JPS61182965A - Thermal printer - Google Patents

Abstract

PURPOSE:To enable stable temperature compensation, by a method wherein an analog signal of a detected temperature of a thermal line head is converted into a digital signal, and the pulse width of an enable signal is varied according to temperature data, thereby compensating for temperature. CONSTITUTION:A temperature sensor part 2 for detecting the temperature of a thermal line head part 1 outputs an analog signal corresponding to the temperature of the head part 1, and the signal is digitized by an A/D converter part 14. The data (b) thus obtained are temperature data to be inputted to an enable signal controlling circuit 15. The circuit 15 modulates the pulse width of an enable signal on the basis of the temperature data (b). When the temperature of the head part 1 is raised, the values of the temperature data (b) are decreased, and the pulse width of the enable signal ENB is reduced, so that a voltage-impressing time for a heating element is shortened, resulting in that heating value is reduced, and an appropriate heating temperature can be obtained. On the other hand, when the temperature of the head part 1 is lowered, an operation reverse to the above is conducted, whereby an appropriate heating temperature can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal printer that has a thermal line head and a temperature sensor and performs temperature compensation for the thermal line head.

Prior Art FIG. 6 shows the configuration of a conventional example. 1 is a thermal line head section, 2 is a temperature sensor section that detects the temperature of the thermal line head section 1, 3 is a power supply, and 4 is a thermal line head 1
5 is a processing means for supplying print data to the control signal output means 4; The processing means 6 includes a microprocessor 6, a random access memory 7 (hereinafter abbreviated as RAM), and a read-only memory 8.
(hereinafter abbreviated as ROM) and an internal interface 9.

The configuration of the thermal line head section 1 is shown in FIG. Further, the timing of each control signal to the thermal line head section 1 is shown in FIG. Here, it is assumed that the heating element group 10 is composed of n heating elements. Serial data 5DATA corresponding to the six heating elements are transferred to the shift register 11 in synchronization with the data clock signal DCLK. When the data transfer is completed, the data is latched into the latch 12 by the strobe signal STB. Drive circuit 13
inputs the data of the latch 12 and drives one heating element group 1o. At this time, the drive circuit 13 is controlled by the enable signal KNB, and the enable signal KNB is low.
When it is H, it is in a non-operating state, and when it is H, it is in an operating state. The operation of the thermal printer consisting of the thermal line head section and each component block configured as described above will be explained.

The print data output from the processing means 5 is converted by the control signal output means 4 into the aforementioned data clock signal DCLK, serial data 5DAT, strobe signal STB, and enable signal ENB, and sent to the thermal line head section 1. be done. On the other hand, the temperature sensor section 2 detects the temperature of the thermal line head section 1 and sends an output corresponding to the temperature to the power source 3.

The power supply 3 applies a power supply voltage corresponding to the output of the temperature sensor section 2 to the thermal line head section 1 .

As can be seen from the above explanation, as the temperature of the thermal line head section 1 increases, the power supply voltage decreases, and conversely, as the temperature decreases, the power supply voltage of the thermal line head section 1 increases. Therefore, even if the temperature of the thermal line head section 1 changes, the temperature is compensated by changing the voltage applied to the head, and an appropriate heat generation temperature can be obtained.

Problems to be Solved by the Invention In such a conventional configuration, the temperature compensation function was performed using an analog circuit, so adjusting the variation in temperature compensation characteristics was complicated, and it was difficult to arbitrarily change the temperature compensation characteristic curve. was difficult. Furthermore, in order to realize wide-range temperature compensation, it is necessary to widen the variable range of the power supply, which has the problem of increasing the cost of the stain source.

The present invention has been made in view of this point, and an object of the present invention is to provide a thermal printer that enables stable temperature compensation.

Means for Solving the Problems In order to solve the above problems, the present invention provides a thermal line head and a temperature sensor section having an enable signal input terminal,
The outputs of the analog/digital converter section (hereinafter abbreviated as MU/D converter section) and A/D converter section that converts the analog signal of the temperature sensor section into a digital signal are sent to the enable signal control circuit as temperature data. Temperature compensation is performed by changing the pulse width of the corresponding enable signal.

According to the above-described structure, the present invention digitizes the output of the temperature sensor section and enables stable temperature compensation.

Embodiment An embodiment of the thermal printer of the present invention is shown in FIG. 14
is a human/D converter unit that converts the analog output of the temperature sensor unit into digital data. Reference numeral 16 denotes an enable signal control circuit that pulse width modulates the enable signal KNB in accordance with the temperature data output from the processing means 6. The other configurations are the same as the conventional example. 1 is a thermal line head section, 2 is a temperature sensor section, 3 is a power supply, 4 is a control signal output means, 5 is a processing means, 6 is a microprocessor, 7 is R
AM, 8 is ROM, and 9 is an internal interface.

The operation of the printer configured as above will be explained.

The temperature sensor section 2 for detecting the temperature of the thermal line head section 1 outputs an analog signal according to the temperature.
It is digitized by the human/D converter section 14. This data is temperature data to be input to the enable signal control circuit 15. The enable signal control circuit 16 performs enable pulse width modulation based on the temperature data, and an example of the circuit is shown in FIG. In Figure 2, 1
8 is a clock signal generation source, 17 is a counter, and 18 is a flip-flop. Further, FIG. 3 is a timing chart of FIG. 2. The temperature data output from the human/D converter section 14 is sent to the strobe signal STB by the counter 1.
7 is loaded.

At the same time, the strobe signal STB is input to the OK terminal of the flip-flop 18, so the enable signal E
NB becomes "H" and the thermal line head section 1 is enabled.

On the other hand, the temperature data loaded into the counter 17 is decremented by 1 within the counter by the clock output from the clock generation source 16. When this value becomes 0, the counter 17 outputs a borrow signal B.

This borrow signal B is input to the clear terminal CLH of the flip-flop 18. Therefore, the enable signal ENB is set to L to release the enable state of the thermal line head section 1.

Note that in FIG. 3, m is the number of clocks that provides the maximum pulse width of the enable signal ENB. Moreover, the temperature data shows a time of m −2. The enable signal ENB, which is the output of the enable signal control circuit 16 described above, is sent to the thermal line head section 1.

As can be seen from the above configuration, the thermal line head section 1
As the temperature increases, the value of the temperature data is reduced and the pulse width of the enable signal ENB is narrowed, which shortens the voltage application time to the heating element.As a result, the amount of heat generated decreases and the appropriate heating temperature is maintained. can get. On the contrary, when the temperature becomes low, the operation opposite to the above is performed, and an appropriate heat generation temperature is obtained.

In the example explained above, the A/D converter section 14 converts the analog signal of the temperature sensor section 2 into a digital signal and sends it directly to the enable signal control circuit 16. However, as shown in FIG. The output of converter 14 is fl
Input as the memory address of the OM conversion table 19,
The output of the ROM conversion table 19 may be sent to the enable signal control circuit. By doing this, when changing the temperature correction curve, by rewriting the memory contents of the FtOM conversion table 19,
It's easy to do.

Effects of the Invention As described above, in the thermal printer of the present invention, since the temperature compensation function is digitally processed, variations in temperature compensation characteristics can be suppressed and stable temperature compensation can be realized. Furthermore, it becomes easy to arbitrarily change the temperature correction characteristic curve. moreover.

The power supply can be of a fixed voltage type, and costs can be reduced compared to conventional variable voltage type power supplies.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a thermal printer according to an embodiment of the present invention, FIG. 2 is a block diagram of the enable signal control circuit, FIG. 3 is a time chart of the enable signal control circuit, and FIG. FIG. 5 is a block diagram showing the configuration of a conventional example, FIG. 6 is a block diagram of the thermal line head section, and FIG. 7 is a time chart of the thermal line head section. 1... Thermal line head section, 2...
-Temperature sensor section, 5...processing means, 14...
. . . A/D converter section, 15 . . . Enable signal control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 6 Figure 7

Claims (1)

[Claims] A thermal line head that allows serial input and has a permission input signal terminal that allows printing drive, a temperature sensor section that detects the temperature of the thermal line head, and an analog signal output that converts the analog signal output of the temperature sensor section into a digital signal. a digital converter section; and an enable signal control circuit that changes the pulse width of the enable signal in accordance with the temperature data by inputting the output of the analog-to-digital converter section; A thermal printer characterized in that the temperature of the thermal line head is compensated by connecting the terminal to the permission input signal terminal of the thermal line head.