JP2008233024A - Optical sensor, image forming device, and assembling method of image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor that can secure the measuring accuracy even when diffusion reflected light quantity from an irradiating object (image carrier) is small, and can contribute to simplification of the image density control and the improvement of reliability. <P>SOLUTION: This optical sensor 1A comprises a mounting substrate 2, an LED 3, a photo-transistor 4 for regularly reflected light, a photo-transistor 5 for diffusion reflected light. The LED 3 is arranged between light receiving means. A polarizing filter 8 for irradiation is installed on the optical path between the LED 3 and a transfer belt 18. A polarizing filter 9 for receiving regularly reflected light is installed on the optical path between the photo-transistor 4 for regularly reflected light and the transfer belt 18. A polarizing filter as a reduction factor of the diffusion reflected light quantity is not disposed on the optical path between the transfer belt 18 and photo-transistor 5 for diffusion reflected light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an optical sensor that receives reflected light of incident light irradiated on an irradiation object, a copier, a printer, a facsimile, a plotter using the optical sensor, a multifunction machine including at least one of these, and the like. The present invention relates to an image forming apparatus and an assembling method of the image forming apparatus.
The present invention can be applied to the measurement of the amount of powder or liquid adhering to the surface of an object that reflects regular reflection light.

In an image forming apparatus such as a copying machine, a printer, or a facsimile, a toner patch for density detection is created on the surface of an image carrier such as an intermediate transfer body in order to obtain a desired image density, and the density of the patch is detected by an optical sensor. There is something to do.
The image forming apparatus performs image density control (process control) such as adjusting the writing light intensity for forming a latent image, a charging bias, and a developing bias based on the detection result by the optical sensor. As the optical sensor, a reflection type optical sensor including a light emitting unit and a light receiving unit is generally used.
The light emitted from the light emitting means is specularly reflected on the surface of the image carrier, but hardly specularly reflected on the toner. Therefore, the output of the light receiving means decreases in inverse proportion to the toner adhesion amount. The optical sensor uses this to measure the toner adhesion amount.

However, in the color toner, when the toner adhesion amount increases, the diffuse reflection light increases. Therefore, when the toner adhesion amount exceeds a certain amount, the output of the light receiving means starts to decrease and increases. An example is shown in FIG. For this reason, an error occurs in the measurement of the adhesion amount.
For this problem, by providing a polarizing filter having a parallel polarization direction between the light emitting means and the image carrier and between the image carrier and the light receiving means, and regulating the polarization directions of the light emission and the light reception, It is known to prevent the diffusely reflected light from being received by the light receiving means for specularly reflected light. (For example, Patent Document 1 and Patent Document 2)

JP 2006-208266 A JP 2006-267139 A JP-A-2005-91252 JP 2006-208266 A JP 2003-121356 A Japanese Unexamined Patent Publication No. 8-219990

However, in Patent Documents 1 and 2, the specular reflection light receiving means for receiving specular reflection light and the diffuse reflection light receiving means for receiving diffuse reflection light are arranged side by side. In order to prevent light from entering, the irradiation polarizing filter provided on the optical path between the light emitting means and the irradiation target is perpendicular to the optical path between the irradiation target and the diffuse reflection light receiving means. It has been necessary to dispose a diffuse reflection light polarizing filter so that the polarization direction is aligned.
However, in this case, if a polarizing filter for diffuse reflection light is arranged, the amount of light is attenuated by this polarizing filter, so that the amount of light reaching the diffuse reflection light receiving means decreases, and the measurement accuracy when the amount of diffuse reflection light from the irradiation object is small Had the side effect of lowering.

The present invention provides an optical sensor capable of ensuring measurement accuracy even when the amount of diffusely reflected light from an irradiation object is small, contributing to simplification of image density control and improving reliability, and an image forming apparatus having the optical sensor. And its purpose.
Also, the amount of diffusely reflected light from the object to be irradiated may be too high, resulting in a decrease in measurement accuracy. Even in such a case, measurement accuracy can be ensured, and image density control can be simplified and reliability can be improved. An object of the present invention is to provide an optical sensor, an image forming apparatus having the optical sensor, and a method for assembling the image forming apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a mounting substrate, light emitting means mounted on the mounting substrate, and regular reflection light received from the light emitting means and reflected by an irradiation object. An optical sensor comprising: a reflected light receiving unit; and a diffuse reflected light receiving unit that receives diffuse reflected light that is irradiated from the light emitting unit and reflected by the irradiation object, wherein the light emitting unit includes the regular reflected light receiving unit and the An illuminating polarizing filter is provided on the optical path between the light emitting means and the irradiation object, and the irradiation object and the specular reflection light receiving means. A polarizing filter for receiving regular reflection light is provided on the optical path between the two, and the optical path between the irradiation object and the diffuse reflection light receiving means is open.

  According to a second aspect of the present invention, there is provided a mounting substrate, a light emitting unit mounted on the mounting substrate, a regular reflection light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by an irradiation object, and the light emission. A diffuse reflected light receiving means for receiving diffuse reflected light that is irradiated from the means and reflected by the irradiation object, wherein the light emitting means is between the regular reflected light receiving means and the diffuse reflected light receiving means. And an illuminating polarizing filter is provided on the optical path between the light emitting means and the irradiation object, and is regularly reflected on the optical path between the irradiation object and the regular reflection light receiving means. A light receiving polarization filter is provided, and a mounting portion to which the diffuse reflection light receiving polarization filter can be attached is provided on the optical path between the irradiation object and the diffuse reflection light receiving means. Characterize

  According to a third aspect of the present invention, there is provided a mounting substrate, a light emitting unit mounted on the mounting substrate, a regular reflection light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by an irradiation object, and the light emission. A diffuse reflected light receiving means for receiving diffuse reflected light that is irradiated from the means and reflected by the irradiation object, wherein the light emitting means is between the regular reflected light receiving means and the diffuse reflected light receiving means. And an illuminating polarizing filter is provided on the optical path between the light emitting means and the irradiation object, and is regularly reflected on the optical path between the irradiation object and the regular reflection light receiving means. A light receiving polarization filter is provided, and on the optical path between the irradiation object and the diffuse reflected light receiving means, there is a mounting portion to which a diffuse reflected light condensing lens for condensing the diffuse reflected light can be attached. What is provided And features.

  According to a fourth aspect of the present invention, there is provided a mounting substrate, a light emitting unit mounted on the mounting substrate, a regular reflection light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by an irradiation object, and the light emission. A diffuse reflected light receiving means for receiving diffuse reflected light that is irradiated from the means and reflected by the irradiation object, wherein the light emitting means is between the regular reflected light receiving means and the diffuse reflected light receiving means. And an illuminating polarizing filter is provided on the optical path between the light emitting means and the irradiation object, and is regularly reflected on the optical path between the irradiation object and the regular reflection light receiving means. A light receiving polarization filter is provided, and on the optical path between the irradiation object and the diffuse reflected light receiving means, there is a mounting portion to which a diffuse reflected light attenuating filter for reducing the diffuse reflected light can be attached. It is provided The features.

  According to a fifth aspect of the present invention, there is provided a mounting substrate, a light emitting unit mounted on the mounting substrate, a regular reflection light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by an irradiation object, and the light emission. A diffuse reflected light receiving means for receiving diffuse reflected light that is irradiated from the means and reflected by the irradiation object, wherein the light emitting means is between the regular reflected light receiving means and the diffuse reflected light receiving means. And an illuminating polarizing filter is provided on the optical path between the light emitting means and the irradiation object, and is regularly reflected on the optical path between the irradiation object and the regular reflection light receiving means. A light receiving polarization filter is provided, and the diffuse reflected light receiving polarizing filter and the diffuse reflected light collecting light that condenses the diffuse reflected light are disposed on an optical path between the irradiation object and the diffuse reflected light receiving means. Light lens and diffuse reflection The together, and either one of the diffuse reflection light ND filter dimming, characterized in that the attachment portion that is attachable is provided.

According to a sixth aspect of the present invention, in the optical sensor according to any one of the second to fifth aspects, the mounting portion includes the diffuse reflection light receiving polarization filter, the diffuse reflection light condensing lens, or the diffusion. It has a slit-like or stepped structure that can be fitted with a reflected light attenuation filter.
According to a seventh aspect of the present invention, in the optical sensor according to any one of the first to sixth aspects, the light emitting means is disposed so as to emit light substantially parallel to the mounting surface of the mounting substrate. And the regular reflection light receiving means and the diffuse reflection light receiving means are arranged so as to receive light substantially parallel to the mounting surface of the mounting substrate.

According to an eighth aspect of the present invention, in the optical sensor according to any one of the first to seventh aspects, the light irradiated from the light emitting unit is collected on an optical path between the light emitting unit and the irradiation object. An illumination light condensing lens that emits light is provided.
According to a ninth aspect of the present invention, in the optical sensor according to any one of the first to eighth aspects, the irradiation from the light emitting unit onto the optical path between the regular reflection light receiving unit and the irradiation object. A specular reflection light condensing lens for condensing specular reflection light of the light irradiated to the object is provided.

According to a tenth aspect of the present invention, in the optical sensor according to any one of the first to ninth aspects, the irradiation polarizing filter and the regular reflection light receiving polarizing filter are integrally formed. To do.
According to an eleventh aspect of the present invention, in the optical sensor according to any one of the first to seventh aspects, the irradiation polarizing filter has a function of condensing the light irradiated from the light emitting means. And
According to a twelfth aspect of the present invention, in the optical sensor according to any one of the first, second, third, fourth, fifth, sixth, seventh, and eleventh aspects, the polarizing filter for receiving regular reflection light is the light emitting means. It has a function which condenses the regular reflection light of the light irradiated to the said irradiation target object from.

  According to a thirteenth aspect of the present invention, an image carrier having a surface for regularly reflecting light, a toner image forming unit for forming a toner image on the image carrier, and the toner image forming unit on the image carrier. An image forming apparatus comprising: an optical sensor for detecting an amount of toner adhesion when toner is adhered; and an image density control unit that performs image density control based on a detection result of the optical sensor. The optical sensor according to any one of claims 1 to 12 is used as a sensor.

  In the invention described in claim 14, the mounting substrate, the light emitting means mounted on the mounting substrate, the specularly reflected light receiving means for receiving the specularly reflected light irradiated from the light emitting means and reflected by the image carrier, and the light emission A diffuse reflected light receiving means for receiving the diffuse reflected light emitted from the means and reflected by the image carrier, and the light emitting means is disposed between the regular reflected light receiving means and the diffuse reflected light receiving means. A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and for receiving the regular reflection light on the optical path between the image carrier and the regular reflection light receiving means. An assembly method of an image forming apparatus including an optical sensor provided with a polarizing filter, wherein a mounting portion to which an optical element can be attached is provided on an optical path between the image carrier and the diffuse reflection light receiving means. Diffusion reaction from the image carrier By mounting an optical element on the mounting part by the degree of light intensity and adjusts the diffuse reflected light.

According to a fifteenth aspect of the present invention, in the method for assembling the image forming apparatus according to the fourteenth aspect, when the diffuse reflection light quantity exceeds a predetermined value, a diffused reflected light receiving polarization filter and a diffusion are used as the optical element in the mounting portion. At least one of the diffuse reflection light attenuating filters for reducing the reflected light is attached, and if the value is below a predetermined value, both the diffuse reflection light receiving polarizing filter and the diffuse reflection light attenuation filter are attached to the attachment portion. It is characterized by not.
According to a sixteenth aspect of the present invention, in the method for assembling the image forming apparatus according to the fourteenth aspect, when the amount of diffusely reflected light is a predetermined value or less, the diffusely reflected light that condenses the diffusely reflected light as the optical element on the mounting portion. A condensing lens is attached.

According to the present invention, even when the amount of diffusely reflected light from the irradiated control object is small, it is possible to make it incident on the diffusely reflected light receiving means without attenuating the amount of light, and the measurement accuracy is improved.
Since the light emitting means and the light receiving means are provided so that light emission and light reception are substantially parallel to the mounting surface of the mounting substrate, the warpage and vibration of the substrate in the direction parallel to the optical path can be reduced, and the diffused light is reliably It is possible to prevent the regular reflection light from entering the light receiving means, and it is possible to perform stable and accurate measurement without changing the incident angle of the regular reflection light to the light receiving polarizing filter. .

Condensing the irradiation light with the irradiation light condensing lens makes it possible to control the size and direction of the irradiation light on the image carrier, so that the regular reflection light is more incident on the diffuse reflection light receiving means. Thus, it is possible to prevent it reliably, and a more accurate measurement result of toner density can be obtained.
By condensing the specularly reflected light by the specularly reflecting light condensing lens, it is possible to control the size of the light receiving range on the image carrier, so that the toner density can be measured more accurately. Become.
Since the polarizing filter for irradiation and the polarizing filter for receiving reflected light are integrated into a single polarizing filter, the polarization direction of the polarizing filter for irradiating and receiving reflected light is precisely the same without increasing assembly time. It becomes possible to.

Since the irradiation polarizing filter has a function of condensing the irradiation light, the size of the irradiation light on the image carrier can be controlled without increasing the assembling time.
Since the polarization filter for receiving regular reflection light has a function of condensing regular reflection light, the size of the light reception range on the image carrier can be controlled without increasing the assembly work time.
Image density control accuracy can be improved, and as a result, high image quality can be realized.

Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
An optical sensor 1A as a part of a toner concentration measuring device mounted on an image forming apparatus, which will be described later, according to this embodiment is mounted on a mounting substrate 2 fixed to the main body of the image forming device, and mounted on the mounting substrate 2. The LED 3 as the light emitting means, the specular reflected light phototransistor 4 as the regular reflected light receiving means, the diffuse reflected light phototransistor 5 as the diffuse reflected light receiving means, and the light emitting means and the light receiving means are covered. And a case 6 for preventing ambient light from entering.
Here, a case 6 molded with black resin is used. The LED 3 is disposed between the phototransistor 4 for specular reflection light and the phototransistor 5 for diffuse reflection light. The light emitting means and the light receiving means are blocked by a light shielding wall 7 formed integrally with the case 6. ing.
Other examples of the light emitting means include a laser diode, and other examples of the light receiving means include a photodiode and a photo Darlington.

The regular reflection light phototransistor 4 receives regular reflection light which is irradiated from the LED 3 and is reflected by a transfer belt 18 which will be described later as an image carrier. The diffuse reflected light phototransistor 5 receives the diffuse reflected light that is irradiated from the LED 3 and reflected by the transfer belt 18.
A slit S1 for light transmission is on the optical path between the LED 3 and the transfer belt 18, and a slit S2 for light transmission is diffusely reflected on the optical path between the phototransistor 4 for regular reflection light and the transfer belt 18. On the optical path between the phototransistor 5 for light and the transfer belt 18, a light transmitting slit S3 is formed. These slits are molded integrally with the case 6.

An irradiation polarizing filter 8 is disposed on the optical path between the LED 3 and the transfer belt 18 (here, slit S1), and on the optical path between the phototransistor 4 for regular reflection light and the transfer belt 18 (here, slit S2). Is provided with a polarizing filter 9 for receiving regular reflection light.
Examples of means for installing the irradiation polarizing filter 8 and the specular reflection light receiving polarizing filter 9 include adhering or fitting to the case 6.
In the present embodiment, a filter installation recess and a lens installation recess for installing a lens to be described later are stepwise on the transfer belt 18 side of the slit S1 and the slit S2 from the belt side toward the inside of the case 6. Is formed. The fitting into these concave portions may be fitting from the lower side of the case 6 (intermediate transfer belt side), or may be insertion fitting from the direction orthogonal to the optical path with the case 6 as an overlapping structure.

Irradiated light polarized by the irradiation polarizing filter 8 is specularly reflected on the surface of the transfer belt 18 without changing the polarization direction, and diffusely reflected on the toner to reflect light having a random polarization direction. Since the regular reflection light receiving polarizing filter 9 transmits only the reflected light whose polarization direction is parallel to the irradiation light, the regular reflection light phototransistor 4 receives almost only the regular reflection light.
As described above, the diffuse reflection light phototransistor 5 is disposed at a position opposite to the position of the regular reflection light phototransistor 4 with respect to the LED 3, and the diffuse reflection light phototransistor 5 is regularly reflected from the transfer belt 18. Since the light does not reach, it is not necessary to provide a polarizing filter on the optical path (slit S3) between the transfer belt 18 and the diffuse reflection light phototransistor 5. That is, the slit S3 is optically opened.

For this reason, even when the amount of diffusely reflected light from the transfer belt 18 is small, the amount of light incident on the diffusely reflected light phototransistor 5 is not attenuated by the polarizing filter, and the amount of toner can be measured with high accuracy. Become.
Further, in the present embodiment, the LED 3, the specular reflection light phototransistor 4, and the diffuse reflection light phototransistor 5 are installed so that the irradiation and reception light paths are substantially parallel to the mounting surface of the mounting substrate 2. Yes. Therefore, the mounting surface of the mounting substrate 2 is substantially perpendicular to the surface of the transfer belt 18.
When mounted in this way, warpage and vibration in a direction parallel to the optical path of the mounting substrate 2 are small as compared with the case where the optical path of irradiation and reception is substantially perpendicular to the mounting surface of the mounting substrate 2. Therefore, the change in the incident angle and reflection angle on the surface of the transfer belt 18 is small, and it is possible to reliably prevent the regular reflection light from entering the diffuse reflection light phototransistor 5.
In addition, since the change in the incident angle of the reflected light from the transfer belt 18 to the regular reflection light receiving polarizing filter 9 is small and the change in the distance and relative angle with the transfer belt 18 is also small, the phototransistor for regular reflection light The change in the output of 4 becomes small, and a more accurate measurement result of the toner density can be obtained.
Actually, a plurality of optical sensors 1 are arranged for each color of toner in the width direction orthogonal to the running direction of the transfer belt 18, and the toner density measuring device is constituted by these.

FIG. 2 shows a second embodiment. In addition, the same part as the said embodiment is shown with the same code | symbol, The description on the structure and function which were already demonstrated is abbreviate | omitted as long as there is no special need, and only the principal part is demonstrated (same in other following embodiment).
In the optical sensor 1B according to the present embodiment, the irradiation light condensing lens 10 that condenses the light emitted from the LED 3 is disposed on the optical path between the LED 3 and the transfer belt 18 (here, the slit S1).
By condensing the irradiation light by the irradiation light condensing lens 11, the size and direction of the irradiation light on the transfer belt 18 can be controlled. Thereby, it is possible to more surely prevent the regular reflection light from entering the diffuse reflection light phototransistor 5 and obtain a more accurate measurement result of the toner density.

In the present embodiment, the light emitted from the LED 3 is transmitted through the slit S1 formed in the case 6 and transmitted through the irradiation polarizing filter 8 after passing through the irradiation light collecting lens 10. The transmission order of the slit S1, the irradiation light condensing lens 10, and the irradiation polarizing filter 8 can be changed and arranged.
In this case, the order of formation of the concave portion for filter installation and the concave portion for lens installation is reversed.

FIG. 3 shows a third embodiment.
In the optical sensor 1C according to the present embodiment, in addition to the configuration of the second embodiment, a phototransistor for specular reflection light is provided on the optical path between the phototransistor 4 for specular reflection light and the transfer belt 18 (here, slit S2). On the optical path between 4 and the transfer belt 18, a regular reflection light condensing lens 11 that collects regular reflection light of light emitted from the LED 3 is disposed.
By condensing the specularly reflected light by the specularly reflecting light condensing lens 11, the size of the light receiving range on the transfer belt 18 can be controlled, so that the toner density can be measured more accurately. It becomes.
In the present embodiment, the reflected light from the transfer belt 18 passes through the regular reflection light receiving polarizing filter 9, passes through the regular reflection light collecting lens 11, and then passes through the slit S <b> 2 formed in the case 6. However, the order of transmission through the regular reflection light receiving polarizing filter 9, the regular reflection light condensing lens 11, and the slit S2 may be changed.
In this case, the order of formation of the concave portion for filter installation and the concave portion for lens installation is reversed.

FIG. 4 shows a fourth embodiment.
In the optical sensor 1D according to the present embodiment, the irradiation polarizing filter 8 and the regular reflection light receiving polarizing filter 9 in each of the above embodiments are configured by a single continuous polarizing filter 15. With this integrated configuration, it is possible to make the polarization directions of the polarizing filters for irradiation and regular reflection light reception the same without being simple and excellent in handleability and without increasing the assembly work time.

FIG. 5 shows a fifth embodiment.
In the optical sensor 1E according to the present embodiment, the irradiation polarizing filter 16 disposed in the slit S1 has a function of condensing the irradiation light from the LED 3. The irradiation polarizing filter 16 is installed in the lens installation recess.
In order for the polarizing filter to have a function of condensing the irradiation light, there is means such as attaching a polarizing film to the optical lens (condensing lens). With this configuration, it is possible to condense the irradiation light and control the size of the irradiation light on the transfer belt 18 without increasing the assembly work time, compared to the case where the polarizing filter and the condensing lens are individually arranged. It becomes possible.

FIG. 6 shows a sixth embodiment.
In the optical sensor 1F according to the present embodiment, the irradiation polarizing filter 16 disposed in the slit S1 has a function of condensing the irradiation light from the LED 3, and receives regular reflection light disposed in the slit S2. The polarizing filter 17 has a function of collecting regular reflection light. The specular reflection light receiving polarizing filter 17 is installed in the concave portion for lens installation.
Similarly to the above, there are means such as attaching a polarizing film to the optical lens (condensing lens) in order to make the polarizing filter have a function of condensing the irradiation light.
With this configuration, the specularly reflected light can be collected and the size of the light receiving range on the transfer belt 18 can be controlled without further increasing the assembly work time.

In each of the above embodiments, the optical path between the diffuse reflected light phototransistor 5 and the transfer belt 18 is opened without providing the diffuse reflected light receiving polarizing filter, and the measurement accuracy is ensured even when the diffuse reflected light amount is small. Although the purpose is, the greater the amount of light reflected from the transfer belt 18, the better. The balance between the sensor characteristics and the reflection characteristics on the image carrier side is important.
Therefore, depending on the reflection characteristics on the image carrier side, the open configuration of the slit S3 can be a cause of a decrease in measurement accuracy.
A seventh embodiment that addresses this problem will be described with reference to FIGS.

In the optical sensor 1G according to the present embodiment, as shown in FIG. 7, a diffused / reflected light receiving polarizing filter can be attached on the optical path between the diffused / reflected light phototransistor 5 and the transfer belt 18 (here, slit S3). A mounting portion 6a is provided.
As shown in FIG. 8, the mounting portion 6a is formed as a U-shaped groove (concave portion) orthogonal to the optical path, and a diffused reflected light receiving polarizing filter 50 is inserted and fitted therein.
The case 6 has an overlapping structure, and a similar mounting portion is formed on the other side of the case 6. A mounting portion may be formed on only one of the case pieces, and the other piece may simply be a lid.

Alternatively, the mounting portion 6a may be opened on the outer surface of the case 6 and inserted from the outside of the case 6 in a direction perpendicular to the optical path.
In the manufacturing process of the image forming apparatus, when checking the detection accuracy of the toner density measuring device, if the amount of diffusely reflected light exceeds a predetermined value, the slit S3 is not opened and the diffused reflected light is received as an optical element. A polarizing filter 50 is installed in the mounting portion 6a to limit the amount of light. In this case, a neutral density filter may be attached instead of the diffuse reflection light receiving polarizing filter 50.

FIG. 9 shows an eighth embodiment (modified example of the mounting portion).
In the present embodiment, in addition to the mounting portion 6, a mounting portion 6 b to which a diffuse reflection light condensing lens 51 that collects diffuse reflection light can be attached is continuously provided. Here, an example is shown in which when the diffuse reflection light receiving polarization filter 50 is mounted, the diffuse reflection light collecting lens 50 is simultaneously mounted to compensate for a slight decrease in the amount of diffuse reflection light. .
When the amount of diffusely reflected light is not more than a predetermined value, only the diffusely reflected light collecting lens 51 is attached. In this case, a holding member 52 that holds the diffuse reflection light condensing lens 51 is attached to the attachment portion 6a.
The holding member 52 has an opening 52 a and is only for holding the diffusely reflected light collecting lens 51.
Of course, if the mounting portions 6a and 6b are formed independently, the holding member 52 is unnecessary.

Similarly to the fifth and sixth embodiments, the diffuse reflection light receiving polarizing filter 50 may be provided with the function of the diffuse reflection light condensing lens 51 and attached with one optical element. In this case, the mounting portion can have a shape corresponding to one optical element.
The basic adjustment in the manufacturing process is that when the image forming apparatus is a high-speed machine, the amount of diffuse reflected light inevitably decreases. Therefore, a diffuse reflected light condensing lens 51 is installed, and the diffuse reflected light receiving polarizing filter 50 is installed. Is not installed.
In the case of a low speed machine, a sufficient amount of light can be obtained, so the diffuse reflection light collecting lens 51 is not installed, but the diffuse reflection light receiving polarizing filter 50 or the neutral density filter is installed.
Thus, if the amount of diffusely reflected light can be appropriately adjusted in the manufacturing stage according to the reflection characteristics on the transfer belt 18 side, standardization with an image forming apparatus having a diffused reflected light receiving polarization filter can be achieved.

Next, FIG. 10 shows an embodiment (ninth embodiment) of an image forming apparatus that includes any one of the optical sensors according to each of the above-described embodiments and that can improve image density control accuracy and achieve high image quality. This will be explained based on.
A four-tandem direct transfer color laser printer (hereinafter simply referred to as “color laser printer”) as an image forming apparatus according to the present embodiment includes one manual feed tray 36 and two paper feed cassettes 34 (first paper feed). 3) (second tray), and a transfer sheet (not shown) as a sheet-like recording medium fed from the manual feed tray 36 is the uppermost one by a feed roller 37. Are separated one by one in order, and conveyed toward the registration roller pair 23. The transfer sheets fed from the first sheet feed tray 34 or the second sheet feed tray 34 are separated one by one from the uppermost one by the sheet feed roller 35 and are transferred to the registration roller pair 23 via the transport roller pair 39. It is conveyed toward.

The fed transfer paper is temporarily stopped by the pair of registration rollers 23, the skew is corrected, and then the leading edge of the image formed on the photosensitive drum 14Y positioned at the uppermost stream described later and the transfer paper in the transport direction. At a timing coincident with the predetermined position, the sheet is conveyed toward the transfer belt 18 by the rotation operation of the registration roller pair 23 by ON control of a registration clutch (not shown).
When the transfer paper passes through a paper suction nip composed of the transfer belt 18 and a paper suction roller 41 in contact with the transfer belt 18, the transfer paper is attracted to the transfer belt 18 by electrostatic force by a bias applied to the paper suction roller 41 and conveyed. Is done.

The transfer paper adsorbed by the transfer belt 18 has toner transferred to the transfer brushes 21B, 21C, 21M, and 21Y disposed at positions facing the photosensitive drums 14B, 14C, 14M, and 14Y of the respective colors with the transfer belt 18 interposed therebetween. By applying a transfer bias (plus) opposite to the charging polarity (minus), the toner images of the respective colors formed on the photoconductor drums 14B, 14C, 14M, and 14Y are converted into yellow (Y) and magenta (M ), Cyan (C), and black (Bk).
The transfer paper that has undergone the transfer process of each color is separated from the transfer belt 18 by the downstream drive roller 19 and is conveyed to the fixing device 24. By passing through a fixing nip formed by the fixing belt 25 and the pressure roller 26 in the fixing device 24, the toner image is fixed on the transfer paper by heat and pressure. In the single-sided printing mode, the fixed transfer paper is discharged to an FD (face-down) tray 30 formed on the upper surface of the apparatus main body.
When the double-sided printing mode is selected in advance, the transfer paper that has exited the fixing device 24 is sent to a reversing unit (not shown), and the front and back sides are reversed by the unit, and then the double-sided transport unit positioned below the transfer unit. It is conveyed to 33. The transfer paper is fed again from the double-sided conveyance unit 33 and conveyed to the registration roller pair 23 through the conveyance roller pair 39. Thereafter, it passes through the fixing device 24 through the same operation as in the single-sided printing mode, and is discharged to the FD tray 30.

Next, the configuration and image forming operation in the image forming unit of the color laser printer will be described in detail.
Since the image forming unit has the same configuration and operation for each color, the configuration and operation for forming a yellow image will be described as a representative, and the other components are denoted by reference numerals corresponding to the respective colors and description thereof is omitted.
An image forming unit 12Y having a charging roller 42Y and a cleaning unit 43Y, a developing unit 13Y, an optical writing unit 16, and the like are provided around the photosensitive drum 14Y positioned on the most upstream side in the transfer paper conveyance direction.
At the time of image formation, the photosensitive drum 14Y is rotationally driven in a clockwise direction by a main motor (not shown), is neutralized by an AC bias (DC component is zero) applied to the charging roller 42Y, and the surface potential becomes a reference potential.

Next, the photosensitive drum 14Y is uniformly charged to a potential substantially equal to the DC component by applying a DC bias with an AC bias superimposed on the charging roller 42Y, and the surface potential is charged to the target charging potential.
Digital image information sent from a controller unit (not shown) as a print image is converted into a binarized LD light emission signal for each color, and a cylinder lens, a polygon motor, an fθ lens, first to third mirrors, and a WTL. Exposure light 16Y is irradiated onto the photosensitive drum 14Y by an optical writing unit 16 having a lens or the like.
The drum surface potential of the irradiated portion becomes approximately −50 v, and an electrostatic latent image corresponding to the image information is formed.

The electrostatic latent image corresponding to the yellow image information on the photosensitive drum 14Y is visualized by the developing unit 13Y. By applying DC with superimposed AC bias to the developing sleeve 44Y of the developing unit 13Y, the toner is developed only in the image portion where the potential is lowered by writing, and a toner image is formed.
The formed toner images on the photosensitive drums 14B, 14C, 14M, and 14Y of the respective colors are transferred onto the transfer paper adsorbed on the transfer belt 18 by the transfer bias.

In the color laser printer according to the present embodiment, in addition to the image forming mode as described above, a process control operation (hereinafter referred to as “process control”) is performed in order to optimize the image density of each color when the power is turned on or after a predetermined number of sheets have passed. Abbreviated as “operation”).
In this process control operation, a density detection patch (hereinafter abbreviated as “P pattern”) as a plurality of gradation patterns for each color is formed on the transfer belt by sequentially switching between a charging bias and a developing bias at an appropriate timing. The output voltage of these P patterns is detected by the optical sensor 1 disposed outside the transfer belt 18 in the vicinity of the driving roller 19, and the output amount is converted by the adhesion amount conversion algorithm to obtain the current developing capability. (Development γ, Vk) is calculated, and control for changing the development bias value and the toner density control target value is performed based on the calculated values.
Although the direct transfer method is shown in the present embodiment, the same can be applied to an image forming apparatus of a tandem type intermediate transfer method.

It is a longitudinal cross-sectional view of the optical sensor which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the optical sensor which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view of the optical sensor which concerns on 3rd Embodiment. It is a longitudinal cross-sectional view of the optical sensor which concerns on 4th Embodiment. It is a longitudinal cross-sectional view of the optical sensor which concerns on 5th Embodiment. It is a longitudinal cross-sectional view of the optical sensor which concerns on 6th Embodiment. It is a longitudinal cross-sectional view of the optical sensor which concerns on 7th Embodiment. It is a perspective view of the optical element mounting part with respect to the diffuse reflected light in 7th Embodiment. It is a perspective view of the optical element mounting part with respect to the diffuse reflected light in 8th Embodiment. It is a schematic block diagram of the image forming apparatus which concerns on 9th Embodiment. 5 is a graph showing a relationship between toner adhesion amount and sensor output for color toner and black toner.

Explanation of symbols

1A, 1B, 1C, 1D, 1E, 1F, 1G Optical sensor 2 Mounting substrate 3 LED as light emitting means
4 Phototransistor for specular reflection light as a means for receiving regular reflection light 5 Phototransistor for diffuse reflection light as a means for receiving diffuse reflection light 6a, 6b Mounting part 8 Polarizing filter for irradiation 9 Polarizing filter for receiving specular reflection light 18 Irradiation object Transfer belt as an image carrier 50 Diffuse reflection light receiving polarizing filter 51 Diffuse reflection light condensing lens

Claims (16)

A mounting substrate; a light emitting unit mounted on the mounting substrate; a specularly reflected light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by the irradiation target; and an irradiation target that is irradiated from the light emitting unit. In the optical sensor having a diffuse reflection light receiving means for receiving the diffuse reflection light reflected by
The light emitting means is disposed between the regular reflection light receiving means and the diffuse reflection light receiving means;
A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and the polarized light receiving polarized light is provided on the optical path between the irradiation object and the regular reflection light receiving means. A filter is provided,
An optical sensor characterized in that an optical path between the irradiation object and the diffusely reflected light receiving means is open. A mounting substrate; a light emitting unit mounted on the mounting substrate; a specularly reflected light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by the irradiation target; and an irradiation target that is irradiated from the light emitting unit. In the optical sensor having a diffuse reflection light receiving means for receiving the diffuse reflection light reflected by
The light emitting means is disposed between the regular reflection light receiving means and the diffuse reflection light receiving means;
A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and the polarized light receiving polarized light is provided on the optical path between the irradiation object and the regular reflection light receiving means. A filter is provided,
An optical sensor, wherein a mounting portion to which the diffused reflected light receiving polarizing filter can be attached is provided on an optical path between the irradiation object and the diffusely reflected light receiving means. A mounting substrate; a light emitting unit mounted on the mounting substrate; a specularly reflected light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by the irradiation target; and an irradiation target that is irradiated from the light emitting unit. In the optical sensor having a diffuse reflection light receiving means for receiving the diffuse reflection light reflected by
The light emitting means is disposed between the regular reflection light receiving means and the diffuse reflection light receiving means;
A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and the polarized light receiving polarized light is provided on the optical path between the irradiation object and the regular reflection light receiving means. A filter is provided,
On the optical path between the irradiation object and the diffuse reflection light receiving means, a mounting portion to which a diffuse reflection light condensing lens for condensing the diffuse reflection light can be attached is provided. Optical sensor. A mounting substrate; a light emitting unit mounted on the mounting substrate; a specularly reflected light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by the irradiation target; and an irradiation target that is irradiated from the light emitting unit. In the optical sensor having a diffuse reflection light receiving means for receiving the diffuse reflection light reflected by
The light emitting means is disposed between the regular reflection light receiving means and the diffuse reflection light receiving means;
A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and the polarized light receiving polarized light is provided on the optical path between the irradiation object and the regular reflection light receiving means. A filter is provided,
On the optical path between the irradiation object and the diffuse reflection light receiving means, a mounting portion to which a diffuse reflection light attenuating filter for reducing the diffuse reflection light can be attached is provided. Optical sensor. A mounting substrate; a light emitting unit mounted on the mounting substrate; a specularly reflected light receiving unit that receives specularly reflected light that is irradiated from the light emitting unit and reflected by the irradiation target; and an irradiation target that is irradiated from the light emitting unit. In the optical sensor having a diffuse reflection light receiving means for receiving the diffuse reflection light reflected by
The light emitting means is disposed between the regular reflection light receiving means and the diffuse reflection light receiving means;
A polarizing filter for irradiation is provided on the optical path between the light emitting means and the irradiation object, and the polarized light receiving polarized light is provided on the optical path between the irradiation object and the regular reflection light receiving means. A filter is provided,
On the optical path between the irradiation object and the diffuse reflection light receiving means, the diffuse reflection light receiving polarizing filter, a diffuse reflection light collecting lens for condensing the diffuse reflection light, and dimming the diffuse reflection light. An optical sensor, comprising: a mounting portion that can be attached together with any one of the diffuse reflection light attenuating filters. The optical sensor according to any one of claims 2 to 5,
The mounting portion has a slit-like or stepped portion structure that can be attached by inserting the diffuse reflection light receiving polarizing filter, the diffuse reflection light condensing lens, or the diffuse reflection light attenuation filter. An optical sensor. In the optical sensor according to any one of claims 1 to 6,
The light emitting means is arranged to emit light substantially parallel to the mounting surface of the mounting board, and the specular reflection light receiving means and the diffuse reflection light receiving means are with respect to the mounting surface of the mounting board. The optical sensor is arranged so as to receive light substantially in parallel. In the optical sensor according to any one of claims 1 to 7,
An optical sensor, wherein an irradiation light condensing lens for condensing light emitted from the light emitting means is provided on an optical path between the light emitting means and the irradiation object. The optical sensor according to any one of claims 1 to 8,
On the optical path between the regular reflection light receiving means and the irradiation object, a regular reflection light condensing lens for collecting the regular reflection light of the light irradiated from the light emitting means to the irradiation object is provided. An optical sensor. The optical sensor according to any one of claims 1 to 9,
The optical sensor, wherein the irradiation polarizing filter and the regular reflection light receiving polarizing filter are integrally formed. In the optical sensor according to any one of claims 1 to 7,
The optical sensor, wherein the irradiation polarizing filter has a function of collecting the light irradiated from the light emitting means. The optical sensor according to any one of claims 1, 2, 3, 4, 5, 6, 7, and 11,
The optical sensor, wherein the regular reflection light receiving polarizing filter has a function of collecting regular reflection light of light irradiated from the light emitting means onto the irradiation object. An image carrier having a surface for regularly reflecting light, a toner image forming unit for forming a toner image on the image carrier, and the toner image formed on the image carrier by the toner image forming unit. In an image forming apparatus comprising an optical sensor for detecting the amount of toner adhesion, and image density control means for performing image density control based on the detection result of the optical sensor,
An image forming apparatus using the optical sensor according to claim 1 as the optical sensor. A mounting substrate; light emitting means mounted on the mounting substrate; specular light receiving means for receiving specularly reflected light emitted from the light emitting means and reflected by the image carrier; and the image carrier irradiated from the light emitting means. A diffuse reflected light receiving means for receiving the diffuse reflected light reflected by the light emitting means, wherein the light emitting means is disposed between the regular reflected light receiving means and the diffuse reflected light receiving means, and the light emitting means and the irradiation target An optical sensor provided with a polarizing filter for irradiation on the optical path between the object and a polarizing filter for receiving regular reflection light on the optical path between the image carrier and the regular reflection light receiving means An image forming apparatus assembly method comprising:
A mounting portion to which an optical element can be attached is provided on the optical path between the image carrier and the diffusely reflected light receiving means, and the optical element is attached to the mounting portion depending on the amount of diffuse reflected light from the image carrier. And adjusting the amount of diffusely reflected light. The method of assembling an image forming apparatus according to claim 14.
When the amount of diffuse reflected light exceeds a predetermined value, at least one of a diffuse reflected light receiving polarizing filter and a diffuse reflected light attenuating filter for reducing diffuse reflected light is mounted on the mounting portion as the optical element. An assembly method for an image forming apparatus, wherein neither the diffuse reflection light receiving polarization filter nor the diffuse reflection light attenuation filter is attached to the attachment portion when the value is less than or equal to the value. The method of assembling an image forming apparatus according to claim 14.
A method of assembling an image forming apparatus, comprising: mounting a diffuse reflected light condensing lens that collects diffuse reflected light as the optical element on the mounting portion when the diffuse reflected light amount is a predetermined value or less.

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