JPS60236768A - Printer - Google Patents

Abstract

PURPOSE:To optimize the control of an applied voltage while allowing the detection of possible breakage in a plurality of heat generating resistors by computing the mean of resistance values of the heat generating bodies detected to control the applied voltage with the mean as reference. CONSTITUTION:A resistance value detection processing section 6 is provided to directly detect resistance values of heating resistors 2a of a printhead 1, detects resistance values of the heating resistors 2a directly to determine the mean thereof from the detection values and electricity to be applied to the heating resistors 2a is controlled by a voltage control section 5 based on the results. To detect the resistance values of the heating resistors 2a, for example, a switch 9 is turned to the resistance value detecting section 6 to detect the oscillation frequencies at a comparator 17, a capacitor 16 and a resistance 15.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal printer used as an output device for personal computers and the like, and in particular, it uses a heating resistor head and prints a thermal paper sheet or a thermal film ribbon as a medium. It is printed on paper as .

Structure of a conventional example and its problems FIG. 1 is a block diagram of a voltage control device for a print head section in a conventional thermal printer.

In the figure, 1 is a print head section, which includes a resistor group 2a in which n resistors 2 for printing are provided in parallel, and a resistance value detection resistor made in the same manufacturing process as the resistor group 2a. It has a body 3.

Reference numeral 4 denotes a printer control section, which includes a resistance value detection processing section 6 that detects the resistance value of the resistance value detection resistor 3 and a voltage controlled by the output of this resistance value detection processing section 6 to drive the resistor group 2a. It has a voltage control section 5.

In the above configuration, the resistance value detection processing section 6 detects the resistance value of the resistance value detection resistor 3 and sends the information to the voltage control section 5. The voltage control section 5 controls the voltage applied to the print head section, assuming that the resistance value detected by the resistance value detection processing section 6 is equivalent to the resistance value of the resistor group 2a.

However, with the above configuration, if there is a difference in resistance between the resistor group 2a used for printing and the resistance value detecting resistor 3, voltage control is impossible, and due to the manufacturing process, the resistor group 2a has a variation of about ±6%, and the n of resistor group 2a
It has the disadvantage that precise voltage control is not possible to absorb variations in resistance values between resistors, and since the resistor group 2a used for printing is not directly detected, when replacing the print head, If part of the resistor group 2a is outside the tolerance (hereinafter referred to as damage), or if the resistor group 2a is out of tolerance during printing,
If some of the resistors a are damaged, it cannot be detected, and the voltage printed on the resistor group 2a is fixed by the resistance value of the resistance value detection resistor 3, resulting in a large load factor. However, there were problems such as heat accumulation and the inability to print with uniform density.

Purpose of the Invention In view of the above drawbacks, the present invention detects damage to a resistor group by directly detecting the resistance value of the resistor group used for printing, and detects if the resistor group is not damaged. By controlling the voltage using the average value of the resistance values, we can prevent deterioration of the heating resistor and extend the life of the heating resistor. At the same time, by applying an appropriate voltage, we can provide a printing device with high printing quality. Another object of the present invention is to provide a printing device with uniform printing density and stable printing quality by controlling the voltage according to the history of the printing load factor.

Structure of the Invention The present invention includes a resistance value detection processing unit that directly detects the resistance value of a resistor group in a print head unit and also detects damage to the resistor group, and a resistance value detection processing unit that directly detects the resistance value of a resistor group in a print head unit and also detects damage to the resistor group, and a This is a thermal printer equipped with a voltage control section that controls the printing voltage and a control device that controls the voltage control section based on the resistance value detected by the resistance value detection processing section. At the same time, the control device stores the history of the load factor, judges changes in the load factor, and always maintains appropriate changes in the applied energy due to changes in the load factor, thereby achieving highly stable printing quality. Furthermore, by detecting damage to the heating resistor, reliability and printing quality can be greatly improved.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a thermal printer in one embodiment of the present invention.

In the figure, 1 is a print head unit, a print head drive unit 7 that drives a resistor group 2a in which n resistors 2 for printing are provided in parallel, and a print head drive unit 7 that modulates the frequency of pulses according to the resistance value. A pulse modulation unit 10 that performs the pulse modulation, a counter unit 11 that counts the pulses output from the pulse modulation unit 10, and a comparison that compares the resistance value with an allowable value based on the output of the counter unit 11 and determines whether the load factor is large based on the memory history. A microprocessor 8 having a determination unit 8C, a storage unit 8a that stores detected resistance values, a history of print data, and tolerance values, and a calculation unit 8b that calculates an average value of the detected resistance values; A voltage control section 6 that controls the voltage applied to the resistor group 2a based on signals from the system, a mechanism control section 19 that controls the mechanism section 20, and an alarm section that issues an alarm based on a signal from the microprocessor 8 when an abnormal resistance value is detected. 21, and a switch 9 that switches between the resistance value detection section 6 and the voltage control section 6 using a signal from the microprocessor 8.

Figures 3 and 3 specifically show the main parts of the above configuration.
This will be explained in detail with reference to FIG. 4, which shows the waveforms of the main parts of the figure, and FIG. 6, which shows the operation flow of FIG. 3.

First, the flowchart shown in FIG. 6 (in the force state, the switch 9 is switched to the resistance value detection section 6 by the microprocessor 8. As a result, the output of the converter 17 is
・When the level (hereinafter referred to as 5) is reached, comparator 17
The potential of the child terminal is determined by the pull-up resistors 12a and 12b, the hysteresis resistor 13, and the heating resistor 2 as shown in Fig. 4a.
The vHl of

During this time, the capacitor 16 is charged via the resistor 16, and as a result, when the potential at one terminal of the comparator 17 becomes ``H'', the output of the comparator 17 changes to a low level (hereinafter referred to as below). Due to this change, the potential of the child terminal of the comparator 17 is changed to vL as shown in FIG.
It becomes l.

During this time, the capacitor 16 is discharged via the resistor 16, and as a result, when the potential at one terminal of the comparator 17 drops to ■L1''!, the output of the comparator 17 returns to H. The above operation is repeated, and as a result, pulse modulation The output of the section 10 has a constant oscillation waveform as shown in Fig. 4.Furthermore, when the resistance value of the heating resistor 2 becomes smaller, the potential of the child terminal of the comparator 17 becomes vH2, as shown in Fig. 4a. The oscillation frequency vL2 is higher than b as shown in FIG. 4C.

In this way, the frequency-modulated pulse according to the resistance value is
It becomes the input pulse train d of the counter section 11 via the buffer 14.

The counter unit 11 converts this pulse train into a microprocessor 8.
It starts counting in response to the signal , and when the count reaches a certain value, an interrupt is sent to the microprocessor 8 . In the state (A), the microprocessor 8 performs constant counting while counting is started and an interrupt from the counter section 11 is received, and when an interrupt from the counter section 11 is received, the microprocessor 8 stops counting. The resistance value is determined based on the count, and the result is stored in the storage section 8a in the state of (2). In the state (4), the microprocessor 8 repeats the above operation n times by controlling the printing gutter drive unit 7, detects the resistance values of all the resistors 2, and then detects the resistance values of all the resistors 2. In state (2), the average resistance value is calculated by the calculation unit 8b included in the microprocessor 8. In state (2), the microprocessor 8 controls the voltage control unit 5 based on the average resistance value obtained in this way, and ( 1
), the switch 9 is switched to the voltage control section 6 side. However, at the stage of detecting the resistance values of n recording resistors, two resistors exhibiting a variation of more than a certain value.
If there is, the microprocessor 8 determines that it is an abnormal resistor in step (1), outputs a stop signal to the mechanism drive unit 19 to stop the mechanism unit 20 in step (2), and then proceeds to step (C). A signal is output to the alarm unit 21 and a warning buzzer 22 sounds.

FIG. 6 is a block diagram showing another embodiment of the present invention, in which the operational amplifier 26 functions as a non-inverting differential amplifier, and the transistors 28, 30, 32 are connected to The output voltage (voUT
) can be varied as shown in FIG. Furthermore, when the load factor on the heating resistor group changes, the microprocessor 8 changes the signal to the voltage control section 5 to appropriately change the voltage.

As described above, the resistor 2 of the print head section 1 is controlled so that a constant electric power is always supplied.

Effects of the Invention The present invention includes a resistance value detection processing section that directly detects the resistance value of the heating resistor of the print head section, a voltage control section that controls the voltage applied to the print head section, and a resistance value detection processing section that directly detects the resistance value of the heating resistor of the print head section. By providing a control device that controls the voltage control unit based on the resistance value, it is possible to perform appropriate voltage control based on the average value of the resistance value, obtain clear printing quality, and extend the life of the heating resistor. be able to. Furthermore, by directly detecting the heating resistor, it is also possible to detect damage to the heating resistor, greatly improving reliability.Also, by controlling the voltage according to the printing load rate using the control device,
Appropriate applied energy can always be applied, stable printing with uniform density can be obtained, and there is no need to install a resistor for resistance value detection or a pattern cut for the rank setting part in the printing device. It is possible to realize a printing device that can obtain a number of excellent effects, such as the configuration of the print head section being simplified.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a voltage control device for a print head section of a conventional thermal printer, and Fig. 2 is a block diagram of a voltage control device for a print throat section of a thermal printer according to an embodiment of the present invention. 3 is a detailed block diagram of the first resistance value detection processing section, FIG. 4 is a principle diagram of the pulse modulation section, FIG. 6 is a flowchart of the same embodiment, and FIG. 6 is a voltage control section. FIG. 7 is a block diagram showing other details of the circuit, and FIG. 7 is a diagram showing the output voltages of the main parts thereof. 1...Print head section, 2...Heating resistor,
3... Resistor for resistance value detection, 4... Printer control section, 5... Voltage control section, 6...
...Resistance value detection processing section, 7 print head drive section, 8...
...control device (micro processor), 9...
・Selector switch, 10...Pulse modulation section, 1
1... Counter section, 18... Alarm section, 1
9...mechanism drive section, 20...mechanism section,
34...Warning buzzer. Name of agent: Patent attorney Toshio Nakao and 1 other person
4 Figure 5

Claims (3)

[Claims] (1) A plurality of recording resistors provided in the thermal print head, a resistance value detection processing unit that detects the resistance value of the recording resistors, and a voltage that controls the printing voltage to the recording resistors. comprising a control unit and a control device that controls the voltage control unit based on the resistance value detected by the resistance value detection processing unit,
A printing device characterized in that the resistance values of the plurality of resistors are detected, the average value thereof is calculated by the control device, and the voltage is controlled based on the average resistance value. (2) The control device compares each resistance value of the recording resistor with an allowable value, and when a resistance value outside the allowable value is present, the control device automatically stops and issues a warning. Printing device as described in section. (3) The control device stores the history of the printing load factor during printing, and controls the voltage to the recording resistor corresponding to the stored value of the load factor. printing device.