JPS61242859A - Thermal head driving device - Google Patents

Abstract

PURPOSE:To uniformize recording density by providing a thermal head with plural heating elements, a detection means to detect the number of heating elements in a fixed region, a variable constant voltage circuit to vary a voltage supplied to a thermal head and a drive circuit to supply a conduction signal to each heating element. CONSTITUTION:A thermal head 1 having plural heating elements receives a constant voltage supply from a variable constant voltage circuit 2, and a conduction signal is supplied from the drive circuit a specified region of each of group ten groups to which plural elements are allocated. Data to be heated is counted by a detection means 4, and the number of data lots every fixed region, i.e. the number of heating elements is sequentially stored into a memory 5. Data on the number of elements every fixed region is sequentially output to the variable constant voltage circuit 2. A constant voltage corresponding to the number of heating elements every fixed region is supplied to the thermal head 1, performing heating and driving at an optimal voltage every region. In other words, when the number of heating elements is small, a low voltage is supplied to the thermal head 1, and when the number is large, a high voltage to the thermal head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermal head driving device that achieves uniform printing and recording density using a thermal head.

[Prior Art] A thermal head has a plurality of heating elements, and a constant voltage circuit supplies a constant voltage, and a drive circuit supplies a conduction signal to each element to generate heat and drive the elements.

In addition, in a line thermal head with a large number of elements arranged,
It is divided into losing groups and conduction is made for each group.

[Problems to be Solved by the Invention] However, the number of heating elements in a certain area varies depending on the content to be recorded, from one element generating heat to all elements generating heat. Therefore, if a constant voltage circuit simply supplies a constant voltage to each heating element in a certain area, if there are few heating elements due to the delay of the constant voltage circuit, the supplied current per element will increase and the concentration will be high. This is a record, and if there are many heating elements, 1
The supply current per element decreases, resulting in low-density recording. When generating heat by dividing a line thermal head with a large number of elements arranged into certain areas, each *t
This means that the degree 'a' differs for each a.

In view of the above points, it is an object of the present invention to provide a thermal head driving device in which the voltage supplied is changed depending on the number of heat generating elements in a certain area, thereby achieving uniform recording density.

Means for Solving Problem L] The present invention provides a thermal head having a plurality of heating elements, a detection means for detecting the number of heating elements in a certain area, and a voltage etc. supplied to the thermal head by the output of the detection means. This thermal head driving device includes a variable constant voltage circuit, etc. that makes the voltage variable, and a driving circuit that supplies a conduction signal to each heating element of the thermal head.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention, and an example will be described in which a plurality of heating elements are divided into groups and driven as a thermal head.

In the figure, a thermal head 1 having a plurality of heating elements is shown.
A constant voltage is supplied from a variable constant voltage circuit 2, a plurality of elements are divided into, for example, 10 groups, and a conductive signal is supplied from a drive circuit 3 to a constant area of each group.

Data to be generated is sequentially sent to the thermal head 1 together with a clock, and this data is counted by a detection means 4 such as a counter, and the number of data for each fixed area is calculated.
In other words, the number of heating elements is stored in the memory 5 in sequence. When all the data is stored in the register of the thermal head 1, the constant area and number of elements data in the memory 5 are stored in the variable constant voltage circuit 2.
The variable constant voltage circuit 2 supplies the thermal head 1 with a constant voltage according to the number of heat generation inhibition points for each constant i region, and outputs a voltage R3i for each region sequentially. In other words, if the number of heat generating elements is small, a small voltage may be supplied to the thermal head 1, and if there are many heat generating elements, a large voltage may be supplied to the thermal head 1.

Incidentally, if the total number of elements in the thermal head 1 is not very large, the entire head may generate heat at once without being divided into groups, and the voltage of the variable constant voltage circuit 2 may be varied according to the total number of heating elements. Further, instead of making the voltage of the variable constant voltage circuit variable, the current of the variable constant voltage circuit may be made variable according to the number of elements that generate heat in a certain area.

[Effects of the Invention] As described above, the present invention supplies a voltage or current according to the number of heating elements in a certain area, so it is possible to always record a constant concentration regardless of the number of heating elements for each element*. is obtained.

[Brief explanation of drawings]

FIG. 1 is a detailed explanation of the configuration of an embodiment of the present invention.

Claims (1)

[Claims] 1. A thermal head having a plurality of heat generating elements, a detection means for detecting the number of heat generating elements in a certain area, and a variable device that varies the voltage or current supplied to the thermal head based on the output of the detection means. A thermal head drive device comprising a constant voltage circuit or a variable constant current circuit, and a drive circuit that supplies a conductive signal to each heating element of the thermal head. 2. When generating heat by dividing a plurality of heating elements of a thermal head into fixed areas, the voltage or current generated by the variable constant voltage circuit or the variable current circuit can be varied according to the number of heating elements in each fixed area. A thermal head driving device according to claim 1, characterized in that: