JPH1056536A - Light source controller and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate degradation in the illuminance of a cold cathoderay tube such as a xenon lamp and to prolong its service life by increasing the illuminance by increasing the output voltage of a lighting device when the illuminance of a lamp in use is lowered. SOLUTION: An image reader is provided with a control part 1 equipped with a light source voltage control means and an image reading means, etc., lighting device 2 for outputting a high voltage proportional to an input voltage supplied by a voltage control part 11 inside the control part 1, xenon lamp (light source) 3 to be turned on by the high voltage applied by the lighting device 2, and photodetector (image sensor) 4 for reading an image on a reading plane by photodetecting reflected light for which light from the xenon lamp 3 is reflected on the reading plane. Then, when the illuminance of the light source such as the xenon lamp 3 gets out of an allowable illuminance range, the voltage to be impressed to the light source is controlled so that the illuminance of the light source can be settled within the allowable illuminance range. Besides, a means for reading the image can be utilized as a lamp illuminance measuring means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a facsimile machine,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus used in a copying machine and the like, and more particularly to a light source control apparatus that can extend the life of a light source when a xenon lamp or the like is used as a light source.

[0002]

2. Description of the Related Art The life of a cold-cathode tube such as a xenon lamp used as a light source in an image reader or the like is mainly determined by deterioration of illuminance. FIG. 5 shows an example of such a change with time of the illuminance of the xenon lamp. In the example shown in FIG.
After the elapse of 00 hours, the illuminance has deteriorated by 20% of the initial value. On the other hand, the life of a facsimile apparatus or the like that uses a xenon lamp as a light source of an image reading apparatus is generally about 700 hours when converted to the lighting time of the xenon lamp. Therefore, when a facsimile machine or the like reaches the end of its life, the xenon lamp has about 300 hours until its life. However, conventionally, a xenon lamp having a remaining life of 300 hours is usually discarded together with the main body that has reached the end of its life, and there is a problem in effective use of resources. The reason is that if a xenon lamp with a remaining life of 300 hours is installed in a new facsimile machine, it will be necessary to replace the xenon lamp whose life has expired halfway after 300 hours. Was hindered.

[0003]

From the viewpoint of resource recycling and cost reduction, it is desirable to reuse a xenon lamp having a life of about 300 hours. However, in the prior art, the replacement of the xenon lamp is inevitable on the way, and new costs are incurred for the replacement, and at the same time, the user needs time and effort to replace the lamp, leaving a long life. This prevented lamp reuse. The present invention has been made in view of the above circumstances, and by solving the conventional problems, by using a cold-cathode tube such as a xenon lamp having a remaining life without replacement during the middle, It is another object of the present invention to provide an image reading apparatus capable of extending the life of a xenon lamp at the time of reuse and a light source control apparatus therefor.

[0004]

According to a first aspect of the present invention, there is provided a light source control apparatus for controlling a light source whose illuminance changes according to an applied voltage. , An illuminance detecting means for detecting the illuminance of the light source, an allowable illuminance storage means for preliminarily storing an illuminance allowable range, and an illuminance tolerance stored in the allowable illuminance storage means detected by the illuminance detecting means. An illuminance comparison unit for comparing with a range, and a light source for controlling a voltage applied to the light source so that the detected illuminance is within the illuminance allowable range when the illuminance detected by the illuminance comparison unit is determined to be outside the illuminance allowable range. And a voltage control means. In the image reading apparatus according to the second aspect of the present invention, the image reading apparatus irradiates light from a light source to a reading surface and reads the reflected light with a light receiving element. A light source whose illuminance changes according to an applied voltage, a light receiving element that receives reflected light of a light emitted from the light source from a reading surface including a white reference plate and converts the light into an analog voltage, and an output from the light receiving element. And an A / D converter for converting an analog voltage to be converted into digital data, and an output voltage data A of the A / D converter when the reflected light reflected from the white reference plate enters a light receiving element. Illuminance comparing means for comparing the illuminance with the illuminance allowable range stored in the illuminance storage means; and when the illuminance comparing means determines that the output voltage data A is out of the illuminance allowable range, the output voltage data A is illuminated. Forgiveness Characterized by comprising a light source voltage control means for controlling a voltage applied to the light source to be in the range. According to the third aspect of the present invention,
3. The light source control device according to claim 1, wherein: an allowable illuminance setting unit that sets a plurality of allowable illuminance ranges in the allowable illuminance storage unit; an illuminance inspection start unit that starts light source control in an inspection mode; An illuminance permissible range selection unit for selecting an illuminance permissible range previously associated with the inspection mode from a plurality of illuminance permissible ranges stored in the permissible illuminance storage unit. According to a fourth aspect of the present invention, in the light source control device or the image reading device according to the third aspect, there is provided a light source control start unit that automatically executes light source control when power is turned on, and the start of execution is instructed by the light source control start unit. Then, the detected illuminance or the output voltage data A is compared with a predetermined illuminance allowable range stored in the allowable illuminance storage means in advance, and the voltage applied to the light source is controlled by the light source voltage control means according to the comparison result. It is characterized by comprising. According to a fifth aspect of the present invention, in the light source control device or the image reading device according to any one of the first to fourth aspects, a permissible light source voltage storage unit for storing a permissible light source voltage range, and a light source controlled by the light source voltage control unit A light source voltage comparing means for comparing the voltage with the light source voltage allowable range stored in the light source voltage storing means, and when the light source voltage is determined to be outside the light source voltage allowable range by the light source voltage comparing means, the effect is determined. Illuminance abnormality notifying means for notifying.

[0005]

According to the present invention, when the illuminance of the light source is out of the allowable illuminance range, the illuminance of the light source is controlled to be within the allowable illuminance range by controlling the voltage applied to the light source. Can be restored. According to the second aspect of the present invention, it is possible to realize the above-described operation by using an image reading unit. According to the third aspect of the present invention, the above-described operation can be realized during operation, and an illuminance inspection before shipment can be performed by selecting an illuminance allowable range smaller than a preset illuminance allowable range during operation. According to the fourth aspect of the invention, the functions of the first and second aspects of the invention can be automatically realized when the power is turned on. In the invention according to claim 5, when the light source voltage exceeds the allowable range in the above,
The user can know that.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 2 is a characteristic diagram showing illuminance-voltage characteristics of a xenon lamp. In the figure, the lighting device output voltage is a voltage applied to the xenon lamp, and when a lighting device input voltage as shown on the horizontal axis on the right side of the drawing is input to the lighting device, the lighting device output voltage shown on the vertical axis is Is output. For this lighting device output voltage,
The illuminance of the xenon lamp is proportional to the applied lighting device output voltage as shown on the left side of the drawing. The present invention increases the illuminance by increasing the output voltage of a lighting device when the illuminance of a used lamp is reduced, thereby compensating for the illuminance deterioration of a cold cathode tube such as a xenon lamp and extending the life. (See FIG. 5). FIG. 1 is a block diagram showing the configuration of an embodiment of an image reading apparatus using the light source control device of the present invention. In this embodiment, the light source control device will be described as one component of the image reading device. However, the light source control device of the present invention is not limited to the image reading device but can be applied to any device using a light source lamp. In order to function as an image reading device, R
What is necessary is just to incorporate a required program in the OM.

As shown in the figure, the image reading apparatus shown in this embodiment has a control unit 1 provided with a light source voltage control unit and an image reading unit, and an input supplied by a voltage control unit 11 in the control unit 1. A lighting device 2 that outputs a high voltage proportional to a voltage, a xenon lamp (light source) 3 that is turned on by the high voltage given by the lighting device 2, and a reflection from which light from the xenon lamp 3 is reflected by a reading surface A light receiving element (image sensor) 4 for receiving light and reading an image on a reading surface is provided. Further, the control unit 1
Is a voltage control unit 11, an AD converter 12 that converts an analog signal output from the light receiving element 4 into a digital signal,
The CPU 13 performs light source voltage control, image reading control, and the like according to a program stored in the OM 14, and AD when light reflected from a white reference plate (not shown) provided on the reading surface is received by the light receiving element 4. A battery-backed SRAM 15 for storing an output voltage A indicating the illuminance digitized by the converter 12, a counter 16 for counting up or down based on an instruction from the CPU 13 in accordance with the value of the output voltage A, A D / A converter 17 for converting the value of 16 into an analog signal, a latch circuit 18 for latching information indicating the inspection mode in response to an instruction from an operation unit (not shown), and the like are provided. The control unit 1 includes an illuminance comparison unit, an allowable illuminance setting unit, an allowable illuminance range selection unit, a light source control start unit, a light source voltage comparison unit, an illuminance abnormality notification unit, and the like. And a voltage controller 11, a CPU 13, and a ROM in the controller 1.
14, the counter 16, and the DA converter 17 constitute light source voltage control means, and the light receiving element 4, the AD converter 12 in the control section 1, and the CPU 13 constitute illuminance detection means. Further, predetermined keys (not shown) of the operation unit, the CPU 13, the RO
M14 constitutes an illuminance inspection start means.

FIG. 3 and FIG. 4 are diagrams showing the operation flow of the above embodiment. Hereinafter, the operation of this embodiment will be described with reference to FIGS. Prior to this operation, according to a message displayed on the display unit (not shown) by the allowable illuminance setting unit, the user inputs an illuminance allowable range during operation and an illuminance allowable range during illuminance inspection from the operation unit. Then, the allowable illuminance setting means acquires the input illuminance allowable range and sets the illuminance allowable range in the allowable illuminance storage area in the SRAM 15. Similarly, it is assumed that the light source voltage allowable range is set in the allowable light source voltage storage area in the SRAM 15. FIG.
As shown in the above, the image reading device and the light source control device shown in this embodiment start operation by three methods: a manual start in the inspection mode, an automatic start in the operation mode, and a start when the power is turned on. can do.
That is, at the time of the illuminance inspection, when a predetermined key in the operation unit constituting the illuminance inspection start unit is pressed, the CPU 13 constituting the illuminance inspection start unit recognizes the depression and starts the operation (S1). At this time, the CPU 13 latches "1" (High level) indicating that the mode is the inspection mode.
Set to 18 (S2). The case where the predetermined key is not pressed is a case where the operation mode is set as described later, and in this case, the latch circuit 18 is reset (Lo).
(W level), and the CPU 13 always automatically starts this operation at the start of image reading (S3). When the power is turned on by operating the power switch or the like, the system is reset by a general method (S4), and the light source control start means uses the battery backup to store the data in the SRAM 15 even when the power is turned off. The illuminance counter value is set in the counter 16 (S5). Note that the value of the counter 16 is lost due to the power-off, returns to the state immediately before the power-off, and the light source control starting means resets the latch circuit 18 to set the operation mode (S6).

When the operation is started by any of the above methods, subsequently, the density (illuminance) of the white reference plate provided on the reading surface is measured. Automatic adjustment (for example, shading correction) is performed by regarding the reflected light from the white reference plate as the reflected light having the maximum light amount. In this embodiment, the illuminance of the light source (xenon lamp) is adjusted. In order to adjust the illuminance of the light source, the control unit 1 sets the light receiving element (image sensor) 4 to an operating state (S7), and switches the xenon lamp 3
The xenon lamp 3 is turned on by turning on the power supply to the power supply (S8), and control is performed so that the reflected light from the white reference plate enters the light receiving element 4. Then, the light receiving element 4 reads the amount of light reflected from the white reference plate (S9), and outputs an analog voltage (voltage of an analog waveform) indicating the illuminance (density) at each position in the read white reference plate width direction. This analog voltage is amplified by an amplifier (not shown), and then converted into a digital voltage in the AD converter 12 (S10). In this conversion, shading correction is performed so that the illuminance (output digital voltage) in the width direction of the white reference plate becomes uniform (S10). Then, the CPU 13 obtains the digital output voltage subjected to the shading correction, and writes, for example, the average output voltage A in a predetermined area of the SRAM 15 (the previously written value is rewritten) (S
11).

Subsequently, the allowable illuminance range selection means obtains the value set in the latch circuit 18 and determines whether the mode is the inspection mode or the operation mode (S12). As mentioned above,
Unless the inspection mode is set by the illuminance inspection start means, the operation mode is set. In this case, (S12, No) SRA
The allowable illuminance range at the time of operation stored in the predetermined area in M15 is stored in the selected illuminance standard value setting area in the SRAM 15 (S13). The illuminance allowable range is indicated by a voltage value so that it can be compared with the output voltage A output from the AD converter. On the other hand, in the case of the inspection mode (S12, Ye
s) The illuminance allowable range in the inspection mode is stored in the selected illuminance standard value setting area (S14). The allowable illuminance range in the inspection mode is set to be narrower than the allowable illuminance range in operation. The reason is that when the xenon lamp with low illuminance decreases from time to time due to aging, increasing the light source voltage to compensate for the lack of illuminance may exceed the allowable value of the light source voltage, and as a result, the life of the lamp may be extended. This is to prevent a problem such as shortening. In general, if a voltage higher than the allowable value is applied, the lamp life will expire in a relatively short time and the xenon lamp will be replaced at the user's site.Therefore, the above-mentioned control should be performed to minimize the possibility. ing. In other words, if the allowable illuminance range is narrowed, the lamp of low illuminance will exceed the allowable value of the light source voltage in the illuminance inspection before shipment, and will be excluded as an inspection failure, eliminating the possibility of replacing the lamp at the customer. It is possible to do.

As described above, the illuminance comparing means outputs the output voltage A
(The detected illuminance) is compared with the allowable maximum value B and the allowable minimum value C stored in the selected illuminance standard value setting area (S1).
Five). In this comparison, it is determined whether or not the output voltage A is within the allowable range. If the output voltage A is out of the range (S16, No),
Further, the magnitude relationship between the two is determined, and if A> B, (S1
7, Yes) The value of the counter 16 is decreased by 1 (S18), and A>
If not B, that is, if A <C (S17, No), the value of the counter 16 is incremented by 1 (S19). Thus, for example, when the value of the counter 16 increases, the output voltage of the DA converter 17 increases, and accordingly, the output voltage of the voltage control unit 11 increases, and accordingly, the output voltage of the lighting device 2 increases. The illuminance of the lamp 3 increases. Subsequently, the light source voltage comparing means compares the increased / decreased value of the counter 16 with the light source voltage allowable range preset in the allowable light source voltage storage area in the SRAM 15 (S20). If (S20, No), the display unit displays an illuminance abnormality (S21).
Proceed to step S22. On the other hand, in step 20 above,
If the light source voltage is within the permissible range (S20, Yes), steps S9 to S11 and steps S15 to S15 are repeated. In the above description, it is unlikely that A> B during operation. However, during the illuminance inspection before shipment, A> B due to the variation of the xenon lamp 3 and the like.
B may occur, and in this case, the voltage applied to the xenon lamp 3 is reduced.

At the time of the first illuminance comparison in step 15,
Alternatively, if the output voltage A is within the allowable range during the illuminance comparison in step 15 that is repeatedly executed (S16, Ye
s) The process proceeds to step S22, where the value of the counter 16 is stored in the battery-backed SRAM 15. This process is based on counters that are not backed up when power is turned off.
This is to prevent the 16 appropriate setting data values from disappearing. Subsequently, the light receiving element 4 is turned off (S
33) The xenon lamp 3 is turned off (S34), and the latch circuit is turned off.
18 is reset (S35), and this operation flow ends.
However, in the operation mode, steps S33 to S35 are executed when the image reading is completed. As described above, the light source control device of the present invention has been described taking the case of an image reading device as an example, but the light source control device of the present invention can be applied to devices other than the image reading device. In this case, the illuminance of the light may be directly detected instead of the reflected light of the light source. Further, a configuration without the inspection mode, a configuration not including the check of the light source voltage allowable range, and a configuration in which the light source voltage control is not performed when the power is turned on are also possible.

[0013]

As described above, according to the present invention, when the illuminance of a light source such as a xenon lamp is out of the allowable illuminance range, the voltage applied to the light source is controlled by controlling the voltage applied to the light source. Since the illuminance can be within the illuminance tolerance range, the life of the light source can be prolonged, so even if a xenon lamp that has been used once is reused in another product, it is necessary to replace the lamp at the customer. There is no. According to the second aspect of the present invention, since the means for reading the image can be used as the lamp illuminance measuring means, the present invention can be implemented without increasing the cost. Furthermore, according to the third aspect of the present invention, it is possible to perform an illuminance inspection before shipment by selecting and setting an illuminance allowable range narrower than a preset illuminance allowable range at the time of operation. Light sources can be eliminated before shipment, and even if the light source voltage is increased due to aging, it is possible to avoid problems such as mixing of uncontrollable light sources into the illuminance allowable range into the product, which is effective in maintaining product reliability. .
In the invention according to claim 4, since the lamp illuminance control is automatically performed when the power is turned on, it is not necessary for the user to perform the illuminance check every time the power is turned on. Further, according to the fifth aspect of the present invention, when the light source voltage exceeds the allowable range in the above, the user can know that, so that it is possible to prevent the processing such as copying when the proper illuminance cannot be obtained. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a main part of an image reading apparatus according to an embodiment of the present invention.

FIG. 3 is an operation flowchart of a main part of an image reading apparatus according to an embodiment of the present invention.

FIG. 4 is another operation flowchart of the main part of the image reading apparatus showing one embodiment of the present invention.

FIG. 5 is a diagram for explaining a problem in a conventional light source control unit.

[Explanation of symbols]

1 control unit, 2 lighting device, 3 xenon lamp, 4
Light receiving element, 11 voltage controller, 12 AD converter, 13 CP
U, 15 SRAM, 16 counter, 17 DA converter

Claims (5)

[Claims] 1. A light source control device for controlling a light source whose illuminance changes according to an applied voltage, an illuminance detection unit for detecting an illuminance of the light source, an allowable illuminance storage unit for storing an illuminance allowable range in advance, Illuminance comparing means for comparing the detected illuminance detected by the illuminance detecting means with the illuminance allowable range stored in the allowable illuminance storage means, and when it is determined that the illuminance detected by the illuminance comparing means is outside the illuminance allowable range. And a light source voltage control means for controlling a voltage applied to the light source such that the detected illuminance falls within the illuminance allowable range. 2. An image reading apparatus which irradiates a reading surface with light from a light source and reads reflected light thereof by a light receiving element, wherein an allowable illuminance storage means for storing an illuminance allowable range in advance, and an illuminance corresponding to an applied voltage. A light source that changes, a light receiving element that receives reflected light of the light emitted from the light source from the reading surface including the white reference plate and converts the reflected light into an analog voltage, and converts the analog voltage output from the light receiving element into digital data. An A / D converter for converting the output voltage data A of the A / D converter when the reflected light reflected from the white reference plate surface enters a light receiving element; Illuminance comparing means for comparing with an allowable range, and a light source such that when the output voltage data A is determined to be outside the illuminance allowable range, the output voltage data A is within the illuminance allowable range. Applied to An image reading device comprising: a light source voltage control means for controlling a voltage applied to the image reading device. 3. The light source control device according to claim 1, or 2.
In the image reading device, an allowable illuminance setting unit that sets a plurality of allowable illuminance ranges in the allowable illuminance storage unit, an illuminance inspection start unit that starts light source control in an inspection mode,
A light source control device comprising: an illuminance allowable range selecting unit that selects an illuminance allowable range previously associated with the inspection mode during the inspection mode from a plurality of illuminance allowable ranges stored in the allowable illuminance storage unit. Image reader. 4. The light source control device or the image reading device according to claim 3, further comprising light source control start means for automatically executing light source control when the power is turned on, and when the start of execution is instructed by said light source control start means, The detected illuminance or the output voltage data A is compared with a predetermined illuminance allowable range stored in advance in the allowable illuminance storage means, and the voltage applied to the light source is controlled by the light source voltage control means according to the comparison result. A light source control device or image reading device characterized by the above-mentioned. 5. The light source control device or the image reading device according to claim 1, wherein said light source voltage storage means for storing a light source voltage allowable range, and said light source voltage controlled by said light source voltage control means. A light source voltage comparing means for comparing with the light source voltage allowable range stored in the light source voltage storing means; and an illuminance for notifying when the light source voltage is determined to be out of the light source voltage allowable range by the light source voltage comparing means. A light source control device or an image reading device, comprising: an abnormality notification unit.