JPS58136169A - Failure detection system for optical system - Google Patents

Abstract

PURPOSE:To detect a failure of the entire optical system with high accuracy, by storing a reference background waveform in advance, and comparing the stored data as a threshold value with a video signal at present. CONSTITUTION:When no original exists in a reading position and the output of original detectors 18, 19 goes to H level, the output of an AND circuit 24 goes to H level and this device is set to a state for the failure detection. A binary circuit 9 reads out a reference background waveform value stored in advance from a memory 10, a comparator 11 compares the value with a present reference background waveform obtained via an amplifier 8 and discriminates whether or not the optical system is in failure. When the level of the video signal waveform obtained from the optical system is lower than the threshold level, a failure signal is outputted from the comparator 11. Through this system, failures of the optical system such as deterioration of fluorescent lamp 1, frosting, dirt of lens and dirt of reflection plate 5 is detected.

Description

[Detailed description of the invention] The present invention relates to an abnormality detection method for an optical system.

Facsimile machines, copying machines, etc. are equipped with optical systems using fluorescent lights in order to read text information, etc. in documents. Dirt or dirt on the surface of the sensor that monitors this type of device can degrade the functionality of this type of device. Therefore, if deterioration of the fluorescent lamp, dirt on the lens system, dirt on the sensor surface, etc. is detected using an authorized detection method, and the amount of light is detected below a predetermined value,
Notify the operator of this as an abnormality.

A conventional method for detecting the deterioration state of the fluorescent lamp will be explained with reference to FIGS. 1 to 3 (a) and (b). First, the first
The figure shows a schematic circuit for detecting light intensity deterioration and blackening of a fluorescent lamp, in which 1 is a fluorescent lamp, 2 is a phototransistor for detecting light weight installed near the end of the fluorescent lamp, and 3 is a circuit for detecting light intensity deterioration and blackening. Similarly,
A phototransistor 4 detects light ii from the center of the fluorescent lamp 1, and a comparator 4 receives output signals from both phototransistors 2 and 3. The same configuration includes phototransistor 2.
When the light intensity of 3 is obtained as specified, the output of the comparator 4 is zero, but when one of the phototransistors detects that the light intensity is insufficient, the difference is outputted from the comparator 4 as an abnormality detection signal. It's huru.

However, with the one shown in Fig. 1, only the deterioration of the fluorescent lamp can be detected, and it is possible to detect dirt on the light detection surfaces of the phototransistors 2 and 3, dirt on the lens (not shown), and even condensation. could not be detected. Furthermore, variations in the characteristics of the phototransistor, errors in mounting in the assembly structure, etc. occurred, and it was difficult to set the detection level.

In addition, Fig. 2 shows another example, in which a reflector plate 5 is provided close to the fluorescent lamp l and serves as a background with approximately the same length as the length of the fluorescent lamp, and the reflection plate 5 reflects the light. The light is collected by lens 6, and the light obtained through lens 6 is CC
It is designed to be input to the D sensor 7. 8 is an amplifier provided at the output stage of the CCD sensor 7; 9 is a binarization circuit that converts the video signal obtained via the amplifier 8 into A/I; and 10 is a digital signal obtained via the binarization circuit 9. A memory 11 for storing signals (background waveforms) has one input of the video signal obtained through the amplifier 8, and a voltage dividing resistor 12゜1.
This is a comparator whose other input is the DC threshold value set by No. 3.

In the circuit configuration shown in FIG. 2, comparator 11. resistance 12
, 13, when the background waveform and video signal are obtained by the binarization circuit 9, the background waveform a and the video signal waveform are as shown in FIG. 3(a). , since the background waveform a is a memorized version of the video signal itself, it is natural that the background waveform a is shown in Fig. 3(a).
As shown in the figure, waveforms a and b match. Therefore, even if the fluorescent lamp has a deteriorated waveform as shown in FIG. 3(a), it cannot be detected.

Therefore, a comparator 11 is provided with the output of the amplifier 8 as one input and the other input as a threshold input, and the output is used as a fluorescent lamp deterioration detection signal, and the threshold value is set as shown in FIG. 3(b). When the level is low, it is determined that the image is black, that is, there is a deteriorated part. In addition, Fig. 3(b)
In, a is the output (video signal) of the 2-I conversion circuit 9%
b is a threshold level, C is a comparator output, and d, e, and f are black signals, which are degraded parts.

Even when a comparator 11 is separately provided as shown in FIG. 2 to detect an abnormality in a fluorescent lamp, only the abnormality (deterioration) of the fluorescent lamp can be detected.

In view of the drawbacks of the prior art, the present invention aims to detect all abnormal modes of an optical system with high precision.

The present invention stores a reference background waveform in advance and uses the stored data as a threshold value to compare with the current video signal. It is characterized by detecting abnormalities in the entire system.

The present invention will now be described in detail with reference to FIGS. 4 to 6. Figure 4 shows the document feed mechanism of a facsimile machine, with paper feed rollers 15 and 16, document feed rollers 17 and +s
, 19 is a document detector, for example, a photo sensor.

Reference numeral 20 indicates a reflecting plate serving as a pack ground, 21 indicates a document holding plate located at a position opposite to the reflecting plate, and 22 and 23 indicate paper ejecting rollers. The original 17 is read at mA. Document reading will be explained according to FIGS. 4(,) to (c). First, document 1 from paper feed loan 15, 16K.
7 is fed and passes the document detection 18, the document detection 1
The output of No. 8 changes from H level to L level.

The original iF#417 has a reflector 20 that becomes the background,
After being inserted between the document holding plates 21 and passing the reading position, the document passes the document detection 19, and the document detection 17 changes from the H level to the L level. Thereafter, the original is ejected by ejecting rollers 22 and 23. When the original 17 disappears from each detection section, each detection output goes from L level to H.
Change in level.

Here, the condition that the document 17 does not exist at the reading position A is satisfied in case (a) in FIG. 4, when the outputs of the document detectors 18 and 19 are both at H level. is. When this condition is met, they will read the video waveform of the reflector 20 that becomes the background,
Abnormality is detected by comparing it with a pre-stored reference background waveform.

In the states (b) and (c) in FIG. 4, the document detector 18 or 19 detects that the document 17 is inserted, and the output of either detector is at the L level, so in this case The binarization control unit determines that the reflector plate serving as the reference background cannot be read, and sends an abnormality detection signal to the central control unit.

Next, FIG. 5 shows an abnormality detection device that operates based on the detection signals from the document detectors 18 and 19 shown in FIG. 4, and the principle of abnormality detection will be explained with reference to FIG.

In FIG. 5, components with the same reference numerals as those in FIG. are doing. The binarization circuit 9 is controlled by the output of an AND circuit 24 which takes the logical product of the document detectors 18 and 19. Also,
The memory 10 digitally stores in advance the amount of light obtained from the background reflector when no original is inserted. The reading (-) is read when the original is not detected by the detectors 18 and 19.

In other words, the document is not at the reading position and the document detector 18,
When both outputs of 19 become H level, AND circuit 2
The output of No. 4 becomes H level, and the device is thereby set to a state capable of detecting an abnormality. Therefore, the binarization circuit 9 reads out the reference background waveform value stored in advance from the memory 10, and the comparator 11 uses that value and the amplifier 8.
The current reference background waveform value obtained through the optical system is compared with the current reference background waveform value to determine whether the optical system has an abnormal light amount.

In addition, FIG. 6 (at is the waveform diagram at that time, waveform 2
5 is a background waveform stored in advance in the memory 10, and 26 is a video signal waveform when the optical system is normal.

Further, 27 is a divided voltage waveform of the background waveform 25, which is set at an appropriate level as a threshold value. This output is input to the negative terminal of the comparator 11. The waveform is a video signal waveform obtained from the optical system, and is the video signal waveform No. 4g when both ends of the fluorescent lamp turn black due to deterioration of the fluorescent lamp.

As shown in the figure, when the level on the waveform side becomes lower than the threshold level 27, an abnormal signal is output from the comparison width 11. Furthermore, the waveform 29 in FIG. 6(b) is a waveform when the lens is closed, and since the level is lower than the threshold level 27, it can be determined that there is an abnormality. Waveform 30 is a waveform when the reflector is dirty, and if the level is lower than the threshold level, it can be determined that there is an abnormality.

Note that when the output of the AND circuit 24 is at L level, the data stored in the memory 10 is not read out, and the binary information obtained by cutting the original is sent from the terminal a, and the abnormality of the optical system is sent from the terminal a. An abnormality detection failure signal is output to notify that detection is not being performed.

As is clear from the above description, according to the present invention, a reference background waveform is stored in advance, and the reproduced reference background waveform is compared with the video signal waveform to detect an abnormality in the optical system. Therefore, the entire abnormal mode of the optical system can be detected with high precision.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic configuration diagrams for explaining the conventional optical system abnormality detection method, Figures 3 (a) and (b) are detection waveform diagrams, and Figures 4 to 6 are diagrams of the present invention. FIGS. 4(a) to 4(c) are diagrams for explaining the operation of the document feeding mechanism, FIG. 5 is a specific circuit configuration diagram, and FIG. 6(a),
(b) is a waveform diagram illustrating the principle of abnormality detection in the optical system. l...Fluorescent lamp, 5.20...Reflector, 6...Lens, 7...Sensor, 8...Amplifier, 9...Binarization circuit, 10...Memory, 11... ...Comparator, 18, 1
9... Original detector, 24... AND circuit. Agent Patent Attorney Tadashi Akimoto Figure 1 Figure 3 (a) Figure 41.1 (a) 344- Figure 5

Claims (1)

[Claims] This method detects abnormalities in the optical system installed to read the original, and the reference background waveform of the original reading system is stored in advance as a threshold value, and the reproduction reference background waveform and the original are stored in advance. Compare the video waveform with the background reflector removed when the paper is not being fed,
An optical system abnormality detection method that outputs an abnormality detection signal when the video waveform becomes lower in level than a playback reference background waveform.