printing device is significantly improved.

[Brief explanation of drawings]

FIG. 1 shows a thermal printer 11 which is an embodiment of the present invention.
FIG. 2 is a circuit diagram for explaining the principle of measuring the resistance value of a heating resistor element, and FIG. 3 is a block diagram showing the configuration of a conventional thermal printer 1.

Claims (1)

[Scope of Claims] A power source that outputs a predetermined energizing power, a plurality of printing means each including a plurality of heat generating resistive elements connected in parallel to the power source, and a plurality of printing means provided between the power source and the heat generating resistive elements, selective detection means for outputting the energizing power to each heat generating resistor element during printing operation and detecting this when measuring the resistance value of each heat generating resistor element; A storage means for storing resistance value data, and a printing operation is performed by controlling the amount of power energized for each printing means based on the printing data inputted for each heating resistor element and the stored contents of the storage means. 1. A heat-generating printing device, comprising: a driving means for driving.