JPS6222794B2 - - Google Patents

Description

[Detailed description of the invention] 1 Field of invention The present invention relates to a thermal recording device.

A thermal recording device consists of heat-generating resistors, which are recording elements, arranged in parallel in a row at high density, a drive circuit that selectively energizes the resistors in accordance with a series of recording signals, and a serial input of a series of recording signals in parallel. Direct-drive type thermal recording devices, in which a drive IC including a shift register circuit for converting to output and a gate circuit for controlling current flow are integrated on the same substrate, have become mainstream, replacing conventional diode and matrix circuit types. It is becoming. This direct drive type thermal recording device enables high-speed recording and also allows the device to be miniaturized.

2. Prior Art An example of a conventional circuit for a direct drive type thermal recording device is shown in FIG. 1 is a common electrode, 2 is a heating resistor, 3 is a driving IC, 4 is an external terminal for power supply for the IC, and 5 is an external terminal for grounding. Recording signal 6
The recording signal that is sequentially shifted to adjacent bits from the serial input terminal 6-1 of the IC in synchronization with the shift clock 7 corresponds to the number of bits (n) included in one IC.
If you shift the serial output terminal 8-1,
The data is further shifted through the serial input terminal 6-2 of the adjacent IC 3-2 connected to the IC 3-2, and is finally shifted by m ICs, that is, n×m bits (in this example, n×m bits).
m={number of heating resistor elements)} shifted.

Next, the enable terminal 9 becomes High (“H”), the gate circuit in front of the drive circuit opens, and the drive circuit of the bit corresponding to the recording signal = 1 becomes conductive during the period when (enable) = H, and the heating resistor The body is energized.

In order to enable even faster operation, the memory circuit is
Driving ICs that include a circuit (n bits) or two circuits (2n bits) are also in practical use, and in this case, one or two latch input terminals for the memory element and a gate circuit input terminal for the memory output are added. .

As mentioned above, the terminals of the drive IC are: 1 drive output terminal, 2 control signal terminals (shift clock, enable, latch, memory enable, etc.), 3 serial signal terminals (recording signal serial input, recording signal serial output), 4 power supply terminals, Consists of four types of ground terminals.

In the conventional configuration example shown in FIG. 1, wiring to the control signal terminal 2, electrode 4, and GND terminal is formed by two-layer wiring using a matrix circuit.

3 Problems with the Prior Art In particular, forming high-density multilayer wiring on a large substrate (for example, 60 x 300 mm) used in a thermal recording device for facsimile requires a complicated process and has a high rate of defects (opens, shorts). Therefore, inspection and correction also required a great deal of effort, making it difficult to manufacture thermosensitive recording devices.

4. Purpose of the Invention The present invention has been made in view of the above-mentioned problems in mounting the drive IC of a direct drive type thermal recording device, and provides a new input/output terminal to reduce the wiring on the board to one layer. For driving with array
The purpose is to provide a thermal recording device using IC.

5. Structure of the Invention In the thermal recording device of the present invention, the drive IC is provided with a serial signal output terminal and a control signal output terminal corresponding to the serial signal input terminal and the control signal input terminal, respectively, and these input terminals and control signal output terminals are provided. The output terminals are provided at substantially symmetrical positions with respect to the central axis of the IC, which is perpendicular to the direction in which the driving IC is arranged.
Corresponding input terminals and output terminals of adjacent driving ICs are electrically connected. As a result, the wiring on the board that connects the input/output terminals between the drive ICs can be reduced to a single layer at most.

6 Embodiments of the invention Examples of the invention will be described below with reference to the drawings. As shown in FIG. 2, with respect to the central axis 10-1 of the driving IC 3-1, which is perpendicular to the direction in which the ICs are arranged in parallel,
A shift clock output terminal 11-1 that exhibits the same voltage level as the shift clock input is provided at a position almost symmetrical to the shift clock input terminal 7-1, and the shift clock input terminal 7-1 of the adjacent IC 3-2 is connected to the shift clock output terminal 11-1.
2 through the on-board wiring 12-1. The input/output terminals and the wiring on the board are connected by wire bonding or the like. In addition, the input and output terminals of the shift clock are connected by electrode wiring inside the IC. Similarly, enable output terminal 1 shows the same level voltage value for enable input terminal 9-1.
3-1 is provided at a nearly symmetrical position with respect to the central axis 10-1, and connected to the adjacent IC via the on-board wiring 14-1.
Connect to the enable input terminal 9-2 of 3-2.
In addition, the serial signal input terminal 6-1 and output terminal 8-1 are also provided at symmetrical positions with respect to the central axis 10-1, and the connections between 8-1 and 6-2 are made by wiring 15-1 on the board.
1.

For ICs that require control signal input other than those listed above, provide output terminals for all control signal input terminals, arrange these input/output terminal pairs approximately symmetrically with respect to the central axis, and use the same method as above to Make connections between ICs.

Note that the control signal and serial signal input terminals 6-1, 7-1, and 9-1 of the first IC are connected to external connection terminals 6, 7, and 9 of the thermal recording device via wiring on the board.
connected to.

Further, 16-1, 16-2, . . . are IC power supply terminals, which are connected to the external connection terminal 5 of the thermal recording device via the wiring 18 on the board. 17,20 is
The GND terminal is connected to the external connection terminal 4 via the wiring 19 on the board. In addition, in FIG. 2, the wiring on the board is only one layer.

A driving IC having a pair of signal input/output terminals as described above can be easily obtained by forming the internal wiring of the IC in multiple layers. Multilayer wiring within an IC is advantageous in terms of manufacturing because, unlike multilayer wiring on large substrates of thermal recording devices, one defect on one wafer does not cause the entire wafer to be defective.
On the other hand, since the board wiring is in one layer, the manufacturing process becomes simple and easy, and the reliability of the product is increased.

7 Modifications of the Invention Next, modifications will be described. Wiring on the board 1
2, 14, and 15 may be omitted, and signal input/output pairs may be provided particularly along the sides facing adjacent ICs, and the ICs may be directly connected to each other by wire bonding. As another modification, not only control signals and serial signals but also IC power terminals may be wired by providing symmetrical input/output pairs on the same IC. Furthermore, the present invention is applicable not only to wire bonding IC chips but also to solder bonding using flip chips or tape carrier type bonding using tape carrier IC chips.

Alternatively, a buffer circuit may be provided inside the IC between the input/output terminal pair of the driving IC to increase the current output.

8 Effects of the invention As described above, according to this invention, direct
In high-density mounting of the drive IC of a drive-type thermal recording device, the wiring pattern formed on the board can be reduced to only one layer, making it possible to complete the complex high-density wiring, formation process, and inspection/correction process in one time. As a result, a thermosensitive recording device that is easy to manufacture and has high reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit (block) diagram showing a configuration example of a conventional thermal recording device, and FIG. 2 is a configuration diagram of a thermal recording device according to an embodiment of the present invention. 1...Common electrode, 2...Heating resistor, 3...Drive IC, 4...External power supply terminal for IC, 5...External terminal for grounding, 6...Recording signal serial input terminal,
7...Shift clock input terminal, 8...Record signal serial output terminal, 9...Enable input terminal,
10... Central axis of IC, 11... Shift clock output terminal, 12, 14, 15, 18, 19... Wiring on board, 13... Enable output terminal, 16...
...Power terminal, 17, 20...GND terminal.

Claims (1)

[Claims] 1 Heat generating resistors arranged in parallel, a drive circuit that selectively energizes these heat generating resistors according to a series of recording signals, and a serial input of the series of recording signals to parallel output to the drive circuit. In a thermal recording device that includes a shift register circuit and a gate circuit for converting a plurality of bits, and is integrally mounted with a driving IC arranged in parallel with the heating resistor, the driving IC controls a shift clock, an output A control signal output terminal that corresponds to each of the control signal input terminals such as enable and shows a voltage value of the same level is provided, and these control signal input/output terminal pairs and the serial input/output terminal pair of the recording signal,
The ICs are arranged in almost symmetrical positions with respect to the central axis of the ICs, which is perpendicular to the direction in which the ICs are arranged in parallel, and the output terminals of each IC are electrically connected to the corresponding input terminals of the adjacent ICs. Features of thermal recording device.