JP2663853B2 - Light intensity monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light intensity monitoring device for notifying a user of a life time of an illumination light source used in an image input device.

[0002]

2. Description of the Related Art A conventional light intensity monitoring apparatus will be described with reference to FIG.

A conventional light intensity monitoring device illuminates a document 3 conveyed to be input with an image, and its light intensity is adjacent to an illumination light source 1 having a deterioration characteristic with time and a document to be imaged. A reference reflector 2 arranged in this image input area and having uniform reflection characteristics in a wavelength range in which an image can be input.
A lens 4 for forming an image obtained by illuminating the original 3 with the illumination light source 1, and a linear image sensor 5 for photoelectrically converting the image formed by the lens 4
And a test terminal 7 to which the photoelectric conversion signal is output, an oscilloscope 8 connected to the test terminal 7 and observing a waveform of the photoelectric conversion signal output to the test terminal 7, and a photoelectric conversion by the linear image sensor 5. An A / D converter 6 for inputting a signal, quantizing the photoelectric conversion signal at an appropriate level, and outputting the quantized signal to the outside.

In such a configuration, in the conventional light intensity monitoring apparatus, when an image is input, the oscilloscope 8 is not connected to the test terminal 7, and the input image data quantized by the A / D converter 6 is externally provided. Is output. When the light emission amount of the illumination light source 1 decreases, an external device (for example, a character recognition device)
Each time a problem occurs, such as a decrease in the image recognition rate in or the output image on the display becomes unclear,
The maintenance person connects the oscilloscope 8 to the test terminal 7 and observes the waveform of the photoelectric conversion signal output from the linear image sensor 5.

[0005] The waveform of the photoelectric conversion signal is, for example, as shown in FIG. 10, and the photoelectric conversion signal waveform 12 is the photoelectric conversion signal waveform 12 based on the input image from the line segment connecting the left end 9 and the right end 10 of the image input range in FIG. 9. 3 shows a waveform of a converted signal. The photoelectric conversion signal level 11 of the reference reflection plate 2 is measured from the waveform 12 of the photoelectric conversion signal, and when the value is equal to or less than a predetermined value, a process such as lamp replacement is performed.

[0006]

In this type of conventional light intensity monitoring device, the absolute value of the light emission intensity of the illumination light source is used as a criterion for lamp replacement time. Due to the cause, the level of the photoelectric conversion signal is measured to be reduced, and it may be determined that the light intensity of the light source is reduced, and it is difficult to accurately measure the lamp replacement time.

[0007] In addition, an oscilloscope must be connected and a waveform observation operation must be performed each time the light intensity is measured, and the operation of confirming the light intensity is lacking in speed.

[0008]

In order to solve the above problems, a light intensity monitoring apparatus according to the present invention comprises an illumination light source for illuminating an image input area and a reference for illuminating a predetermined area in the image input area . A light source, a lens that forms an image of the image input area, a photoelectric conversion unit that photoelectrically converts the image, an A / D conversion unit that quantizes the photoelectrically converted signal, and only the illumination light source is turned on. the obtained that images obtained in a state obtained by quantizing
The first value and the value obtained when only the reference light source is turned on.
That image and the second value obtained by quantizing, said a is that images obtained illumination light source and said reference light source together with off state based on the third value obtained by quantizing, the second value and the third Difference from value
A ratio calculating unit for calculating a ratio value of a difference value between the first value and the third value with respect to the minute value , and when the illumination light source is started using the ratio value calculated by the ratio calculating unit. A comparison unit that compares the value of the ratio calculated in the above with the value of the ratio calculated by the ratio calculation unit at the time of confirming the change in the light emission intensity of the illumination light source, according to the result of comparison in the comparison unit. And a display unit for issuing a warning.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment in which the light intensity monitoring device of the present invention is applied to an image input device.

In FIG. 1, the light intensity monitoring apparatus of the present invention includes an illumination light source 1 for illuminating a document 3 conveyed so as to receive an image. The light intensity of the illumination light source 1 has a characteristic of deteriorating with time. Adjacent to the conveyance path of the document 3,
A reference reflector 2 having a uniform reflection characteristic in a wavelength range in which an image can be input is arranged in the image input area. When monitoring the light intensity of the illumination light source 1, the reference light source 2 is illuminated, and a reference light source 13 whose light intensity deteriorates with time is sufficiently smaller than that of the illumination light source 1 with time. An image obtained by irradiating the original 3 with light from the illumination light source 1 is formed by a lens 4, and a linear image sensor 5 is formed.
Is subjected to photoelectric conversion. This photoelectrically converted signal is represented by A
It is quantized by the / D converter 6. The output of the A / D conversion unit 6 is supplied to a measurement light intensity storage unit 15, a reference light intensity storage unit 16, a background light intensity storage unit 17, and an external output 25 provided as needed by a switch 14 controlled by a control unit 24. Is switched to and output. The measurement light intensity storage unit 15
The image signal level value obtained by the reference reflector 2 obtained when the illumination light source 1 is turned on and the reference light source 13 is turned off is stored. The reference light intensity storage unit 16 stores an image signal level value obtained by the reference reflector 2 obtained when the illumination light source 1 is turned off and the reference light source 13 is turned on. Further, the background light intensity storage unit 17 stores an image signal level value obtained by the reference reflector 2 obtained in a state where both the illumination light source 1 and the reference light source 13 are turned off (only background light). The control unit 24
The A / D converter 6 controls the timing at which the input image is quantized, and the switch 14 outputs a control signal for switching the output destination of the input image signal. The ratio calculation unit 18 calculates the ratio value by calculating the values stored in the measured light intensity storage unit 15, the reference light intensity storage unit 16, and the background light intensity storage unit 17 as input values. The value of the ratio calculated when the illumination light source 1 is started to be used by the ratio calculator 18 is used as an initial value ratio by a switch 19 switched by the controller 24.
Is stored in the initial value storage unit 20 via When confirming the change in the light emission intensity of the illumination light source 1, the value of the ratio calculated by the ratio calculator 18 at that time is defined as a measured value ratio,
The switch 19 switched by the control unit 24
Is stored in the measured value storage unit 21 via the. The comparison unit 22
The value of the ratio stored in the initial value storage unit 20 is compared with the value of the ratio stored in the measured value storage unit 21 to calculate the rate of change. And compare it with the reference value. As a result of comparing the change rate with the reference value in the comparing section 22, when the change rate is lower than the reference value, a message or an alarm prompting lamp replacement is displayed on the display section.

Next, the operation of the light intensity monitoring apparatus of the present invention will be described with reference to FIG. 1 and a flowchart showing the operation of the light intensity monitoring apparatus of the present invention in FIG.

First, a new illumination light source 1 for irradiating the original 3 is provided in the apparatus (step 21). On this occasion,
Prior to normal use, the procedure shown in FIG. 3 (described in detail later) uses the luminous intensity of the illumination light source 1, the luminous intensity of the reference light source 13, and the background light intensity as input values to obtain a ratio value R.
(0) is calculated (step 22). After the ratio value R (0) calculated in step 22 is stored in the initial value storage unit 20, an external device (for example, an image input device) provided with the light intensity monitoring device of the present invention is normally used (step S22). 2
3). If an external device is used for a certain period, the illumination light source 1
The use of the external device causes a problem due to the decrease in the light emission intensity of the device, and the user detects the problem (step 24).
When the malfunction of the external device is detected, the ratio value R (t1) is calculated by using the light emission intensity of the illumination light source 1, the light emission intensity of the reference light source 13, and the background light intensity as input values according to the procedure shown in FIG. 25). Next, R
(0) and R (t1) are compared (step 26), and the rate of change A is compared with a predetermined reference value k (step 27). At this time, if the change rate A is smaller than the reference value k, a message is displayed on the display unit 23 to replace the illumination light source 1 (step 28). When the change rate A is larger than the reference value k, it indicates that the illumination light source 1 does not need to be replaced.

Next, after the illumination light source 1 is started to be used, the values of the ratio R ( The processing procedure for calculating t) will be described with reference to the flowchart shown in FIG.

First, the illumination light source 1 is turned on and the reference light source 13 is turned off (step 31), and an image is input in this state. At this time, as shown in FIG. 4A, the output signal V _mes (t) reflected by the reference reflector 2 and photoelectrically converted by the linear image sensor 5 is transmitted to the control unit 24 as shown in FIG. 4C is quantized by the A / D converter 6 in synchronization with the rising edge of the sample signal output from the switch, and the output of the result shown in FIG.
(Step 32). The value at this time, that is, the photoelectric conversion output V _{me s} (t) of the reference reflector 2 when only the illumination light source 1 is turned on is represented by I _mes (t) of the light emission intensity of the illumination light source 1 and light of the background light. The intensity is I _o (t),
When the reflectance of the reference reflector 2 is r _p (t) and the imaging system gain such as the transmittance of the lesbian is K, it is determined by Expression [1].

[0016] _{V mes (t) = {I} mes (t) + I o (t)} · r p (t) · K [1] Next, turns off the illumination light source 1, and turns on the reference light source 13 (Step 33) In this state, an image is input. At this time, as shown in FIG. 5A, the output signal level V _ref (t) reflected by the reference reflecting plate 2 and photoelectrically converted is obtained as shown in FIG.
The quantized signal is quantized by the A / D converter 6 in synchronization with the rising edge of the sample signal output from the controller 24 shown in (b), and the result (FIG. 5C) is transmitted via the switch 14 to the reference light intensity. It is stored in the storage unit 16 (step 34). The value at this time, that is, the photoelectric conversion output V _ref (t) of the reference reflection plate 2 when only the reference light source 13 is turned on is represented by I _ref, which is the emission intensity of the reference light source 13 (a constant because there is almost no deterioration with time). Is determined by Expression [2].

[0017] _{V ref (t) = {I} ref + I o (t)} · r p (t) · K [2] Next, the illumination light source 1 and the reference light source 13 are both turned off (step 35), the condition Use to input an image. At that time, FIG.
The output signal level V _o (t) reflected by the reference reflector 2 and photoelectrically converted as shown in FIG. 6A is synchronized with the rising edge of the sample signal output from the control signal 24 shown in FIG. It is quantized by the A / D converter 6 and the result (FIG. 6)
(C)) is stored in the background light intensity storage unit 17 via the switch 14 (step 36). The value at this time, that is, the photoelectric conversion output V _o (t) of the reference reflector 2 using only the background light is determined by Expression [3].

[0018] stored in the respective _{V o (t) = I o} (t) · r p (t) · K [3] Measurement light intensity storage unit 15, the reference light intensity storage unit 16 and the background light intensity storage unit 17 Value V
_mes (t), V _ref (t), and V _o (t) are ratio operation units 1
In step 8, the operation of equation [4] is performed, and the ratio value R (t) is calculated (step 37).

[0019]

When a new illumination light source 1 is mounted, time t
An initial value R (0) when = 0 is calculated. R (0) by the operation regardless of the reflectivity r _p of the reference reflection plate 2, a function that is determined only by the emission intensity of the emission intensity and the reference light source 13 of the illumination light source 1. Here, R (0) is stored in the initial value storage unit 20 via the switch 19.

When the time when the external device is detected and the light intensity of the illumination light source 1 is monitored is t = t1, R (t1) is calculated according to the procedure shown in FIG. The result is stored in the measured value storage unit 21 via the switch 19.

The procedure of FIG. 3 is stored in the control unit 24 in advance, and the processing is executed without any special operation.

Next, the operation of the comparing section 22 will be described. From R (0) and R (t1) calculated according to the processing procedure of FIG. 3, a change rate A of R (t1) with respect to R (0) is calculated according to equation [5].

[0024]

When the change rate A falls below a predetermined reference value k, the display unit 23 displays a message on a display or the like or flashes a warning lamp to prompt the user to replace the illumination light source 1. Or let it. If the change rate A is larger than the reference value k, it indicates that the illumination light source 1 does not need to be replaced yet.

In the present embodiment, the user performs an operation of confirming a change in the light emission intensity of the illumination light source 1 only after the user detects a malfunction of the external device, but the power of the external device is turned on, that is, If the control unit 24 automatically checks the change of the light emission intensity at the same time as using the external device,
Since the emission intensity can be checked each time the illumination light source 1 is used, the time for replacing the illumination light source 1 can be specified more accurately, and the operation can be simplified.

In this embodiment, as shown in FIG.
The emission spectral characteristic 70 of the reference light source 13 is different from the spectral emission characteristic 71 of the illumination light source 1, and the reflection characteristic 72 of the reference reflector 2 has a uniform reflectance in a wavelength range 73 in which the linear image sensor 5 has sensitivity. As mentioned above,
As shown in FIG. 8, when the reference light source 13 and the illumination light source 1 have the same emission intensity spectral characteristic 80, the integration range is the same when the reference light source 13 is illuminated and when the illumination light source 1 is illuminated. The spectral reflectance of the reference reflector 2 is arbitrary, and may be like a curve 81 as shown in FIG. Therefore, in such a case, it is not necessary to provide the reference reflection plate 2, and any document can be used regardless of a white background, color suspension, or the like.

Further, in this embodiment, the linear image sensor 5 is used as a photoelectric conversion device, but another photoelectric conversion device, for example, an area image sensor or the like may be used.

[0029]

As described above, the light intensity monitoring apparatus of the present invention detects the relative value of the ratio between the illumination light and the reference light, thereby detecting the relative value of the reference reflection plate over time. The measured value is not affected by a large change in reflectance. As a result, compared to the method of measuring the absolute value of the illumination light intensity to check the deterioration of the illumination light source with time, it is more resistant to disturbance and can accurately know the lamp replacement time. In addition, since it is not necessary to connect and operate a device such as an oscilloscope for measuring the light intensity, the operation is simplified and the light intensity can be monitored quickly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a light intensity confirmation procedure according to one embodiment of the present invention.

FIG. 3 shows a ratio value R when a new illumination light source is installed.
9 is a flowchart showing a processing procedure for calculating (0).

FIG. 4 is a graph showing a photoelectric conversion signal when only an illumination light source is turned on.

FIG. 5 is a graph showing a photoelectric conversion signal when only a reference light source is turned on.

FIG. 6 is a graph showing a photoelectric conversion signal when both the illumination light source and the reference light source are turned off.

FIG. 7 is an explanatory diagram in the case where the reflection characteristics of a reference reflector have a uniform reflectance in a wavelength range where the sensitivity of the linear image sensor is provided.

FIG. 8 is an explanatory diagram in the case where a reference light source has the same light intensity characteristics as an illumination light source.

FIG. 9 is a configuration diagram showing a conventional light intensity monitoring device.

FIG. 10 is an explanatory diagram of a photoelectric conversion signal waveform of an input image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination light source 2 Reference reflector 3 Document 4 Lens 5 Photoelectric converter 6 A / D converter 7 Test terminal 8 Oscilloscope 9 Left end of image input range 10 Right end of image input range 11 Photoelectric conversion signal level by reference reflector 12 Photoelectric conversion Signal waveform 13 Reference light source 14 Switch 15 Measurement light intensity storage unit 16 Reference light intensity storage unit 17 Background light intensity storage unit 18 Ratio operation unit 19 Switch 20 Initial value storage unit 21 Measurement value storage unit 22 Comparison unit 23 Display unit 24 Control unit 25 External output 70 Emission intensity spectral characteristic of reference light source 71 Emission intensity spectral characteristic of illumination light source 72 Reflection characteristic of reference reflector 73 Wavelength range in which linear image sensor has sensitivity 80 Emission intensity spectral characteristic of reference light source and illumination light source 81 Reference reflection Reflection characteristics of plate

Claims (7)

(57) [Claims] And 1. A illumination source for illuminating the image input area, and a reference light source for illuminating a predetermined region of the image input area, and a lens for forming an image of the image input area, for photoelectrically converting the image a photoelectric conversion unit, an a / D converter for quantizing the photoelectrically converted signal, the first value a is that images obtained while lighting only the illumination light source is quantized, only the reference light source a second value to be that image obtained at the lighting state is quantized, both provided that images obtained at off state of the illumination light source and the reference light source based on the third value obtained by quantizing, the second Value and the third value
A ratio calculator for calculating a ratio of a difference value between a first value and a third value with respect to a difference value between the first and third values, and starting using the illumination light source in the ratio value calculated by the ratio calculator. A comparison unit that compares the value of the ratio calculated at the time of comparison with the value of the ratio calculated by the ratio calculation unit at the time of confirming the change in the emission intensity of the illumination light source. And a display unit for issuing a warning according to the following. 2. The light intensity monitoring device according to claim 1, wherein the illumination light source and the reference light source have the same emission intensity spectral characteristics. If wherein the emission intensity spectral characteristic of the illumination light source and the reference light source is different, pre-reference reflector which have a reflectance of uniform wavelength range having the photoelectric conversion section is sensitive
2. The method according to claim 1, wherein the first and second areas are arranged in a predetermined area.
3. The light intensity monitoring device according to claim 1. 4. An external output terminal for outputting a signal quantized by the A / D converter to an external device, wherein an output destination of the signal quantized by the A / D converter is the external output terminal. A measured intensity storage unit for storing the first value ;
Said reference light intensity storage unit for storing the second value and the first
A first switch that switches to one of the background light intensity storage units that stores a value of 3; a value of the ratio calculated by the ratio calculation unit, the ratio of the ratio calculated when the illumination light source is started to be used. A second switch that switches the output to an initial storage unit that stores a value or a measurement value storage unit that stores a value of a ratio calculated at the time of confirming a change in emission intensity of the illumination light source; The light intensity monitoring device according to claim 1 , further comprising a control unit that controls the first switch and the second switch. 5. The deterioration over time of the light emission intensity of the reference light source,
2. The light intensity monitoring device according to claim 1 , wherein the light intensity of the illumination light source is sufficiently smaller than the deterioration over time. 6. Oite the illumination light source for illuminating the image input area at start of use, Tokura when lit only the illumination light source
First signal level of the input image, at the image input area
Tokura when only the lit reference light source for illuminating the constant region
On the basis of the third signal level of the second signal level and the input image obtained in the case of the background light only of the input image, the difference value between the second signal level and the third signal level
Difference between the first signal level and the third signal level
The first calculates the value of the ratio, Timing of predetermined time using said illumination source has passed the
In ring, the fourth signal level of the incoming <br/> force image obtained when lit only the illumination light source, the fifth signal level and the previous input image obtained when lit only the reference light source
Serial based on the sixth signal level of the input image obtained in the case of the background light only, the fifth signal level and a sixth signal level
Signal level and the sixth signal level with respect to the difference value from the
Calculating a second value of the ratio of the difference value between the bell, comparing the first value of the ratio between the second value of the ratio, the result of the comparison, the user of the replacement time of the illumination light source A light intensity monitoring method characterized by giving a notice. 7. Oite the illumination light source for illuminating the image input area at start of use, Tokura when lit only the illumination light source
First signal level of the input image, at the image input area
Tokura when only the lit reference light source for illuminating the constant region
On the basis of the third signal level of the second signal level and the input image obtained in the case of the background light only of the input image, the difference value between the second signal level and the third signal level
Difference value between the first signal level and a third signal level pairs
The value of the first ratio is calculated, and the power of the external device using the illumination light source is turned on.
This is obtained when only the illumination light source is turned on during imaging.
That fourth signal level of the input image, the sixth signal <br/> of the fifth signal level and the input image in which the obtained when the background light only of the input image obtained when lit only the reference light source A fifth signal level and a sixth signal based on the
A fourth signal level and a sixth signal level corresponding to a difference value with respect to the level.
Calculating a second ratio value of the difference value from the signal level , comparing the first ratio value with the second ratio value, and using the result of the comparison to determine the replacement time of the illumination light source. A light intensity monitoring method.