JPH0356367Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is an improved thermal head used in thermal transfer type or thermal type printing devices (thermal printers), and prevents uneven printing of the thermal head. The present invention relates to an improved technique for a thermal head that can always print with a proper print density and that can also easily attach and detach the head.

[Prior Art] Recently, the above-mentioned thermal printers have a circuit to prevent uneven printing of the thermal head, that is, a circuit that supplies a predetermined applied voltage and current to the heating element, taking into consideration the temperature of the place (environment) where it is used. In addition, devices equipped with a circuit for adjusting print density have been developed (see FIG. 8). This type of conventional thermal printer Pt is preset so that the printing density of the thermal head can be varied in several stages, and a circuit is provided in the device body 28 to enable density adjustment as necessary. Print density is adjusted by changing the applied voltage and current pulse width by operating a dial 29 on the exterior panel.
Therefore, the thermal head is also constructed to accommodate this, and FIGS. 6A and 6B show a conventional thermal head _A2 . In this case, on the surface 20a of the substrate 20 made of ceramic or the like,
Generally, a heat generating part 21 and a lead part 22 connected to the heat generating part 21 and having lead wires 22a and a common lead wire 22b corresponding to the number of dots of each heat generating element 21a are provided. and thermal head
A ₂ is connected to a terminal of a flexible cable 23 for connecting the lead portion 22 to the main body of the printer and the lead pull-out portion 24 with an adhesive 25 such as bond.

As mentioned above, in this conventional method,
Once a predetermined printing density is set, the heating element 21a of the thermal head _A2 is always supplied with an applied voltage or current with the same pulse width, so that the surroundings of the thermal head _A2 are If the temperature changes, or the print density changes slightly due to the temperature difference of the heating element 21a itself between the beginning of printing and the middle of printing, this causes uneven printing, so do not operate the dial 29 from beginning to end. There were functional problems, such as having to make adjustments using the system, making it cumbersome to operate.

On the other hand, these days, as shown in Figures 7 and 9,
Lead extraction portion 24 on the surface 20a side of the substrate 20
By attaching an integrated circuit 26 to the printer, the number of lead wires 22a and terminal pins can be reduced, head replacement can be facilitated, and printers have been developed that can also handle the automatic adjustment of print density.

However, in the case of this conventional method,
An integrated circuit 26 is installed on the surface 20a of the thermal head _A2.
The structure is such that the thermal head A 2 is attached to the platen 30 during printing, so there is a space constraint to prevent it from coming into contact with the platen 30, so the shape is long and large, or the thermal head A ₂ gets in the way when it comes into contact with the platen. Structural problems that are said to be more likely to occur occur. Therefore, there are drawbacks such as uneven printing in terms of functionality, large size, and excessive space consumption, and in order to solve one, the other must be sacrificed, and miniaturization and printing performance are promoted at the same time. It has become a constant source of knowledge for me. Note that 27 is a drawer lead.

[Problems to be solved by the present invention] The present invention focuses on printing problems caused by differences in the usage environment and temperature changes, and the difficulty in downsizing the head body, as in the past. The object of the present invention is to provide a thermal head in which the head main body and printing device can be made compact, functionally it can automatically eliminate printing unevenness, and the head can be easily attached and detached.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a method for detecting the temperature of the heat generating part in a thermal head which is equipped with a heat generating part on the front side of a substrate made of ceramic or the like. An integrated circuit containing a built-in means and for controlling the current or applied voltage supplied to the heat generating part according to the detection signal from the detection means is provided on the back side of the substrate through at least one or more through holes. This is a thermal head with the following configuration.

[Function] With the above configuration, when the detection means detects a subtle change in ambient temperature, etc., the voltage or current detection signal from this detection means is input to the CPU in the integrated circuit, and the detection signal is input to the CPU in the integrated circuit. Therefore, it is compared and calculated with the reference value (optimal printing) inputted into the CPU in advance, and the obtained control signal operates the driver circuit to supply the necessary power to the heating element. can be automatically controlled so that the optimum amount of heat is always obtained. At the same time, since the integrated circuit with a built-in detection means such as a temperature sensor is installed in a position where the board does not touch the platen during printing, that is, on the back side of the board, the integrated circuit does not get in the way of the platen, resulting in a smaller size. is possible.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described based on the drawings.

1 to 4 show a first embodiment, and FIG. 1 is a perspective view showing the entire thermal head of this embodiment, and this thermal head A ₁
, on the surface 1a of the rectangular ceramic substrate 1,
For example, a heating element 2 consisting of 24 dots, lead wires 3 and common lead wires 3a corresponding to the number of dots on this heating element 2, and each lead wire 3 and common lead wire 3a are connected through a plurality of through holes 4. An integrated circuit 5 installed in the same place is provided. As shown in the longitudinal sectional view of FIG. 2 and the enlarged cross-sectional view of FIG.
It is integrally mounted on the b side with a resin exterior, and is composed of a control circuit incorporating a temperature sensor 6 as shown in the block diagram of FIG. This integrated circuit 5 is constructed on a ceramic substrate 1 as described above.
a temperature sensor 6 that detects the ambient temperature of the temperature sensor 6, a CPU 7 connected to the temperature sensor 6 via a pulse width controller 10, and a driver circuit that supplies power to the heating element 2 according to the output signal of the CPU. 8 and an external manual controller 9 that adjusts the print density by varying the voltage or current applied to the heating element 2 so that it can be operated manually.

The temperature sensor 6 is constituted by a resistance temperature sensor such as a thermistor or a varistor, and its detection portion is in contact with or in close proximity to the ceramic substrate 1, and is formed integrally with the integrated circuit 5, so that the temperature of the heat generating portion 2 is always maintained. It has become possible to detect changes.

The CPU 7 is composed of a comparison calculation circuit, a memory, etc., and compares the detection signal from the temperature sensor 6 with the optimum heat generation level input in advance from the data signal input section 14 and stored in the memory.
When a difference occurs, a control signal can be sequentially output to the driver circuit 8. These signals are always optimally timed by the clock signal from the clock pulse generator 15.

The driver circuit 8 is configured to receive a control signal from the CPU 7 and supply the necessary power to the heating element 2.

The external manual controller 9 manually adjusts the pulse width of the current supplied to the heating element 2 or the voltage applied thereto, thereby adjusting the amount of heat generated by the heating element 2. In other words, in addition to automatic operation,
It is configured so that the print density can always be maintained at an appropriate level by adding manual operation. In addition, in the figure, 11 is a resin exterior, and 12 is a lead wire.

With this configuration, the integrated circuit 5
This eliminates the restriction between the spacer and the platen 16, making it more compact. Then, during the printing operation, the thermal head
When a temperature change occurs in heating element 2 of A ₁ , first,
The temperature sensor 6 detects the magnitude of the temperature change, and a corresponding current or voltage analog signal is generated by the AD conversion circuit and pulse width controller 10 (not shown).
The signal is input to the CPU 7 via. Then,
The CPU 7 compares and calculates the reference value stored in the memory with the temperature signal (detection signal) from the temperature sensor 6, and if there is a difference, sends a control signal corresponding to the difference to the driver circuit 8. Output.

Upon receiving this signal, the driver circuit 8 supplies power to the heating element 2 according to the magnitude of the control signal, so that the optimum amount of heat generation can always be obtained.

FIG. 5 shows a second embodiment, in which case:
The resin for externally protecting the integrated circuit 5 covers not only the integrated circuit 5 but also the entire back surface of the ceramic substrate 1, so that the entire back surface is in a flat state. As a result, the thermal head _A1 can be easily attached to the head mounting portion.
In the figure, reference numeral 13 denotes a heat radiation hole, and by providing a large number of heat radiation holes 13 in the resin sheath 11, the temperature rise of the ceramic substrate 1 near the heating element 2 can be suppressed.

[Effects of the invention] As described above, the present invention has a thermal head equipped with a heat generating part on the front side of a substrate made of ceramic or the like, which has a built-in detection means for detecting the ambient temperature of the heat generating part. Since an integrated circuit for controlling the current or applied voltage supplied to the heat generating part based on the detection signal from the detector is provided on the back side of the substrate via at least one or more through holes, the detection means The heat generating part detection function and the comparison calculation function with the reference temperature of the integrated circuit allow the heat generating part to always obtain the optimum print density even when the ambient temperature of the head changes, and the integrated circuit Because it was attached to the back side of the ceramic board,
There are no restrictions on the arrangement with the platen, the head body becomes more compact, and there are practical benefits in that it does not get in the way when it comes into contact with the platen. In addition to the above-mentioned embodiments, the present invention may have a single through hole that is shared, and various design changes are possible within the scope of the technical idea described in the claims of the utility model registration.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a first embodiment of the thermal head according to the present invention, Fig. 2 is a longitudinal cross-sectional view of the same, Fig. 3 is a block diagram showing the circuit configuration, and Fig. 4 is a partially enlarged cross-sectional view of the same. 5 is a vertical sectional view of the second embodiment, FIG. 6 A is a front view showing a conventional thermal head, FIG. 6 B is a side view of the same, and FIG. 7 is another conventional example. FIG. 8 is a front view, FIG. 8 is a perspective view showing the thermal printer, and FIG. 9 is a side view showing how the thermal head and platen are attached. 1 is a ceramic substrate, 1a is a ceramic substrate 1
surface 1a, 2 is a heating element, 3 is a lead wire, 3a is a common lead wire, 4 is a through hole, 5 is an integrated circuit, 6 is a temperature sensor, 7 is a CPU, 8 is a driver circuit, 9 is an external manual controller, 10
is a pulse width controller, 11 is a resin exterior, 12 is a
13 is a lead wire, 13 is a heat radiation hole, 14 is a data signal input part, 15 is a clock signal input part, 16 is a platen, 20 is a board, 21 is a heat generating part, 21a is a heat generating element, 22 is a lead part, 22a is a lead line, 22
b is a common lead wire, 23 is a flexible cable, 24 is a lead drawer, 25 is an adhesive, 26 is an integrated circuit, 28 is a device body, 29 is a dial, 3
0 is a platen, and A ₁ and A ₂ are thermal heads.

Claims (1)

[Scope of utility model registration request] A thermal head having a heat generating part on the front side of a substrate made of ceramic or the like has a built-in detection means for detecting the temperature of the heat generating part, and a detection signal from the detection means is supplied to the heat generating part. 1. A thermal head, characterized in that an integrated circuit for controlling current or applied voltage is provided on the back side of a substrate via at least one through hole.