JPH11346373A - Fault detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault detector that simply detects a fault from pluralities of output signals of function blocks to be checked in a state that the circuit is configured with a small scale and the function block to be checked that is going to be checked is normally in operation. SOLUTION: The detector is provided with a selector section 4 that receives an output signal from a checked function block 22 operated normally and selects and outputs an instructed output signal among the output signals, and with a fault detection processing section 15 that compares a count measured value 12 resulting from counting the output signal selected and outputted by the selector section 4 that receives a selection output instruction for a check period with a count expected value 13 resulting from counting a normal output signal for the check period and that discriminates whether or not the count measured value 12 is within a permissible range of the count expected value 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a failure detecting device for detecting a failure of a function block to be inspected, such as a clock generator of an image processing device.

[0002]

2. Description of the Related Art Conventional failure detection devices include those used in image processing devices such as digital cameras, facsimile machines, digital copiers and printers, and these devices are mainly composed of digital circuits. It checks whether a functional block such as a clock generation unit operates normally and performs self-diagnosis of a failure.

[0003] As a method of detecting a failure in a conventional failure detection device, one described in Japanese Patent Application Laid-Open No. Hei 5-183673 is known. As shown in FIG. 8, the failure detection device includes a selector 21, a test signal generator 23, and a controller 2.
4 and an expected output value generating section 25 and a comparing section 26. The output signal of the functional block 22 to be inspected is inspected to detect a failure of the functional block 22 to be inspected.

Here, an operation of detecting a failure of the function block 22 to be inspected in the failure detection device will be specifically described. First, the control unit 24 controls the selector unit so that the test signal 27 from the test signal generation unit 23 is input to the test function block 22 instead of the input signal 20 input to the test function block 22 during normal operation. Instructing the test function block 21 from the normal operation to the failure detection mode.

[0005] The output signal 1 output from the test function block 22 to which the test signal 27 has been input is input to the comparator 26. On the other hand, in the expected output value generation unit 25, based on the instruction from the control unit 24, when the test signal 27 is input to the function block 22 to be inspected to be normal, it is output from the function block 22 to be inspected. Then, an output expected value signal 28 as a signal which will be generated is generated and output to the comparison unit 26.

The comparator 26 compares the output signal 1 with the expected output signal 28. Output signal 1 and output expected value signal 2
8 is output from the failure detection result output 29, and if there is a difference between the two signals, the diagnosis result of “failure” is output as the failure detection result output. 29.

[0007]

However, in the conventional fault detecting device, as shown in FIG. 8, a test signal generation is performed in place of the input signal 20 at the time of normal operation input to the function block 22 to be tested. In order to receive the test signal 27 from the section 23,
Unless the normal operation 2 is interrupted and switched to the operation in the failure detection mode, the failure of the function block 22 to be inspected cannot be detected.

Further, a dedicated test signal 27 and an output expected value signal 2 are provided to the function block 22 to be inspected.
8 is required, and the test signal generator 23 for generating the test signal 27 and the output expected value generator 25 for generating the output expected value signal 28 are required. There is a problem with the circuit configuration.

When there are a plurality of output signals of the function block under test 22 to be tested in the same device, a failure detection device corresponding to each output signal must be provided in each function block 22 to be tested. Therefore, there is a problem that a failure detection device having almost the same function is duplicated in the same device.

According to the present invention, a circuit is formed on a smaller scale than in the prior art, and failures can be simplified for a plurality of output signals of the function block under test while the function block under test is normally operated. It is an object of the present invention to provide a failure detection device for detecting a failure.

[0011]

According to the present invention, there is provided a failure detecting device for selecting and outputting an output signal of a function block to be inspected which is operating normally, and counting an output signal from the selector during a test period. A failure detection processing unit is provided for comparing the measured count value with the expected count value and determining whether the measured count value is within the allowable range of the expected count value.

According to the present invention, a circuit is constructed in a smaller scale than in the prior art, and a fault is caused to a plurality of output signals of the function block to be tested while the function block to be tested is normally operated. It is possible to provide a failure detection device that performs simple detection.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to a first aspect of the present invention is directed to a failure detecting apparatus for detecting a failure of a functional block to be inspected, the output signal of a normally operating functional block to be inspected. A plurality of input signals, a selector unit for selectively outputting an output signal designated among these output signals, a count measurement value obtained by counting the output signal instructed to the selector unit and selectively output during a test period, and A failure detection device provided with a failure detection processing unit that compares an output signal to be counted with the expected count value counted in the inspection period and determines whether the measured count value is within the allowable range of the expected count value. And a plurality of output signals of the function block to be inspected while the function block to be inspected is normally operated. It is possible to detect a failure in a simplified manner for.

According to a second aspect of the present invention, there is provided a failure detecting device for detecting a failure of a functional block to be inspected, wherein a plurality of output signals of a normally operating functional block are inputted. A selector section for selecting and outputting an output signal designated among these output signals; a counter section for counting an output signal from the selector section during a test period; and a counter for indicating an output signal to be selected to the selector section. A control unit that instructs the test period to output a count expected value counted in the test period for an output signal to be normal, a count measurement value counted by the counter unit, and the count expected value. And a discriminating unit for discriminating whether or not the measured count value is within the allowable range of the expected count value. A circuit is configured in a smaller scale than before, and a fault can be easily detected with respect to a plurality of output signals of the function block under test while the function block under test is normally operated. .

According to a third aspect of the present invention, in a failure detection device for detecting a failure of a functional block to be inspected, an output signal of a normally operating functional block to be inspected is designated. A level conversion unit that performs level conversion based on a threshold value and outputs the output signal, a count measurement value obtained by counting the output signal in which the level conversion unit performs the level conversion by instructing the threshold value during a test period, and an output signal to be normal A failure detection device provided with a failure detection processing unit that compares the expected count value counted during the inspection period with the expected count value and determines whether the measured count value is within the allowable range of the expected count value. Even if the output signal of the functional block to be tested is a multi-valued signal, the output signal of the functional block to be tested remains in a state where the functional block to be tested is normally operated. It is possible to detect a failure in a simplified manner for.

According to a fourth aspect of the present invention, there is provided a failure detection device for detecting a failure of a functional block to be inspected, wherein a plurality of output signals of a normally operating functional block are inputted. A selector section for selectively outputting an output signal designated among the output signals; a level conversion section for level-converting and outputting the output signal selected by the selector section based on a designated threshold value; And a level measurement unit that counts an output signal obtained by instructing the level conversion unit to selectively output and instructs the level conversion unit to specify the threshold value in the inspection period, and an output signal that is normal is counted in the inspection period. A failure detection device provided with a failure detection processing unit that compares the expected count value with the count value and determines whether the measured count value is within the allowable range of the expected count value. Therefore, even when the output signal of the functional block to be inspected is a multi-level signal, a failure is caused for a plurality of output signals of the functional block under test while the functional block under test is normally operated. It can be easily detected.

Hereinafter, a failure detection device according to the present invention will be described based on a specific embodiment. (Embodiment 1) As shown in FIG. 1, a failure detection apparatus according to Embodiment 1 of the present invention designates one of a plurality of output signals 1 to 3 of a function block under test 22 which is operating normally. A selector section 4 for selectively outputting the selected output signal, a count measurement value 12 in which the output signal selected and output by instructing the selector section 4 is counted in the inspection period, and a normal output signal is counted in the inspection period. The fault detection processing unit 1 compares the measured count value 12 with the expected count value 13 to determine whether the measured count value 12 is within the allowable range of the expected count value 13.
5 is provided. This failure detection processing unit 15
As shown in FIG. 2, the counter unit 6, the determination unit 7, and the control unit 8
And a basic circuit provided with.

This failure detection device is for detecting a failure such as a clock generation unit or a generation of a synchronization signal of an image processing device such as a digital camera, a facsimile device, a digital copying machine or a printer.

Here, a case will be described in which the function block under test 22 is specifically used as a clock generation unit of a digital camera to detect a failure. The clock generator outputs a plurality of signals obtained by dividing and decoding the input signal.

Normally operating functional block under test 2
The plurality of output signals 1 to 3 output from 2 are input to the selector unit 4 as shown in FIG. The selector unit 4 is controlled so as to selectively output the output signal specified by the control unit 8.

Here, for example, when it is instructed to selectively output the output signal 1, the selector section 4 selects and outputs the output signal 1 among a plurality of output signals 1 to 3. The output signal 1 selected and output by the selector unit 4 is output to the counter unit 6
Has been entered. The counter unit 6 is controlled based on a counter control signal 11 from the control unit 8, and counts the number of pulses of the output signal 1 during a period T in which the enable signal of the counter control signal 11 is at the Hi level as a test period. I do.

Specifically, as shown in FIG. 3, when the counter section 6 receives the reset signal of the counter control signal 11, it resets the count measurement value 12, and the enable signal of the counter control signal 11 is at Hi level. In the period T, the number of pulses of the output signal 1 is counted. The count measurement value 12 counted by the counter unit 6 is input to the determination unit 7 as shown in FIG.

On the other hand, the expected count 13 obtained by counting the output signal 1 of the function block under test 22 which is determined to be normal by the counter unit 6 during the test period is also input to the determination unit 7. The expected count value 13 is recorded in, for example, the control unit 8.

The determination section 7 compares the measured count value 12 with the expected count value 13 to determine whether the measured count value 12 is within the allowable range of the expected count value 13. When the count measurement value 12 is within the allowable range of the expected count value 13, for example, when the measured count value 12 and the expected count value 13 match or almost match, the output signal 1 is set to “normal”. The diagnosis result is output to the failure detection result output 14. Also, the count measurement value 1 assuming that the count measurement value 12 is not within the allowable range.
If 2 and the expected count value 13 are far apart,
A diagnosis result that sets the output signal 1 to “failure” is output to the failure detection result output 14.

As described above, the output signals 2 and 3 are similarly inspected based on the instruction from the control unit 8. The timing of resetting the counter unit 6 and the period T in which the enable is at the Hi level are controlled by the control unit 8 according to the selected output signal. That is, the period T in which the enable is at the Hi level is set according to the pulse frequency predicted when the output signal is normal, and similarly, the expected count value 13 input from the control unit 8 to the determination unit 7 is similarly set. Is a value corresponding to the selected output signal.

With this configuration, the function block 22 to be inspected can be replaced without interrupting the normal operation state of the function block 22 to be inspected to be inspected for failure. The output signal selected and output from the function block under test 22 can be tested in the normal operation state, and failures can be easily detected for a plurality of output signals from the function block under test 22. Can be detected. For example, when the measured count value 12 is far from the expected count value 13, a failure such as a short-circuit or disconnection of a signal line related to the output signal selected and output from the test target function block 22 or some malfunction of the test target function block 22. Can be easily detected,
Maintenance work such as unit replacement of the function block under test 22 can be performed efficiently.

The function block 2 to be inspected as in the prior art
2, it is not necessary to input the test signal 27, so that the test signal generation unit 23 and the selector unit 21 shown in FIG. 8 can be eliminated, and the fault detection device can be configured on a smaller scale than in the prior art. it can.

Further, since it is not necessary to provide an independent failure detection processing unit 15 for each of the output signals 1 to 3 of the function block 22 to be inspected, the output signal to be inspected is not greatly increased without increasing the circuit scale. The fault can be detected for a plurality of output signals only by increasing the control information of the counter unit 6 and the information of the expected count value 13 corresponding to the number of output signals.

In the first embodiment, a plurality of output signals output from a single functional block to be inspected are selectively output by the selector unit and individually inspected. The same effect is obtained even when a plurality of output signals are input to the selector unit.

As shown in FIG. 4, when a plurality of unit-replaceable boards 17a to 17c are individually detected for faults, a fault detection processing unit 15 is provided on the common unit board 16, and any one of the input output signals is output. Selector units 4a to 4c capable of selecting a high impedance state in which no output is performed are provided on the unit exchangeable substrates 17a to 17c, respectively.
By constructing a plurality of unit exchangeable substrates 17
Only a specific output signal of a specific unit-exchangeable board among the counters 6a to 17c is determined based on an instruction from the controller 8.
The failure can be detected individually for the plurality of unit-replaceable boards 17a to 17c.

Further, unit exchangeable boards 17a to 17c
Even when the output signals in these boards are further increased and a plurality of output signals are inspected, the selector 8 is connected to the common unit board 16 and the unit exchangeable board 17 by the control unit 8 as a wiring. A plurality of output signals can be inspected only by slightly increasing the wiring of the selector control signal 9 to the unit and the wiring of the output signal 18 from the selector unit to the counter unit 6.

By providing a means for outputting a message from the common part board in characters, voice, or the like, it is possible to prompt replacement of a unit replacement type board determined to be out of order.

(Embodiment 2) As shown in FIG. 5, the fault detecting device according to the first embodiment of the present invention is different from the fault detecting device according to the first embodiment in that the output signal selected by the selector 4 Is provided on the basis of a threshold value instructed by the control unit 8 and a level conversion unit 5 for outputting the converted level to the counter unit 6 is provided.

The level conversion section 5 converts the level of the output signal selected by the selector section 4 based on the threshold value specified by the level conversion characteristic control signal 10 from the control section 8 and outputs the output signal.

The operation of detecting a failure in the function block under test 22 in this failure detection device will be specifically described with reference to FIGS. First, as shown in FIG. 6, the output signal that becomes the first normal signal during normal operation is short-circuited for some reason by the output signal that becomes the second normal signal during normal operation. Hi level and Low
A case where a ternary signal having an intermediate level is obtained will be described.

When the input signal of the level converter 5 is a ternary signal and the threshold of the level converter 5 is set to THR1 as shown in FIG. The output from the unit 5 becomes the level-converted output signal R1 as shown in FIG. FIG.
When the threshold value of the level conversion unit 5 is set to THR2 as shown in (b), the output from the level conversion unit 5 becomes the level-converted output signal R2 as shown in FIG.
Becomes

That is, the input signal of the level converter 5 is
In the case of the ternary signal shown in (1), by changing the threshold value of the level conversion unit 5 from the control unit 8, the count measurement value 12 output from the counter unit 6 becomes a different value. Specifically, when the threshold value of the level conversion unit 5 is set to THR1, the count measurement value 12 counted by the counter unit 6 during the period T that is the enable Hi level is “7”.
When the threshold value of the level conversion unit 5 is set to THR2, the count measurement value 12 counted by the counter unit 6 during the period T that is the enable Hi level is “4”. At this time, the expected count value 13
Is "9" as shown in FIG.

With such a configuration, even if the measured count value 12 is close to the expected count value 13, the setting of the threshold value of the level conversion unit 5 is changed and the inspection is performed again, so that the inspection is performed. A more complicated abnormality can be detected for a signal line related to an output signal of the function block to be inspected.

Further, by changing the threshold value of the level conversion unit 5 for binarizing the multi-level signal, it is possible to detect a failure in the multi-level signal. Further, since the output signal of the functional block to be inspected can be level-converted, accurate inspection can be performed even when the level of this output signal is low.

The selector of the first embodiment only needs to support digital signals, but the selector of the third embodiment needs to support analog signals.
In the third embodiment, a selector unit for selectively outputting a plurality of detected signals of a function block to be inspected based on an instruction from a control unit, and a threshold value designated by the control unit for an output signal selected by the selector unit And a level conversion unit for converting the output signal to the counter unit based on the above-mentioned condition. However, when this selector unit is deleted, it is not possible to individually select a plurality of output signals from the function block to be tested. A single output signal of the tested functional block can be level-converted to detect a failure, and a more complicated abnormality can be detected for a signal line related to the output signal.
A failure can be detected even when the output signal output from the tested functional block is a multi-level signal.

[0041]

As described above, according to the fault detecting device of the present invention, a plurality of output signals of the function block to be inspected which are operating normally are inputted, and the designated output signal is selected from these output signals. A selector unit to be output, a count measurement value obtained by counting an output signal instructed to the selector unit and selectively output in a test period, and a count expected value in which a normal output signal is counted in the test period are compared. By providing a failure detection processing unit that determines whether the count measurement value is within the allowable range of the expected count value,
Without interrupting the normally operating state of the functional block to be inspected to be inspected as in the prior art and changing it to the state for failure inspection, the functional block under inspection remains in the normal operating state. The failure of the functional block to be inspected can be easily detected, and maintenance work such as replacement of the unit of the functional block to be inspected can be performed efficiently.

Also, since it is not necessary to input a test signal to the function block to be inspected as in the conventional case, the test signal generating unit and the selector unit can be eliminated, and the failure detection device can be reduced in size as compared with the prior art. Can be configured.

Furthermore, since it is not necessary to provide an independent failure detection processing unit for each of a plurality of output signals of the functional block to be inspected, the output signal to be inspected can be supported without increasing the circuit scale so much. By simply increasing the control information of the counter unit 6 and the information of the expected count value by the amount of the output signals, a fault can be automatically detected for a plurality of output signals.

Also, the output signal of the function block to be inspected, which is operating normally, is level-converted based on the threshold value specified by the control unit, and is output to the counter unit. In the case of the installed failure detection device,
Even if the output signal of the functional block to be inspected is a multi-level signal, a fault is simply detected with respect to the output signal of the functional block under inspection while the functional block under test is operated normally. be able to.

Further, a selector section for selecting and outputting an output signal designated among a plurality of output signals of the function block to be inspected which is operating normally, and a threshold value designated by the selector section for outputting the output signal selected by the selector section. In the case of a failure detection device provided with a level conversion unit that performs level conversion and output based on the function block, even if the output signal of the function block to be tested is a multi-level signal, the function block to be tested is operated normally. In this state, a failure can be easily detected with respect to a plurality of output signals of the function block to be inspected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a failure detection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a basic configuration of a failure detection processing unit according to the first embodiment;

FIG. 3 is a diagram showing operation timings of a counter unit according to the first embodiment;

FIG. 4 is a block diagram showing a configuration of a failure detection device different from the first embodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a failure detection device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing operation timings of a level conversion unit according to the second embodiment.

FIG. 7 is a level conversion characteristic diagram of a level conversion unit according to the second embodiment.

FIG. 8 is a block diagram showing a configuration of a conventional failure detection device.

[Explanation of symbols]

 1-3 output signal 4 selector unit 4a-4c selector unit 5 level conversion unit 6 counter unit 7 determination unit 8 control unit 9 selector control signal 10 level conversion characteristic control signal 11 counter control signal 12 count value 13 expected count value 14 failure detection Result output 15 Failure detection processing unit 16 Common part board 17a-17c Unit exchangeable board

Claims (4)

[Claims] In a failure detecting apparatus for detecting a failure of a functional block to be inspected, a plurality of output signals of a normally operating functional block to be inspected are input and designated among these output signals. A selector section for selectively outputting an output signal; a count measurement value obtained by counting the output signal selected and output by instructing the selector section during a test period; and a count expected value at which a normal output signal is counted during the test period. And a failure detection processing unit for determining whether the count measurement value is within the allowable range of the expected count value. 2. A failure detecting device for detecting a failure of a functional block to be inspected, wherein a plurality of output signals of a normally operating functional block to be inspected are input and designated among these output signals. A selector section for selectively outputting an output signal; a counter section for counting an output signal from the selector section during a test period; an output signal to be selected to the selector section; A control unit that controls the output signal to output an expected count value counted during the inspection period; and compares the count measured value counted by the counter unit with the expected count value, and the count measured value is the expected count value. And a determining unit for determining whether the current value is within the allowable range. 3. A failure detecting device for detecting a failure of a functional block to be inspected, the level of an output signal of a normally operating functional block to be inspected being converted based on a specified threshold value and output. A level conversion unit, a count measurement value obtained by counting the output signal obtained by performing the level conversion by indicating the threshold value to the level conversion unit in a test period, and a count expected value in which the output signal to be normal is counted in the test period. And a failure detection processing unit that determines whether the count measured value is within the allowable range of the expected count value. 4. A failure detecting device for detecting a failure of a functional block to be inspected, wherein a plurality of output signals of a normally operating functional block to be inspected are inputted and designated among these output signals. A selector unit for selectively outputting an output signal; a level conversion unit for performing level conversion on the output signal selected by the selector unit based on a specified threshold and outputting the signal; and instructing the selector unit to selectively output the signal. A count measurement value obtained by counting the output signal whose level has been converted by indicating the threshold value to the level conversion unit during the inspection period is compared with a count expected value at which the output signal to be normal is counted during the inspection period. A failure detection device comprising: a failure detection processing unit that determines whether a value is within an allowable range of an expected count value.