JPH0815930A - Device and method for controlling density - Google Patents

Abstract

PURPOSE:To provide a device capable of accurately performing density control processing without making a measuring error at the time of forming a toner image to be measured. CONSTITUTION:The case that a reflected light quantity detection part 52 is connected to sensor output(output to a CPU 60) and also a light source light quantity detection part 57 is connected to a comparison amplification part 55 and the case that the detection part 52 is connected to the amplification part 55 and also the detection part 517 is connected to the sensor output(output to the CPU 60) are switched to connect them. In the case the sensor output is connected to the detection part 52 by a monitor switching means 58, a changeover switch 69 is connected to the detection part 52 and the gain adjustment of a reflected light quantity detecting gain amplifier is performed. In the case the sensor output is connected to the detection part 57 by the switching means 58, the switch 69 is connected to the detection part 57 and the gain adjustment of a light source light quantity detection gain amplifier is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a density control method and apparatus applicable to an image forming apparatus using an electrophotographic process, for example, a density control method and apparatus capable of measuring the density of a developer image and controlling the image density. It is a thing.

[0002]

2. Description of the Related Art Generally, there is a color image forming apparatus as an apparatus requiring image density control. In this type of color image forming apparatus, a process of transferring a recording image formed by charging, exposing and developing on a photosensitive drum onto a recording paper is repeated a plurality of times to form a superimposed image of a plurality of colors on the recording paper, and a color image is formed. There is a way to get an image.

Such a general color image forming apparatus will be described below with reference to the drawings. FIG. 21 is a sectional view of a general color image forming apparatus. As shown in FIG.
The entire apparatus is provided with a photosensitive drum 1 and a roller charger 3, and a toner and a toner storage portion arranged on the right side of the photosensitive drum 1 and a developing means for developing are integrally formed into a cartridge. Cartridges 4a, 4b, 4c,
4d is carried by a rotatable support member, and each developing cartridge 4a, 4b, 4 is mounted on the same cylinder centered on the support member rotation shaft 9.
c and 4d are set.

Developing cartridges 4a, 4b, 4c, 4d
Inside, yellow toner, magenta toner, cyan toner, and black toner are stored, respectively. Also,
A transfer roller 10 having a function of holding a transfer sheet (not shown) and transferring an image on the photosensitive drum 1 onto the transfer sheet (not shown) is arranged on the left side of the photosensitive drum. With the above configuration, the photosensitive drum 1 is driven in the direction of the arrow in the figure by a driving unit (not shown) at a peripheral speed of 100 mm / sec.

On the other hand, a laser diode 11, which constitutes an exposure device, a polygon mirror 13 which is driven to rotate at a high speed by a high speed motor 12, a lens 14, and a folding mirror 15 are arranged above the inside of the main body of the device. The charging roller 3
Is -700V DC voltage and AC frequency 700Hz V
An alternating voltage of pp (peak to peak) -1500V is superposed and uniformly charged to -700V.

When a signal according to magenta image information is input to the laser diode 11 described above, the laser diode 11 emits light with a corresponding light intensity. The emitted laser light is applied to the photosensitive drum 1 through the optical path 16. The position of the photosensitive drum 1 irradiated with the laser beam is about −100V. In this way, a magenta electrostatic latent image is formed on the photosensitive drum 1. Then, the photosensitive drum 1 advances in the direction of the arrow and is visualized by the developing cartridge 4a.

Subsequently, the visible image is transferred to the transfer drum 10. To describe this transfer process in detail, the transfer paper cassette 17 is synchronized with the image on the photosensitive drum 1.
The transfer paper is fed from inside by a pickup roller 18, the transfer paper is held by a gripper 22, and the toner image on the photosensitive drum 1 is transferred onto the transfer paper by a voltage between the photosensitive drum 1 and the transfer roller 10 by a high voltage power source (not shown). By the transfer, the magenta image is transferred to the transfer paper.

When the photosensitive drum 1 further advances in the direction of the arrow, it is visualized by the developing cartridges 4a, 4b, 4c and 4d. To describe the transfer process in detail, the transfer sheet is fed from the transfer sheet cassette 17 by the pickup roller 18 in synchronization with the image on the photosensitive drum 1, and the transfer sheet is held by the gripper 22, and the toner image on the photosensitive drum 1 is held. Is a photosensitive drum 1 and a transfer roller 10 by a high voltage power source (not shown).
It is transferred onto the transfer paper by the voltage between them.

By performing the same process for cyan, yellow and black in the above process, it is possible to form toner images of a plurality of colors on the transfer paper. The transfer paper on which the color image is formed is peeled off from the transfer roller 10 by the separation charging device 2 and the separation claw 24, and is fused and fixed by the known heating and pressure fixing device 25 to obtain a color image. Further, the toner remaining on the transfer paper on the photosensitive drum 1 without being transferred is cleaned by a cleaning device 26 such as a fur brush 28 or a blade means.

The density control in such a general color image forming apparatus will be described with reference to FIG. In FIG. 22, a density sensor 50 irradiates a patch formed on the transfer drum 10 with light, measures the reflected light and the light from the light source, and outputs the amount of reflected light when the reflectance of the measurement patch is large. When the reflectance is small, the light source light amount is output. Then, a CPU (not shown) predicts the output value of the density sensor in advance, fetches data in accordance with the predicted value, controls the density calculation, and controls the developing bias.

[0011]

However, in the above-mentioned conventional example, the detection signal of the density sensor has variations due to the characteristics of the light emitting element and the like. Therefore, when measuring patches, the CPU
However, there was a problem that the measurement range was exceeded when the data was imported to and a measurement error occurred.

Alternatively, the sensor output may be minimized depending on the toner reflectance.
Therefore, A at the time of loading the data into the CPU
The conversion error during D / D conversion became large, and accurate detection data could not be sent. Then, when converting the concentration, the CPU cannot use logarithmic processing in calculation, and therefore an approximate expression must be used.

[0013]

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following structure as one means for achieving the above-mentioned object. That is, it is applicable to an image forming apparatus using an electrophotographic process,
A density control device for measuring and controlling the density of a toner image formed on an image carrier of the image forming apparatus, the light irradiating means for irradiating the toner image formed on the image carrier of the image forming apparatus with light. A detecting means for detecting the reflected light from the toner image formed on the image carrier and the light source light of the light irradiation means, and the light intensity of the reflected light and the light source light detected by the detecting means And a light emission intensity setting unit for setting the light emission intensity of the light irradiation unit.

Alternatively, a light emitting source for irradiating the toner image formed on the image carrier with light, and a reflected light from the toner image formed on the image carrier and a light emitted from the light source are received. Two light receiving elements for converting into electric signals corresponding to the received light intensity, reflected light voltage setting means for presetting a detection signal voltage value from the light receiving element of the reflected light, and a signal from the light receiving element of the reflected light. Adjusting means for adjusting the light emission intensity of the light emitting light source so that the value is the value set by the reflected light voltage setting means.

Alternatively, a light emitting source for irradiating the toner image formed on the image carrier with light, an adjusting means for adjusting the emission intensity of the light source, and a toner image formed on the image carrier are used. Two light receiving elements for receiving the reflected light and the light source light of the light emitting source and converting it into an electric signal corresponding to the received light intensity, detection signal voltage setting means for presetting the detection signal voltage value of the light receiving element, and the reflection An output switching means for selecting either the output signal from the light receiving element of the light or the output signal of the light receiving element of the light source to output as the density measurement result; and the light receiving element selected by the output switching means. Output control means for adjusting the signal level from the light receiving element so that the output has the voltage value set by the voltage value setting means, and the adjusting means is selected by the output switching means. And drives the light emission source signals from the light receiving elements that are not in a predetermined level amplification.

Furthermore, the present invention can be applied to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming conditions based on the measurement result. A concentration control device for
Light irradiating means for irradiating the toner image formed on the image carrier of the image forming apparatus with light, reflected light from the measured toner image formed on the image carrier, and light source light of the light irradiating means. Detecting means for detecting the light intensity of the toner image to be measured from the reflected light and the light intensity of the light source light detected by the detecting means, and set the emission intensity of the light irradiation means by the reflectance And reflectance image control means for controlling the formation conditions.

Alternatively, it can be applied to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming conditions based on the measurement result. A density control device for irradiating a toner image formed on an image carrier of the image forming apparatus with light, and light reflected from a measured toner image formed on the image carrier, Detecting means for detecting the light source light of the light irradiating means, reflected light voltage setting means for presetting a reference detection voltage value of the reflected light in the detecting means, reflected light detection output signal detected by the detecting means, and And a comparison image control means for controlling the image forming conditions by comparing the set voltage value of the reflected light voltage setting means and setting the light emission intensity of the light irradiation means based on the comparison result.

Furthermore, the present invention can be applied to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming conditions based on the measurement result. A concentration control device for
Light irradiation means for irradiating the toner image formed on the image carrier of the image forming apparatus with light, and reflected light detection means for detecting reflected light from the measured toner image formed on the image carrier. A light source light detection means for detecting the light source light of the light irradiation means, a reflected light voltage setting means for presetting a reference detection voltage value of the reflected light in the reflected light detection means, and the light in the light source light detection means Irradiation light voltage setting means for presetting a reference detection voltage value of irradiation light from the irradiation means, output switching means for outputting one of the reflected light detection means and the light source light detection means as a density sensor output, The output switching means is provided with comparison and amplification means for comparing and amplifying the output of the non-output detection means with the set value of the corresponding voltage value setting means, and the output switching means Wherein the switching the output of the example section.

For example, for black (Bk) toner, the output from the light receiving element of the light emitting source is output as a density measurement signal, and for color (Y, M, C) toner, the output from the light receiving element of the reflected light is density. It is characterized in that it is output as a measurement signal.

[0020]

With the above-described structure, the variation control is performed before the toner image to be measured is formed, and the density control processing can be performed with high accuracy without causing a measurement error when the toner image to be measured is formed. Therefore, with respect to the density detection of the image forming apparatus, it is possible to prevent variations in the density sensor output due to the characteristics of the light emitting element, and also to output the density sensor output to the reference value in advance even when the density sensor output is reduced due to dirt on the image carrier. By adjusting the levels, stable concentration control can always be performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings. [First Embodiment] FIG. 1 is a diagram showing the structure of a first embodiment of the present invention. In FIG. 1, reference numeral 50 denotes a density sensor unit that irradiates a toner image (hereinafter referred to as “patch”) formed on the transfer drum 10 with light and sends an output signal to the CPU 60.
Reference numeral 0 denotes a CPU that receives a signal from the density sensor unit 50 and performs arithmetic processing to determine and control the developing bias.

In the density sensor unit 50, 51 is a light emitting light source which is a light source of the density sensor, in this embodiment an infrared semiconductor laser (infrared LED), and 52 is a built-in light receiving element for detecting the amount of light reflected from the patch. The detected GA is converted into an electric signal corresponding to the detected light quantity, and then the GA of the CPU 60, which will be described later, is made by a built-in light quantity detection gain amplifier (not shown).
The reflected light amount detection unit amplifies and outputs a signal level set by a value set by the IN setting unit 64.

Reference numeral 53 denotes a light emitting source 5 by a built-in light receiving element.
The light source 51 is a light source light amount detection unit that detects the amount of emitted light from No. 1 and converts it into an electrical signal corresponding to the detected amount of light, and then amplifies and outputs it to a predetermined signal level by a built-in light amount detection gain amplifier (not shown). I am monitoring the light from. Reference numeral 54 denotes D / which converts a digital signal from the CPU 60 into a corresponding analog signal and outputs the analog signal to the comparison / amplification unit 55.
An A converter, 55 compares the value set by the D / A converter 54 with the signal from the light source light amount detection unit 53, and D
A comparison / amplification unit that controls the light emitting light source 51 until it becomes equal to the set value of / A.

In the CPU 60, reference numeral 61 is an A / D capturing section for converting an analog output signal from the density sensor section 50 into a corresponding digital signal, and 62 is an appropriate set value according to the patch to be measured. D / A converter 5
4 is a REF setting unit, and 63 is a digital value from the A / D loading unit 61 that is loaded from the density sensor unit 50 by measuring the reference ground during operation in the variation adjustment mode described later, and the REF setting unit 62. It is a comparison unit that compares the predicted voltage value of the reference background with the given set value.

Reference numeral 64 is a GAIN setting section, which is a comparison section 63.
When the variation is detected with respect to the predicted voltage value of the reference background as a result of the comparison in, the light amount detection gain amplifier of the reflected light amount detection unit 52 is adjusted to hold down to the predicted voltage value. A density conversion unit 65 calculates the density from the output signal value from the density sensor unit 50. A developing bias controller 66 controls a developing device (not shown) with respect to the developing bias determined as a result of the density control by the density converter 65.

The density control apparatus of the present embodiment having the above-mentioned configuration can be applied to the image forming apparatus as shown in FIG. 21, for example. Then, for example, the density sensor unit 50 for measuring the patch of the transfer drum 10 shown in FIG. 21 may be arranged as shown in FIG. Next, the variation adjustment mode control before entering the patch measurement mode for performing the density control in the present embodiment having the above configuration will be described with reference to the flowchart of FIG.

In this embodiment, the variation adjustment mode is started before entering the patch measurement mode in which actual density control is performed. When the variation adjustment mode starts, C
The process of PU 60 proceeds to the process of FIG. At this time, CP
U60 previously holds the detected light level of the reference background as a predicted value, and the CPU 60 calculates the REF value at which the optimum output amplitude is obtained according to the held predicted value of the detected light level of the reference background in step S1. It is set in the REF setting unit 62.

Next, in step S2, the reference background is measured, and the output signal from the reflected light amount detecting section 52 from the density sensor section 50 is received. Then, in the subsequent step S3, the comparison unit 63 compares the REF setting value set in the previous step S1,
It is determined whether it is within the predicted range of the CPU. If the detection signal does not fall within the prediction range, a detection error will occur in the patch measurement mode, so it is necessary to adjust the light amount detection gain amplifier incorporated in the reflected light amount detection unit 52. Therefore, if the detection signal is not within the prediction range, the process proceeds from step S3 to step S4, and the GAI
The setting value for the N setting unit 64 is changed, and the amplification factor of the light amount gain amplifier of the reflected light amount detection unit 52 is controlled so that the detection signal as a result of comparison by the comparison unit 63 falls within the predicted range. Then, returning to step S3, the adjustment of the light amount detection gain amplifier is continued until the measured value of the reference background falls within the prediction range. Then, the patch measurement mode is started when the measured value falls within the predicted range.

FIG. 3 shows a detailed configuration of the light amount detection gain amplifier of the reflected light amount detecting section 52 shown in FIG. In FIG.
70 is a light receiving element that receives the reflected light from the transfer drum 10, 71 is a light amount detection gain amplifier that amplifies the electrical signal from the light receiving element 70, and 72 is a gain adjustment signal sent as a digital signal from the GAIN setting section 64 of the CPU 60. This is a D / A converter for converting into a corresponding analog signal, and the gain adjustment corresponding to the set value for the D / A converter 72 is performed, and the output signal is held within the predicted range (measured value). Then, this output signal is taken in by the CPU 60.

Further, instead of the adjustment by the CPU 60 as described above, it is also possible to manually adjust by adjusting the volume of the reflected light amount detecting section 56. As described above, according to the present embodiment, with respect to the density detection of the color image forming apparatus, the CPU 60 directly adjusts the gain of the light amount detection gain amplifier 71 to output the density sensor according to the characteristics of the light emitting element of the light emitting light source 51. Can be corrected in advance. Also, even when the density sensor output is lowered due to dirt on the photosensitive drum of the image forming apparatus,
By adjusting the output level to the reference value in advance, stable density control can always be performed.

[Second Embodiment] In the above-described embodiment, G is calculated based on the comparison result of the comparison circuit 63 shown in FIG.
The output signal level from the density sensor unit 50 is adjusted by the gain setting in the AIN setting unit 64. However, the present invention is not limited to the above example, and the density sensor unit 50
By changing the gain of the light amount detection gain amplifier 71 of the reflected light amount detection unit 52, the light emitting light source 51 can be replaced with a configuration in which the variation of the density sensor output due to the characteristics of the light emitting element is prevented.
Even if the amount of light emitted from the light emitting element is controlled, the same output signal can be adjusted. The second aspect of the present invention configured as described above
The configuration of the embodiment is shown in FIG.

In FIG. 4, the same components as those in FIG. 1 described above are designated by the same reference numerals and detailed description thereof will be omitted. In FIG. 4, the configurations of the reflected light amount detection unit 56 of the density sensor unit 50, the REF setting unit 67, and the REF adjustment unit 68 of the CPU 60 are different. The reflected light amount detection unit 56 of the density sensor unit 50 of the second embodiment is different from the configuration of FIG.
There is no special GAIN adjustment from U60, and the detection signal from the light receiving element is amplified and output with a preset gain.

In the second embodiment, instead of adjusting the output signal level from the density sensor section 50 by setting the gain in the GAIN setting section 64 based on the comparison result of the comparison circuit 63, the comparison circuit is changed. Based on the 63 comparison results,
The setting value for the REF adjusting unit 68 is changed, and the REF setting unit 6 is changed.
The output signal is suppressed within a predetermined range by supplying the set value from 7 to the D / A converter 54 to control the amplification degree of the comparison amplification unit 55 and the emission intensity of the emission light source.

As described above, according to the second embodiment,
The same effect as that of the first embodiment can be achieved, and the configuration of the reflected light amount detection unit 56 of the density sensor unit 50 can be simplified. As described above, according to the second embodiment, it is possible to hold the measured value within the predicted range by adjusting the REF instead of adjusting the gain amplifier and adjusting the amount of emitted light. In this way, the same effect as that of the first embodiment can be achieved, and the configuration of the reflected light amount detection unit 56 of the density sensor unit 50 can be simplified.

[Third Embodiment] In the above description, an example in which the output signals from the reflected light amount detecting units 52 and 56 are fetched by the CPU 60 has been described. However, the present invention is not limited to the above example, and the effects of application can be obtained even if the detection signal from the light source light amount detection unit is incorporated.
A third embodiment of the present invention configured to take in a detection signal from the light source light amount detection unit will be described below.

FIG. 5 is a diagram showing the configuration of the third embodiment according to the present invention. 5, the same components as those in FIGS. 1 and 4 described above are denoted by the same reference numerals and detailed description thereof will be omitted. In the third embodiment, G in the CPU 60 of the first embodiment described above
Instead of setting the set value in the AIN setting unit 64 in the reflected light amount detection unit 56, the set value is set in the light source light amount detection unit 57, and the light source light amount detection unit 57 is configured as shown in FIG. Then, the output signal from the light source light amount detection unit 57 is taken into the CPU 60.

In FIG. 5, the comparison amplification unit 55 compares the value set by the D / A converter 54 with the signal from the reflected light amount detection unit 52, and the detected signal from the reflected light amount detection unit 56 and the D / A converter. The emission light source 51 is controlled until the set value of 54 becomes the same, and the emission light amount at this time is detected by the light source light amount detection unit 53, and this is used as an output signal. In the third embodiment, by providing the above configuration, in the variation adjustment mode described above, the output signal from the light source light amount detection unit 53 is compared with the prediction range set by REF, and the output signal falls within the prediction range. If not, it is possible to suppress variations by adjusting the gain of the light source light amount detection gain amplifier by the gain setting unit 64. Therefore, in the actual image forming process, the variations in the image forming process can be corrected and eliminated in advance, as in the first and second embodiments described above.

[Fourth Embodiment] In the third embodiment described above, the output signal level from the density sensor unit 50 is set by the gain setting in the GAIN setting unit 64 based on the comparison result of the comparison circuit 63 shown in FIG. Was being adjusted. However, the present invention is not limited to the above example, and by adjusting the gain of the light amount detection gain amplifier of the light source light amount detection unit 57 of the density sensor unit 50, the light emission intensity and the density sensor output depending on the characteristics of the light emitting element and the like. The output signal can be adjusted in the same manner by controlling the amount of light emitted from the light emitting element of the light emitting source 51 instead of the configuration for preventing the variation. FIG. 6 shows the configuration of the fourth embodiment according to the present invention thus configured.

In FIG. 6, FIG. 5 of the third embodiment described above.
The same numbers are given to the same configurations as those of the above, and the detailed description is omitted. In FIG. 6, since the configuration of the light source light amount detection unit of the density sensor unit 50 does not require the adjustment of the output signal by the CPU 60, there is no special GAIN adjustment from the CPU 60, and the gain is set by the light receiving element with a preset gain. Is amplified and output. Therefore,
The same configuration as the light source light amount detection unit 53 of the first embodiment shown in FIG. 1 described above is sufficient. Also, the REF setting unit 6 of the CPU 60
7. The configuration of the REF adjusting unit 68 is different.

In the fourth embodiment, instead of adjusting the output signal level from the density sensor section 50 by setting the gain in the GAIN setting section 64 based on the comparison result of the comparison circuit 63, the comparison circuit is changed. Based on the 63 comparison results,
The setting value for the REF adjusting unit 68 is changed, and the REF setting unit 6 is changed.
The output signal is suppressed within a predetermined range by supplying the set value from 7 to the D / A converter 54 to control the amplification degree of the comparison amplification unit 55 and the emission intensity of the emission light source.

As described above, according to the fourth embodiment,
Instead of adjusting the gain amplifier, perform REF adjustment,
It is possible to keep the measured value within the predicted range by adjusting the amount of emitted light. In this way, the same effects as those of the first embodiment can be achieved, and the configuration of the light source light amount detection unit of the density sensor unit 50 can be simplified. [Fifth Embodiment] In the above description, the gain adjustment for eliminating the variation can be performed only by the reflected light amount detection unit or the light source light amount detection unit. However, the present invention is not limited to the above example. The configuration is not limited, and both may be configured to be executable and switchable to be executable. The fifth embodiment of the present invention having the above-described structure will be described below.

FIG. 7 is a diagram showing the configuration of the fifth embodiment according to the present invention. In FIG. 7, the same components as those of the respective embodiments described above are designated by the same reference numerals and detailed description thereof will be omitted. In FIG. 7, reference numeral 58 denotes a monitor switching unit realized by an analog switch or the like, which connects the reflected light amount detection unit 52 to the sensor output (output to the CPU 60) and the light source light amount detection unit 57 to the comparison amplification unit 55. The case and the case where the reflected light amount detection unit 52 is connected to the comparison amplification unit 55 and the light source light amount detection unit 57 is connected to the sensor output (output to the CPU 60) are switched and connected.

Reference numeral 69 denotes a changeover switch. When the sensor output is connected to the reflected light amount detecting section 52 by the monitor changing means 58, the changeover switch 69 is connected to the reflected light amount detecting section 52, and a reflected light amount detecting gain amplifier is provided. Adjust the gain of. Also, the monitor switching means 5
When the sensor output is connected to the light source light amount detection unit 57 by 8, the changeover switch 69 is connected to the light source light amount detection unit 57 and adjusts the gain of the light source light amount detection gain amplifier. The changeover switch 69 is the CPU 6 as shown in FIG.
It is also possible to provide not on the 0 side but on the concentration sensor section 50 side. The effects can be exactly the same.

In addition, as shown in the above-mentioned first to fourth embodiments, it is also possible to perform the REF setting adjustment without adjusting the light amount detection gain amplifier, and also to adjust the light amount detection gain amplifier with a volume. It is also possible to make adjustments. Fifth
In the embodiment, the measured toner image is black (B
k) In the case of toner, the output signal amplitude becomes large when the light source light amount detection unit 53 is used as a sensor output, and the color (Y, M,
C) In the case of toner, since the reflected light amount detection unit 52 is configured to output the sensor as a sensor output, the amplitude of the output signal becomes large. Therefore, when the output signal amplitude is large, the variation of the signal has the greatest influence. Therefore, it is also possible to switch the switch 67 so that the light source light amount detection gain amplifier is adjusted for black (Bk) toner and the reflected light amount detection gain amplifier is adjusted for color (Y, M, C) toner.

As described above, the above-mentioned first to fifth
According to each embodiment of the present invention, with respect to the density detection of the color image forming apparatus, it is possible to prevent the density sensor output from varying due to the characteristics of the light emitting element and the like by adjusting the light amount detection gain amplifier. Further, even when the density sensor output is lowered due to dirt on the drum or the like, it is possible to always perform stable density control by adjusting the output level to the reference value in advance.

[Sixth Embodiment] Next, a sixth embodiment according to the present invention will be described. 8 and 9 are views showing the configuration of the sixth embodiment according to the present invention. 8 and 9 are different only in the state of the monitor switching means 156, and the other configurations are the same.

In FIGS. 8 and 9, a density sensor unit 150 irradiates a patch formed on the transfer drum 10 with light and sends an output signal to the CPU 160.
In the density sensor unit 150, 151 is the density sensor 15
Infrared LED which is a light source of 0, 152 is a reflected light amount detection unit,
A light source light amount detection unit 153 monitors light from the infrared LED. Reference numeral 154 is a D / A converter, and 155 is a comparison amplification unit.

Reference numeral 156 denotes monitor switching means realized by an analog switch or the like, which connects the reflected light amount detection unit 152 shown in FIG. 8 to the sensor output and the light source light amount detection unit 153 to the comparison amplification unit 155. It is possible to selectively execute the case where the reflected light amount detection unit 152 shown in FIG. 9 is connected to the comparison amplification unit 155 and the light source light amount detection unit 153 is connected to the sensor output. In the case of the connection shown in FIG. 8, the value set by the D / A converter 154 is compared with the signal from the light source light amount detection unit 153, and the light emitting light source 151 is controlled until it becomes the same as the set value of D / A. On the other hand, in the case of the connection shown in FIG. 9, the value set by the D / A converter 54 is compared with the signal from the reflected light amount detection unit 52, and the light emitting light source 51 is controlled until it becomes equal to the set value of D / A. .

Reference numeral 160 denotes a CPU, and the density sensor unit 1
The signal from 50 is received and arithmetic processing is performed to determine the developing bias value. In the CPU 160, 161 is an A / D
It is a capturing unit, and A / D converts the output signal from the density sensor unit 150. A density conversion unit 162 calculates the density from the A / D value of the output signal. A development bias determination unit 163 is determined by the density data, and stores the optimum development bias value for the reference density value as data. A developing bias control unit 164 controls the developing device 170 with respect to the determined developing bias.

FIG. 10 shows a control flowchart in the sixth embodiment having the above configuration. The density control of the sixth embodiment will be described with reference to FIG. First, in step S11, whether the patch to be measured is color toner,
Alternatively, it is checked whether the detection signal level of the reflected light detection unit 152 is high and the reflectance of the toner is high. If the toner is color toner, or if the detection signal level of the reflected light detection unit 152 is equal to or higher than a predetermined threshold value and the reflectance is high, the reflected light amount detection method shown in step S12 is selected, and the monitor switching means 156 is shown in FIG. The reflected light amount detection unit 152 shown is connected to the sensor output, and the light source light amount detection unit 153 is set to be connected to the comparison amplification unit 155.

[0051] Then at step S13, CPU 160 determines whether beats patches advance how much concentration (or form), and sets the light emission intensity to the D / A setting unit 165 according to the magnitude of the concentration, the light emitting source 151 is emitted with a predetermined intensity. Then, in the subsequent step S14, the patch measurement is started,
In step S15, the detection signal from the reflected light detector 152 is read. Then, in step S16, the density conversion unit 162 performs arithmetic processing for color toner data to calculate the density value of the patch.

Subsequently, in step S17, the developing bias determining section determines the optimum developing bias value from the calculated density value. Then, in step S18, the developing bias controller 164 controls the developing device 170 according to the determined bias value. On the other hand, if the measurement patch is the black toner or the one having a small reflectance in step S11, the process proceeds to step S20, the light source light amount detection method is selected, and the monitor switching means 156 is used to display the reflected light amount detection unit 15 shown in FIG.
2 is connected to the comparison amplification unit 155, and the light source light amount detection unit 153 is connected.
Is connected to the sensor output. Then, in step S21, the D / A setting unit 16 sets the reflected light amount voltage according to the magnitude of the patch density recognized by the CPU 160.
The emission intensity is set to 5, and the emission light source 151 is caused to emit light with a predetermined intensity.

Then, in the subsequent step S22, patch measurement is started, and in step S23, the detection signal from the light source light amount detection section 153 is read. Then, in step S24, the light source light amount when the patch is measured is detected, and the density conversion unit 162 of the CPU 160 performs a calculation process for black toner data to calculate a density value. Then, the process proceeds to step S17 and thereafter, the optimum developing bias is determined from these density values, and the developing device is controlled.

FIG. 11 shows a reflection characteristic of the color toner in the infrared light region when a patch is formed with the color toner using the reflected light amount detection section 152 as a sensor output, and thus a high output sensor output is possible. On the other hand, as for the relationship between the measured density of black toner and the sensor output, as shown in FIG. 12, when the density is high, a high output sensor output is possible. That is, as shown in FIG. 12, since the black toner exhibits absorption characteristics in the infrared light region, for example, the density of 0 to O.V. It is effective in a high reflectance region up to about 7.

As a result, a high sensor output can be obtained by adopting the reflected light amount detection method in the case of color toner and in the case of low reflectance as in the sixth embodiment. On the other hand, when the color toner is not used and the reflectance is high, the light source light amount detection method is employed to control the circuit so that the reflected light amount becomes constant. FIG. 13 shows the relationship between the measured density of black toner and the sensor output when the light source light amount detector 153 is used as the sensor output. In this case, since the circuit is controlled so that the amount of reflected light becomes constant, the amount of emitted light increases as the toner concentration increases. Therefore, as the toner concentration increases, the sensor output also increases. Further, [ref] in FIG. 13 is a voltage value of the reflected light amount,
Since the set value of the reflected light amount level can be changed by the D / A converter 154, there is an advantage that the same sensor output level can be obtained in any density region. Here, a method of calculating the density from the color toner data and the black toner described above, and a method of determining the developing bias value from the calculated density value will be described below. First, the method of calculating the concentration will be described. Definition of Density Generally, when the incident light from the light emitting light source is Io and the reflected light from the light reflector (eg, patch) irradiated with this incident light is Ir, the density D of the light reflector in the reflective optical system is as follows. Can be expressed by D = −log ₁₀ (Ir / Io) (A) When the above formula (A) is expanded, formula (1) described later is obtained. Then, the density formula of the black toner can be derived from the formula (69), which will be described later.
From the expansion of the formula, the formula (Ir / Io) = 10 ^−D (B) is obtained. The above formula (B) is used for the incident light Io and the reflected light I
It represents the absorptivity of the light reflector with r, and is used when the characteristic of the reflector is absorption, that is, black toner. On the other hand, since the color toner exhibits a reflection characteristic, and the reflectance to the reflector has a relationship of (reflectance) + (absorption rate) = 1, the formula corresponding to the color toner of the formula (B) is (Ir / Io) = 1-10 ^−D (C), which is a modification of the formula (7) described later. Therefore, the density formula of the color toner is the formula (14) described later. . Next, a method of determining the developing bias value from the calculated density value will be described below. The (developing bias)-(density) characteristics as shown in FIG. 23 are stored in advance in the CPU of this embodiment as a table.
For example, the CPU first attempts to output a toner patch having the information of the density A. If the density of the patch read by the density sensor is a, then the CPU
Since what is supposed to be the density A is judged to be a, the developing bias value is set to be increased by ΔV in order to correct this. Then, by applying a developing bias with the developing bias value set in this way, the toner supply amount of the developing device is determined, and control is performed by developing this toner amount on the image carrier.

As described above, according to the present embodiment, it is possible to perform density measurement (a high-output sensor output is possible) by an optimum method for each density in any density range, and it is possible to obtain a very high accuracy. Can be measured. [Seventh Embodiment] In the above-described color image forming apparatus, the fluctuation of the image density and the reproducibility of gradation are unstable with respect to the environment of use, especially the humidity environment. One of the causes is the dependency of the transfer characteristic on the humidity, and in order to obtain a constant transfer current, the transfer bias is set to 2000V to 400V.
It is necessary to change it to 0V. A seventh embodiment according to the present invention in which this point is improved will be described below.

FIG. 14 is a block diagram showing the configuration of the seventh embodiment according to the present invention. In FIG. 14, FIG.
Also, the same components as those in the sixth embodiment shown in FIG. In FIG. 14, reference numeral 167 is an environment sensor, which detects the moisture absorption of the in-machine paper, the humidity of the transfer drum surface, and the like. Reference numeral 168 denotes an environmental data storage unit in which data on at least three patterns of high temperature and high humidity, normal temperature and normal humidity, and low temperature and low humidity is registered in advance.
Then, under each environment, the developing bias value is determined based on the density and the optimum developing bias curve. 171
Is a transfer high voltage controller, which controls the transfer drum 10 based on the data from the environment data storage 168.

Next, the control in the seventh embodiment having the above configuration will be described below with reference to the flowchart of FIG. In FIG. 15, the same step numbers are given to the same control as the control of the sixth embodiment shown in FIG. 10, and the detailed description will be omitted. In the seventh embodiment, the process of step S16 or step S24 is not followed by the process of step S17 but the process of step S25 shown in FIG.

In step S25, the CPU 160 fetches the environmental data by the environmental sensor 167 after the density values of the color and black toners are calculated, and in step S26, determines the optimum developing bias value and transfer bias value under the environment. . This is the environment sensor 16
In the environment detected in step 7, the registration data in the environment data storage unit 168 will be referred to by another person to make the determination. Then, the biases of the developing device 170 and the transfer drum 10 are controlled according to the optimum developing bias value and transfer bias value determined in step S27. 24 and 25 show other specific examples of the environmental changes in the seventh embodiment described above. That is,
As shown in FIG. 24, by giving the information from the environment sensor to the output signal of the concentration sensor, it is possible to correct the output fluctuation due to the environmental fluctuation and not store the environmental data in the CPU side. Further, as a similar effect, as shown in FIG. 25, a temperature / humidity correction circuit may be incorporated in the concentration sensor and the output may be corrected by connecting the temperature / humidity correction circuit to the sensor output section.

As described above, according to the seventh embodiment,
Concentration control applicable to changes in environmental conditions can be performed. The method of the seventh embodiment is applicable to any of the reflected light amount detection method and the light source light amount detection method shown in the sixth embodiment as shown in FIG. [Eighth Embodiment] FIG. 16 shows the structure of an eighth embodiment according to the present invention.

In FIG. 16, the same components as those in the above-described embodiment are designated by the same reference numerals and detailed description thereof will be omitted. 16 in the figure
Reference numeral 9 denotes a developing bias data storage unit, which has a table of optimum developing bias values corresponding to the A / D capture values in the A / D capture unit 161 of the density sensor 150 output. Then, the developing bias determining section 163 determines the developing bias value by referring to the table registered in the developing bias data storage means 169. With the above configuration, the developing bias can be controlled without performing density conversion.

The control of the eighth embodiment having the above construction will be described below with reference to the flowchart of FIG. FIG.
7 is a flow chart showing the density control in the eighth embodiment. 17, the same control as that shown in FIG. 10 described above is denoted by the same step number, and detailed description thereof will be omitted. In the eighth embodiment, instead of proceeding from step S15 to step S16 or from step S23 to step S24, the process proceeds to step S30 shown in FIG.

That is, in the eighth embodiment, the CPU1
Reference numeral 60 has an optimum developing bias value as a table in the developing bias data storage means 169 beforehand.
In step S14 or step S22, the density sensor unit 150 performs patch measurement, and in step S15 or step S23, the detection data is fetched by the CPU 160. Then, in the subsequent step S30, the optimum developing bias value is retrieved to determine the developing bias, and the developing device 170 is controlled by the developing bias value determined in step S30.

Incidentally, as in the case of the seventh embodiment, the eighth
Also in this embodiment, the environment sensor 167, the environment data storage unit 168, and the transfer high voltage control unit 171 may be arranged. In this case, the developing bias data storage unit 169 has a table corresponding to each environment, and the developing bias is determined using this table. As described above, according to the present embodiment, it is not necessary to calculate the concentration, and various correspondences can be dealt with only by changing the registered contents in the table. For example, even with respect to variations in characteristics of each device, etc. Appropriate measures can be taken only by changing the table registration contents.

[Ninth Embodiment] FIG. 18 shows a ninth embodiment of the present invention.
The structure of an Example is shown. In FIG. 18, the same components as those in the above-described embodiment are designated by the same reference numerals and detailed description thereof will be omitted. In FIG. 18, reference numeral 166 is an approximate expression processing unit, which calculates the density value by using an approximate expression using the Maclaurin expansion when performing the density conversion processing.

Now, the density conversion processing of the density conversion section 162 using the approximate expression processing section 166 in the ninth embodiment will be described in detail. <1> Black toner As described above, the Bk toner absorbs in the infrared light region. Now, suppose that the incident light I ₀₁ is radiated to the background (denoted by the density Du) in the state where the patch is not hit, and the reflected light I _r1 is obtained.

[0067]

## EQU1 ## The relational expression I _r1 = I ₀₁ × 10 ^-Du (1) is obtained. Next, on the base of the density Du, the density D
When the incident light I ₀₂ is emitted when the patch of p is placed, and the reflected light I _r2 is obtained,

[0068]

(2) I _r2 = I ₀₂ × 10 ^{− (kDp + Du)} (2) Here, k is a proportional coefficient. Formula (1), (2)
Let V _{ref 1} and V _ref2 be the voltage values of the reflected light in

[0069]

(3) V _ref1 = I ₀₁ × 10 ^-Du (3) V _ref2 = I ₀₂ × 10- ^{(kDp + Du)} (4) Therefore, the patch density Dp is obtained by dividing (4) to (3).

[0070]

[Equation 4]

(5) As a result, the patch density Dp is

[0072]

(Equation 5)

Is given as <2> Color Toner As described above, the color toner is reflected in the infrared light region. Therefore, as in the case of the black toner, if the incident light I ₀₁ is radiated to the base material in the state where the patch is not hit and the reflected light I _r1 is obtained,

[0074]

## ^{EQU6 ##} The relational expression I _r1 = I ₀₁ × (1-10 ^-Du ) (7) is obtained. Here, the reflectance of the base is Ru
As

[0075]

## ^EQU00007 ## ^{Defining as} 10- ^Ru = 1-10- ^Du (8),

[0076]

## ^{EQU8 ##} The relational expression I _r1 = I ₀₁ × 10 ^-Du (9) is obtained. Next, on the base of the density Du, the density D
When the incident light I ₀₂ is radiated when the patch of p is placed and the reflected light I _r2 is obtained.

[0077]

I _r2 = I _r2 × {1-10 ^−kDp (1-10 ^−Du )} = I _r2 × {1-10 ^{− (kDp + Ru)} } (10) Where K is a proportional coefficient. In the above equations (1) and (2), the voltage values of the reflected light are V _ref1 and V
_ref2

[0078]

V _ref1 = I ₀₁ × 10 ^-Ru (11) V _ref2 = I ₀₂ × { ^{1-10-(kDp + Ru)} } (12) When (11) is substituted into (12),

[0079]

[Equation 11]

(13) When the density Dp is calculated from this,

[0081]

(Equation 12)

It is given as (14). Here, in order to unify the black toner and the color toner, the toner density Dp is

[0083]

(Equation 13)

(15) is set. Transforming equation (15),

[0085]

[Equation 14]

(16) 1 / LOG _e 10 = 0.434, (B−A) / A = x,
If Dp = f (x)

[0087]

F (x) = − 0.434 × k × LOG _e (1 + x) (17) Here, if the Maclaurin expansion formula is applied to LOG (1 + x) in formula (17),

[0088]

[Equation 16]

FIG. 19 shows a graph of equation (15). For example, when the density of two digits after the decimal point is required as the density, the expression (18) can be approximated only within the range (0.5 ≦ B / A ≦ 1) of (1) in FIG. Therefore, for those exceeding the range of (0.5 ≦ B / A ≦ 1), if the value of B / A is doubled, the range of (2) (0.25 ≦ B / A ≦ 1)
The range of B / A ≦ 0.5 falls into the range of (1). Since the approximate expression of (18) can be used in the range of (1), this is applied.

At this time, since B / A is doubled, it must be finally divided by 2 in the calculation processing state, but since logarithmic calculation is being performed, LOG _e 2 is finally subtracted. Therefore, the approximate expression in the range of (2) is

[0091]

[Equation 17]

For those exceeding the range of (2), if the value of B / A is multiplied by 4, the range of (3) (0.125≤
The range of B / A ≦ 0.25 falls within the range of (1). At this time, since B / A is multiplied by 4, it must be finally divided by 4 in the arithmetic processing, but since logarithmic calculation is performed, LOG _e 4 is finally calculated. Therefore, the approximate expression in the range of (2) is

[0093]

(Equation 18)

In the same manner as above, the following equations can be obtained by performing the operations in the ranges (3) to (6). Range (1) ... D = f (x) Range (2) ... D = f2 (x) = f (x) +0.301 Range (3) ... D = f3 (x) = F (x) +0.602 (4) range ... D = f4 (x) = f (x) +0.903 (5) range ... D = f5 (x) = f (x) +1 .204 (6) range ... D = f6 (x) = f (x) +1.505 When the concentration is calculated based on the above approximate expression,
For example, if accuracy D ± 0.005 is required, f
For (x), it is sufficient to use terms up to the fourth order.

FIG. 20 shows a flowchart of the above arithmetic processing. Further, in the ninth embodiment, the range (1) to (6): the approximation of the densities of 0 to 1.8 has been described, but the similar processing is continued to approximate the densities of 1.8 or more. It is possible to do. The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0097]

As described above, according to the present invention, it is possible to perform the density control process with high accuracy by adjusting the variation before forming the toner image to be measured and without causing a measurement error when forming the toner image to be measured. It is a thing. Therefore, with respect to the density detection of the image forming apparatus, it is possible to prevent variations in the density sensor output due to the characteristics of the light emitting element, and also when the density sensor output is reduced due to dirt on the image carrier,
By adjusting the output level to the reference value in advance, stable concentration control can always be performed.

Further, regarding the density detection of the color image forming apparatus, by switching the sensor output between the reflected light amount detection system and the light source light amount detection system, a high density sensor regardless of the difference in color toner or black toner or the difference in reflectance. The output can be obtained and the detection data error can be reduced.
In addition, the density calculation accuracy is improved by using the approximate expression process.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment according to the present invention.

FIG. 2 is a flowchart showing operation control of this embodiment.

FIG. 3 is a circuit diagram showing a detailed configuration of a light amount detection unit of the present embodiment shown in FIG.

FIG. 4 is a diagram showing a configuration of a second exemplary embodiment according to the present invention.

FIG. 5 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 6 is a diagram showing the configuration of a fourth exemplary embodiment according to the present invention.

FIG. 7 is a diagram showing a configuration of a fifth exemplary embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 10 is a flowchart showing the control of the sixth embodiment.

FIG. 11 is a diagram for explaining a density sensor output in the reflected light amount detection method in the sixth embodiment.

FIG. 12 is a diagram for explaining the output of a density sensor in the reflected light amount detection method in the sixth embodiment.

FIG. 13 is a diagram for explaining the density sensor output in the light source light amount detection method in the sixth embodiment.

FIG. 14 is a diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 15 is a flowchart showing the control of the seventh embodiment.

FIG. 16 is a diagram showing a configuration of an eighth exemplary embodiment of the present invention.

FIG. 17 is a flowchart showing the control of the eighth embodiment.

FIG. 18 is a diagram showing the configuration of a ninth exemplary embodiment according to the present invention.

FIG. 19 is a diagram showing an approximate expression curve used in the ninth embodiment.

FIG. 20 is a flowchart showing the control of the ninth embodiment.

FIG. 21 is a cross-sectional view of a color image forming apparatus to which a density control device is applied.

FIG. 22 is a diagram showing a density sensor unit of a density control device in a color image forming apparatus and its peripheral arrangement.

FIG. 23 is a diagram showing a developing bias-density characteristic table stored in advance in the CPU in the seventh embodiment.

FIG. 24 is a diagram showing another configuration example of the seventh embodiment.

FIG. 25 is a diagram showing another configuration example in the seventh embodiment.

[Explanation of symbols]

 1 Photosensitive Drum 3 Roller Charger 4 Development Cartridge 10 Transfer Drum 11 Laser Diode 13 Rotating Polygonal Mirror 17 Transfer Paper Cassette 18 Pickup Roller 22 Gripper 23 Adsorption Roller 24 Separation Claw 25 Fixing Device 26 Cleaning Device 27 Transfer Roller Cleaning Device 28 Fur Brush 50 Density sensor unit 51 Emission light source 52,56 Reflected light amount detection unit 53,57 Light source light amount detection unit 54 D / A converter 55 Comparison amplification unit 58 Monitor changeover switch 60 CPU 61 A / D acquisition unit 62,67 REF setting unit 63 Comparison unit 64 gain setting unit 65 density conversion unit 66 development bias control unit 68 REF adjustment unit 70 light receiving element 71 light amount detection gain amplifier 72 D / A converter 150 for performing gain adjustment density sensor unit 151 emission light source 152 Reflected light amount detection unit 153 Light source light amount detection unit 154 D / A converter 155 Comparison amplification unit 156 Monitor switching means 160 CPU 161 A / D acquisition unit 162 Density conversion unit 163 Development bias determination unit 164 Development bias control unit 165 D / A setting unit 166 Approximate expression processing unit 167 Environmental sensor 168 Environmental data storage unit 169 Development bias data storage unit 170 Developer 171 Transfer high voltage control unit

Claims (38)

[Claims] 1. A density control device which is applicable to an image forming apparatus using an electrophotographic process and which measures and controls the density of a toner image formed on an image carrier of the image forming apparatus, wherein Light irradiation means for irradiating the toner image formed on the image carrier of the apparatus with light, and detection means for detecting the reflected light from the toner image formed on the image carrier and the light source light of the light irradiation means. And a light emission intensity setting unit that sets the light emission intensity of the light irradiation unit based on the light intensities of the reflected light and the light source light detected by the detection unit. 2. A light receiving signal of a light receiving signal of reflected light from a toner image formed on the image carrier of the detecting means or a light receiving signal of light source light of the light emitting means is output as a density measurement signal. 2. The concentration control device according to claim 1, wherein the light emission intensity setting means amplifies the light reception signal which is not output as a density measurement signal by a desired amplification degree to drive the light irradiation means. 3. The detecting means receives the reflected light from the toner image formed on the image carrier and the light source light of the light irradiating means, and converts the light into an electric signal corresponding to the intensity of the received light. 3. The light receiving section for outputting, and an output signal from a light receiving section of the light receiving section, which is reflected by a toner image formed on the image carrier, is output as a density measurement signal. Concentration control device. 4. The detecting means receives the reflected light from the toner image formed on the image bearing member and the light source light of the light irradiating means, and converts the light into an electric signal corresponding to the intensity of the received light. 3. The density control device according to claim 2, further comprising a light receiving section for outputting, and outputting an output signal from at least the light source light receiving section of the light emitting means of the light receiving section as a density measurement signal. 5. The detecting means receives the reflected light from the toner image formed on the image carrier and the light source light of the light irradiating means, and converts the light into an electric signal corresponding to the intensity of the received light. The light receiving unit for outputting is included, and the amplification of the reflected light receiving unit of at least the toner image formed on the image carrier of the light receiving unit is adjusted so that the value of the output signal from the light receiving unit becomes a predetermined level. 3. The concentration control device according to claim 1, wherein the concentration control device is adjustable. 6. The detecting means receives the reflected light from the toner image formed on the image carrier and the light source light of the light irradiating means, and converts the light into an electric signal corresponding to the intensity of the received light. It is possible to include a light receiving unit for outputting and adjust the amplification degree of at least the light source light receiving unit of the light emitting unit of the light receiving unit so that the value of the output signal from the light receiving unit becomes a predetermined level. 3. The concentration control device according to claim 1, wherein the concentration control device is characterized in that. 7. A light emitting source for irradiating a toner image formed on an image carrier with light, and a reflected light from the toner image formed on the image carrier and a light emitted from the light source. Two light receiving elements for converting into electric signals corresponding to the received light intensity, reflected light voltage setting means for presetting a detection signal voltage value from the light receiving element for the reflected light, and a signal from the light receiving element for the reflected light. A density control device comprising: an adjusting unit that adjusts the emission intensity of the emission light source so that the value becomes the setting value of the reflected light voltage setting unit. 8. The adjusting means compares the signal from the light receiving element of the reflected light with the set value of the reflected light voltage setting means, and controls the light emission intensity of the light emitting light source based on the comparison result. The concentration control device according to claim 7, wherein 9. An amplification device for amplifying a signal from a reflected light receiving element from a toner image formed on the image carrier, and adjusting an amplification degree of the amplification means to output an output signal from the light receiving element. 9. The concentration control apparatus according to claim 7, wherein the value of is adjustable to a predetermined level. 10. An amplification means for amplifying a signal from the light source light receiving element is provided, and the amplification degree of the amplification means is adjusted so that the value of the output signal from the light receiving element can be adjusted to a predetermined level. 9. The concentration control device according to claim 7, wherein the concentration control device is present. 11. A light emitting source for irradiating a toner image formed on an image bearing member with light, adjusting means for adjusting the emission intensity of the light emitting source, and a toner image formed on the image bearing member. Two light-receiving elements that receive the reflected light and the light source light of the light-emitting source and convert it into an electric signal corresponding to the received light intensity; a detection signal voltage setting unit that presets a detection signal voltage value of the light-receiving element; An output switching unit that selects either the output signal from the light receiving element of the light or the output signal of the light source from the light receiving element as the concentration measurement result, and the light receiving element selected by the output switching unit. Output control means for adjusting the signal level from the light receiving element so that the output becomes the voltage value set by the voltage value setting means, and the adjusting means is selected by the output switching means. A density control device characterized by amplifying a signal from a light receiving element which has not been present, to a predetermined level to drive the light emitting light source. 12. A black (Bk) toner outputs an output from a light receiving element of the light emitting source as a density measurement signal, and a color (Y, M, C) toner outputs a density measurement of an output from the light receiving element of the reflected light. The density control device according to claim 11, wherein the density control device outputs the signal as a signal. 13. A density control method applicable to an image forming apparatus using an electrophotographic process, for measuring and controlling the density of a toner image formed on an image carrier of the image forming apparatus, the image forming method comprising: Prior to the density measurement at the time of image formation by the apparatus, the toner image formed on the image carrier of the image forming apparatus is irradiated with light by the light irradiation means, and the toner image formed on the image carrier is Of the reflected light and the light source light of the light irradiating means, respectively. The light emitting intensity of the light irradiating means is set from the light intensity of the reflected light and the light source light of the light irradiating means. A density control method characterized in that variations in density measurement output can be corrected by controlling emission intensity. 14. A light receiving signal of either a light receiving signal of reflected light from a toner image formed on the image bearing member or a light receiving signal of light source light of the light irradiating means is output as a density measurement signal, and the light receiving signal is output. 14. The density control method according to claim 13, wherein the light emission intensity correction of the irradiation means drives the light irradiation means by amplifying the light reception signal which is not output as a density measurement signal by an amplification degree corresponding to the light emission intensity setting. . 15. The density measurement signal is output by adjusting the amplification factor of the received light signal of the reflected light from the toner image formed on the image carrier to adjust the value of the received light signal to a predetermined level. 15. The concentration control method according to claim 13, wherein the concentration control method is possible. 16. A method for adjusting a gain of a light receiving signal from the light source light of the light irradiating means to adjust the value of the light receiving signal to a predetermined level so that the light can be output as a concentration measurement signal. 15. The concentration control method according to claim 13 or 14. 17. A density control method applicable to an image forming apparatus using an electrophotographic process, for measuring and controlling the density of a toner image formed on an image carrier of the image forming apparatus, the image forming method comprising: Prior to the density measurement at the time of image formation by the apparatus, the toner image formed on the image carrier of the image forming apparatus is irradiated with light by the light irradiation means, and the toner image formed on the image carrier is Of the reflected light and the light source light of the light irradiating means, and the emission intensity of the light source light is adjusted so that the light reception signal voltage value of the reflected light becomes a preset set value. Method. 18. The light emission intensity is adjusted by comparing a light reception signal of the reflected light with a set value of a light reception signal voltage value of the reflected light, and controlling the light emission intensity of the light source light based on a comparison result. 18. The concentration control method according to claim 17, wherein: 19. The method according to claim 17, wherein the amplification factor of the received light signal of the reflected light is adjusted so that the value of the received light signal becomes a predetermined level, and the density measurement signal can be output. 19. The concentration control method according to any one of 18. 20. The method according to claim 17, wherein the amplification degree of the received light signal of the light source light is adjusted so that the value of the received light signal becomes a predetermined level, and the signal can be output as a concentration measurement signal. 19. The concentration control method according to any one of 18. 21. A light emitting source for irradiating a toner image formed on an image bearing member with light, and a light source for receiving a reflected light from the toner image formed on the image bearing member and a light source light of the light emitting source. A concentration control method of a concentration measuring device comprising: two light receiving elements for converting into an electric signal corresponding to a light receiving intensity, wherein the light emitting intensity of the light emitting light source is adjusted, and an output signal from the light receiving element of the reflected light or the Select one of the output signals from the light receiving element of the light source to output as the concentration measurement result, and set the detection signal voltage value of the selected light receiving element to the preset voltage value set by the light receiving element. The density control method is characterized in that a signal from the unselected light receiving element is adjusted to a predetermined level to drive the light emitting source. 22. For black (Bk) toner, the output from the light receiving element of the light emitting light source is output as a density measurement signal, and for color (Y, M, C) toner, the output from the light receiving element of the reflected light is density measured. 22. The concentration control method according to claim 21, wherein the concentration is output as a signal. 23. The present invention is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control device, which is a light irradiation unit that irradiates a toner image formed on an image carrier of the image forming apparatus with light, and a reflected light from a measured toner image formed on the image carrier and Detection means for detecting the light source light of the light irradiation means, and the reflectance of the toner image to be measured is obtained from the reflected light detected by the detection means and the light intensity of the light source light. A density control device comprising: a reflectance image control means for setting an emission intensity and controlling an image forming condition. 24. It is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control device, which is a light irradiation unit that irradiates a toner image formed on an image carrier of the image forming apparatus with light, and a reflected light from a measured toner image formed on the image carrier and Detecting means for detecting the light source light of the light irradiating means, reflected light voltage setting means for presetting a reference detection voltage value of the reflected light in the detecting means, reflected light detection output signal detected by the detecting means, and And a comparison image control means for controlling the image forming conditions by comparing the set voltage value of the reflected light voltage setting means and setting the light emission intensity of the light irradiation means based on the comparison result. Apparatus. 25. It is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control device for irradiating a toner image formed on an image carrier of the image forming apparatus with light, and a reflected light from a measured toner image formed on the image carrier. Reflected light detection means for detecting, light source light detection means for detecting light source light of the light irradiation means, reflected light voltage setting means for presetting a reference detection voltage value of the reflected light in the reflected light detection means, and Irradiation light voltage setting means for presetting a reference detection voltage value of the irradiation light from the light irradiation means in the light source light detection means, and a density sensor output from either the reflected light detection means or the light source light detection means. Output comparing means and a comparison amplifying means for comparing and amplifying the output of the non-output detecting means in the output switching means with the set value of the corresponding voltage value setting means, depending on the reflectance of the measured toner image. A concentration control device, wherein the output of the output switching means is switched. 26. The image forming apparatus is capable of forming a color image, and the output switching unit selectively outputs the light source light detection unit output for black (Bk) toner to output a color (Y,
26. The density control device according to claim 25, wherein the M, C) toner selectively outputs the output of the reflected light detecting means. 27. Further, a bias data storing means for holding optimum developing bias data corresponding to the output of the light source light detecting means and the output of the reflected light detecting means, and the developing bias is determined based on the output data from the bias data storing means. 27. The density control device according to claim 23, further comprising: a developing bias determining unit that controls the developing bias. 28. Environmental variation detecting means for detecting environmental variation, environmental bias data storage means for holding optimum developing bias data for the output of the output switching means under each environment of the environmental variation detecting means, and output switching means output. 27. The density control device according to claim 23, further comprising an environmental bias determining unit that determines a developing bias based on the data. 29. A density conversion means for calculating the density value of the toner image to be measured from the output of the output switching means, and a density bias data storage means for holding optimum developing bias data for the density data calculated by the density conversion means. 3. A density bias deciding means for deciding a developing bias to be held in the density bias data storing means on the basis of a density value calculated by the density calculating means.
The concentration control device according to any one of claims 3 to 26. 30. An environmental change detecting means for detecting environmental change is provided, wherein the density calculating means calculates the density value of the toner image to be measured from the output of the output switching means under each environment of the environmental change detecting means. 30. The concentration control device according to claim 29, which is characterized in that. 31. The concentration control device according to claim 29, wherein the concentration conversion means applies an approximate expression when performing the concentration conversion. 32. It is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control method, which comprises irradiating a toner image formed on an image bearing member of the image forming device with light by means of a light irradiating device before measuring the density of the image formed by the image forming device, and The reflectance of the toner image to be measured is obtained from the reflected light from the toner image formed on the carrier and the light source light of the light irradiating means, and the reflectance of the measured toner image from the light intensity of the reflected light and the light source light. A density control method characterized in that variations in density measurement output can be corrected by controlling the light emission intensity of the light irradiation means by the reflectance. 33. It is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control method, which comprises irradiating a toner image formed on an image bearing member of the image forming device with light by means of a light irradiating device before measuring the density of the image formed by the image forming device, and The reflected light from the toner image formed on the carrier and the light source light of the light irradiating means are respectively received and the reference detection voltage value for the detection signal of the received reflected light is set in advance to detect the reflected light. It is possible to correct the variation in the density measurement output by comparing the output signal with the reference detection voltage value of the reflected light and controlling the emission intensity of the light irradiation means based on the comparison result. That concentration control method. 34. It is applicable to an image forming apparatus using an electrophotographic process, measures the density of a toner image formed on an image carrier of the image forming apparatus, and controls the image forming condition based on the measurement result. A density control method, which comprises irradiating a toner image formed on an image bearing member of the image forming device with light by means of a light irradiating device before measuring the density of the image formed by the image forming device, and The reference detection voltage value for the reflected light from the toner image formed on the carrier and the light source light of the light irradiating means and the detection signal of the reflected light received and the irradiation light from the light irradiating means The reference detection voltage value is set in advance, and one of the reflected light from the toner image formed on the image bearing member and the light source light of the light irradiation means is set according to the reflectance of the measured toner image. Select a degree sensor output, density control method characterized by enabling correct variations of the density measurement output by comparing and amplifying the reference detection voltage value corresponding to the received light output of the person who was not selected. 35. The image forming apparatus is capable of forming a color image, and the density sensor output switching selectively outputs the light source light detection output for black (Bk) toner to output a color (Y,
The density control method according to claim 34, wherein the reflected light detection output is selectively output for the M and C) toners. 36. Further, the optimum developing bias data corresponding to the light source light detection output and the reflected light detection output is held, and the developing bias is determined based on the held data. Item 36. The concentration control method according to any one of Items 35. 37. An environmental change can be detected, optimum developing bias data for the output of the density sensor under each detected environment is held, and the developing bias is determined based on the held data. 32. The concentration control method according to claim 32. 38. The density value of the toner image to be measured is calculated from the output of the density sensor, optimum developing bias data for the calculated density data is held, and the developing bias is determined based on the held data. The concentration control method according to any one of claims 32 to 35.