JP2001292281A - Image input device, image forming device, image input method and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that the S/N is lowered and especially read accuracy in a high density part becomes low when increasing the gain by means of an analog processor while using a lamp with the reduced quantity of light. SOLUTION: This device has an illuminating light source for illuminating an object, a photoelectric converting means for reading a subject illuminated by the illuminating light source and outputting an electric signal, an operating time measuring means for measuring the operating time of the illuminating light source, and a control means for performing control so that the quantity of light from the illuminating light source for illuminating the object can become more than the case of read in an ordinary mode in the case of reading the subject in a prescribed mode by means of the photoelectric converting means when the operating time measured by the operating time measuring means reaches a prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image input device, an image forming device, an image input method, and an image forming method.

[0002]

2. Description of the Related Art In an image forming apparatus such as a digital copying machine or a color copying machine, the following method is known as a method for adjusting the image processing characteristics of the image forming apparatus. That is, the image forming apparatus is activated to form a specific test pattern on a recording sheet, which is a recording material. Then, the test pattern on the formed recording material is read by an image reading unit, and the read image information is read. This is a method for improving the stability of image quality by feeding back processing conditions of the electrophotographic process and image signal processing such as a look-up table (LUT) for performing gamma correction. In such an image forming apparatus, the original light source for illuminating the original has a sufficient initial light amount for illuminating the original, but a decrease in the amount of light generally cannot be avoided if the total lighting time is long. And when the light quantity decreases,
When the light amount does not decrease, in other words, compared with a case where a sufficient light amount is obtained, photoelectric conversion means such as a CCD (hereinafter, referred to as a CCD)
Although abbreviated as CCD, it goes without saying that an image pickup tube or an XY address type sensor may be used. In general, a method such as increasing the gain in an analog processor unit that processes the signal output from the above-described method is adopted. This is because a predetermined dynamic range is ensured by increasing the gain.

[0003]

However, when the gain is increased by an analog processor using a lamp having a reduced light amount, the S / N ratio is reduced, and the reading accuracy particularly in a high density portion is reduced. Such a decrease in the S / N ratio due to an increase in the gain may not only cause a decrease in test pattern reading accuracy at the time of calibration of the image forming apparatus, but may also cause a decrease in image quality at the time of original copy operation.

[0004]

The present invention is configured as described below to solve the above-mentioned problems. That is, the image input device according to claim 1 measures an illumination light source for illuminating a subject, photoelectric conversion means for reading the subject image illuminated by the illumination light source and outputting an electric signal, and a usage time of the illumination light source. Illuminating the subject from the illumination light source when the usage time measured by the usage time measuring unit reaches a predetermined time and the subject image is read in a predetermined mode by the photoelectric conversion unit. Control means for controlling the amount of light to be emitted to be greater than when reading in the normal mode.

[0005] The image input device according to claim 4 is
Photoelectric conversion means for reading an object image illuminated by the illumination light source and outputting it as an electrical signal; usage time measurement means for measuring the usage time of the illumination light source; and the usage time measured by the usage time measurement means reaching a predetermined time Control means for controlling the amount of charge stored in the photoelectric conversion means to be larger than when reading the subject image in the predetermined mode by the photoelectric conversion means in the predetermined mode. I do.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising:
An illumination light source for illuminating a subject, a photoelectric conversion unit that reads the subject image illuminated by the illumination light source and outputs an electric signal, a use time measurement unit that measures a use time of the illumination light source, and based on the electric signal. An image forming unit that forms and outputs an image, a correcting unit that corrects an image forming condition of the image forming unit based on a result of reading the image formed by the image forming unit by the photoelectric conversion unit, and the use unit. When the use time measured by the time measurement unit reaches a predetermined time, and the image formed by the image forming unit is read by the photoelectric conversion unit, the amount of light illuminated on the image from the illumination light source is usually And control means for controlling the number of readouts to be larger than when reading the subject image.

Further, the image forming apparatus according to claim 9 is
Photoelectric conversion means for reading an object image illuminated by an illumination light source and outputting an electric signal; usage time measurement means for measuring the usage time of the illumination light source; and image forming means for forming and outputting an image based on the electric signal Correction means for correcting the image forming conditions of the image forming means based on a result of reading the image formed by the image forming means by the photoelectric conversion means, and the use time measured by the use time measurement means When a predetermined time is reached, and when the image formed by the image forming unit is read by the photoelectric conversion unit, control is performed such that the amount of charge stored in the photoelectric conversion unit is set to be larger than when reading a normal subject image. And control means for performing the control.

According to a tenth aspect of the present invention, in the image input method, a step of measuring a use time of an illumination light source for illuminating a subject, and a step of reading the subject image illuminated by the illumination light source by a photoelectric conversion unit and outputting an electric signal. And when the usage time measured in the step of measuring the usage time reaches a predetermined time, and when the subject image is read in a predetermined mode by the photoelectric conversion unit, the amount of light for illuminating the subject from the illumination light source is determined. The method is characterized in that it has a step of controlling so as to increase the number of readings in the normal mode.

The image input method according to a thirteenth aspect of the present invention is the image input method, comprising: measuring a use time for measuring a use time of an illumination light source for illuminating a subject; and converting the subject image illuminated by the illumination light source by photoelectric conversion means. A step of outputting a read electrical signal; and the photoelectric conversion means when the use time measured by the step of measuring the use time reaches a predetermined time and the subject image is read in a predetermined mode by the photoelectric conversion means. And controlling the amount of accumulated electric charge at the time of reading in the normal mode.

Further, the image forming method according to the present invention is characterized in that:
Measuring the use time of the illumination light source for illuminating the subject, outputting the electrical signal by reading the subject image illuminated by the illumination light source by photoelectric conversion means, and forming an image based on the electrical signal. Illuminating the image from the illumination light source when the usage time measured in the step of measuring the usage time reaches a predetermined time and the image formed in the step of forming the image is read by a photoelectric conversion unit. Controlling the amount of light to be greater than when reading a normal subject image.

According to another aspect of the present invention, there is provided an image forming method comprising the steps of: measuring a use time of an illumination light source for illuminating an object; reading the image of the object illuminated by the illumination light source by a photoelectric conversion unit and outputting an electric signal; Reading the image formed by the step of forming the image based on the electrical signal, the step of forming the image based on the electric signal, and the step of measuring the used time reaching the predetermined time. And controlling the amount of charge stored in the photoelectric conversion unit to be larger than that in a case where a normal subject image is read.

An image input device according to claim 18 is an illumination light source for illuminating a subject, photoelectric conversion means for reading the subject image illuminated by the illumination light source and outputting an electric signal, and measuring the number of times of image processing. The number of image processing times measured by the image processing number measuring means, the number of image processing times measured by the image processing number measuring means reaches a predetermined number, and the object image is read from the illumination light source by the photoelectric conversion means in a predetermined mode. Is characterized in that the amount of light for illuminating is larger than when reading in the normal mode.

An image input device according to claim 21 is a photoelectric conversion device for reading an object image illuminated by an illumination light source and outputting an electric signal; an image processing frequency measuring device for measuring the number of image processing; When the number of times of image processing measured by the number of times of image processing measurement reaches a predetermined number of times, and when the subject image is read in a predetermined mode by the photoelectric conversion means, and the accumulated light amount of charges in the photoelectric conversion means is read in a normal mode Control means for controlling so as to increase the number.

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: an illumination light source for illuminating a subject; a photoelectric conversion unit for reading the subject image illuminated by the illumination light source and outputting an electric signal; Means for measuring the number of times of image processing to be performed, image forming means for forming and outputting an image based on the electric signal, and forming the image based on a result of reading the image formed by the image forming means by the photoelectric conversion means Correction means for correcting the image forming conditions of the means, and the number of times of image processing measured by the number of times of image processing measurement means reaches a predetermined number of times, and the image formed by the image forming means is read by the photoelectric conversion means Control means for controlling the amount of light for illuminating the image from the illumination light source to be greater than when reading a normal subject image; Characterized in that it has.

The image forming apparatus according to the twenty-sixth aspect is a photoelectric conversion means for reading a subject image and outputting an electric signal, an image processing number measuring means for measuring the number of image processing times, and an image processing apparatus based on the electric signal. An image forming unit that forms and outputs the image processing unit; a correcting unit that corrects an image forming condition of the image forming unit based on a result of reading the image processing formed by the image processing forming unit by the photoelectric conversion unit; When the number of times of image processing measured by the number of times of image processing reaches a predetermined number of times, and the image forming condition is corrected based on a result of reading the image formed by the image forming unit by the photoelectric conversion unit. And control means for controlling the amount of charge stored in the photoelectric conversion means to be greater than when reading a normal subject image. And wherein the door.

In the image input method according to the present invention, the step of measuring the number of times of image processing, the step of reading a subject image illuminated by an illumination light source and outputting an electric signal, and measuring the number of times of image processing When the number of times of the image processing measured in the step reaches a predetermined number, and when reading in the predetermined mode by the step of reading the subject image and outputting the electric signal, the amount of light for illuminating the subject image from the illumination light source is usually The method is characterized in that the method includes a step of performing control so as to increase the number of readings in the mode.

The image input method according to claim 30, wherein the step of measuring the number of times of image processing, the step of reading a subject image illuminated by an illumination light source by photoelectric conversion means and outputting it as an electric signal, When the number of times of image processing measured by the step of measuring reaches a predetermined number, and when the subject image is read in the predetermined mode by the photoelectric conversion unit, the charge accumulation amount in the photoelectric conversion unit is read more than in the normal mode. Control step to increase the number.

An image forming apparatus according to claim 31 is a step of measuring the number of times of image processing, a step of reading a subject image illuminated by an illumination light source by photoelectric conversion means and outputting an electric signal, Forming the image based on the number of times of image processing and measuring the number of times of image processing reach the predetermined number of times, and reading the image formed by the step of forming the image by the photoelectric conversion unit And controlling the amount of light for illuminating the image from the illumination light source so as to be larger than when reading a normal subject image.

An image forming apparatus according to a thirty-fourth aspect includes a step of measuring the number of times of image processing, a step of reading a subject image illuminated by an illumination light source by a photoelectric conversion unit and outputting an electric signal, Forming an image based on the number of times of image processing and measuring the number of times of image processing reach the predetermined number of times, and reading the image formed by the step of forming the image by photoelectric conversion means And controlling the amount of charge stored in the photoelectric conversion unit to be larger than that in a case where a normal subject image is read.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows an outline of an electrophotographic digital image forming apparatus according to a first embodiment of the present invention. Reference numeral 2 denotes a platen glass for placing a document, and 4 denotes a fluorescent lamp which functions as an illumination light source for document illumination controlled by a power supply 42 having a built-in measuring device 43 for measuring the use time of the light source. 6 is a CCD for converting the reflected light from the original into an analog electric signal, and 11a, 11b and 11c are lamps 4.
A mirror 5 for guiding the reflected light from the original reflected by the CCD to the CCD 6, and a lens 5 for forming an image of the light guided by the mirrors 11 a, 11 b, and 11 c on the CCD 6. 3 is C for obtaining shading correction data.
A standard white plate read by a CD 6, an analog processor section 7, an image processing section 8, a laser control section 9,
Denotes a laser unit that emits a laser beam corresponding to an image signal. The analog processor unit 7 performs analog signal control such as sample / hold and signal amplification on the analog electric signal output from the CCD, and further performs A / D conversion of the signal in 8 bits (256 values). Here,
Although an example in which 8-bit A / D conversion is performed has been described, the present invention is not limited to this. The image processing unit 8 will be described later. The laser control unit 9 converts the binarized image signal into a laser ON / OFF signal for each pixel via the image processing unit 8, and supplies a laser drive current to the laser unit 10. Reference numeral 12 denotes a photosensitive drum having a photosensitive layer composed of amorphous silicon, an organic compound semiconductor, or the like, and rotates clockwise in the figure.
Reference numeral 13 denotes a primary charger for uniformly charging the photosensitive drum 12. The laser beam emitted from the laser unit 10 scans the surface of the photoconductor uniformly charged by a polygon mirror and a mirror 11d (not shown) to form a latent image. Reference numeral 14 denotes a developing device that visualizes a latent image on the surface of the photoconductor with toner, 15 denotes a transfer device that transfers the toner image on the surface of the photoconductor to a sheet material such as plain paper, and 16 denotes a surface of the photoconductor surface that is not transferred. Is a cleaner that collects the toner remaining in the printer. A fixing device 17 fixes the toner on the sheet material after transfer by heating and melting the toner on the sheet material.

Next, the image processing section 8 will be described with reference to FIG. First, in order to solve the problem at the time of image reading due to the light distribution characteristics of the lamp 4 for each pixel of the CCD 6,
The input 8-bit image signal is transmitted through the standard white plate 3
The shading correction is performed based on the white reference signal read by D6, and after that, an image signal having a sharpness corresponding to a reading mode such as a character mode or a photograph mode is filtered by a filter in consideration of the characteristics of the document reading means and the printer characteristics. Is converted. Further, since the input image signal is a signal representing the amount of reflected light of the original, LOG conversion is performed with characteristics as shown in FIG. 3 to convert the input image signal into an image signal representing the output density. In response to the signal, the character mode shown in FIG.
Input / output characteristic conversion is performed so that the output image corresponds to each mode such as a photograph mode. Further, the image forming apparatus 1
FIG. 5 (a) shows the relationship between the input surface image signal to the laser control unit 9 and
Has a non-linear printer output characteristic (γ) as shown in FIG.
Therefore, printer gamma correction conversion as shown in FIG. After a series of these conversions, the 8-bit signal is binarized by an error diffusion process and sent to the laser controller 9.

Hereinafter, an image input method and an image forming method to which the present invention is applied in the image forming apparatus 1 will be described. In general, printed documents of text documents rarely exceed the maximum reflection density of 1.2, and even if they are of relatively high density such as an electrophotographic output document, if the document is mainly text, the point of interest in the copy output is The character solid and the cleanness of the base are optimal, and the characteristics such as the character mode in FIG. 4 are optimal. However, the maximum reflection density of a silver halide photograph or a design becomes about 2.0, and the point of interest in the copy output of the photograph or the design is to maintain the gradation in the entire density range of the surface image. Therefore, as for the input / output characteristics, it is desirable that the output has a gradation characteristic up to the high density portion as in the photograph mode of FIG. However, in the image forming apparatus 1, the light source for irradiating the document generally has a light amount with respect to the use time (total lighting time) when the power supply condition is constant when the initial light amount is 100% as shown in FIG. Tends to decrease. That is, when the same current is supplied to the light source as the total lighting time increases, the light amount emitted from the light source decreases. Therefore, the level of the analog signal output from the CCD 6 also decreases. In order to amplify the reduced signal, it is necessary to increase the signal amplification value, that is, the gain, in the analog processor unit 7. Here, the problem is image deterioration caused by a decrease in S / N when the gain is increased. This is particularly remarkable in a high-density region where the original has little reflection, and causes problems such as a loss of high-density gradation and a dirty high-density region. That is, it is possible to dramatically reduce the cause of image degradation by reducing the gain in the analog processor unit 7. For that purpose, the light amount may be increased by increasing the power supplied to the light source.

On the other hand, increasing the amount of light indefinitely causes the following disadvantages. That is, when the voltage supplied to the light source is increased to a value equal to or more than a predetermined amount of power per unit time (rated power), the life of the illumination light source is significantly shortened. Also, the increase in the amount of heat generated by the increase in power consumption
There is a possibility that the platen glass 2 and the standard white plate 3 may be deformed by heat, and it is better not to increase the amount of light indefinitely from the viewpoint of limiting the power of the entire image input apparatus and image forming apparatus.

Therefore, in this embodiment, the light amount of the illumination light source is increased only in the predetermined mode in which the gradation of the high density portion is required. For example, in the case of a black-and-white copying machine, the light amount is increased only in the "photograph mode", and in the case of a full-color copying machine, the light amount is increased only in the "photographic paper photo mode". The amount of light was not increased. Accordingly, image input can be performed without shortening the life of the illumination light source and without unnecessarily increasing power consumption, and image deterioration can be significantly reduced.

As described above, by increasing the amount of light of the illumination light source only in the predetermined mode, it is possible to prevent the image deterioration caused by the total lighting time of the light source for a long time, in an innovative and effective manner. it can. This is very effective especially in a high density region of an image. This will be described in detail below.

In the image forming apparatus 1, usually, 50,0
The lamp 4 emits light at a luminance of about 00LUX. In this method, for example, a rectangular AC voltage having a predetermined duty ratio is supplied to a lamp to emit light. Specifically, for example, the power supply unit 42 generates a 6 kHz rectangular AC voltage as shown in FIG.
The light amount of the lamp 4 is adjusted by changing the duty ratio according to the output of the light amount sensor 41. Needless to say, the increase in the duty ratio of the rectangular AC voltage does not disregard the safety of the fluorescent lamp.

At the time of normal reading, a light amount of about 50,000 LUX is obtained at a duty ratio of about 40%. Therefore, a predetermined gain G and offset S are set in the analog processor 7 according to the light amount. If this is expressed by an equation, the output Vout for the input signal Vin from the CCD 6 is as follows: Vout = G · Vin + S (1), and this signal Vout is A / D converted.

On the other hand, when a predetermined mode requiring a high gradation such as a photograph mode is designated, and when the total lighting time of the lamp 4 exceeds a predetermined time, for example, 500 hours as measured by the time measuring device 43, The power supply 42 supplies a rectangular AC voltage having a power per unit time and a duty ratio of about 50% so that the lamp 4 emits light at about 1.25 times the luminance of the normal state. When the total lighting time exceeds 1000 hours, a duty ratio of about 60% is supplied. When the total lighting time exceeds 1500 hours, a rectangular AC voltage having a duty ratio of about 70% is supplied. Even if this is not the case, the same effect can be obtained by measuring the number of times of image processing with the image processing times counter. That is, the number of times of image processing in the present embodiment refers to a number of times of image input, the number of times of image formation, or the number of times of image formation that can be used to estimate the use time of the power lamp. It is possible to anticipate a decrease in the light amount of the light source, thereby supplying power per unit time to increase the light amount of the lamp 4. Specifically, a gain G ′ and an offset S ′ corresponding to the light amount of the light source are set in the analog processor 7, and Vout = G ′ · Vin + S ′ (2) with respect to the signal Vin input from the CCD 6. Perform analog processing such that

The gain G 'at this time is the normal gain G
Is about 4/5, so the S / N is improved accordingly. In other words, image deterioration is remarkably improved, and the image quality at the time of copying a document having a rich gradation characteristic especially in a high density portion such as a silver halide photograph is remarkably improved. Further, by using this in a predetermined mode corresponding to a limited use such as a photograph mode, a great effect such as the life of the illumination light source and low power consumption can be obtained.

As described above, according to the present embodiment,
In a predetermined mode, such as a silver halide photography mode, which requires reading of a document with a high S / N ratio up to a high density portion, the amount of light of the document illuminating light source is increased from that in normal operation, and a low gain corresponding to the amount of light is obtained by an analog processor. Is used, the image quality at the time of copying an original having a rich gradation in a high density portion such as a silver halide photograph is improved. Further, by performing this control only in a predetermined mode corresponding to a limited use such as a photograph mode, the life of the light source is not unnecessarily shortened, and a reduction in power consumption is maintained.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In the image forming apparatus of the second embodiment, in order to improve the image quality, the sheet material (recording) is performed by the image forming apparatus at the time of maintenance by a serviceman, such as adjustment at a factory before shipping to a market, or at the time of image quality calibration by a user. The test pattern output on the paper is read by the document reading unit, and the apparatus corrects the surface image signal processing based on the read result, or corrects electrophotographic process conditions such as charging conditions, exposure conditions, and development conditions. It is configured to perform. For example, a maximum density patch test pattern output from a printer is read, and a target charging potential of the electrophotographic photosensitive member, a laser exposure intensity, and a developing bias are controlled based on the data. In such an image forming apparatus, when a light source for irradiating a document with a light amount specified by the rating as in the first embodiment is used in the document reading unit, the following inconvenience occurs. That is, when it is necessary to obtain a signal with high accuracy of the reflected light at a high density such as at the time of reading a test pattern, but irradiates with a light amount insufficient to obtain the signal, CC
The gain of the analog amplifier that amplifies the signal output from D must be increased. As a result, the signal-to-noise ratio decreases, the high-density portion of the test pattern cannot be read correctly, and the control error increases. Therefore, when reading a test pattern that requires accuracy in a high-density part, and when the total lighting time of the lamp 4 exceeds a predetermined time, for example, 500 hours, as measured by the time measuring device 43, the light amount of the lamp is increased. Control so that. Further, the same effect can be obtained with an image processing frequency counter or the like without using the time measuring device 43. That is, the number of times of image processing in the present embodiment refers to the number of times of use of the power lamp such as the number of times of image input, the number of times of image formation, and the number of times of image formation. It is possible to anticipate a decrease, whereby power per unit time is supplied to increase the amount of light of the lamp 4. Needless to say, the supply of power for increasing the light amount does not disregard safety.

Here, at the time of maintenance by a service person, the maximum density patch test pattern output is read and
A plane image forming apparatus that controls the laser exposure intensity based on the data will be described as an example. The light source for irradiating the original in the original reading unit is a fluorescent lamp.

In the image forming apparatus 1, usually 50,0
The fluorescent lamp 4 is caused to emit light at a luminance of about 00LUX. As for the light quantity of the fluorescent lamp 4, a predetermined light quantity can be obtained by returning the output of the lamp light quantity sensor 41 to the power supply unit 42. The power supply unit 42 generates a 6-kHz rectangular AC voltage as shown in FIG. 6 and supplies it to the fluorescent lamp 4. The power supply unit 42 changes the duty ratio according to the output of the sensor 41 to change the light intensity of the fluorescent lamp 4. To change. At the time of normal reading, a light amount of about 50,000 LUX is obtained at a duty ratio of about 40%. A predetermined gain G and offset S are set in the analog processor 7 according to the light amount. CCD6
, The output Vout is as follows: Vout = G · Vin + S (3), and this signal Vout is A / D converted.

During maintenance by a service person, the maximum density patch test pattern output is read, and the laser exposure intensity is controlled based on the data. At this time, the power supply device 42 controls the duty ratio so that the lamp 4 emits light with a luminance of about 75,000 LUX, which is about 1.5 times the normal state. In the case of the lamp 4 of the present embodiment, a light amount of about 75,000 LUX can be obtained at a duty ratio of about 60%.

In the analog processor 7, a gain G 'and an offset S' corresponding to the light amount are set.
Analog processing is performed on the signal Vin input from the Vin = G ′ · Vin + S ′ (4). Signal Ddar of test pattern portion of maximum density patch portion after A / D conversion
In this embodiment, control is performed according to the following equation so that the maximum density is as close to 1.6 as possible according to the value of k.

L = (1.6 / Ddark) × lo (5) where l is a laser drive current sent from the laser control unit 9 to the semiconductor laser of the laser unit 10, and lo is its initial value In this embodiment, it is 20 mA. When a duty ratio that provides a luminance of about 50,000 LUX is used, the maximum density after laser drive current control by reading a test pattern has a variation of about 1.40 to 1.75, In this embodiment, the variation can be suppressed to about 1.50 to 1.70. Also, by using this in only the reading maximum density control, the low power consumption of the image forming apparatus 1 by using the fluorescent lamp is maintained.

As described above, according to the present embodiment,
When reading the test pattern, especially when reading the test pattern for determining the maximum output density of each color, the light amount of the document illumination light source is increased from that in normal operation, and the analog processor uses a low gain according to the light amount, so that the image can be read. Image quality stability in the high density region of the forming apparatus is improved.

In the first and second embodiments, the light amount of the light source is controlled. However, the incident accumulation amount of charge in photoelectric conversion is controlled by controlling the charge accumulation time as a means equivalent to the control of the light amount. It does not matter. This is performed, for example, as follows.

In the document reading portion of the image forming apparatus shown in FIG. 1, the lamp 4 and the mirror 11a are moved at a constant speed in the direction of the arrow in the figure, that is, a scanning speed (scan speed).
Proceed with. The reflected light from the document illuminated by the lamp 4, that is, the document read image, is
The light is condensed on the CCD 6 via the lenses 1b and 11c and the lens 5. Scan speed of 300 for normal document reading
mm / sec, the scanning speed at the time of reading the silver halide photograph mode or the test patch is, for example, 200 mm / s.
ec. By doing so, the charge accumulation time of the CCD 6 is increased, and an effect equivalent to increasing the light amount of the lamp 4 is obtained. At this time, the sampling / hold timing in the analog processor is naturally changed according to the scanning speed. Further, the timing of the entire processing system may be controlled by changing the clock speed of the analog processor or the image processing device according to the scanning speed. It is of course possible that the image processing apparatus has a storage device such as a hard disk and accumulates image signals so that the printing process speed does not change even when the scanning speed changes. According to the above-described method, a decrease in print productivity can be minimized in a case where another copy is generated from one document.

In the above-described embodiment, the power supply to the lamp is performed by the rectangular wave of the voltage. However, the power may be supplied by a rectangular wave, for example, a sine wave may be used.

In the above embodiment, the laser drive current control by reading a test pattern has been described. However, a plurality of output gradation patch test patterns are read, and a printer γ correction table is created based on the data. The present invention is also effective when some correction of the image forming apparatus is performed by the document reading unit of the image forming apparatus.

In this embodiment, a fluorescent lamp has been described as an example of a light source. However, an image input device using other light sources, for example, a xenon lamp or a halogen lamp, may be used.
The present invention is also effective in an image forming apparatus. here,
When using a discharge lamp such as a xenon lamp,
Generally, the luminance is changed by modulating the lighting frequency. That is, when increasing the amount of light of a discharge lamp such as a xenon lamp, the frequency of the supplied power is increased, thereby increasing the lighting frequency, thereby increasing the number of times of excitation of the gas in the light source per unit time. Conversely, when reducing the amount of light, the frequency of power supplied to the xenon lamp is reduced, thereby lowering the lighting frequency, thereby reducing the number of excitations per unit time. In the present embodiment, the light source time measuring device 43 is used.
Is built in the power supply 42, but the time measuring device may be built independently of the power supply unit or in another unit. Further, the effect of the above embodiment can be achieved by measuring the use time with an image input device or an external device of the image forming device and controlling the power supply unit based on the measurement result.

As described above, instead of controlling the gain of the analog processor, the reference potential of the A / D converter at the time of shading data sampling may be increased by the amount corresponding to the increase in the lamp light amount.

Further, the present invention is applicable not only to the image forming apparatus such as the copying machine described in the above embodiment, but also to an image input apparatus such as a film scanner, a document scanner, and a facsimile which generally inputs a subject image by photoelectric conversion. Needless to say, this can also be carried out.

[0046]

As described above, according to one feature of the present invention, when it is required to read a document having a high S / N ratio up to a high density portion using a lamp having a reduced light amount, the light amount is temporarily reduced. Thus, the original can be read with a good S / N ratio up to the high density portion.

According to another characteristic, when an image signal having a good S / N ratio is required up to a high density portion by a lamp with a reduced light amount, the amount of accumulated charge is temporarily increased to increase the high density. It is possible to read a document having a good S / N ratio up to the copy unit.

Further, according to the present invention, it is possible to provide a high-quality image even in an image forming apparatus using a lamp having a reduced light amount.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an electrophotographic digital image forming apparatus according to an embodiment.

FIG. 2 is a diagram illustrating an operation in an image processing unit.

FIG. 3 is a diagram illustrating LOG conversion in the present embodiment.

FIG. 4 is a diagram illustrating characteristics of an output image corresponding to each mode.

FIG. 5 is a diagram showing characteristics of reproducing the density of a document image.

FIG. 6 is a diagram illustrating characteristics of a duty ratio supplied to a power supply.

FIG. 7 is a diagram showing a light amount with respect to a total lighting time of a xenon lamp.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H027 DA45 DB01 EA01 EA02 EA04 EA15 EC10 FD00 2H109 AA02 AA23 AB02 AB03 5B047 AA01 BB02 BC11 BC14 CA19 CB04 5C072 AA01 CA02 CA12 CA15 CA18 9A001 HH23 HZ34 KK16

Claims (34)

[Claims] An illumination light source for illuminating a subject, photoelectric conversion means for reading the image of the subject illuminated by the illumination light source and outputting an electric signal, use time measurement means for measuring a use time of the illumination light source, When the usage time measured by the usage time measuring means reaches a predetermined time, and the subject image is read in the predetermined mode by the photoelectric conversion means, and the light amount illuminating the subject from the illumination light source is read in the normal mode. Control means for performing control to increase the number of images. 2. The illumination light source when the use time measured by the use time measurement means reaches the predetermined time and the subject image is read in the predetermined mode by the photoelectric conversion means. 2. The image input device according to claim 1, wherein when the power amount supplied to the illumination light source is read in the normal mode, the power amount is controlled to be larger than the power amount supplied to the illumination light source. 3. The control means, wherein the use time measured by the use time measurement means reaches the predetermined time,
And controlling the lighting frequency of the illumination light source when reading the subject image in the predetermined mode by the photoelectric conversion means to be higher than the lighting frequency of the illumination light source when reading in the normal mode. The image input device according to claim 1. 4. A photoelectric conversion means for reading a subject image illuminated by an illumination light source and outputting an electric signal, a use time measurement means for measuring a use time of the illumination light source, and the use time measured by the use time measurement means. Reaches a predetermined time, and when the subject image is read in the predetermined mode by the photoelectric conversion means, control means for controlling the amount of charge stored in the photoelectric conversion means to be greater than when reading in the normal mode, An image input device comprising: 5. The apparatus according to claim 1, wherein the control unit sets the normal mode after the subject image is read by the photoelectric conversion unit in the predetermined mode. Image input device. 6. An illumination light source for illuminating a subject, photoelectric conversion means for reading the image of the subject illuminated by the illumination light source and outputting an electric signal, use time measurement means for measuring a use time of the illumination light source, Image forming means for forming and outputting an image based on an electric signal, and correction for correcting image forming conditions of the image forming means based on a result of reading the image formed by the image forming means by the photoelectric conversion means Means for illuminating the image from the illumination light source when the use time measured by the use time measurement means reaches a predetermined time and the image formed by the image forming means is read by the photoelectric conversion means. An image forming apparatus comprising: a control unit configured to control a light amount to be larger than a case where a normal subject image is read. 7. The control unit controls the amount of power supplied to the illumination light source when reading the image to be greater than a predetermined amount of power supplied to the illumination light source when reading the normal subject image. The image forming apparatus according to claim 6, wherein: 8. The control means controls the lighting frequency of the illumination light source when reading the image to be higher than the lighting frequency of the illumination light source when reading the normal subject image. The image forming apparatus according to claim 6. 9. A photoelectric conversion unit for reading an object image illuminated by an illumination light source and outputting an electric signal; a use time measurement unit for measuring a use time of the illumination light source; and forming an image based on the electric signal. An image forming means for outputting;
Correction means for correcting the image forming conditions of the image forming means based on a result of reading the image formed by the image forming means by the photoelectric conversion means, and a predetermined time for the use time measured by the use time measurement means And when the image formed by the image forming unit is read by the photoelectric conversion unit, the amount of charge stored in the photoelectric conversion unit is controlled to be larger than when reading a normal subject image. And an image forming apparatus. 10. A step of measuring a use time of an illumination light source for illuminating a subject, a step of reading the subject image illuminated by the illumination light source by a photoelectric conversion unit and outputting an electric signal, and a step of measuring the use time. When the use time measured by the has reached a predetermined time, and the subject image is read in a predetermined mode by the photoelectric conversion means,
Controlling the amount of light illuminating the subject from the illumination light source to be greater than when reading in the normal mode. 11. The method according to claim 11, wherein the step of controlling includes: when the use time measured in the use time measurement step reaches a predetermined time and the subject image is read in the predetermined mode by the photoelectric conversion unit. 11. The image input method according to claim 10, wherein the power supply to the light source is controlled so as to be larger than the power supply to the illumination light source when reading in the normal mode. 12. The method according to claim 11, wherein the controlling step includes the step of: determining that the usage time measured by the step of measuring the usage time reaches the predetermined time, and reading the subject image in the predetermined mode by the photoelectric conversion unit. The image input method according to claim 10, wherein the lighting frequency of the illumination light source is controlled to be higher than the lighting frequency of the illumination light source when reading in the normal mode. 13. A step of measuring a use time of an illumination light source for illuminating a subject, a step of reading the subject image illuminated by the illumination light source by a photoelectric conversion unit, and outputting an electric signal, and a step of measuring the use time. When the use time measured by the method reaches a predetermined time, and the subject image is read in the predetermined mode by the photoelectric conversion means, the amount of charge accumulation in the photoelectric conversion means is set to be larger than that in the case of reading in the normal mode. And an image input method. 14. A step of measuring a use time of an illumination light source for illuminating a subject, a step of reading the subject image illuminated by the illumination light source by a photoelectric conversion unit and outputting an electric signal, and an image based on the electric signal. Forming the image, and when the use time measured in the use time measurement step reaches a predetermined time and the image formed in the image forming step is read by the photoelectric conversion unit, the illumination light source And controlling the amount of light for illuminating the image to be greater than when reading a normal subject image. 15. The controlling step sets the amount of power supplied to the illumination light source when reading the image is greater than the amount of power supplied to the illumination light source when reading the normal subject image using the illumination light source. 15. The image forming method according to claim 14, wherein the control is performed as follows. 16. The controlling step controls the lighting frequency of the illumination light source when reading the image to be higher than the lighting frequency of the illumination light source when reading the normal subject image. The image forming apparatus according to claim 14, wherein 17. A step of measuring a use time of an illumination light source for illuminating a subject, a step of reading the subject image illuminated by the illumination light source by a photoelectric conversion unit and outputting an electric signal, and an image based on the electric signal. Forming the image, and when the use time measured by the use time measuring step reaches a predetermined time, and the image formed by the image forming step is read, the charge accumulation in the photoelectric conversion unit. Controlling the amount to be greater than when reading a normal subject image. 18. An illumination light source for illuminating a subject, a photoelectric conversion unit for reading the subject image illuminated by the illumination light source and outputting an electric signal, an image processing number measurement unit for measuring the number of image processing, and the image processing When the number of times of image processing measured by the number-of-times measuring means reaches a predetermined number, and when the subject image is read in the predetermined mode by the photoelectric conversion means, the amount of light illuminating the subject from the illumination light source is read in the normal mode. Control means for performing control to increase the number of images. 19. The illumination light source when the number of times of image processing measured by the number of times of image processing reaches a predetermined number of times and the subject image is read in the predetermined mode by the photoelectric conversion means. 19. The image input apparatus according to claim 18, wherein the supplied electric energy is controlled so as to be larger than the electric energy supplied to the illumination light source when reading in the normal mode. 20. The illumination light source when the number of times of image processing measured by the number of times of image processing reaches the predetermined number of times and the subject image is read in the predetermined mode by the photoelectric conversion means. 19. The image input apparatus according to claim 18, wherein control is performed such that the lighting frequency of the illumination light source is higher than the lighting frequency of the illumination light source when reading in the normal mode. 21. A photoelectric conversion unit for reading an image of a subject illuminated by an illumination light source and outputting an electric signal; an image processing frequency measuring unit for measuring the number of image processing; and the image processing frequency measured by the image processing frequency measuring unit. A predetermined number of times, and when the subject image is read in the predetermined mode by the photoelectric conversion means, control means for controlling the accumulated light quantity of the electric charge in the photoelectric conversion means to be larger than when reading in the normal mode, An image input device comprising: 22. The apparatus according to claim 14, wherein said control means switches to said normal mode after reading said subject image by said photoelectric conversion means in said predetermined mode.
2. The image input device according to claim 1. 23. An illumination light source for illuminating a subject, photoelectric conversion means for reading the subject image illuminated by the illumination light source and outputting an electric signal, image processing frequency measurement means for measuring the number of image processing times, and the electric signal Image forming means for forming and outputting an image based on the image forming means, and correcting means for correcting image forming conditions of the image forming means based on a result of reading the image formed by the image forming means by the photoelectric conversion means. Illuminating the image from the illumination light source when the number of times of image processing measured by the number of times of image processing reaches a predetermined number of times and the image formed by the image forming unit is read by the photoelectric conversion unit; Control means for controlling the amount of light to be greater than when reading a normal subject image. Place. 24. The apparatus according to claim 18, wherein the control unit controls the amount of power supplied to the illumination light source when reading the image to be greater than a predetermined amount of power determined for the illumination light source. Image forming device. 25. The control unit controls the lighting frequency of the illumination light source when reading the image to be higher than the lighting frequency of the illumination light source when reading the normal subject image. The image forming apparatus according to claim 23, wherein: 26. A photoelectric conversion means for reading a subject image and outputting an electric signal, an image processing number measuring means for measuring the number of image processing, an image forming means for forming and outputting an image based on the electric signal, Correction means for correcting the image forming conditions of the image forming means based on the result of reading the image formed by the image forming means by the photoelectric conversion means, and the number of times of image processing measured by the number of times of image processing measurement means When the predetermined number of times has been reached, and the image forming condition is corrected based on the result of reading the image formed by the image forming unit with the photoelectric conversion unit, the amount of charge stored in the photoelectric conversion unit is reduced to a normal value. An image forming apparatus comprising: a control unit configured to perform control so as to increase the number of read images more than when a subject image is read. 27. A step of measuring the number of image processing, a step of reading an object image illuminated by an illumination light source by a photoelectric conversion unit and outputting an electric signal, and a step of measuring the number of image processing. Controlling to make the amount of light for illuminating the subject image from the illumination light source larger than when reading in the normal mode when the subject image is read in the predetermined mode by the photoelectric conversion means when the number of times reaches a predetermined number of times. An image input method comprising: 28. The controlling step, wherein the number of times of image processing measured in the step of measuring the number of times of image processing reaches the predetermined number of times and the subject image is read in the predetermined mode by the photoelectric conversion means. 28. The image input method according to claim 27, further comprising controlling the amount of power supplied to the illumination light source to be larger than a predetermined amount of power supplied to the illumination light source when reading in the normal mode. 29. The controlling step, wherein the number of times of image processing measured in the step of measuring the number of times of image processing reaches the predetermined number of times and the subject image is read in the predetermined mode by the photoelectric conversion means. 28. The image input device according to claim 27, wherein the lighting frequency of the illumination light source is controlled to be higher than the lighting frequency of the illumination light source when reading in the normal mode. 30. A step of measuring the number of times of image processing, a step of reading a subject image illuminated by an illumination light source by a photoelectric conversion unit and outputting an electric signal, and a step of measuring the number of times of image processing Has reached a predetermined number of times, and controlling when the subject image is read in the predetermined mode by the photoelectric conversion means, so that the amount of charge stored in the photoelectric conversion means is larger than when reading in the normal mode. An image input method characterized in that: 31. A step of measuring the number of times of image processing, a step of reading an object image illuminated by an illumination light source by a photoelectric conversion unit and outputting an electric signal, a step of forming an image based on the electric signal, Illuminating the image from the illumination light source when the number of image processings measured in the step of measuring the number of processings reaches a predetermined number of times and the image formed in the step of forming the image is read by the photoelectric conversion unit; Controlling the amount of light to be emitted so as to be greater than when reading a normal subject image. 32. The controlling step, wherein the amount of power supplied to the illumination light source when reading the image is made larger than the amount of power supplied to the illumination light source when reading the normal subject image. The image forming method according to claim 31, wherein the control is performed. 33. The controlling step controls the lighting frequency of the illumination light source when reading the image to be higher than the lighting frequency of the illumination light source when reading the normal subject image. The image forming method according to claim 31, wherein 34. A step of measuring the number of times of image processing, a step of reading an object image illuminated by an illumination light source by photoelectric conversion means and outputting an electric signal, a step of forming an image based on the electric signal, When the number of times of image processing measured by the step of measuring the number of times of processing reaches a predetermined number of times, and when the image formed by the step of forming the image is read by the photoelectric conversion means, the charge of the photoelectric conversion means Controlling the accumulated amount to be larger than when reading a normal subject image.