JP3783309B2 - Printer drive circuit device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printer drive device, and more particularly to a protection circuit device in the event of a drive element failure.
[0002]
[Prior art]
Conventionally, in a drive circuit of a printer, a drive element that has a risk of destruction from the occurrence of an abnormal signal due to a drive element failure has two stages of drive elements to provide redundancy, and one of the drive elements fails. However, the remaining drive elements are devices that prevent the printer control circuit from being destroyed by cutting the abnormal signal.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, even if the drive element fails, the printer control side does not have a failure detection means, so that in the worst case, there is a danger that the printer control can be continued with the drive element failed. Had problems.
[0004]
Further, in order to provide further redundancy, the drive element has three or more stages, and when the drive element fails up to two stages, the remaining drive element cuts an abnormal signal, thereby preventing the printer control circuit from being destroyed. However, it has a problem that it does not become a fundamental solution only by reducing the incidence rate.
[0005]
The present invention has been made to solve such problems, and in the printer drive circuit, the drive element is composed of two stages of the minimum necessary power supply means and drive means to detect a failure of the drive element. The failure detection means for performing the operation and the time-limited energization means for the drive element are provided, and even when the failure of the drive element is detected, the time-limited energization only for the timer set time provided for each drive element of the power supply means and the drive means By doing so, even if one of the drive elements fails, the other drive element prevents the printer drive circuit from being destroyed by cutting the abnormal signal. The timer setting time can be arbitrarily set according to each drive circuit design condition. Accordingly, an object of the present invention is to provide a safe and reliable printer drive circuit device.
[0006]
[Means for Solving the Problems]
The printer drive circuit device according to the present invention is a printer drive circuit device for driving a current through an inductor and driving with the energy generated at that time, and is a power supply application means for applying a power supply voltage to the inductor. A first switching element connected on a current-carrying line of the inductor, and a drive means for driving the inductor, the second switching element connected on a current-carrying line of the inductor A failure detection means for detecting a short-circuit failure of the second switching element by detecting a current on the conduction line and connected to the conduction line of the inductor; and a current detection from the failure detection means Triggered by a signal, it is a preset time that can only occur when there is an abnormality and A time-limiting energization means having a timer that times up when measuring a time that can be protected against, and a control means for controlling the power supply means and the drive means to drive the inductor, before the start of driving of the inductor Control means for initializing the timer and outputting a signal for stopping the timer after driving of the inductor is completed, and when there is no short-circuit failure of the second switching element, In the short-circuit failure state of the second switching element, the timer is stopped without being stopped by the control means, and the time limit energizing means is the first timer when the timer is up. A signal for shutting off the switching element is output, and the control means And notifies the disabled. The set time may be variable.
[0007]
According to the present invention, the failure detection means for detecting the failure of the inductor drive circuit and the time-limit energization means for the printer drive element are provided, and the time-limit energization is performed only for the set timer time, thereby providing the power supply means or drive means. Even if one of the main drive elements fails, the other drive element can prevent the printer control circuit from being destroyed by cutting off the abnormal signal and stop the subsequent drive. can do.
[0008]
Further, the power supply means supplies a power supply voltage to a plurality of commonly connected inductors, the drive means and the failure detection means are provided in each of the plurality of inductors, and the time-limit energization means is supplied from the failure detection means. In this case, it is not necessary to have a plurality of time-limit energization means, so that it is possible to achieve a reasonable and inexpensive effect.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail using an embodiment of the present invention.
[0010]
FIG. 1 is a functional block diagram showing an embodiment of a printer drive circuit device according to the present invention. The operation when the drive circuit failure detection of each element such as a motor and a plunger of the printer is performed will be described. The drive element of the inductor 1 of each element such as the motor and the plunger includes a power supply means 2 including a transistor and the like. Drive means 3 is used. By turning on both the transistors, a current is supplied from the power source (+ Vp) to the inductor 1 to drive. The failure detection means 4 detects the state of the inductor 1 on the power supply line, and the detection signal becomes a trigger signal to the time limit energization means 8 composed of a timer IC or the like. In the timer setting means 7 including a data latch IC for setting the time to the timer IC, the time limit energization time is set on the printer control side, that is, the time limit energization means 8 is initially set. The power supply means 2 is connected to the port A5 and the drive means 3 is connected to the port B6, and printer control such as printing is performed.
[0011]
In the printer drive circuit device of the present invention, first, the timer setting means 7 sets the energization time that can be protected only when the design is abnormal and can be protected against damage to the parts as the time limit energization time. Next, in the case where a failure has occurred in the drive circuit, the failure detection means 4 generates a failure signal, and the time limit energization means 8 is started using this failure signal as a trigger. When the time limit expires, the circuit is protected by interlocking and maintaining the power supply means 2 and the drive element that is the main body of the drive means 3 in a direct cut-off and cut-off state.
[0012]
FIG. 2 is a circuit block diagram showing an embodiment of a printer drive circuit device according to the present invention. CPU 9, ROM 10, RAM 11 and power supply means 2 for controlling the printer as an example of PNP transistor 13 and drive means 3 are shown. As an example, an NPN transistor 14, a transistor and resistor 18 as an example of the failure detection means 4, a timer IC 15 including a counter IC as an example of the time limit energizing means 8, a data latch IC 16 including a register IC as an example of the timer setting means 7, etc. It is configured. The control unit 12 is configured with the CPU 9, the ROM 10, and the RAM 11 as main components. Control processing of the power supply means 2, the drive means 3, the timer setting means 7 and the like is programmed, stored in the ROM 10, and executed.
[0013]
Next, the contents of the control operation of the control unit 12 and the operation sequence of the circuit will be described with reference to the flowcharts of FIGS.
[0014]
First, the ROM 10 stores in advance digital data (hereinafter referred to as time-limited energization data) obtained by converting the energization time as a drive element failure error, that is, the normal energization time that is impossible in the case of normal operation. Keep it. (STEP 31)
Next, before the inductor 1 energization control, the control unit 12 initializes the time energization means 8 by reading the time energization data from the ROM 10 and latching it in the data latch IC 16 by the timer setting means 7. (STEP 32) This state is maintained when the inductor 1 is not energized, that is, during standby of the printer.
[0015]
Next, when transitioning to driving of the inductor 1, when there is no drive element failure in the inductor drive circuit and the printer is normally controlled, the time for driving the inductor 1 is set in the time limit energizing means 8. It is shorter than time. When the drive means 3 is turned OFF → ON, the time limit energization means 8 is triggered via the failure detection means 4. However, after the drive means 3 is turned ON → OFF, the control unit 12 stops the timer of the time limit energization means 8. (STEP 33) In the normal state, the above printer control is repeated. (STEP 34)
On the other hand, in the standby state after the above STEP 32, when the power supply means 1 or the drive means 3 is suddenly not driven, a short-circuit failure of the drive element occurs, and the failure detection means 4 detects an abnormal current flowing in the inductor drive circuit. The timer of the time-limit energization means 8 counts up without stopping the timer under the control of the control unit 12. In synchronization with the timer counting up, the power supply applying means 2 and the drive means 3 are shut off in hardware via the AND circuit 19 and a flag for transmitting a drive circuit element failure to the control unit 12 is provided with a flip-flop IC17. It ’s been through. The control unit 12 monitors and monitors this flag. If the flag is present, the controller 12 regards the drive circuit as faulty, stops the subsequent control, and ensures safety. (STEP 35)
FIG. 5 is a functional block diagram showing an embodiment of the printer drive circuit device of the present invention, in which power is supplied to a plurality of inductors 1 (three in FIG. 5) to which PNP transistors 13 as power application means 2 are commonly connected. is doing. Each inductor 1 is connected to a transistor and a resistor 18 which are the failure detection means 4, and operates a timer IC 15 which is a time-limited energization means 8 by using a logical sum of the failure detection means as a trigger.
[0016]
In this embodiment, the drive element is a transistor and the timer IC is described as a general-purpose logic IC as an example. However, the present invention can be applied regardless of the form of these circuit elements, and the drive element is a relay or FET. Needless to say, even if other types of ICs are used or gate arrays are used, the same effect can be obtained.
[0017]
【The invention's effect】
As described above, according to the present invention, the printer drive element has two stages of the power supply application means and the drive means for the minimum required drive element, and the failure detection means for detecting the failure of the drive element and the drive element. Even when a failure of the drive element is detected, a failure of one of the drive elements is caused by performing a limited-time energization only for the timer set time provided to each drive element of the power supply means and the drive means. Even in this case, the other driving element cuts off the abnormal signal to prevent the printer control circuit from being destroyed. The timer setting time can be arbitrarily set according to each drive circuit design condition. As described above, it is possible to provide a safe and reliable printer protection apparatus.
[0018]
In this case, the power supply means further supplies power to a plurality of commonly connected inductors, and the drive means of the plurality of inductors activates the time-limited energization means by using the logical sum from the respective fault detection means as a trigger. In this case, since it is not necessary to have a plurality of time-limited energization means, a rational and inexpensive circuit is provided.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing an embodiment of a printer drive circuit device of the present invention.
FIG. 2 is a circuit block diagram showing an embodiment of a printer drive circuit device of the present invention.
FIG. 3 is a flowchart showing the content (normal time) of the control operation of the printer drive circuit device of the present invention.
FIG. 4 is a flowchart showing the contents (at the time of abnormality) of the control operation of the printer drive circuit device of the present invention.
FIG. 5 is a functional block diagram showing an embodiment of a printer drive circuit device according to claim 2 of the present invention;
[Explanation of symbols]
1 Inductor 2 Power supply means 3 Drive means 4 Failure detection means 5 Port A
6 Port B
7 Timer setting means 8 Time energization means 9 CPU
10 ROM
11 RAM
12 Controller 13 PNP transistor (for power supply application)
14 NPN transistor (for drive)
15 Timer IC
16 Data latch IC
17 Flip-flop IC

Claims (3)

In the drive circuit device of the printer that drives with the energy generated at that time by passing a current through the inductor,
A power supply means for applying a power supply voltage to the inductor, including a first switching element connected on a current-carrying line of the inductor;
Drive means for driving the inductor, including a second switching element connected on a current-carrying line of the inductor;
A failure detecting means connected to the energization line of the inductor and detecting a short-circuit failure of the second switching element by detecting a current on the energization line;
Time-limited energization means provided with a timer that starts when triggered by a current detection signal from the failure detection means and times up to a preset time that cannot be other than an abnormal time and can protect against damage to parts When,
Control means for controlling the power supply means and the drive means to drive the inductor, and outputs a signal for initializing the timer before starting to drive the inductor and stopping the timer after driving of the inductor is finished. Control means to
In a state where there is no short-circuit failure of the second switching element, the timer is stopped by the control means, and in a short-circuit failure state of the second switching element, the timer is not stopped by the control means. Time up,
The time limit energizing means outputs a signal for shutting off the first switching element and notifies the control means of a failure when the timer expires.   2. The drive circuit device for a printer according to claim 1, wherein said power supply applying means supplies a power supply voltage to a plurality of commonly connected inductors, and said drive means and said failure detecting means are provided in each of said plurality of inductors. The drive circuit device for a printer, wherein the time-limited energization means operates with a logical sum of signals from the failure detection means as a trigger.   3. The printer drive circuit device according to claim 1, wherein the set time can be variably set.

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