JP3409534B2 - Drive circuit failure detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an abnormal signal of an inductor drive circuit which may occur when a drive element of a drive unit of a printer fails, and stops the inductor drive at that time. The present invention also relates to a safe and secure printer protection device for preventing destruction of a printer control circuit. 2. Description of the Related Art Conventionally, in this type of technology, in a drive circuit of a printer, a circuit in which there is a danger of destruction due to generation of an abnormal signal due to failure of the drive element is provided with two drive elements in order to provide redundancy. In this case, even if one of the driving elements fails, the remaining driving elements cut the abnormal signal to prevent the printer control circuit from being destroyed. [0003] However, in the above-mentioned prior art, even if the drive element fails, the drive control element has no failure detection means on the printer control side. There is a problem that there is a risk that the printer control may be continued while the printer is being operated. Further, in order to provide further redundancy, when the drive elements are provided in three or more stages, and when the drive elements fail up to two stages, the remaining drive elements cut an abnormal signal, thereby destroying the printer control circuit. As a device to prevent
There was a problem that merely reducing the incidence did not provide a fundamental solution. Further, when a means for detecting a failure of a drive element is provided, there is a problem that a dedicated failure detection port for connecting to an I / O port must be prepared. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and the printer drive element has at least two stages of a power supply means and a drive means for a printer, which are required at least. Means are provided so that even if one of the drive elements fails, the other drive element prevents the printer control circuit from being destroyed by cutting off the abnormal signal. At this time, the failure detection means is a failure detection and dual-purpose means for switching the signal direction on the same signal line as the power supply means or the drive means, thereby rationalizing the number of ports connected to the I / O ports to a minimum. It is an object of the present invention to provide an inexpensive but safe printer protection device. [0007] A failure detection device for a drive circuit according to the present invention comprises: drive circuit control means for controlling the drive circuit;
A first state detecting means for detecting an operation state of the load driving means, a control signal from the driving circuit control means to the load driving means, and a detection result signal from the first state detecting means to the driving circuit controlling means are transmitted. The drive circuit control means outputs a control signal having a predetermined value, removes the control signal, removes the detection signal appearing on the first signal line, and retrieves the control signal of the drive circuit. It is characterized by detecting a failure. In this case, the drive circuit further includes a power supply control means for controlling supply of power to the load drive means, a second state detection means for detecting an operation state of the power supply control means, and a drive circuit. A second signal line that transmits a control signal from the control unit to the power supply control unit and a detection result signal from the second state detection unit to the drive circuit control unit, wherein the drive circuit control unit includes: After outputting a control signal of a predetermined value to each of the first and second signal lines, the control signal is removed, and thereafter, a detection result signal appearing on the first and / or second signal lines is taken in. You may make it detect. In these cases, the drive control means has an input / output circuit capable of switching between input and output, and a signal line is connected to the input / output circuit. Can be removed from the signal line. In these cases, the control signal having a predetermined value output by the drive control means and the value of the detection result signal indicating a normal state output by the state detection means are in the same logical value range. It is desirable. Thereby, even when the control signal is removed from the signal line, if the drive circuit is normal, the state is maintained, so that the normal operation is not affected, and otherwise the control signal is different from the control signal. Since the logical value appears and the set state is released, the abnormal operation can be released early. According to the present invention, there is provided a printer in which a current is supplied to an inductor and an electromagnetic force generated at that time is driven as energy, wherein a power supply means for applying power to the inductor, a power supply from the power supply means, and The drive means for driving the power supply means, the failure detection means connected to the current supply line of the inductor and detecting the failure of the power supply means or the drive means, and the control of the failure detection means are performed from the same signal line as the power supply means or the drive means. A switch control means for stopping the energization of the inductor when the failure of the power supply means or the drive means is detected by performing the dual function by switching the signal direction. It is. According to the above construction of the present invention, the printer driving element has at least two stages of a power supply means and a drive means for the printer which are required at least, and a failure detection means for detecting a failure is provided. Even if one of the elements fails, the other drive element prevents the printer control circuit from being destroyed by cutting off the abnormal signal. The failure detection means is a failure detection / completion means for switching the signal direction on the same signal line as the power supply means or the drive means, so that a failure of the drive circuit can be detected. When the failure is detected, the power supply to the inductor can be easily stopped by turning off the power supply means and the drive means. Further, the rationalization for minimizing the number of ports connected to the I / O ports is performed, and only one circuit configuration is required, which contributes to downsizing of the system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a printer drive circuit failure detecting apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing one embodiment of a drive circuit failure detecting device for a printer according to the present invention. The operation of detecting the failure of the drive circuit of each element such as the motor and the plunger of the printer will be described.
The power supply means 2 composed of a transistor or the like and the drive means 3 are used as the drive elements. By turning on both of the transistors, a current flows from the power supply (+ Vp) to the inductor 1 to drive it. The failure detection means 4
The state of the inductor 1 on the power supply line is detected, the detection signal is connected to the I / O port A5 and the I / O port B6, and the I / O port A5 is connected to the control signal of the power supply means 2 and the I / O port. The port B6 functions as a control signal for the drive means 3 as well. The apparatus for detecting a failure in the drive circuit of a printer according to the present invention is executed by switching the signal direction of the I / O port A5 or I / O port B6. Normal I / O
The port A5 or the I / O port B6 serves as a drive control output of the inductor 1, but when used for failure detection, the signal direction of the I / O port A5 or the I / O port B6 is switched and input. I / O port A5 or I
The input signal level to the / O port B6 is set differently depending on the ON / OFF state of the power supply unit 2 and the drive unit 3 to the inductor 1, and the failure detection unit 4 determines whether or not the drive element has failed. If it is determined that the drive element has failed, the switch control means 7 determines that the drive element has not failed, the power supply means 2 or the drive means 3.
To protect the circuit by cutting off the current to the inductor 1. FIG. 2 is a circuit block diagram showing an embodiment of a printer driving circuit failure detecting apparatus according to the present invention. The CPU 8, ROM 9, RAM 10,
I / O port A5, I / O port B6, power supply means 2
PNP transistor 13, drive means 3 as an example
NPN transistor 14, failure detection means 4
Is composed of a transistor, a resistor and the like. The control unit 11 is configured with the CPU 8, the ROM 9, and the RAM 10 as main components. The control processing of the power supply unit 2, the drive unit 3, the failure detection unit 4, the switch control unit 7, and the like is programmed, stored in the ROM 9, and executed. The failure detection control is executed by switching the signal direction of the I / O port A5 or I / O port B6. When used for failure detection, the signal direction of I / O port A5 or I / O port B6 is switched and input. The input signal level to the I / O port A5 or the I / O port B6 differs depending on the state of the power supply unit 2 and the drive unit 3 to the inductor 1. In each of the ON / OFF states, the following logical state is represented by the I / O port. A5, I
Logic transmission to / O port B6. When the PNP transistor 13 (power supply means 2) is OFF and the NPN transistor 14 (drive means 3) is OFF, the I / O port A5 input LOW ... PNP transistor 13 (power supply means 2) Failure HIGH: No failure in the drive element When the PNP transistor 13 (power supply means 2) is ON and the NPN transistor 14 (drive means 3) is ON, the I / O port B6 input LOW ... NPN transistor 14 (drive) Means 3) is failure HIGH. If it is determined that the drive element has no failure, the drive element, the PNP transistor 13 or the NPN transistor 14 on the side determined not to have failed is turned off, and the inductor 1 is turned off. The circuit is protected by cutting off the current. Next, the contents of the control operation of the control unit 11 will be described with reference to the flowchart of FIG. When the control unit starts operating to detect a failure in the printer drive circuit (step 30), the I / O ports A5 and B6, which are output port settings for performing print control until then, are set. Switching to the input port (step 31), the failure detection means 4 confirms the logic of the I / O port, and determines whether the power supply means 2 or the drive means 3 has a failure. (Step 3
2) Next, when the failure determination means 4 determines that the power supply means 2 or the drive means 3 has a failure and determines that the drive element has failed,
The switch control means 7 turns off the drive element, the power supply means 2 or the live means 3 on the side determined not to have failed, and protects the circuit by cutting off the conduction of the inductor 1 drive circuit. (Step 33). On the other hand, when it is determined that there is no failure in the driving element, the I / O port A5 and the I / O port B6 are switched to the output ports (step 34), and the printing control is continued. In this embodiment, the driving element is described as a transistor as an example. However, the present invention can be applied regardless of the form of these circuit elements. Needless to say, it has the effect described above. As described above, according to the present invention, the printer driving element has at least two stages of a power supply applying means to the printer and a driving means, and the failure detecting means for detecting a failure is provided. Even if one of the drive elements fails, the other drive element prevents the printer control circuit from being destroyed by cutting the abnormal signal. The failure detection means is a failure detection / completion means for switching the signal direction on the same signal line as the power supply means or the drive means, thereby enabling the failure detection of the drive circuit. When the failure is detected, the power supply control means and the drive control means are turned off, so that the inductor and the power supply can be easily separated. Further, the rationalization for minimizing the number of ports connected to the I / O ports is performed, so that only one circuit configuration is required, which contributes to downsizing of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional block diagram showing an embodiment of a failure detection device for a printer driving circuit according to the present invention. FIG. 2 is a circuit block diagram showing one embodiment of a failure detection device for a printer driving circuit according to the present invention. FIG. 3 is a flowchart illustrating the control operation of an example of a failure detection device for a printer drive circuit according to the present invention. [Description of Signs] 1 Inductor 2 Power supply means 3 Drive means 4 Failure determination means 5 I / O port A 6 I / O port B 7 Switch control means 8 CPU 9 ROM 10 RAM 11 Control unit 13 PNP transistor (for applying power) ) 14 NPN transistor (for drive)

Claims (1)

(57) An apparatus for detecting a failure of a drive circuit, comprising: load drive means for driving a load; and power supply means for supplying power to the load, wherein the control means controls the drive circuit. Drive circuit control means having first and second input / output circuits capable of switching between input and output; first state detection means for detecting an operation state of the load drive means; A first signal line for transmitting a first control signal from the drive circuit control means to the load drive means and a first detection result signal from the first state detection means to the drive circuit control means; Connected to the first input / output circuit; second state detection means for detecting an operation state of the power supply means; and second control from the drive circuit control means to the power supply means. Signal and the second state detecting means A second signal line for transmitting a second detection result signal to the drive circuit control means from the second input / output circuit, the second signal line being connected to the second input / output circuit. Switching the first and second input / output circuits to output and outputting first and second control signals to the first and second signal lines, respectively, to thereby load the load driving means and the power supply means. Control and
Further, the load driving means and the power supply are provided by switching the first and second input / output circuits to input and taking in the first and second detection result signals appearing on the first and second signal lines. A failure detection device for a drive circuit, wherein a failure of a supply unit is detected, and when one of the failures is detected, the other unit is controlled to cut off the current supply to the load.