JP2000250303A - Concentration detector for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the concentration detector 1 of an image forming device capable of stably obtaining detection result extremely easily and adequately corrected even though the sensitivity of a photosensor is fluctuated. SOLUTION: A second light emitting element 42 is provided separately from a light emitting element 41 emitting light with which a toner image Tpatch for control is irradiated inside the supporting body 44 of the photosensor 4, and also a reference reflecting surface 45 irradiated with the light emitted from the element 42 and making the reflected light received by a light receiving element 43 is provided. A sensitivity correcting means 5 correcting the sensitivity of the photosensor 4 by utilizing the output value of the element 43 obtained when the element 43 receives the reflected light is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a photosensor for detecting the density of a toner image for controlling image forming conditions formed on an image carrier in an image forming apparatus such as a copying machine or a printer. The present invention relates to a density detection device, and more particularly to a density detection device having an improvement useful for correcting the sensitivity of a photosensor.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, a toner image is generally formed on an image carrier such as a photoconductor, and the toner image is finally formed on a recording paper or the like. Then, the image is formed by transferring the image onto the fixing device. In such an image forming apparatus, since it is necessary to maintain that the toner image is properly and stably formed in accordance with a preset image forming condition, for example, a control image is formed on an image carrier. Toner image (patch)
Is formed, and the density of the toner image is detected by a density detecting device, and the detection result is fed back to control means for controlling the image forming conditions to change the setting of the necessary image forming conditions.

The above-mentioned density detecting device includes a photosensor having a light emitting element such as a light emitting diode and a light receiving element such as a photodiode, and irradiates light from the light emitting element to a control toner image on an image carrier. In many cases, the density of the control toner image is detected from an output value obtained by receiving the reflected light (specular reflected light or diffuse reflected light) at that time by a light receiving element. By the way, this photosensor can be roughly classified into a regular reflection type sensor configured to receive specularly reflected light out of reflected light, and a diffusion type configured to receive diffused reflected light out of reflected light. There is a reflection type sensor.

[0004]

However, in an image forming apparatus provided with such a density detecting device, the amount of light emitted from the light emitting element of the photo sensor and the sensitivity of the light receiving element vary among the elements, or It fluctuates due to environmental changes such as temperature, the deterioration of the element itself over time, and adhesion of toner and the like. As a result, initial performance is not maintained and accurate density detection becomes difficult, and as a result, accurate image formation There was a problem that the control of the condition became impossible.

In order to solve such a problem, the following various countermeasures have been proposed, but all of them have some problems and have not been sufficiently satisfactory.

[0006] That is, Japanese Patent Application Laid-Open No. 5-322760 discloses a movable reference plate in which a reference patch for comparing the density with an image is inserted or affixed between a density detection sensor (photo sensor) and an image to be detected. Is rotatably provided, so that when the density comparison is not necessary (non-detection), the movable reference plate is always positioned between the sensor and the image, so that the sensor or the reference patch is contaminated with toner. In FIG. 1, a density detecting device for preventing the occurrence of an error or correcting an optical sensor is shown. However, in the case of this conventional example, in particular, since the movable reference plate having the reference patch is displaced, the positional relationship (including the angle and the like) between the reference patch and the density detection sensor may fluctuate. The correction result of the sensor may vary.

Japanese Patent Application Laid-Open No. Hei 7-225501 discloses that when a concentration detection sensor is not detected, it is moved by a moving means into a housing container having a lid and housed with a lid, and provided in the housing container. Calibration is performed using the components that have been used, which prevents contamination of the sensor by toner, enables stable concentration detection over a long period of time, and ensures accurate calibration of the sensor without the influence of external light. An enabled image forming apparatus is shown. However, in the case of this conventional example, since the density detection sensor itself is displaced, the positional relationship between the sensor and the image to be detected may vary as in the case of the above-described conventional example. The correction result of the sensor may vary.

Further, Japanese Patent Application Laid-Open No. 9-6121 discloses that
After the density detection sensor is displaced so that the measurement surface (light receiving surface) is directed toward the exposure apparatus at the time of calibration, the sensor is calibrated using light from the exposure apparatus. An image forming apparatus in which calibration of a density detection sensor can always be performed accurately is shown. However, even in the case of this conventional example, since the density detecting sensor itself is displaced, there is a problem similar to that of the above-described conventional example.

Incidentally, Japanese Utility Model Publication No. 8-679 proposed by the present applicant discloses that the light quantity of a light emitting element is detected by a monitor means and the light quantity is adjusted so as to eliminate the deviation between the detection result and the reference light emission quantity. After adjusting the reference light amount of the light emitting element by the means, the light reflected from the toner image by the adjusted light from the light emitting element is detected by the light receiving element by the light receiving element so as to eliminate the deviation between the result and the reference light receiving amount. There is disclosed a density detecting device which corrects a light receiving signal, thereby accurately detecting a density without being affected by deterioration of a light emitting element and deterioration of a photosensitive material. However, in the case of this conventional example, a monitor means for detecting the amount of emitted light is required in addition to the light receiving element in the density detection sensor, so that the cost is high, and the performance of the monitor means varies between lots. The correction result of the sensor may vary.

In addition, in any of the conventional density detecting sensors, an image carrier for carrying a toner image has a low reflectance such as a belt member such as a paper transport belt or an intermediate transfer belt, or diffuse reflection light. When the diffusion coefficient is large, the amount of light reflected by the image carrier is small and the amount of light received by the light receiving element is very small. For this reason, for example, in the case of a color (cyan, magenta, yellow, etc.) toner having a relatively high reflectance in the toner itself, particularly, each of the sensors in the case where there is a control toner image on the image carrier and in the case where there is no control toner image. Even if an attempt is made to detect the density of the toner image by comparing the output values, the output value when the image carrier is detected, especially when the toner image is not present, becomes small. Was difficult to detect.

Accordingly, the present invention solves the above problems, and the detection result can be corrected very easily and accurately even if the sensitivity of the photosensor of the density detecting device fluctuates without causing a significant increase in cost. To provide a density detecting device for an image forming apparatus, which can stably obtain the density.

[0012]

According to a first aspect of the present invention, there is provided an image forming apparatus which emits light for irradiating a control toner image formed on an image carrier of an image forming apparatus. A light-emitting element and a light-receiving element for receiving at least reflected light of the irradiation light reflected by the toner image are provided with a photosensor disposed inside a box-shaped support, and an output of the light-receiving element in the photosensor is provided. A density detection device that detects the density of the toner image based on the
A second light-emitting element is provided inside the support of the photosensor separately from the light-emitting element, and a light emitted from the second light-emitting element is radiated so that the reflected light is received by the light-receiving element. This is a density detecting device of an image forming apparatus provided with a surface.

According to a second aspect of the present invention, which is capable of achieving the above object, there is provided a density detecting device based on the first aspect, wherein the light emitting element is provided inside a support of the photosensor. An image forming apparatus according to the present invention differs from the image forming apparatus in that a reference reflection surface to which a part of emitted light is applied is provided, and a second light receiving element for receiving light reflected from the reference reflection surface is provided separately from the light receiving element. It is a density detection device.

In the concentration detecting devices of the first invention and the second invention, the second light-emitting element or the second light-receiving element is provided, respectively. May be provided at the same time.

Here, the reference reflecting surface may be one in which a separate reference reflecting member is attached to a predetermined portion of the support, or one in which a part of the support is a reflecting surface. In the latter case, it is possible to integrally mold the support at the time of molding, and it is possible to reduce the difference between the supports (sensors) of the reference reflecting surface (all the reference reflecting surfaces are equivalent). .

In each of the density detecting devices of the first and second aspects of the present invention, a light-emitting opening and a light-receiving opening of the support are opened in the support of the photosensor. A cleaning member that slides on the detection surface and moves so as to open or shield at least one of the two openings to clean the detection surface may be provided (the invention according to claims 3 and 4).

Further, in the case of the device of the first invention, the concentration detecting device of the first invention and the second invention receives light from the second light emitting element of the support of the photosensor via the reference reflection surface. In the optical path leading to the element, light amount adjusting means for adjusting the amount of light passing through the optical path is provided (the invention according to claim 5). In the case of the device of the second invention, the light sensor is supported. In the optical path from the light emitting element of the body to the second light receiving element via the reference reflecting surface, a light amount adjusting means for adjusting the amount of light passing through the optical path may be provided (the invention according to claim 6).

The density detecting device according to the first aspect of the present invention utilizes the output value when the light emitted from the second light emitting element is reflected by the reference reflecting surface and received by the light receiving element. The image processing apparatus further includes a sensitivity correction unit that corrects the sensitivity of the photosensor (the invention according to claim 7).

Further, in the density detecting device according to the second aspect of the present invention, the light emitted from the light emitting element is reflected by a reference reflection surface and is used by utilizing an output value when the light is received by the second light receiving element. The image processing apparatus further includes sensitivity correction means for correcting the sensitivity of the photo sensor (the invention according to claim 8).

For example, in the case of the first invention, the sensitivity correction means according to the first invention or the second invention uses the output value of the light receiving element when receiving the reflected light from the control toner image as a reference reflection value. A process in which a value obtained by dividing the output value of the light receiving element when the reflected light from the surface is received is used as a detection result of the photo sensor is performed (an invention according to claim 9). The detection result of the photo sensor is a value obtained by dividing the output value of the light receiving element when receiving the reflected light from the toner image by the output value of the second light receiving element when receiving the reflected light from the reference reflecting surface. (The invention according to claim 10).

According to the first and second inventions having the photosensor and the sensitivity correcting means as described above, the light which enters the light receiving element after being reflected by the reference reflecting surface from the light emitting element is received. The output value of the sensor obtained at this time can be used as a reference value, whereby the result of detection (light reception) of diffuse reflection light from the control toner image is relative to the result of detection (light reception) from the reference reflection surface. It can be specified by a value, and even when diffusely reflected light is received, an output value of a level necessary for density detection can be obtained.
Moreover, by providing the second light emitting element as in the first invention or providing the second light receiving element as in the second invention, the second light emitting element or the second light receiving element is turned on.
The output value of the light received from the reference reflection surface and the output value of the light received from the control toner image can be arbitrarily and easily selected and obtained simply by performing the OFF operation.

In addition, according to the density detecting device provided with such a photosensor and sensitivity correction means, a reference plate for calibration as in the conventional example is not provided outside (the support of) the sensor. Correction of the sensor (output signal) can be easily performed. Further, when correcting the sensor, the photosensor can be always kept in a fixed state without having to rotate or displace, so that the correction of the sensor can be accurately performed without variation. In addition, since the reference reflection surface is disposed inside the support of the sensor, the reflection surface is not contaminated by toner (strictly speaking, the light emitting opening and the light receiving opening formed in the sensor support). It is necessary to provide a light-transmitting dust-proof member), and it is possible to avoid variations in sensor correction due to toner contamination on the reference reflection surface. As a result, a highly reliable and highly accurate sensor output signal is obtained. Can also be corrected.

The sensitivity correction means according to the first invention or the second invention may be arranged such that, when the cleaning member is provided, in the detection device according to the first invention, the cleaning member moves during cleaning to move the two cleaning members. When at least one of the openings is shielded from light, the second light-emitting element emits light (the invention according to claim 11). In the detection device of the second invention, the cleaning member moves during cleaning. When at least one of the two openings is shielded from light, the second light receiving element is set to receive light (the invention according to claim 12).

In this case, since the detection surface of the photo sensor can be cleaned and at least one opening of the sensor detection surface is shielded from light by the cleaning member, the second light emitting element or the second light receiving element is turned on. When operated, it prevents the light receiving element of the first invention or the second light receiving element of the second invention from receiving extra light that enters from outside the sensor support through any opening in the detection surface. However, it is possible to obtain a more appropriate output value that accurately receives the reflected light from the reference reflecting surface.

Further, in the case where the light amount adjusting means is provided, the sensitivity correcting means in the first invention and the second invention is arranged such that both of the light amount adjusting means and the reference reflecting surface are separated from the second light emitting element. When each output value of the light receiving element when the light amount of the irradiation light reaching to or the light amount of the reflected light from the reference reflection surface to the light receiving element is changed in a plurality of steps, when the output value is similarly changed in the plurality of steps in the reference time Either compare with each reference output value of the light receiving element and perform a process of softly correcting the detection result of the photo sensor based on the difference information between the two output values to perform offset and gain adjustment, or based on the difference information In this method, the output of the light emitting element or the light receiving element is feedback-controlled to adjust the offset and the gain (the invention according to claims 13 and 14).

In this case, even if the initial characteristics of the light-emitting elements and the light-receiving elements vary, an appropriate correction can be made according to the difference, so that a more appropriate sensor output value can be obtained.

Further, in the density detecting apparatus according to the first aspect of the present invention having such a sensitivity correcting means, all of the plurality of light emitting elements including the second light emitting element are emitted inside the support of the photo sensor. One monitor light receiving element for receiving each light in common is provided, and the sensitivity correction means uses a variation of the light amount characteristic of each light emitting element obtained by the monitor light receiving element as a correction coefficient. The correction coefficient is multiplied by the detection coefficient of the photosensor, and the detection result is corrected (the invention according to claim 15).

In this case, when at least one of the plurality of light-emitting elements undergoes a time-dependent output fluctuation or environmental fluctuation, the fluctuation becomes a disturbance factor for the sensitivity correction of the sensor. Even if the detection result of the sensor is corrected by the correction coefficient determined based on the variation (difference) of the light amount characteristic of each light emitting element obtained from the monitoring light receiving element, it is possible to sufficiently cope with the problem.

Further, in the density detecting apparatus according to the second aspect of the present invention having such sensitivity correcting means, all of the plurality of light receiving elements including the second light receiving element are commonly provided inside the support of the photo sensor. One reference light emitting element that emits light to be irradiated
And the sensitivity correction means stores in advance a variation of the light receiving characteristic of each light receiving element obtained by irradiation with the reference light emitting element as a correction coefficient, and stores the correction coefficient of the photo sensor. A process for correcting the detection result by multiplying the detection result is performed (the invention according to claim 16).

In this case, when a temporal output fluctuation or environmental fluctuation occurs in at least one of the plurality of light receiving elements, such fluctuation becomes a disturbance factor for the sensitivity correction of the sensor. Even if the detection result of the sensor is corrected by the correction coefficient determined based on the variation of the light receiving characteristic of each light receiving element obtained by the irradiation of the reference light emitting element, it is possible to sufficiently cope with the problem.

Further, in the density detecting device according to the first aspect of the present invention having such a sensitivity correcting means, the light emitting element for diffuse reflection and the light emitting element other than the second light emitting element are provided inside the support of the photosensor. By providing both of the light-emitting elements for reflection, and by arranging the light-receiving elements so that the light-receiving elements commonly receive the reflected light emitted from both light-emitting elements and reflected by the control toner image, The photo sensor is switched to one of a diffuse reflection type sensor and a regular reflection type sensor and can be used, and the sensitivity correction unit, even when using a regular reflection type sensor, reflects light reflected from the reference reflection surface. A process for correcting the sensitivity of the regular reflection type photosensor using the output value of the light receiving element when receiving light (the invention according to claim 17).

Further, in the density detecting apparatus according to the second aspect of the present invention having such a sensitivity correcting means, both the light emitting element for diffuse reflection and the light emitting element for specular reflection are provided as light emitting elements inside the support of the photo sensor. A diffuse reflection type sensor is provided by arranging the light receiving element such that the light receiving element commonly receives reflected light emitted from both light emitting elements and reflected by the control toner image. And a regular reflection type sensor, and the sensitivity correction means can be used when the reflected light from the reference reflection surface is received even when the regular reflection type sensor is used. The processing for correcting the sensitivity of the regular reflection type photosensor using the output value of the light receiving element is performed (the invention according to claim 18).

[0033]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Embodiment 1] FIG. 1 is a schematic diagram of a concentration detecting apparatus according to an embodiment of the present invention. The density detecting device 1 is formed on an image carrier (photosensitive drum or belt, intermediate transfer belt or drum, paper transport belt or drum, etc.) 2 in a color image forming apparatus such as a copying machine or a printer using an electrophotographic system. A photosensor 4 for optically detecting the density of a toner image (patch) _Tpatch for controlling image forming conditions, and a sensor controller 5 for controlling the operation and output signals of the photosensor 4 are provided.

The photo sensor 4 includes a first light emitting element 41 and a second light emitting element 42 such as a light emitting diode, a light receiving element 43 such as a photodiode, and the light emitting elements 41, 42 and the light receiving element 43 are accommodated and installed. A light-shielding holder 44 made of plastic as a supporting member, and a reference reflecting surface 45
And the main part is constituted.

The holder 44 has a substantially rectangular parallelepiped shape, that is, a box-like shape. The inside of the holder 44 irradiates the light H ₁ emitted from the first light emitting element 41 with an object (in this example, the control H ₁₎ . Toner image T _patch or image carrier 2)
Idemitsu Yokoro 46a and a certain diffuse reflection light H ₂ of the reflected light reflected from the irradiated object is incident on the holder 44 receiving element for guiding so as to exiting from within the holder 44 toward the and an optical path 46b for light incident to guide so as to be received in 43, the irradiation optical path 46c for guiding the reference reflecting surface 45 of light H ₃ emanating from the second light emitting element 42, the reflected light of the light H ₃ (hereinafter, Simply referred to as “reference reflected light”) H
A reflected light path 46d for guiding the light ₄ to the light receiving element 43 is formed. In the drawing, reference numeral 47a denotes a light exit opening formed in the holder 44, 47b denotes a light entrance opening formed in the holder 44, and 48 denotes light transmission made of glass, transparent plastic, or the like which is attached so as to cover the openings 47a and 47b. 49 indicates a sensor detection surface.

The photo sensor 4 according to this embodiment is a so-called diffuse reflection type photo sensor that receives specific diffuse reflection light H ₂ from an irradiation target and detects the density. Further, the second light emitting element 42 is not limited to having the same light emitting characteristics and the like as the first light emitting element 41, and may have a different one. Further, the reference reflecting surface 45 is formed by forming a part of the holder 44 as it is as a reflecting surface, and the reflecting surface 45 in this embodiment is formed integrally with the holder 43 at the time of plastic molding. The reflection characteristics of the reference reflection surface 45 may be other than a smooth surface (for example, a fine uneven surface, a saw-tooth surface).
, But are not particularly limited,
Usually, it is appropriately set according to the setting condition of the reference light receiving amount.

In general, the photosensor 4 may be any of a regular reflection type sensor and a diffuse reflection type sensor.
As shown in FIG. 2, if the amount of light received by the light receiving element 43 is large when there is no control toner image, the sensor output is saturated and the sensitivity (difference in output value) is reduced. Therefore, the light receiving amount of the light receiving element 43 is set to a lower “reference light receiving amount”. The setting (adjustment) of the reference light receiving amount includes the dimensions of the optical paths 46a, b, c, and d (particularly, the cross-sectional areas of the optical paths), the reflection characteristics of the reference reflecting surface 45, the first light emitting element 41 and the second light emitting element. The light emission amount of the element 42,
This is performed by appropriately setting the amount of light passing through the light amount adjusting means provided on the necessary optical paths 46a, b, c, and d as necessary.

Further, the photo sensor 4 has a structure in which the second light emitting element 42 irradiates the reference reflecting surface 45 exclusively. Therefore, as shown in FIG. 3, the dynamic range D1 of the received light amount of the second light-emitting element 42 reflected light H ₄ obtained from the reference reflecting surface 45 when irradiated with (sensor output), for example, the first Light H emitted from the light emitting element 41
A sensor (for example, a sensor shown in FIG. 8) configured to irradiate a part of _{1 on} the reference reflecting surface 45 becomes larger than a dynamic range D2 of a light receiving amount (a dashed line) of the sensor, and the accuracy of the sensor output value can be improved. There are advantages. Further, in the photosensor 4, the dynamic range of the received light amount of the reflected light from the control toner image and the received light amount of the reference reflected light from the reference reflecting surface 45 can be fully used by 100%.
It is possible to detect each reflected light with high accuracy without wasting loss and to standardize the reference reflected light.

On the other hand, the sensor controller 5 in the density detecting device 1 controls the light emitting operation and the light emitting amount of the first light emitting element 41 and the second light emitting element 42 and outputs the output value by the light receiving of the light receiving element 43. A correction process is performed according to a preset control program as necessary, and the corrected output value is transmitted to a central control unit or the like for performing a process of controlling image forming process conditions of the image forming apparatus as a sensor detection result. It is supposed to. Therefore, the sensor control 5 functions as sensitivity correction means for the photosensor 4.

Incidentally, in this embodiment, the density detection by the photo sensor 4 is performed at a preset time (for example, when the power of the image forming apparatus main body is turned on, when a specified time is reached, or when the specified number of image formation sheets is reached). Etc.). Further, the control toner image T _patch formed at the time of the density detection is formed on the image carrier 2 as a single-color toner image of each color having a predetermined density and dimensions by an image forming system of the image forming apparatus. ,
As the image carrier 2 moves, it is detected when the image carrier 2 passes immediately below the photosensor 4.

Next, the operation of the density detecting device will be described.
This will be described with reference to the flowchart of FIG.

In the image forming apparatus equipped with such a density detecting device 1, when it is determined that the preset density detecting time has come as described above (step 1: S
1) A process for correcting the sensitivity of the photosensor 4 and a detection of the density of the control toner image are executed by the central control unit and the sensor controller 5 on the image forming apparatus main body side according to a predetermined control program (S2).

First, the characteristics of the diffuse reflection type photosensor 4 will be described.
characteristic of the sensor output with respect to the toner amount per unit area of the _patch (V _{pa tch)} is adapted to obtain a result as shown in FIG. This characteristic is almost the same as that of the conventional diffuse reflection type sensor. In particular, the output on the (clean) image carrier surface where there is no control toner image on the image carrier 2 is almost zero. . In other words, since the surface of the image carrier 2 having no toner image has a low reflectance or a high diffusivity of diffuse reflection light, the light reflected on the surface and actually received by the light receiving element 43 is received. The amount of H ₂ becomes extremely small, and as a result, the sensor output value (V _clean ) at that time becomes a value close to almost zero.

In the conventional diffuse reflection type sensor, an output value: _Vclean obtained when the reflection characteristic on the surface of the clean image carrier 2 having no control toner image is normally detected. When an output value obtained when a control toner image is detected: V _patch divided by the reference output value: V _clean (V _patch / V _clean ) is used as a detection result, the value obtained by dividing the value is V _patch / V _clean. as shown in FIG. 6, the sensor output value: V for _{clea n} is a small value close to nearly zero, as described above, it becomes a large value to rapidly or infinity becomes increasing value. This allows
The darker the control toner image (the larger the amount of toner)
The sensor output becomes saturated and accurate detection measurement cannot be performed. In addition, if the sensor output value: V _{clean of the} image carrier 2 having no control toner image fluctuates even a little, the above-mentioned value (V _patch / V
_clean ) also fluctuates greatly, which also makes accurate detection measurement impossible.

Therefore, in this embodiment, the sensor
Output value: V_cleanInstead of the reflected light from the reference reflecting surface 45
H_FourSensor output value obtained by: V_standardBased on
It is used as a value. That is,
In step 2, as shown in the flowchart of FIG.
First, as a pre-process of the sensitivity correction process, the second light emitting element
The element 42 emits light (ON) and the light emitting element 4
Light H emitted from 2 _ThreeWas reflected by the reference reflecting surface 45
Reflected light H_FourIs detected by the sensor 4 (light receiving element 43).
(S10). And then you get
Output value: V_{stan dard}Is a control toner as shown in FIG.
This value is constant regardless of the amount of toner in the image.
For example, it is temporarily stored in a storage unit such as the sensor controller 5.
It is. Note that V_standardIs detected, the second light emitting element 4
No. 2 does not emit light (is turned off).

Subsequently, as a density detection operation, a predetermined control toner image (patch) _Tpatch is formed on the image carrier 2 by the image forming apparatus, and the photosensor 4 detects the toner image _Tpatch. (S11). Then, as a post-process of the sensitivity correction process, the sensor output value obtained at the time of detecting the density: _Vpatch is the previously stored reference output value:
Value divided by V _standard : (V _patch / V _standard ) ...
Is calculated (S12). This V _patch
Although the value of / V _standard is a detection result of the sensor as described later, this value is different from the value (V _patch / V _clean ) when V _clean is used as a reference, as shown in FIG. This can be obtained as a value that can be sufficiently identified with respect to an increase or decrease in the toner amount of the control toner image. Note that the detection results of this sensor include the output value of the light receiving element in a state where no light emission is performed by all the light emitting elements (when OFF)
So-called dark voltage: value of V ₀₀ was subtracted from the value of the detection result of the sensor, i.e. _{{(V patch -V 00) /} (V
It is more preferable to use ( _standard− V ₀₀ )} since a more accurate detection result can be obtained (this is the same for each sensor hereinafter).

Step 2 (steps 10-1)
After performing the sensitivity correction processing and density detection in 2),
The value calculated earlier is determined as the detection result of the photo sensor 4 (S3). Then, it is determined whether or not the detection result (sensor output value) exceeds a preset allowable range that requires setting change of the image forming process condition (S
4) It is unnecessary to change the setting of the image forming process conditions within the allowable range. However, when the value exceeds the allowable range, the setting change of the condition is required. Is performed (S5). Process conditions set according to the result of the density detection include, for example, an exposure light amount, a charging potential, a developing bias potential, and a toner density, but are not limited thereto.

By performing such sensitivity correction, as shown in FIG. 7, even if the density of the control toner image is high (even if the amount of toner is large), the sensitivity of the sensor is not saturated, and The image density is reliably detected and measured by the photo sensor 4.

As shown in FIG. 1, the reference reflecting surface 45 is provided inside the holder 44, and the detection surface 49 of the holder 44 covers the openings 47a and 47b with a dustproof member 48. Is provided, dust such as toner does not enter the inside of the holder 44 through the openings 47a and 47b, and the reflection surface 45 is not contaminated by the adhesion of the toner or the like. Therefore, the amount of the reflected light H ₄ reflected by the reference reflecting surface 45 is
4 does not fluctuate due to a change in the surface state. Therefore, the sensor output value V _standard due to the reflected light H ₄
Is also obtained as a stable value. Thereby, the output value (V _patch / V _standard ) which is the detection result of the photo sensor 4
Is also stable.

As described above, according to the density detecting device 1, even if the photo sensor 4 is of the diffuse reflection type, a sufficient sensor output can be obtained and the sensor sensitivity can be corrected very easily. And accurate detection results can be obtained. As a result, the control setting of the image forming process condition performed based on the detection result is also accurately performed.

[Embodiment 2] FIG. 8 is a schematic diagram of a concentration detecting apparatus according to another embodiment of the present invention. This density detecting device 1 includes the photo sensor 4 according to the first embodiment.
In place of the second light emitting element 42 in FIG.
Except employing a photosensor 40 having a second light receiving element 51 for receiving reflected light H ₄ from the one in which the same configuration as the concentration detection apparatus according to the first embodiment.

That is, the photo sensor 40 in this embodiment receives the diffused reflected light H ₂ from the surface of the image carrier 2 and the control toner image, and receives the _second (first) light receiving element 43 and the second light receiving element 43. Of the first light emitting element 4
The part of the light H ₅ of the light H ₁ emitted from the first irradiation light path 46
is irradiated on the reference reflecting surface 45 through a, has a structure to receive the reflected light H ₄ in which the light ₅ is reflected by the reference reflecting surface 45 through the reference optical path 46b to the second light receiving element 51. In addition, the second light receiving element 51 includes the first light receiving element 43.
The light receiving characteristics and the like are not limited to being the same, and may be different.

The density detecting device 1 provided with the photo sensor 40 is the same as the density detecting device according to the first embodiment except for the following points. .

That is, when the density detection time comes (FIG. 4), the sensitivity correction processing and the density detection are executed (FIG. 4).
"S2"), at this time, prior to the density detection operation, FIG.
A second light receiving element 51 causes received (ON) as shown in the flowchart of, so as to detect the reflected light H ₄ from the reference reflecting surface 45 by its second light receiving element 51 (S20). Thereby, the sensor output value V _standard of the reference reflection surface is obtained. After the detection of _Vstandard , the output value of the second light receiving element 51 is not detected (recognized), or even if it is detected, nothing is reflected on other processing.

Thereafter, in the same manner as in the first embodiment, the formation of the control toner image and the detection of the toner image by the sensor 4 (first light receiving element 43) are performed (S21). A value (V _patch / V _standard )... Obtained by dividing the sensor output value V _patch of the control toner image obtained at that time by the reference output value V _standard is calculated (S22). Then, when the calculated value is determined as the detection result of the photo sensor 40 (“S3” in FIG. 4), the control setting of the necessary image forming process conditions is performed based on the detection result (FIG. 4). "S4",
"S5").

[Embodiment 3] FIGS. 10 and 11 are a schematic sectional view and a bottom view (detection surface) showing a concentration detecting apparatus according to another embodiment of the present invention, and FIG.
11 shows a case where the cleaning member 6 for cleaning the detection surface 49 is provided on the photo sensor 4 in FIG. 11, and FIG. 11 shows a case where the cleaning member 6 for cleaning the detection surface 49 is provided in the photo sensor 40 in the second embodiment. .

That is, the cleaning member 6 shown in FIGS. 10 and 11 slides on the detection surface 49 (actually, the dustproof member 48) on the detection surface 49 side of each of the photosensors 4 and 40. It swings in the directions of arrows C and D about the rotating shaft 60 so that the light exit opening 47a and the light entrance opening 47b on the detection surface 49 are simultaneously opened and shielded. And this cleaning member 6
The surface that is in sliding contact with the detection surface 49 is made of a material that can remove foreign substances such as toner adhered to the detection surface by the sliding contact and does not damage the detection surface 49, and at least the openings 47a and 47b. Are formed of a material having a light-shielding property. The cleaning member 6 stops at the opening position P1 during non-cleaning (a in each drawing),
It is set so that it can be located at the light shielding position P2 at the time of cleaning. For example, it is oscillated (positions P1, P2) by driving means (not shown) controlled by the sensor controller 5 described above.
2).

Further, in the density detecting apparatus 1 provided with such a cleaning member 6, when the detection surface 49 is cleaned by the cleaning member 6 (strictly, when both the openings 47a and 47b are shielded from light).
In addition, the second light emitting element 42 or the second light receiving element 51 is operated so as to detect the reflected light H ₄ from the reference reflecting surface 45.

Next, main operations of the density detecting device according to each of the embodiments will be described.

In any of the density detecting devices 1, when not being cleaned, as shown in FIGS. 10A and 11A, respectively.
The cleaning member 6 is located at the opening position P1, and the light exit opening 47a and the light entrance opening 47b on the detection surface 49 of the photosensors 4 and 40 are simultaneously opened. Thus, both the photo sensor 4, 40, together with the light H ₁ from the first light emitting element 41 is made possible Idemitsu from the opening 47a to the outside of the holder 44, light H that is diffused and reflected by the toner image for control, etc. ₂ can enter the inside of the holder 44 (optical path 46b for entering light) from the opening 47b. As a result, the photosensors 4 and 40 can detect the density of the control toner image.

On the other hand, at the time of cleaning, as shown in FIGS. 10B and 11B, the cleaning member 6 is located at the light shielding position P2, and the light exit opening 47a and the light entrance opening 47b on the detection surface 49 of the photo sensor 4. Are simultaneously shielded from light. At the same time, the second light receiving element 51 or second light emitting element 42 emits light is received, the detection of the reflected light H ₄ from the reference reflecting surface 45 is performed.

[0063] At this time, the photosensor 4, the opening for light H ₆ is the light incident from the outside of the sensor as shown in FIG. 10b 47b
Therefore, only the reflected light H ₄ of the light H ₃ emitted from the second light emitting element 42 and reflected by the reference reflecting surface 45 is received by the light receiving element 43. Further, in the photo sensor 40, as shown in FIG. 11B, the light H ₆ from the outside of the sensor does not enter the light output optical path 46a through the light output opening 47a.
The reference reflecting surface 45 is irradiated with only a part of the light H ₅ from the light emitting element 41, and the reflected light H ₃ is applied to the second light receiving element 5.
1 is received. Only the reflected light H ₄ which but reflected by from is received by the light receiving element 43.

Therefore, both openings 47a, 47a
By the sensor detects the reference reflecting surface 45 while shielding the 47b, the respective since the opening extra external light H ₆ from does not enter the inside sensor, the reflected light H ₄ from the reference reflecting surface 45 the light-receiving elements ₄₃ , ₅₁ can receive light accurately. The output value V _st of the reference reflection surface detected in this way is
_andard may be temporarily stored in a predetermined storage unit and set so as to be used at the time of detecting the density of the control toner image, or at the time of this cleaning, as shown in FIGS. You may set so that density detection may be performed simultaneously. In any case, as a result, a more accurate output value V _standard of the reference reflection surface is obtained, and thus a more appropriate sensor output value (output result) can be obtained. Further, even in a sensor provided with such a cleaning member 6, as described above, the value {(V _patch -V ₀₀₎ obtained by subtracting the dark voltage V ₀₀ as the detection result of the sensor / (V
It is desirable to use _standard −V ₀₀ )｝.

Although the cleaning member 6 is of a type that simultaneously shields both openings 47a and 47b during light shielding, the cleaning member 6 has at least one of the openings 47a and 47b (preferably a sensor). The opening 47 in 4
The sensor b may have any configuration that can shield the opening 47a in the sensor 40).

[Embodiment 4] FIGS. 12 and 13 are schematic diagrams showing a density detecting apparatus according to another embodiment of the present invention. FIG. FIG. 13 shows a case where the adjusting mechanism 7 is provided, and FIG. 13 shows a case where the light amount adjusting means 7 is provided in the photosensor 40 in the second or third embodiment, respectively.

That is, in each of the photosensors 4 and 40, the light emitting element 4 passing through the irradiation light path is provided in the irradiation light path 46c between the light emitting elements 42 and 41 and the reference reflection surface 45.
A light amount adjusting mechanism 7 for adjusting the light amounts of the light beams H ₃ and H ₅ from the light sources 2 and 41 is provided. This light amount adjustment mechanism 7
Is set so that the sensor controller 5 adjusts the light amount to a plurality of levels. The light amount adjusting mechanism 7 is applicable as long as the light amount can be adjusted in at least a plurality of stages. For example, an aperture mechanism such as a shutter aperture of a camera, or a light source that traverses an optical path is used. Shutter mechanism that can change the optical path cross-sectional area by sliding movement, and a filter that uses filter means that can uniformly change the amount of light transmission over the entire surface, such as a liquid crystal filter that can change the light transmittance A mechanism or the like is applied. The light amount adjusting mechanism 7 includes a reference light path 46 between the reference reflection surface 45 and the light receiving elements 43 and 51.
It may be provided on the d side. In this case, the optical H ₄ reflected by the reference reflecting surface 45 is to adjust the amount of light passing through the reference optical path.

In the density detecting apparatus 1 provided with such a light amount adjusting mechanism 7, the light amount adjusting mechanism 7 can set the light amount level (0, 1, 2,. ) And the reference reflected light H ₄ from the reference reflecting surface 45 at each light amount level.
By measuring the output characteristics of the light receiving elements 43 and 51 that have received light, and examining the results in comparison with the output characteristics of the light receiving elements at the initial stage, necessary correction processing is performed on the output results of the photo sensor 4. Is set. The output characteristics of the light-receiving element in the initial stage include the same light amount as described above in a preset reference period, for example, the initial stage in which the photo sensor 4 is mounted on the image forming apparatus and the image forming operation by the apparatus is enabled. The value measured at the level (each reference output value) is used.

FIG. 14 shows the light H emitted from the light emitting elements 42 and 41 to the reference reflecting surface 45 by the light amount adjusting mechanism 7 arranged in the irradiation optical path 46c in the embodiment shown in FIGS. ₃ The light quantity of (H ₅ ) is switched to a plurality of preset light quantity levels 0, 1, and 2 to
3 (51) shows the results of measuring the output characteristics of the light receiving element when receiving light, respectively. As shown in this figure, for example, when offset adjustment is required,
A result is obtained in which the measured output characteristic always increases (or decreases) by the same amount (offset amount S) with respect to the normal initial characteristic at each of the light amount levels 0, 1, and 2. on the other hand,
When the gain adjustment is required, the measured output characteristics are regularly or irregularly proportioned to the normal initial characteristics (gain amounts G ₁ , G ₂ ) as the light amount levels 0, 1, 2 change. Decreases (or increases).

Therefore, by examining the output characteristics obtained by switching the light amount level in a plurality of stages in comparison with the output characteristics in the normal initial stage, the output characteristics of the photosensor 4 are offset by the offset amount or the gain amount. Since it is found that there is a characteristic variation (difference information), the detection result of the photo sensor 4 is corrected based on the difference information. This is also the sensitivity correction of the sensor using the output of the reflected light H ₄ from the reference reflecting surface 45. The correction at this time is performed by adding or subtracting the offset amount or the gain amount in the light amount level of the light emitting elements 42 and 41 when irradiating the control toner image to the output value of the light receiving elements 43 and 51 during the irradiation. Software (by processing operation on data)
Will be corrected. In addition, the output control circuit of the light emitting elements 42 and 41 or the light receiving elements 43 and 51 for irradiating the control toner image feeds back the difference information of the offset amount or the gain amount to the sensor controller 5 to output the output characteristic of the element. May be corrected by controlling.

FIG. 15 shows a case where the light amount adjusting mechanism 7 is provided in the reflection optical path 46d instead of the irradiation optical path 46c in the embodiment shown in FIGS. From the light receiving element 43 (5
By switching the plurality of light intensity levels 0, 1, 2 set in advance the amount of the reference reflected light H ₄ reaching 1) light-receiving element 43
(51) shows the result of measuring the output characteristics of the light receiving element when receiving light, respectively. In this case as well, similar to the above-described case (FIG. 14), the same correction processing based on the characteristic variation (difference information) corresponding to the offset amount or the gain amount relating to the output characteristic of the photosensor 4 is performed.

[Fifth Embodiment] FIGS. 16 and 17 are schematic views showing a density detecting apparatus according to another embodiment of the present invention. FIG. 16 shows the photosensor 4 in the first, third or fourth embodiment. Is provided with a monitor light receiving element 52,
FIG. 17 shows a case where the photosensor 40 according to the second, third, or fourth embodiment includes the reference light emitting element 53, respectively.

That is, in the photo sensor 4, the light H ₁ and H ₅ emitted from the first light emitting element 41 and the second light emitting element 42 can be received in common through the guiding optical paths 46e and 46f, respectively. A light receiving element 52 is additionally provided. The light receiving element 52 and the guide light paths 46e and 46f
The arrangement position and the like are arbitrary as long as the common light emission amount can be monitored. On the other hand, the photo sensor 40
In this embodiment, a reference light emitting element 53 for emitting light for irradiating the first light receiving element 43 and the second light receiving element 51 in common via the auxiliary light paths 46g and 46h is additionally provided. The arrangement of the light receiving element 43 and the auxiliary optical paths 46g and 46h is arbitrary as long as the above-mentioned common light irradiation is possible.

The density detecting device 1 provided with such a light receiving element 52 for monitoring or a light emitting element 53 for reference.
Are set such that the following correction is performed on the detection result of the photo sensor 4.

That is, at a preset time (for example,
For example, in the initial stage when the photo sensor 4 is attached to the image forming apparatus and the image forming operation by the apparatus is enabled), in the photo sensor 4, the first light emitting element 41 and the second The light emission amounts (H ₁ , H ₅ ) of the light emitting elements 42 are measured, and the respective light emitting elements 41,
42, a difference (variation amount) from the light emission characteristic in the initial stage is obtained, and the difference is converted into a correction coefficient k that has been collated in advance to compensate for the difference, and the correction coefficient k is stored in a storage unit such as the sensor controller 5. It is memorized. Then, by multiplying (multiplying) the detection result (V _patch / V _standard ) of the photosensor 4 regarding the density of the control toner image obtained after the monitoring by the correction coefficient k, the detection result is obtained by the light emitting elements 41 and 42. Is set so as to be corrected in accordance with the amount of change.

On the other hand, in the photo sensor 40, the light emitted from the reference light emitting element 53 is shared by the first light receiving element 43 and the second light receiving element 51 at the above-mentioned preset time. The amount of light received at the time of irradiation is measured to obtain a difference (variation) between the light-emitting characteristics of each of the light-receiving elements 43 and 51 in the initial stage, and is converted into a correction coefficient m that has been collated in advance to compensate for the difference. After that, the correction coefficient m is stored in the storage unit in the same manner as in the above case. Then, the detection result of the photosensor 4 regarding the density of the control toner image obtained after the common irradiation (V _patch / V
_standard ) multiplied by the correction coefficient m (multiplied)
Thus, the detection result is set to be corrected according to the variation of the light receiving elements 43 and 51.

[Embodiment 6] FIGS. 18 and 19 are schematic views showing a density detecting apparatus according to another embodiment of the present invention. FIG. 18 shows a photodetector according to Embodiment 1, 3, 4 or 5. FIG. 19 shows a case where the sensor 4 is a diffuse reflection type and regular reflection type sensor, and FIG. 19 shows a case where the photosensor 40 in the second, third, fourth or fifth embodiment is a diffuse reflection type and regular reflection type sensor. .

That is, in each of the photosensors 4 and 40, the light emitting element 56 for diffuse reflection is used as the light emitting element.
And a light-emitting element 57 for specular reflection.
The diffused reflected light H ₃ and the regular reflected light H ₈ obtained when the control toner image is irradiated with the irradiation lights H ₆ and H ₇ emitted from the light receiving elements ₆ and 57 are shared by one (shared) light receiving element 43. In this case, light is received, and either one of the diffuse reflection type sensor and the regular reflection type sensor can be used.

When the density detecting device 1 having the diffuse reflection type and regular reflection type photosensors 4 and 40 is used as a diffuse reflection type sensor, the density detection device 1 diffuses and reflects light from the control toner image. The output value V _patch of the light receiving element 43 when H ₃ is received, and the reflected light H ₄ from the reference reflecting surface 45 is received by irradiation from the light emitting element 42 (57) as described in the first embodiment. _{Divided by} the output value V _{standa rd} of the light receiving element 43 at the time (V _patch / V
_standard ) is set as the detection result of the diffuse reflection type sensor, and even when used as a specular reflection type sensor, the value processed in the same way as above is set as the detection result of the specular reflection type sensor. I have. That is, the output value V _patch of the light receiving element 43 when receiving the regular reflection light H ₈ from the control toner image is received, and the reflection light H ₄ from the reference reflection surface 45 is received by irradiation from the light emitting element 42 (57). The value (V _patch / V _standard ) divided by the output value V _standard of the light receiving element 43 at this time is used as the detection result of the specular reflection sensor.

According to such a density detecting device 1, for example, when the control toner image is an image composed of color toner, the photo sensor 4 is used as a diffuse reflection type sensor, and the control toner image is If the image is made of black toner, it can be used as a regular reflection sensor and used to detect the density of each control toner image. Moreover, even when used as a diffuse reflection type or specular reflection type sensor, a sufficient sensor output can be obtained,
The sensor sensitivity can be corrected very easily,
An accurate detection result can be obtained. As a result, even in an image forming apparatus in which the control toner image is formed by both the color toner and the black toner, the control setting of the image forming process conditions is performed based on the accurate detection result obtained individually by each type of sensor. Can be performed more accurately.

[Other Embodiments] In the first to sixth embodiments, the case where a part of the holder 44 is formed as the reference reflection surface 45 as the photosensors 4 and 40 has been exemplified. A sensor configured such that a reference reflection plate (member) separate from 44 is attached to the formation portion of the reference reflection surface 45 in the holder 44 and the surface of the reflection plate is used as the reference reflection surface 45 may be used. . In this case, as long as the reference reflecting plate used as the reference reflecting surface 45 has a surface (one side) capable of obtaining the reflection characteristics required for setting the reference light receiving amount, the material, structure, and the like are particularly limited. Not something. Specifically, for example, a plate formed of a synthetic resin or the like as a white or gray flat plate and configured to obtain diffuse reflected light (or specular reflected light) on the surface thereof can be used.

The density detecting apparatus 1 according to the first to sixth embodiments is mainly used for a digital color image forming apparatus. In addition, an analog type color image forming apparatus, a digital type It may be used for an analog type monochrome image forming apparatus. Further, the image carrier on which the control toner image is formed is connected to the photosensors 4 and 40 of the density detecting device 1.
If optical detection by is possible, as described above,
The type, form, and the like are not specifically limited.

[0083]

As described above, according to the present invention,
Even if the sensitivity of the photo sensor of the density detection device fluctuates, it is possible to obtain a stable detection result easily and accurately even if the sensitivity of the photo sensor of the density detection device fluctuates without incurring a significant cost increase by adding light emitting elements and light receiving elements. it can. In particular, it is possible to arbitrarily and easily obtain an output value that receives light reflected from the reference reflection surface only by turning ON / OFF the second light emitting element or the second light receiving element.

Further, as compared with the conventional example in which the calibration plate is provided outside the sensor, the sensitivity of the sensor can be corrected more accurately, easily, and stably without variation. As a result, the image forming condition (image forming process condition) of the image forming apparatus can be more accurately and stably controlled by using the accurate detection result of the sensor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a density detection device according to a first embodiment.

FIG. 2 is a correlation diagram showing the relationship between the amount of received light and the sensitivity specification in a sensor, where (a) shows a case of a regular reflection type sensor and (b)
Indicates the case of a diffuse reflection type sensor.

FIG. 3 is a diagram for explaining sensor output characteristics by receiving light reflected from a reference reflection surface of the photosensor according to the first embodiment;

FIG. 4 is a flowchart showing operation contents of a control system relating to density detection, sensitivity correction, and process condition setting.

FIG. 5 is a flowchart showing an operation content of a control system related to sensitivity correction according to the first embodiment.

FIG. 6 is an explanatory diagram showing output characteristics of the diffuse reflection sensor according to the first embodiment.

FIG. 7 is an explanatory diagram illustrating a state of a detection result (value divided) obtained by using an output value of the diffuse reflection sensor according to the first embodiment and a conventional example.

FIG. 8 is a schematic diagram of a density detection device according to a second embodiment.

FIG. 9 is a flowchart showing an operation content of a control system relating to sensitivity correction according to the second embodiment.

10A and 10B are a schematic cross-sectional view and a bottom view showing a density detecting device according to a third embodiment on the premise of the photosensor of the first embodiment, wherein FIG. 10A shows a state when no cleaning is performed, and FIG. Indicates the state of time.

FIGS. 11A and 11B are a schematic cross-sectional view and a bottom view showing a density detecting device according to a third embodiment on the premise of the photosensor of the second embodiment, where FIG. 11A shows a state without cleaning, and FIG. Indicates the state of time.

FIG. 12 is a schematic diagram showing a density detection device according to a fourth embodiment on the premise of the photosensor of the first or third embodiment.

FIG. 13 is a schematic diagram showing a density detection device according to a fourth embodiment on the premise of the photosensor of the second or third embodiment.

FIG. 14 is a diagram illustrating an example of a measurement result of an output characteristic when a light amount adjustment mechanism is provided in an irradiation optical path according to a fourth embodiment.

FIG. 15 is a diagram illustrating an example of a measurement result of an output characteristic when a light amount adjustment mechanism is provided in a reference optical path in the fourth embodiment.

FIG. 16 is a schematic diagram showing a density detecting device according to a fifth embodiment based on the photosensor of the first, third, or fourth embodiment.

FIG. 17 is a schematic diagram showing a density detection device according to a fifth embodiment on the premise of the photosensor of the second, third, or fourth embodiment.

FIG. 18 is a schematic diagram showing a density detecting device according to a sixth embodiment based on the photosensor of the first, third, fourth, or fifth embodiment.

FIG. 19 is a schematic diagram showing a density detecting device according to a sixth embodiment based on the photosensor of the second, third, fourth, or fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Density detection device, 2 ... Image carrier, 4, 40 ... Photocell
Sensor, 5 ... sensor controller (sensitivity correction means), 6
... Cleaning member, 7 ... Light amount adjusting means, 41 ... (First) light emission
Element, 42... Second light receiving element, 43... (First) light receiving element
Child, 44: holder (support), 45: reference reflection surface, 47
a: light exit aperture, 47b: light entrance aperture, 49: detection surface,
51: second light receiving element, 52: light receiving element for monitor,
53: Light emitting element for reference, 56: Light emitting element for diffuse reflection
57, a light-emitting element for regular reflection, T _patch… Toner for control
-Statue.

Continued on the front page (72) Inventor Toru Yoshida 2274 Hongo, Ebina-shi, Kanagawa Prefecture, F-term in Fuji Xerox Co., Ltd. (reference) 2G059 AA01 BB20 EE02 FF08 KK01 LL04 MM05 MM14 MM17 MM18 2H077 CA11 DA03 DA47 DA63 DA93 DB02 DB08 DB12 DB22 GA12

Claims (18)

[Claims] 1. A light emitting element for emitting irradiation light for irradiating a control toner image formed on an image carrier of an image forming apparatus, and a light receiving element for receiving at least reflected light of the irradiation light reflected by the toner image. A density detection device for detecting the density of the toner image based on an output of a light receiving element in the photo sensor, wherein the photo sensor is provided inside the box-shaped support; Inside the support, a second light-emitting element was provided separately from the light-emitting element, and a reference reflection surface was provided, in which light emitted from the second light-emitting element was irradiated and the reflected light was received by the light-receiving element. A density detector for an image forming apparatus. 2. A light-emitting element for emitting irradiation light for irradiating a control toner image formed on an image carrier of an image forming apparatus, and a light-receiving element for receiving at least reflected light of the irradiation light reflected by the toner image. A density detection device for detecting the density of the toner image based on an output of a light receiving element in the photo sensor, wherein the photo sensor is provided inside the box-shaped support; A reference reflection surface on which a part of light emitted from the light emitting element is irradiated is provided inside the support, and a second light receiving element for receiving light reflected from the reference reflection surface is provided separately from the light receiving element. A density detecting device for an image forming apparatus. 3. The density detecting device according to claim 1, wherein
The support surface of the photosensor slides on a detection surface provided with a light exit opening and a light entrance opening of the support, and moves so as to open or shield at least one of the two openings. A density detecting device provided with a cleaning member for cleaning the image. 4. The density detecting device according to claim 2, wherein
The support surface of the photosensor slides on a detection surface provided with a light exit opening and a light entrance opening of the support, and moves so as to open or shield at least one of the two openings. A density detecting device provided with a cleaning member for cleaning the image. 5. The density detecting device according to claim 1, wherein
A light amount adjusting means for adjusting an amount of light passing through the optical path from the second light emitting element of the support of the photo sensor to the light receiving element via the reference reflecting surface is provided. apparatus. 6. The density detecting device according to claim 2, wherein
A density detecting means, wherein a light amount adjusting means for adjusting a light amount passing through the optical path is provided in an optical path from the light emitting element of the support of the photo sensor to the second light receiving element via the reference reflecting surface. apparatus. 7. The density detecting device according to claim 1, wherein light emitted from the second light emitting element is reflected by a reference reflecting surface and received by the light receiving element. A density detecting device comprising sensitivity correction means for correcting the sensitivity of the photosensor using an output value. 8. The density detecting device according to claim 2, wherein light emitted from said light emitting element is reflected by a reference reflection surface and received by said second light receiving element. A density detecting device comprising sensitivity correction means for correcting the sensitivity of the photosensor using an output value. 9. The density detecting device according to claim 7, wherein
The sensitivity correction means is a value obtained by dividing an output value of the light receiving element when receiving reflected light from the control toner image by an output value of the light receiving element when receiving reflected light from the reference reflecting surface. A density detection device that performs a process based on a detection result of a photosensor. 10. The density detecting device according to claim 8, wherein the sensitivity correction means calculates an output value of the light receiving element when receiving a reflected light from the control toner image and calculates a reflected light from a reference reflecting surface. A density detecting apparatus, wherein a value obtained by dividing the output value of the second light receiving element when receiving light is used as a detection result of a photo sensor. 11. The density detecting device according to claim 7, wherein when the cleaning member is provided, the sensitivity correction unit is configured to move the cleaning member during cleaning to shield at least one of the openings. A concentration detecting device set to emit light by the second light emitting element. 12. The density detecting device according to claim 8, wherein, when the cleaning member is provided, the sensitivity correction means is configured to move the cleaning member during cleaning to shield at least one of the openings. A concentration detection device configured to perform light reception by a second light receiving element. 13. The density detecting device according to claim 7, wherein when the light quantity adjusting means is provided, the sensitivity correction means uses the light quantity adjusting means to irradiate the light from the second light emitting element to the reference reflection surface. Each output value of the light receiving element when the light amount of the reflected light from the reference reflection surface to the light receiving element is changed in a plurality of steps, and each output value of the light receiving element when the light amount is similarly changed in the plurality of steps at the reference time In comparison with the reference output value, a process of correcting the detection result of the photo sensor by software based on the difference information between the two output values and performing offset and gain adjustment, or a light emitting element or A density detecting device for performing a process of adjusting an offset and a gain by feedback-controlling an output of a light receiving element. 14. The density detecting device according to claim 8, wherein, when the light amount adjusting means is provided, the sensitivity correcting means uses the light amount adjusting means to irradiate the light from the second light emitting element to the reference reflecting surface. Each output value of the light receiving element when the light amount of the reflected light from the reference reflection surface to the light receiving element is changed in a plurality of steps, and each output value of the light receiving element when the light amount is similarly changed in the plurality of steps at the reference time In comparison with the reference output value, a process of correcting the detection result of the photo sensor by software based on the difference information between the two output values and performing offset and gain adjustment, or a light emitting element or A density detecting device for performing a process of adjusting an offset and a gain by feedback-controlling an output of a light receiving element. 15. The monitor according to claim 7, wherein each light emitted from all of the plurality of light emitting elements including the second light emitting element is received in common inside the support of the photo sensor. A light-receiving element for monitoring, and the sensitivity correction means stores in advance, as a correction coefficient, a variation in the light amount characteristic of each light-emitting element obtained by the light-receiving element for monitoring, and the correction coefficient Multiplying the detection result of the photosensor by the multiplication of the photosensor to correct the detection result. 16. The density detecting device according to claim 8, wherein a reference light for emitting light for irradiating all of the plurality of light receiving elements including the second light receiving element in the support of the photo sensor is provided. One light emitting element is provided, and the sensitivity correction means stores in advance a variation of the light receiving characteristic of each light receiving element obtained by the reference light emitting element as a correction coefficient, and stores the correction coefficient in a photo A density detection device that performs a process of multiplying a detection result of a sensor and correcting the detection result. 17. The density detecting device according to claim 7, wherein both a light emitting element for diffuse reflection and a light emitting element for specular reflection are provided inside the support of the photosensor as light emitting elements excluding the second light emitting element. In addition, by disposing the light receiving element so that the reflected light emitted from both of the light emitting elements and reflected by the control toner image is received by the light receiving element in common, the photo sensor is a diffuse reflection type sensor. It can be switched to any one of the regular reflection type sensors and can be used, and the sensitivity correction means, even when using the regular reflection type sensor, receives the reflected light from the reference reflection surface. What is claimed is: 1. A density detecting device for performing processing for correcting the sensitivity of a regular reflection photosensor using an output value. 18. The concentration detecting device according to claim 8, wherein both a light emitting element for diffuse reflection and a light emitting element for regular reflection are provided as light emitting elements inside the support of the photosensor. The light receiving element is disposed such that the light receiving element emits the reflected light reflected by the control toner image in common with the light receiving element, so that the photo sensor can be either a diffuse reflection type sensor or a regular reflection type sensor. The sensitivity correction means can be switched to one of them, and the sensitivity correction means can receive the reflected light from the reference reflection surface even when using the regular reflection type sensor.
A density correction device for performing a process of correcting the sensitivity of the regular reflection type photosensor using the output value of the light receiving element.