JPH112600A - Optical density measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-accuracy optical density detection by integrally holding a light emitting element and a photo detecting element by a holding member, and moving the holding member between both first and second measuring positions. SOLUTION: When a solenoid of an actuator 11 is not excited, a turning part 111b is arranged to be vertical to a photoreceptor drum 21, and an AIDC sensor 64 is put in a first measuring position. On the other hand, when it is excited, an operating shaft 112a is moved to the main body 112b side, and the turning part 111b is inclined to the outer peripheral surface 21a of the photoreceptor drum 21, that is, it is put in a second measuring position where the light emitting and entering surface of the AIDC sensor 64 is inclined to the outer peripheral surface 21a. Thus, a lever member 111, the solenoid type actuator 112 and a coiled spring 113 operate as a holding member moving mechanism. That is, in the state of keeping the relative positional relation between the light emitting element and the photo detecting element, the AIDC sensor 64 can be moved between both first and second measuring positions, and optical density measurement can be made in the respective positions so as to simplify the mechanism of the device and attain low-priced constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting device having a light-emitting element and a light-receiving element. The light reflected from the light-emitting element is received by the light-receiving element. The present invention relates to an optical density measuring device for measuring an optical density. Further, the present invention relates to an optical density measuring device for optically measuring the amount of toner on an image carrier in an image forming apparatus.

[0002]

2. Description of the Related Art In a color copying machine, as shown in FIG. 12, an image of a toner mark 310 is first formed on a specific portion of an outer peripheral surface 221a of a photosensitive drum 221 and an optical density (toner adhesion) of the toner mark 310 is formed. (Corresponding to the amount) is detected by the reflection density sensor 264, and the toner adhesion amount is often controlled based on the output value of the reflection density sensor 264. The types of toner to be detected are roughly classified into black toner and color toners represented by cyan, magenta, and yellow.

Conventionally, when detecting the optical density of black toner and the optical density of color toner, the light emitting element 301 and the light receiving element 302 that constitute the reflection density sensor 264 are positioned within the same plane P. They are common in that they are arranged along the same plane P so that outgoing / incoming light is emitted. This plane P
Indicates that the photosensitive drum 2
21 is a plane extending along the longitudinal direction of the photosensitive drum 21 and perpendicularly intersecting the outer peripheral surface 221a of the photosensitive drum 221. For easy understanding, a plane Q passing through the location of the toner mark 310 and circumscribing the outer peripheral surface 221a of the photosensitive drum 221 is shown in the figure.

To detect the optical density of black toner, the light emitting element 301 and the light receiving element 302 are
The toner mark 310 is disposed at a position where the incident angle i and the reflection angle r of the light with respect to the toner mark 310 are equal to each other across a normal line N (which is within the plane P) passing through the line. The light emitting element 301 has a toner mark 310
The light L is emitted to the position P1
Detects the regular reflection light L1 from the toner mark 310.
On the other hand, when detecting the optical density of the color toner, the light receiving element 302 is moved to a position P2 (shown by a broken line) on the normal line N by a moving mechanism (not shown). At this position P2, the light receiving element 302 receives irregularly reflected light L2 due to the toner mark 310.
Is detected.

[0005]

However, in the above-described method, every time the position of the light receiving element 302 is switched,
It is necessary to finely adjust the relative position of the light receiving element 302 with respect to the light emitting element 301, and there is a problem that the mechanism of the device becomes complicated. Accordingly, the manufacturing cost of the device increases.

In the above-described method, when the optical density of the color toner is detected, as shown in FIG. 13 (shown in FIG. 12 as viewed from a direction perpendicular to the plane P), the toner mark 310 is detected. Is partly reflected by the surface of the toner particles 311 and enters the light receiving element 302, which causes a problem that the detection accuracy is not good.

[0007] If light receiving elements are separately arranged at the two positions P1 and P2, the number of light receiving elements increases, resulting in high cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical density measuring apparatus capable of detecting optical densities of black toner and color toner with high accuracy and low cost.

Another object of the present invention is to provide a compact and inexpensive optical density measuring apparatus for measuring the optical density of a color toner.

[0010]

In order to achieve the above object, an optical density measuring apparatus according to claim 1 has a light emitting element and a light receiving element, and the light from the light emitting element reflected by the surface to be measured. A light receiving element, and measuring the optical density of the surface to be measured based on the amount of received light, wherein the light emitting element and the light receiving element emit and receive light in the same plane. A holding member that integrally holds the element and the light receiving element, and a holding member that can move the holding member between a first measurement position and a second measurement position for measuring the optical density of the surface to be measured. A member moving mechanism is provided.

In the optical density measuring device of the first aspect, the light emitting element and the light receiving element are integrally held by a holding member so that light enters and exits in the same plane. While maintaining the relative positional relationship between the light emitting element and the light receiving element, the holding member moving mechanism allows the holding member to move between the first measurement position and the second measurement position for measuring the optical density of the surface to be measured.
Moved to and from the measurement position. Therefore, when the holding member is at the first measurement position or the second measurement position,
The optical density of the surface to be measured can be measured at each measurement position.

[0012] In this case, the distance between the light emitting element and the light receiving element is smaller than when one of the light emitting element and the light receiving element is stopped and the other is moved to switch the measurement position. There is no need to finely adjust the relative positional relationship of the devices, and the mechanism of the device is simplified. Therefore, the device is configured at low cost.

According to a second aspect of the present invention, in the optical density measuring apparatus according to the first aspect, when the holding member is at the first measurement position, the light emitting element and the light receiving element emit light. When the plane of incidence (hereinafter referred to as the “light exit / incident surface”) is substantially perpendicular to the surface to be measured and the holding member is at the second measurement position, the light exit / incident surface is It is characterized by being inclined with respect to the surface to be measured.

Here, the term "substantially perpendicular" to the surface to be measured means that the angle formed between the light outgoing and incident surface and the surface to be measured is within a range of 90 ° ± 5 °. Means

In the optical density measuring device according to the second aspect, when the holding member is at the first measuring position, the specularly reflected light from the surface to be measured can be made incident on the light receiving element. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered black toner. It is assumed that the incident angle and the reflection angle of the light with respect to the surface to be measured are set to be equal within the light exit / incident surface. On the other hand, when the holding member is at the second measurement position, the irregularly reflected light from the surface to be measured enters the light receiving element. Here, the light exit / incident surface is
Since it is inclined with respect to the surface to be measured, it is also inclined with respect to a plane including a light emission path of the light emitting element and a path of regular reflection light from the surface to be measured. Therefore, the specularly reflected light component is less likely to be incident on the light receiving element, and almost only the diffusely reflected light that should be observed is incident. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered color toner.

According to a third aspect of the present invention, there is provided an optical density measuring device having a light emitting element and a light receiving element, wherein the light from the light emitting element reflected by the surface to be measured is received by the light receiving element, and based on the received light amount. In an optical density measuring device for measuring the optical density of the surface to be measured, a holding member for integrally holding the light emitting element and the light receiving element so that the light emitting element and the light receiving element emit and enter light in the same plane. And wherein the holding member is arranged so that the light incident / incident surface is inclined with respect to the surface to be measured.

In the optical density measuring device according to the third aspect, the light emitting element and the light receiving element are integrally held by a holding member so that light enters and exits in the same plane. In a state where the relative positional relationship between the light emitting element and the light receiving element is maintained, the holding member is arranged such that the light emitting / receiving surface is inclined with respect to the surface to be measured. In this arrangement,
Irregularly reflected light from the surface to be measured enters the light receiving element. Here, since the light outgoing / incoming surface is inclined with respect to the surface to be measured, the light outgoing / incoming surface is also formed with respect to a plane including a light emitting path of the light emitting element and a path of specularly reflected light from the surface to be measured. It is inclined. Therefore, the light receiving element includes
Specularly reflected light components are less likely to be incident, and almost only diffusely reflected light that should be observed essentially is incident. Therefore, the optical density according to the amount of the adhered color toner can be accurately measured.

Further, in this optical density measuring apparatus, since the light emitting / receiving surface is inclined with respect to the surface to be measured, the light emitting / incoming surface is perpendicular to the surface to be measured. The size of the device in the direction perpendicular to the surface to be measured is reduced. Therefore, the device is configured to be compact. In addition, only one light receiving element is required, and the apparatus is configured at low cost.

[0019]

Embodiments of the present invention will be described below in detail.

FIG. 1 shows an entire configuration of a digital type full-color copying machine to which the optical density measuring apparatus of the present invention is applied. The copying machine generally includes an image reader unit 1, a laser scanning unit 10, a full-color image forming unit 20, and a paper supply unit 50.

The image reader unit 1 includes a scanner 2 for reading an image of a document set on a platen glass 9, and an image signal processing unit 6 for converting the read image into image data. The scanner 2 is a well-known type equipped with a contact type color image sensor (CCD) 3, and is driven by a motor 5 to move in the direction of arrow a and scan an original. The CCD 3 outputs R (red). G (green) and B (blue) three primary color signals
The data is read line by line and output to the image signal processing unit 6. The image signal processing unit 6 converts the three primary color signals from the CCD 3 into Y
(Yellow), M (magenta), C (cyan), Bk
The image data is converted into 8-bit image data corresponding to the four colors (black) and transferred to the synchronization buffer memory 7.

The laser scanning unit 10 is a well-known unit that modulates a laser beam emitted from a laser diode to form an electrostatic latent image on a photosensitive drum 21 rotating in the direction of a mark-loss b. The laser scanning unit 10 performs gradation correction on the print data input from the buffer memory 7 in accordance with the gradation retention of the photoconductor, and then performs D / A conversion to generate a laser diode drive signal. Then, the laser diode emits light based on the driving signal.

The full-color image forming unit 20 is composed mainly of a photosensitive drum 21 and a transfer drum 31. Around the photosensitive drum 21, a charging charger 2 is provided.
2, a developing unit 40, a cleaner 23 for cleaning residual toner,
An eraser lamp 24 for erasing residual charges is provided. The developing unit 40 includes developing units 41C, 41M, 41Y, and 41B each containing a magnetic carrier and a developer containing cyan, magenta, yellow, and black toners sequentially from the top.
The corresponding developing device is driven each time an electrostatic latent image of each color is formed on the photosensitive drum 21. In the developing devices 41C, 41M, and 41Y containing the color toner,
Optical ATDC for replenishing each color toner
Sensors 43C, 43M, and 43Y are provided. The cyan, magenta, yellow, and black toners are stored in the hoppers 42C, 42M, 42Y, and 42Bk, respectively, and are supplied to the developing units 41C, 41M, 41Y, and 41Bk by toner supply control described later. Further, a potential sensor 63 for detecting the surface potential of the photosensitive drum 21 and an AIDC sensor 64 for detecting the image density of the test toner image are arranged around the photosensitive drum 21.

The transfer drum 31 is rotatably driven in the direction of arrow c at the same speed as the photosensitive drum 21 and transfers a toner image onto a sheet wound around the surface thereof. The transfer drum 31 has a claw member 32 for chucking the leading end of the sheet and a claw member 33 for separating the sheet. A transfer charger 34 is disposed inside the transfer drum 31 at a position facing the photosensitive drum 21. Further, the transfer drum 31 is located at a position away from the transfer charger 34 by a predetermined distance in the rotation direction.
The two discharging chargers 35 and 36 are disposed so as to face each other, and the transfer drum 3 is positioned at a predetermined distance in the rotation direction from the discharging chargers 35 and 36.
A cleaner 37 for the residual toner is arranged outside of the first cleaner 1.

The paper supply unit 50 includes two paper supply trays 51 and 52.
And sheets are fed one by one from one of the trays 51 and 52 selected by the operator. The fed sheet is transported on a transport path 53 and is transferred to the transfer drum 31.
It is wrapped around.

When a full-color image is formed, cyan, magenta, yellow, and black toner images are sequentially formed on the photosensitive drum 21, and each toner image is transferred onto a sheet wound around the transfer drum 31. The images are sequentially transferred and superimposed by the discharge from. When the four color images are combined on the sheet, the claw member 32 releases the chucking of the sheet, and the claw member 33 operates to separate the sheet from the transfer drum 31.
The separated sheet is fixed to a fixing device 56 by a conveying belt 55.
After the toner is fixed here, the toner is discharged from the discharge roller 57 onto the tray 58.

As shown in FIG. 2, the optical density measuring apparatus according to one embodiment includes an AIDC sensor 64, an L-shaped lever member 111 for holding and moving the AIDC sensor 64, and a CPU (not shown). Solenoid actuator 1 controlled by (central processing unit)
12 and a coil spring 113.

FIG. 6 (a) shows the outer shape of the AIDC sensor 64 as viewed obliquely, and FIG. 6 (b) shows the AIDC sensor 64.
4 shows a vertical section. As can be seen from FIG.
The AIDC sensor 64 has a rectangular parallelepiped block-shaped holding member 1.
A light-emitting element 101 and a light-receiving element 102 are embedded in the light-emitting element 03, and the light-emitting element 101 and the light-receiving element 102 are integrally held so that light enters and exits on the same plane (light incident / incident surface) P. That is, the holding member 103 is formed with a pair of round holes 104 and 105, each of which is inclined by 45 ° with respect to this surface 103a, in a direction away from each other as it goes deeper through one surface 103a. For convenience of positioning the light emitting element 101 and the light receiving element 102, the round holes 104 and 105 do not completely penetrate the holding member 103, but stop halfway. A light-emitting element 101 and a light-receiving element 102 each having a columnar outer shape are inserted and attached to the inside of the round holes 104 and 105, respectively. The light exit / incident surface P includes an optical axis 101c of the light emitting element 101 and an optical axis 102c of the light receiving element 102 (see FIG. 4). As a result of the light emitting element 101 and the light receiving element 102 being integrally held by the holding member 103, when the surface 103a of the holding member 103 on the side of the round holes 104 and 105 faces the surface 21a to be measured, the light emitting element 101 The light L emitted from the light emitting surface 101a enters the measured surface 21a at a fixed incident angle i (= 45 °). The specularly reflected light from the measured surface 21a is reflected at a reflection angle r (= 45 °) equal to the incident angle i, and enters the light receiving surface 102a of the light receiving element 102.

The lever member 111 in FIG. 2 is connected to a linear shaft portion 111a that penetrates and holds the holding member 103 of the AIDC sensor 64, and is bent and connected to one end of the shaft portion 111a. And a linear turning part 111b arranged along the light entrance / exit plane P. The shaft portion 111a is integrally attached to the holding member 103 of the AIDC sensor 64, and holds the AIDC sensor 64 (that is, the holding member 103) at a predetermined distance from the outer peripheral surface 21a of the photosensitive drum 21. The shaft portion 102a itself is rotatably supported around its own center by a support portion (not shown). An operating shaft 112a of a solenoid actuator 112 disposed on the side is engaged with a tip (an end farther from the shaft portion 111a) of the turning portion 111b, and is opposite to the actuator 112 with respect to the turning portion 111b. One end of a coil spring 113 arranged on the side is attached. The main body 112b of the actuator 112 is held at a fixed position by a holder (not shown), and the other end of the coil spring 113 is attached to a fixed portion 114.

When the solenoid of the actuator 112 is not excited (turned off), the operating shaft 112a is extended by the tension of the coil spring 113, and the turning portion 111b is arranged perpendicular to the outer peripheral surface 21a of the photosensitive drum 21a. Become.
As a result, as shown in FIG.
The light outgoing / incident surface P extends along the longitudinal direction of the photosensitive drum 21 and is substantially perpendicular to the outer peripheral surface 21a of the photosensitive drum 21. The position of the AIDC sensor 64 at this time is defined as a “first measurement position”. For easy understanding, a plane Q passing through the toner mark 110 and circumscribing the outer peripheral surface 21a of the photosensitive drum 21 is also shown in the drawing. At this time, the angle formed between the light exit / incident surface P and the plane Q is set within a range of 90 ° ± 5 °.

On the other hand, as shown in FIG. 3, when the solenoid of the actuator 112 is excited (turned on), the operating shaft 112a
Move to the side. As a result, the turning portion 111b is
It turns around the center of the shaft portion 111a together with 1a, and is inclined with respect to the outer peripheral surface 21a of the photosensitive drum 21. As a result, as shown in FIG. 7B, the light incident / incident surface P of the AIDC sensor 64 is
inclined with respect to a. The position of the AIDC sensor 64 at this time is referred to as a “second measurement position”. The angle formed by the light exit / incident surface P and the plane Q is represented by θ. At this time, the angle θ
Is set within a range of, for example, 45 ° ± 5 °.

As described above, the lever member 111, the solenoid type actuator 112 and the coil spring 113 work as a holding member moving mechanism. That is, the light emitting element 101
The AIDC sensor 64 can be moved between the first measurement position and the second measurement position while maintaining the relative positional relationship between the first measurement position and the light receiving element 102. Thus, the optical density can be measured at each of the first measurement position and the second measurement position. In this case, the light emitting element 1
It is not necessary to finely adjust the relative positional relationship between the light receiving element 102 and the light receiving element 102, and the mechanism of the apparatus can be simplified. Therefore, the device can be configured at low cost.

In addition, the turning portion 111 of the lever member 111
b is arranged along the light exit / incident surface P of the AIDC sensor 64, so that the light exit / incident surface P of the photosensitive drum 21 depends on the angle formed by the turning portion 111 b with the outer peripheral surface 21 a of the photosensitive drum 21. The angle formed by the outer peripheral surface 21a, that is, the angle formed by the light output / incident surface P and the plane Q can be easily set.

Further, the actuator 112 is turned on and off to move the position of the AIDC sensor 64 between the first measurement position and the second measurement position.
When switching between the measurement position and the AIDC sensor 64,
Since the holding member 103 (see FIG. 3) rotates only around the shaft portion 111a and hardly moves in parallel, the space around the photosensitive drum 21 can be saved, and the apparatus can be made compact.

When the user presses a print key (not shown) on the operation panel, before the original is actually copied, FIG.
Alternatively, as shown in FIG. 5, first, an image of a patch-like toner mark 110 is formed on the outer peripheral surface 21a of the photosensitive drum 21 using cyan, magenta, yellow, or black toner.

When detecting the optical density of the black toner, the actuator 112 is turned off by a CPU (not shown), and the AIDC sensor 64 is disposed at the first measurement position as shown in FIG. As described above, at this time, AI
The light output / incident surface P of the DC sensor 64 is perpendicular to the outer peripheral surface 21a of the photosensitive drum 21. When the AIDC sensor 64 is at the first measurement position, the light L emitted from the light emitting element 101 emits the toner mark 1 at a constant incident angle i (= 45 °).
10, the light receiving element 102 detects specularly reflected light (light reflected at a reflection angle r equal to the incident angle i) L1 from the toner mark 110. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered black toner.

On the other hand, when detecting the optical density of cyan, magenta or yellow toner, that is, the color toner, the actuator 112 is operated by a CPU (not shown).
Is turned on, and the AIDC sensor 64 is disposed at the second measurement position as shown in FIG. As described above, at this time, A
The light output / incident surface P of the IDC sensor 64 is inclined by an angle θ (= 45 °) with respect to the outer peripheral surface 21 a of the photosensitive drum 21. When the AIDC sensor 64 is at the second measurement position, the light receiving element 102 detects irregularly reflected light L2 due to the toner mark 110. Here, since the light output / incident surface P is inclined with respect to the outer peripheral surface 21a of the photosensitive drum 21, it is shown in FIG. 7C (corresponding to a portion viewed from above in FIG. 7B). As shown, the light emitting element 101 is also inclined with respect to a plane U including the light emission path and the path of the regular reflection light L1 by the toner mark 110. Therefore, the regular reflection light component is less likely to be incident on the light receiving element 102, and almost only the irregularly reflected light L <b> 2, which should be originally observed, is incident. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered color toner.

Here, in order to effectively eliminate the influence of the specularly reflected light component, the angle θ between the light outgoing / incident surface P and the plane Q must be defined.
Is desirably set to 70 ° or less. However, if θ becomes too small, the AIDC sensor 64 approaches the outer peripheral surface 21a of the photosensitive drum 21 too much, and the photosensitive drum 2
The toner scattered from the outer peripheral surface 21a of the first photoconductor 1 is stained, and other elements around the photoconductor drum 21 (e.g., a developing device)
And interfere with. Therefore, θ should be set to be larger than 0 °.

FIG. 10 shows the amount of toner adhering to the outer peripheral surface 21a of the photoreceptor drum 21 (the amount of toner on the photoreceptor) and the amount of incident light on the light receiving element 102 when the optical density of the color toner is measured in this manner. Shows the relationship. As can be seen, according to the present invention, the increase in the amount of incident light is gentler on the side where the amount of toner on the photosensitive member is smaller than in the related art (when the light receiving element is arranged at the position P2 in FIG. 12). As a result, the linearity in the correspondence between the amount of toner on the photoconductor and the amount of incident light on the light receiving element is improved.
Therefore, according to the present invention, it is possible to accurately measure the optical density according to the amount of adhered color toner over a wide range.

At the stage of actually copying a document, image forming conditions are controlled based on the measured optical density of black toner or color toner.

When calibrating the detection sensitivity of the AIDC sensor 64, as shown in FIG. 9, the actuator 112 is turned off with no toner mark provided on the outer peripheral surface 21a of the photosensitive drum 21, and the AIDC sensor 64 is turned off. 64 first
Place at the measurement position. As described above, the AIDC sensor 6
4 is perpendicular to the outer peripheral surface 21 a of the photosensitive drum 21. In this state, light is emitted from the light emitting element 101 toward the outer peripheral surface 21 a of the photosensitive drum 21, and the light reflected by the outer peripheral surface 21 a of the photosensitive drum 21 is detected by the light receiving element 102. In a state where an image such as a toner mark is not formed, the outer peripheral surface 21 of the photosensitive drum 21
Since a is a mirror surface and its reflectance is constant, the detection sensitivity of the AIDC sensor 64 can be calibrated based on the amount of incident light on the light receiving element 102 at this time.

As shown in FIG. 8, when the actuator 112 is turned on to move the AIDC sensor 64 from the first measurement position to the second measurement position, the AIDC sensor 6
Since the holding member 103 (see FIG. 3) rotates around the shaft portion 111a, the incident point of light on the outer peripheral surface 21a of the photosensitive drum 21 actually moves from X1 to X2 (note that the incident point is incident). The outer peripheral surface 21 of the photosensitive drum 21 passes through the point X2.
A plane circumscribing a is represented by Q '. ). For this reason,
When the AIDC sensor 64 is moved from the first measurement position to the second measurement position, the detection timing of the AIDC sensor 64 is changed according to the incident point X2. That is, the rotation speed of the photosensitive drum 21 and the photosensitive drum 2
The detection timing of the AIDC sensor 64 is shifted on the basis of the angle φ at which the incident points X1 and X2 are viewed from the center O of 1. Thereby, when the AIDC sensor 64 is at any of the first measurement position and the second measurement position,
The light emitted from the light emitting element 101 can be successfully incident on the toner mark, and the optical density of the toner mark can be measured.

In order to always detect the optical density at the incident point X1 without changing the detection timing of the AIDC sensor 64, the light outgoing / incident surface P of the AIDC sensor 64 must be located on the outer peripheral surface 21a of the photosensitive drum 21. When tilting the holding member 103 of the AIDC sensor 64 with respect to the incident point X1
May be rotated by a predetermined rotation angle around the angle. However,
In this case, the AI around the photosensitive drum 21
Requires more travel space for DC sensor 64.

FIG. 11 shows the surface 120 of the transfer belt 120.
9 shows another embodiment in which the optical density measuring device of the present invention is applied to measure the optical density of the toner mark 130 formed on the area a. In this embodiment, the holding member 103 of the AIDC sensor 64 (the same one as shown in FIG. 6 and the like) is connected to the surface 1 of the transfer belt 120 as the surface to be measured.
It is fixedly arranged at a position separated by a predetermined distance from 20a. More specifically, the light exit / incident surface P of the AIDC sensor 64 extends along the longitudinal direction of the cylindrical rollers 121 and 122 for driving the transfer belt 120, and is inclined at an angle θ with respect to the outer peripheral surface 21a of the photosensitive drum 21. It is arranged. The detection timing of the AIDC sensor 64 depends on the moving speed of the transfer belt 120 and the toner mark 13.
It is assumed that it is properly adjusted in accordance with the position of 0.

In this arrangement, light emitted from the light emitting element 101 enters the toner mark 130, and light irregularly reflected by the toner mark 130 enters the light receiving element 102. here,
Since the light exit / incident surface P is inclined with respect to the surface 120a of the transfer belt 120, the light exit path of the light emitting element 101 and the toner mark 13 are formed in the same manner as shown in FIG.
0 is also inclined with respect to the plane U including the path of the specularly reflected light L1. Therefore, the regular reflection light component is less likely to be incident on the light receiving element 102, and almost only the irregularly reflected light L <b> 2, which should be originally observed, is incident. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered color toner.

Further, in this arrangement, since the light exit / incident surface P is inclined with respect to the surface 120a of the transfer belt 120, the light exit / incident surface P is perpendicular to the surface to be measured. In addition, the size of the device in a direction perpendicular to the surface 120a of the transfer belt 120 can be reduced. Therefore, the device can be made compact. In addition, only one light receiving element 102 is required, and the apparatus can be configured at low cost.

In each of the above-described embodiments, an image serving as a patch-shaped toner mark is
A document placed near the home position of the document scanner can be used. Further, instead of using an actual image, an image of a toner mark may be formed using data stored in a memory.

[0048]

As is apparent from the above description, in the optical density measuring device of the first aspect, the holding member is moved to the first measurement position and the second measurement position while the light emitting element and the light receiving element are integrally held by the holding member. Since the light-emitting element and the light-receiving element are moved between the measurement positions, the light-emitting element and the light-receiving element are compared with a case where one of the light-emitting element and the light-receiving element is stationary and the other is moved to switch the measurement position. There is no need to fine-tune the relative positional relationship between them, and the mechanism of the device can be simplified. Therefore, the device can be configured at low cost.

In the optical density measuring apparatus according to the second aspect, when the holding member is at the first measurement position, the light outgoing / incident surface is substantially perpendicular to the measured surface, so that the light reflected from the measured surface is specularly reflected. Can be incident on the light receiving element, and the optical density corresponding to the amount of black toner adhered can be measured accurately. On the other hand, when the holding member is at the second measurement position, the light incident / incident surface is inclined with respect to the measured surface. Therefore, the regular reflection light component is less likely to be incident on the light receiving element, and only the diffuse reflection light which is to be observed is almost incident. Therefore, the optical density according to the amount of the adhered color toner can be measured with high accuracy.

In the optical density measuring apparatus according to the third aspect, since the light outgoing / incident surface is arranged so as to be inclined with respect to the surface to be measured, the specularly reflected light component is less likely to be incident on the light receiving element. Only the irregularly reflected light that should be observed is incident. Therefore, it is possible to accurately measure the optical density according to the amount of the adhered color toner. In addition, since the light incident / incident surface is inclined with respect to the surface to be measured, the device in the direction perpendicular to the surface to be measured is compared with the case where the light incident / incident surface is perpendicular to the surface to be measured. Dimensions can be reduced. Therefore, the device can be made compact. Moreover, only one light receiving element is required, and the apparatus can be configured at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an overall configuration of a color copying machine to which an optical density measuring device according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an arrangement of each part when the AIDC sensor is at a first measurement position.

FIG. 3 is a perspective view showing an arrangement of each part when the AIDC sensor is at a second measurement position.

FIG. 4 is a perspective view showing an arrangement of a light entrance / exit surface corresponding to FIG. 2;

FIG. 5 is a perspective view showing an arrangement of a light entrance / exit surface corresponding to FIG. 3;

FIG. 6 is a diagram showing a configuration of an AIDC sensor.

FIGS. 7 (a) and 7 (b) show the arrangement of the light output / incident surface when the AIDC sensor is at the first measurement position and the second measurement position, respectively, as viewed from the center axis direction of the photosensitive drum. FIG. (c) is a diagram showing a light path as viewed from above in (b).

FIG. 8 is a diagram showing incident points of light on the outer peripheral surface of the photosensitive drum.

FIG. 9 is a diagram illustrating a method of calibrating the detection sensitivity of the AIDC sensor.

FIG. 10 shows the relationship between the amount of toner on the photoconductor obtained by the optical density measuring device of the present invention and the amount of incident light on the light receiving element.
It is a figure shown in comparison with a conventional example.

FIG. 11 is a diagram showing another embodiment to which the optical density measuring device of the present invention is applied to measure the optical density of a toner mark formed on the surface of a transfer belt.

FIG. 12 is a diagram showing a configuration of a conventional optical density measuring device.

FIG. 13 is a diagram illustrating a problem of the conventional optical density measuring device.

[Explanation of symbols]

 Reference Signs List 21 photoconductor drum 64 AIDC sensor 101 light emitting element 102 light receiving element 103 holding member 111 lever member 112 solenoid actuator 113 coil spring 120 transfer belt

Claims (3)

[Claims] 1. A light-emitting element and a light-receiving element, wherein light from the light-emitting element reflected by the surface to be measured is received by a light-receiving element, and the optical density of the surface to be measured is measured based on the amount of light received. In the optical density measuring device, a holding member that integrally holds the light emitting element and the light receiving element so that the light emitting element and the light receiving element emit and enter light in the same plane, and measure an optical density of the surface to be measured. An optical density measurement device comprising a holding member moving mechanism that can move the holding member between a first measurement position and a second measurement position for performing the operation. 2. The optical density measuring apparatus according to claim 1, wherein, when the holding member is at the first measurement position, a plane on which the light emitting element and the light receiving element emit and enter light is located on the surface to be measured. The light-emitting element and the light-receiving element are inclined with respect to the surface to be measured when the holding member is at the second measurement position. Optical density device. 3. A light-emitting element and a light-receiving element, wherein light from the light-emitting element reflected by the surface to be measured is received by the light-receiving element, and the optical density of the surface to be measured is measured based on the amount of light received. The optical density measurement device, further comprising: a holding member that integrally holds the light emitting element and the light receiving element so that the light emitting element and the light receiving element emit light in and out of the same plane, wherein the holding member includes the light emitting element An optical density measurement device, wherein a plane through which light enters and exits the light receiving element is arranged to be inclined with respect to the surface to be measured.