JPH0537023A - Driving device for light emitting diode - Google Patents

Abstract

PURPOSE:To enable automatically monitoring faults in a device by sending an indicating signal to driving means in checking faults and determining whether the device is faulty or not based on an output signal from detecting means and the indicating signal. CONSTITUTION:A control means 20 generates indicating signals A1-A3 and B1-Bn to indicate which one of light emitting diodes 121-12n to turned on. Receiving any of indicating signals A1-A3 and B1-Bn a driving means 10 opens/closes the current path of one of the light emitting diodes 12,-12-corresponding to the signal. A detecting means 26 detects whether a current is fed to the light emitting diodes 121-12n or not. In checking faults, the indicating signals A1-A3 and B1-Bn are sent to the driving means 10, and it is judged based on output signals C1-Cn from the detecting means 26 and the indicating signals whether the device is faulty or not. This enables automatically monitoring faults in the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for lighting a light emitting diode, and more particularly to a driving device having a function of monitoring a failure of the light emitting diode and the device itself.

[0002]

2. Description of the Related Art In a device using a segment type display which displays numbers 0 to 9 depending on the combination of light emitting diodes to be turned on, the numbers are not correctly displayed due to a failure of the light emitting diodes or a driver for turning on the number. There is. Therefore, in this type of conventional equipment,
Before display, turn on all the light emitting diodes of one digit at the same time, then turn off all the light emitting diodes at the same time, so that all the light emitting diodes of the digit are turned on and off correctly. It is confirmed visually by the person.

However, light emitting diode and driver failures also occur during use of the display. For this reason, in this type of equipment, particularly in medical equipment such as a liquid pump for injecting a liquid medicine and a life support device, it has been necessary to frequently confirm the failure of the display.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to have a device itself automatically monitor for device failures.

[0005]

According to the present invention, there is provided a driving device for a light emitting diode, a control means for generating an instruction signal for specifying a light emitting diode to be turned on, and the light emitting diode corresponding to the instruction signal. Driving means for opening and closing the current path, and detecting means for detecting whether or not a current is supplied to the light emitting diode, and the control means supplies the instruction signal to the driving means at least once during failure monitoring. Then, based on the output signal of the detection means and the instruction signal at that time, it is characterized in that whether or not the device is out of order is determined. Another driving device of the present invention is a device that divides a plurality of light emitting diodes into a plurality of groups and controls the light emitting diodes for each group and each light emitting diode in the group, wherein the light emitting diodes to be lighted Control unit for generating a first command signal for instructing a group and a second command signal for instructing the light emitting diodes in the group to be lit, and the first command signal for receiving the first command signal. First driving means for opening and closing the current path of the group corresponding to the signal; and second driving means for receiving the second command signal and opening and closing the current path of the light emitting diode corresponding to the second command signal. A detection means for detecting whether or not a current is supplied to the light emitting diode, and the control means outputs the first and second instruction signals to the control means during failure monitoring. Supplying at least once to the unit, on the basis of the output signal and the instruction signal of the detecting means at that time, characterized in that to determine whether the device is faulty.

During fault monitoring, the light emitting diode is flashed at least once. At this time, the determination means determines whether or not the device has a failure depending on whether or not the output signal of the detection means and the instruction signal output by itself match. According to the present invention, a device failure can be automatically monitored during normal display by the light emitting diode.

It is preferable that the detecting means includes a plurality of detectors which are commonly connected to one light emitting diode of each group and are connected to the second driving means. This simplifies the device since it is not necessary to provide a detector for each light emitting diode.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A driving device 10 shown in FIG. 1 includes a plurality of light emitting diodes 12 ₁ to 12 n and a plurality of groups 14, 16, _1.
The light emitting diodes are divided into eight groups, and the light emitting diodes are controlled for each group and each light emitting diode in the group. The light emitting diodes 12 _{1 to} 12 n in _one group are, for example, one digit (1
It can be the number of segments used to display numbers. However, in the case of a display other than the numerical display, for example, a display that displays differently for each light emitting diode, any number can be used.

The drive unit 10 has a first indication signal for indicating the groups 14, 16 and 18 of light emitting diodes to be turned on, that is, digit selection signals A ₁ , A ₂ , A ₃ and the light emitting diodes to be turned on in the group. A second instruction signal for instructing, that is, a segment selection signal B ₁ ~
Control circuit 20 for generating Bn and digit selection signal A
A first drive circuit 22 that opens and closes a current path of a predetermined group based on ₁ , A ₂ , and A ₃ , and segment selection signals B _{1 to} B
Second, which opens and closes a current path of a predetermined light emitting diode based on n
Drive circuit 24 and a detection circuit 26 for detecting whether or not a current is supplied to the light emitting diode.

The first drive circuit 22 includes groups 14, 1
Multiple transistors 2 individually associated with 6 and 18
8, 30, and 32. In contrast, the second driving circuit 24 includes one light emitting diode the number of groups and same number of transistors 34 ₁ to 34N. Further, the detection circuit 26 includes the same number of detectors 35 _{1 to} 35n as the number of light emitting diodes in one group. Detector 35 _{1 to} 35n
Each comprises a light emitting diode and a phototransistor pair.

The transistor 28 of the first drive circuit 22,
30 and 32 are the corresponding groups 14,
In the common current path of the light emitting diodes 12 _{1 to} 12 n of 16 and 18 (in the illustrated example, the current path connected to the negative side terminal of the DC power supply), the current path is connected to the digit selection signal A ₁ ,
It is connected to open and close according to A ₂ and A ₃ . Each transistor of the second drive circuit 24, each detector of the detection circuit 26, and each light emitting diode of each group correspond to each other. Each transistor of the second drive circuit 24 has a corresponding light emitting diode 12 _{1 to} 12 n.
To the current path (in the illustrated example, the current path connected to the positive terminal of the DC power supply), the current path is connected to the segment selection signal B ₁
It is arranged so as to open and close according to ~ Bn.

Each light emitting diode of the detectors 35 _{1 to} 35 n has a corresponding transistor 34 _{1 of} the second drive circuit 24.
˜34n and the corresponding light emitting diodes 12 ₁ to 12n of the groups 14, 16 and 18 are connected in series. Each phototransistor of the detectors 35 _{1 to} 35 n is connected to the control circuit 20.

Each of the light emitting diodes 12 _{1 to} 12 n of each of the groups 14, 16 and 18 has a digit selection signal A ₁ , A.
₂ and A ₃ and the segment selection signals B _{1 to} Bn are specified. Further, both selection signals are an ON signal for turning on the corresponding transistor when the light emitting diode is turned on, and an OFF signal for turning off the corresponding transistor when turning off the light (not turning on). Therefore, for example, when the light emitting diodes 12 ₁ of the group 14 are turned on, both the digit selection signal A ₁ and the segment selection signal B ₁ are ON signals, whereby the transistors 28 and 34 ₁ are turned ON, and the light emitting diodes 12 1 ₁
And the light emitting diode of the detector 35 ₁ are turned on.

The control circuit 20 always repeatedly outputs the digit selection signals A ₁ , A ₂ , and A ₃ in sequence, and the segment selection signal B corresponding to the digit selection signal.
Outputs _{1 to} Bn. This allows groups 14,1
Since predetermined light emitting diodes 6 and 18 are turned on and the other light emitting diodes are turned off, predetermined information is displayed.

[0015] In the driving device 10, when the circuit elements are normal, the light emitting diode and the detector 35 ₁ ~35n emitting diodes of each group 14, 16 and 18,
It is turned on or off depending on both selection signals. However, if any of the circuit elements is broken or short-circuited, the light emitting diode of each group and the light emitting diode of each detector are not turned on or off according to both selection signals. The lighting of the light emitting diode of each of the detectors 35 _{1 to} 35 n is detected by the corresponding phototransistor. Detection signal C ₁ to Cn of the detectors 35 ₁ ~35n is supplied to the control circuit 20, used for fault monitoring device in the control circuit 20. Failure monitoring in the control circuit 20, in the course of displaying predetermined information, and digit selection signal, a segment selection signal, is periodically performed by using the detection signal C ₁ to Cn.

Fault monitoring in the control circuit 20 will be described below with reference to FIG. The control circuit 20 first selects the light emitting diodes of the group 14, turns on the light emitting diodes that have been turned on until immediately before the failure monitoring sequence, and turns off the other light emitting diodes (step 1). To do this, digit select signal A ₁
Is turned on, other digit signals are turned off, a predetermined segment selection signal is turned on, and other segment selection signals are turned off.

Next, the control circuit 20 compares whether or not the on / off states of the segment selection signals B _{1 to} Bn and the detection signals C _{1 to} Cn at this time match (step 2). If they match as a result of the comparison in step 2, the control circuit 20 selects the light emitting diodes of the group 16, turns on the light emitting diodes that have been turned on until immediately before the failure monitoring routine, and turns off the other light emitting diodes. Then, the segment selection signals B _{1 to} Bn and the detection signals C _{1 to} Cn at this time are compared with each other to see if they are on or off (step 4). As a result of the comparison in step 4, if they match each other, the control circuit 20 selects the light emitting diode of the group 18, lights the light emitting diode that has been lighted up to immediately before the failure monitoring routine, and sets the other light emitting diodes to light. The light is turned off (step 5), and it is compared whether or not the on / off states of the segment selection signals B _{1 to} Bn and the detection signals C _{1 to} Cn at this time match (step 6).

As a result of the comparison in step 6, if they match, the control circuit 20 causes all the digit selection signals A to be detected.
₁ , A ₂ , A ₃ are turned off, all the segment selection signals B _{1 to} Bn are turned on (step 7), and it is determined whether all the detection signals C _{1 to} Cn are off (step 7). 8).

As a result of the judgment in step 8, if all the detection signals C _{1 to} Cn are off, the control circuit 20 ends the failure monitoring routine. When the results of the comparison in steps 2, 4 and 6 do not match, and step 8
If at least one of the detection signals is turned on in, the control circuit 20 reports that the device is abnormal (step 9).

According to the above fault monitoring routine, the device can be used even when the light emitting diode which does not need to be turned on is not turned on due to the disconnection failure of the light emitting diode itself or the corresponding circuit element. In this case, a failure of the light emitting diode that does not need to be turned on or the corresponding circuit element is detected during failure monitoring during the period when the light emitting diode that does not need to be turned on should be turned on.

In the drive unit 10, if each circuit element is normal, the digit selection signals A ₁ , A ₂ , A _{3 are selected.}
, Segment selection signals B _{1 to} Bn, and detection signals C ₁ to
The relationship with Cn is as follows. a) When both the digit selection signal and the segment selection signal are on, the detection signal is on (the light emitting diode lights up). b) When the digit selection signal is on and the segment selection signal is off, the detection signal is off (the light emitting diode is off). c) When the digit selection signal is off and the segment selection signal is on, the detection signal is off (the light emitting diode is off). d) When both the digit selection signal and the segment selection signal are off, the detection signal is off (the light emitting diode is off). The control circuit 20 performs failure monitoring by regularly monitoring the states of a), b), c), and d) above. Therefore, by causing the states of a), b), c), and d) to occur for each group or each light emitting diode, and determining whether or not the segment selection signal and the detection signal match each time, the device fails. It may be determined whether or not there is. Further, it may be possible to determine whether or not the device has a failure based on the above a) and d).

[Brief description of drawings]

FIG. 1 is a wiring diagram of an electric circuit showing an embodiment of a driving device of the present invention.

FIG. 2 is a diagram for explaining a failure monitoring method.

[Explanation of symbols]

10 drive device 12 ₁ ～12N emitting diodes 14, 16, 18 light emitting diode group 20 control circuit 22 first driving circuit 24 and the second driving circuit 26 detecting circuit 35 ₁ ～35N detector A _1, A _2, A ₃ the first indication signal B ₁ to Bn second indication signal C ₁ to Cn detection signal

Claims (3)

[Claims] 1. A control means for generating an instruction signal for instructing a light emitting diode to be turned on, a drive means for receiving the instruction signal and opening / closing a current path of the light emitting diode corresponding to the instruction signal, and a current for emitting light. And a detection means for detecting whether or not the diode is supplied to the diode, wherein the control means supplies the instruction signal to the drive means at least once at the time of failure check, and the output signal of the detection means at that time and the output signal. A device for driving a light emitting diode, which determines whether or not the device has failed based on an instruction signal. 2. A device that divides a plurality of light emitting diodes into a plurality of groups and controls the light emitting diodes for each group and for each light emitting diode in the group, and indicates a group of the light emitting diodes to be turned on. Control means for generating a first command signal for controlling and a second command signal for instructing the light emitting diodes to be lit in the group, and receiving the first command signal and corresponding to the first command signal. A first driving means for opening and closing a current path of the group; and a second driving circuit for receiving the second command signal.
The second drive means for opening and closing the current path of the light emitting diode corresponding to the command signal of, and a detection means for detecting whether or not a current is supplied to the light emitting diode, the control means, at the time of failure check, The first and second instruction signals are supplied to the drive means at least once, and it is determined whether or not the device has a failure based on the output signal of the detection means and the instruction signal at that time. , Light-emitting diode drive device. 3. The drive device according to claim 2, wherein the detection means includes a plurality of detectors that are commonly connected to one light emitting diode of each group and connected to the second drive means.