JPS63193856A - One-dimensional element device - Google Patents

Abstract

PURPOSE:To enhance the yield of production and make it possible to easily cope with a trouble generated in use, by connecting each corresponding driving element in each driving circuit to each element in a one-dimensional element part, and connecting the corresponding driving elements in respective driving circuits in parallel to each other. CONSTITUTION:A heat generating part 1 as a one-dimensional element part comprises n pieces of heat generating resistors 111-11n. A driving circuit part 2 provided for the heat generating part 1 is divided into a first driving circuit 21 comprising n pieces of driver transistors 211-21n and a second driving circuit 22 comprising n pieces of driver transistors 221-22n. For example, the heat generating resistor 111 can be driven by the transistor 211 or the transistor 221, the two transistors being connected in parallel to each other. When the driver transistor at one part of the first driving circuit 21 is troubled, the second driving circuit 22 is operated in place of the first driving circuit 21.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a primary element device such as a thermal head or a line sensor installed in a facsimile machine, a printer, etc. The present invention relates to a primary element device that makes it possible to correct defects in a drive circuit section by providing a circuit.

[Summary of the invention]

The present invention provides a primary element device having a primary element section made up of a plurality of elements arranged in a line, and a drive circuit made up of drive elements corresponding to each element of the element section. The corresponding drive elements of each drive circuit are connected to each element of the drive circuit, and the drive elements of each drive circuit that correspond to each other are connected in parallel with each other, and further a simple switching element is provided for each of them. This improves the yield during manufacturing, and also makes it possible to deal with failures during use without replacing the entire device.

[Conventional technology]

For example, a circuit for one dot of a thermal head is generally shown as shown in FIG. In this figure, the print signal is first input from the print signal input terminal (113) according to the clock signal input from the clock signal input terminal (114).
) to the shift register (110), and then this signal is input to the launch circuit (109) according to a strobe signal input manually from the launch pulse input terminal (112).
transferred to and held. The data held in the launch circuit (109) has its printing timing adjusted by an enable signal input from an enable signal input terminal (111), and drives a driver transistor (102) via a gate element (103). Heat generating resistor (101)
energizes and generates heat. Since it is necessary to flow a large current sufficient for printing through the heating resistor (101), the area occupied by the driver transistor (102) is usually large. In particular, when using thin film transistors, the area has to be larger than when using bulk transistors due to mutual conductance limitations. Therefore, most of the area of the circuit is occupied by the driver transistor (102), and the reliability of the entire circuit is greatly affected by the reliability of this part. In other words, the yield of the thermal head is greatly influenced by the driver transistor (102). However, conventional thermal head primary element devices have only a single drive circuit for each element, and failure of just one drive element may require replacement of the entire primary element device. Ta.

Similar problems can arise with line sensors.

[Problem that the invention seeks to solve]

The present invention was proposed in view of the above-mentioned conventional situation, and it improves the yield during manufacturing, and
It is an object of the present invention to provide a primary element device that can easily deal with failures during use.

[Means for solving problems]

The primary element device of the present invention proposed to achieve this object is composed of a primary element section consisting of a plurality of elements arranged in a line, and a drive element corresponding to each element of the element section. At least two drive circuits are provided, each corresponding drive element of each drive circuit is connected to each element of the primary element part, and the drive elements of each of the drive circuits that are in correspondence with each other are connected in parallel to each other. It is characterized by consisting of:

[Effect]

In this way, in the primary element device of the present invention, the corresponding drive elements of each of the plurality of drive circuit sections are connected in parallel, so that, for example, a failure occurs in one of the driver transistors that are the drive elements. Even if the driver transistor is connected in parallel, a normal driver transistor is selected and operation can be resumed. In addition, if at least two driver transistors connected in parallel are all normal, by operating them simultaneously, the on-resistance of the retriever transistor can be reduced, increasing the driving ability against the heat-generating resistor. Can be done.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG. 1, but the present invention is not limited thereto.

A first embodiment in which the primary element device of the present invention is applied to a thermal head will be described below with reference to the drawings. Figure 1 shows a schematic circuit configuration of a thermal head. In this figure, the heat generating part (
1) includes a plurality of, for example, n heating resistors (IL,
112.11:l,...,...,11. , ),
A drive circuit section (2) is provided for the heat generating section (1), and the drive circuit section (2) further includes, for example, n driver transistors (21, 21□, 2h,
..., 21. , ), the first drive circuit (2
1), and n driver transistors (2
2,,22□223. ..., 22. ) and a second drive circuit (22). That is, for example, if we focus on the heating resistor (Ill), it can be driven by the driver transistor (21□) or (22,), and these two driver transistors are connected in parallel to each other. That is why it is being done. Similar correspondence holds true for the heating resistor (11□) and those numbered thereafter.

The drive circuit section (2) is connected to the gate circuit section (3), where n driver transistors (21, 2h, 21!, . . . , 21) belonging to the first drive circuit are connected to the gate circuit section (3).
．． 1) are respectively corresponding gate elements (311, 31□
, 313°..., 31a), and driver transistors (221, 22!, 2) belonging to the second drive circuit.
2s,..., 22. l) are connected to corresponding gate elements (32, 32□, 323°..., 32.), respectively.

Switching between the first drive circuit and the second drive circuit is performed as follows. That is, the gate element (31, 3
1! ,31+,...,31. ) are gate-controlled by the first enable signal El supplied to the input terminal (4), and the gate elements (32,, 32□, 323...
.

32°) is arranged to be gated by a second enable signal E2 applied to the input terminal (5). In the normal state, the enable signal E2 is kept low.
2 is a gate element (32,, 32□.

321. ..., 32. ) is kept shut off (off).

On the other hand, the enable signal El is an operating pulse similar to the conventional one that becomes "H" depending on the printing timing. The print data output circuit (6) has a plurality of the aforementioned latch circuits (109) and shift registers (110) corresponding to each dot, and print data from the print data output circuit (6). The signals are sent to the gate elements (311, 31□, 313...) according to the enable signal E1 supplied to the input terminal (4).
, 31. , ) through the driver transistor (
21+, 21□, 21s,..., 21. ), and the heating resistors (111, 11□, lla,...
, 11. ) to generate heat. If a defect occurs in any of the driver transistors (21□21□, 2h, ..., 21.), an external enable signal E is generated.
The gate elements (32, 32□) are set by constantly setting l to @L" and by setting the enable signal E2 to an operation pulse that becomes "H" according to the printing timing as described above.

323,...,32. , ) side is activated and the driver transistor (22,, 22□, 223..
..., 22. , ) to control bird movements. In other words, when a driver transistor fails at one location (21) in the first drive circuit, the entire circuit is switched to the second drive circuit (22) even if other transistors belonging to the same circuit are normal. It will now work. In addition, both drive circuits (2
If both 1) and (22) are normal, operating them at the same time will reduce the on-resistance of the driver transistor by about 1/2, thereby doubling the driving capacity for the heat generating part (1). . In addition, since the operating pulse of these gate elements is several milliseconds, the main body of the gate element is small, and even if two of these are provided for each heating resistor, it is necessary to provide two driver transistors each. Since it does not exceed the area, it can be implemented satisfactorily in practice.

Note that since the enable signals E1 and E2 can be selected externally, even if a defect occurs during use, it can be easily repaired.

Next, a second embodiment of the present invention will be described with reference to FIG. In this second embodiment, in order to simplify the explanation, the same numbers for each element and circuit as in the first embodiment are used.

FIG. 2 shows a circuit for one dot of the thermal head. In this figure, the parallel connection circuit of the driving element (211) and the driving element (22□) is connected to the heating resistor (1
11), and a switching transistor (711) is connected between the input part of each drive element (211) and (22+) and the output of the gate element (30).
) and (72,) are inserted. Furthermore, the switching transistor (71,) has a bias resistor (81,) and (81J), and the switching transistor (72,) has a bias resistor (82,) and (82k).
) are connected. Here, each resistor (81, L (8
1,), (82,), and (82b) are R1, respectively.

When R1,, R2□R2b, R11 in normal state
By selecting each resistance value (R1-, Rlb, R2□R2,) so that the relationship of (Rlb and ++2a>R2b holds), the switching transistor (711) is in the on state (normal on), and the switching transistor ( 721) is turned off (normally off), and the driver transistor (211) is selected. If a defect occurs in the driver transistor (211), the resistors (81,) and (82, ) is then trimmed and removed.The switching transistor (711) is then turned off by having its base grounded by the resistor (81J), while the switching transistor (72,) is turned off by having its base grounded by the resistor (82,). When the voltage reaches almost the power supply voltage, the driver turns on.
Transistor (22+) is selected. therefore,
The operation of the circuit shown in FIG. 2 is as follows. The print signal is first input from the print signal input terminal (13) to the shift register (10) according to the clock signal input from the clock signal input terminal (14), and then this signal is input to the launch pulse input terminal (12). The signal is transferred to the launch circuit (9) and held in accordance with the strobe signal input from the launch circuit (9). The print data held in the latch circuit is transferred to the switching transistor (71,) by the enable signal input from the enable signal input terminal (11).
(72,), and are further supplied to the driver transistors (21+) and (22,), but under normal conditions, the switching transistor (
The output from the driver transistor (2
1,).

Note that the load on the gate circuit (3) in this circuit configuration is the driver transistor (21+) and (22,).
Therefore, the capacitance of the switching transistors (71+) and (711) may be small. Therefore, even if the switching transistors are added, the area of the entire primary element device does not increase significantly. Also, the resistances (81,), (81,), (82,) and (82
, ) is the driver transistor (2L).

(22, Since it is used only when 'I' is selected, there is no problem even if the resistance value is sufficiently large.

Practically, the above circuits are connected in parallel in the direction of arrow X in FIG. 2 to form a thermal head, so the driver transistor (21+) in the above text is the The driver transistor (22,) belongs to the second drive circuit (22) in the same embodiment.

However, in the second embodiment, unlike the first embodiment described above, the first drive circuit and the second drive circuit are not selectively switched due to failure of only one driver transistor. , is characterized in that it can be switched in units of one dot.

In the above embodiment, a case was described in which a drive circuit consisting of two parallel drive elements was connected to one heating resistor, and a switching element was provided for each drive element. In fact, a larger number is possible. In reality, even if there are only two drive circuits as described above, the probability that both the first drive circuit and the second drive circuit have defects at the same time is extremely low, so the practical problem is It is presumed that there is no such thing. Further, such a circuit configuration can also be applied to a line sensor using a photodiode or the like instead of the above-mentioned heating resistor as a primary element.

〔Effect of the invention〕

As is clear from the above description, in the primary element device of the present invention, by providing a spare drive circuit for each primary element and a switching element for each of these drive circuits, it is possible to Even if a defect occurs in a drive element, the entire drive circuit can be switched to another drive circuit, or only the defective part can be switched to another drive circuit for use. This eliminates the need to replace the entire primary element device in the event of a failure, greatly improving yield during manufacturing and improving reliability during use. Furthermore, for example, the number of units connected in parallel (k is 2
If all drive elements (integers greater than or equal to) are normal, then
By operating all of these, the driving capacity can be doubled, which is also effective in saving power.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a thermal head according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of one dot of a thermal head according to a second embodiment of the present invention, and FIG. 3 is a circuit diagram of a thermal head according to a second embodiment of the present invention. 1 is a circuit diagram of one dot of a conventional general thermal head; FIG. 1... Heat generating section 2... Drive circuit section 21... First drive circuit, 22... Second drive circuit 3...
- Gate circuit section 9... Launch circuit 10..., Shift register 711.72.
... Switching transistors 81, 81b,
82. , 82.・・Bias abrasive anti-sulfur 6-metal abrasive 1 g missing, 2 rouge reamer head 1 fig. l
Shisera I's 1F knit turnaround Figure 2: Fukuhei no Ji-71 Shihead's 11. :・Tsureno's episode i is also shown in Figure 3.

Claims (1)

[Claims] At least two drive circuits are provided, each consisting of a primary element section consisting of a plurality of elements arranged in a line, and a drive element corresponding to each element of the element section. A primary element device characterized in that respective corresponding drive elements of the drive circuits are connected, and respective drive elements of the respective drive circuits that are in a corresponding relation to each other are connected in parallel to each other.