JPH0815142A - Optical density sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an optical density sensor in which the cleaning property of the condenser lens on the measurement surface side is improved. [Structure] Light emitting element (light emitting portion) E and light receiving element (light receiving portion)
A sensor that includes D and a holder H that supports them and that detects the concentration of the object by irradiating an object with the light from the light emitting element E and receiving the reflected light from the object with the light receiving element D. In the optical density sensor, a condenser lens L1 for narrowing the irradiation light is arranged in front of E, and a condenser lens L2 for narrowing the reflected light is arranged in front of the light receiving element D. Condensing lenses L1 and L2
One of the surfaces is a flat surface. According to the present invention, even if the surfaces of the condenser lenses L1 and L2 are contaminated with toner or dust, the surfaces of the lenses L1 and L2 can be easily wiped off with a cloth or the like, and therefore highly accurate. Concentration measurement can always be performed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a light emitting portion, a light receiving portion and a holder for supporting them, irradiating the object with light from the light emitting portion and receiving reflected light from the object at the light receiving portion. An optical density sensor for detecting the density of

[0002]

2. Description of the Related Art Generally, in an image forming apparatus adopting an electrophotographic system, a stable image cannot be obtained if the image density changes due to various conditions such as environmental changes and the number of prints.

Therefore, conventionally, a toner for density detection (hereinafter referred to as a patch) is formed by a toner on a photosensitive drum or a transfer drum on a trial basis, and the density of the patch is detected by an optical density sensor. A stable image is obtained by controlling the image density by feeding back the detection result to the image forming conditions such as the exposure amount and the developing bias.

As shown in FIG. 9, the optical density sensor is composed of a light emitting element E such as an LED and a photodiode, a light receiving element D such as CdS, and a holder H that supports these light emitting element E and the light receiving element D. The light emitted from the light emitting element E is applied to a patch P formed on a photosensitive drum, a transfer drum or the like (not shown), and the reflected light from the patch P is received by the light receiving element D. The density of the patch P is measured from the relationship between the reflected light amount and the reflected light amount.

By the way, since the patch to be measured in the image density control is unfixed, if the distance between the optical density sensor and the patch is too short, the toner scattered from the patch easily stains the optical density sensor. Therefore, it is desirable to separate the patch and the optical density sensor as much as possible.

However, since the light from a light emitting element such as an LED is diffused light, the irradiation area increases as the distance between the patch and the optical density sensor increases, so that the size of the patch must be increased accordingly. In addition, the toner consumption for the patch increases. In addition, the amount of irradiation light per unit area on the patch and the amount of light reflected from the patch entering the light receiving element are also reduced, so that the detection accuracy of the sensor is lowered.

Therefore, conventionally, as shown in FIG. 10, by inserting a condenser lens L1 in front of the light emitting element E to narrow down the irradiation light, the size of the patch is changed while widening the distance between the sensor and the patch. I didn't have to. The condenser lens L1 also increases the irradiation light amount per unit area on the patch. Further, by increasing the size of the light receiving window W for taking in the reflected light and inserting the condenser lens L2 therein, the amount of reflected light incident on the light receiving element D is also increased.

[0008]

However, since the condenser lenses L1 and L2 are convex as shown in FIG. 10, dust, scattered toner, and the like are measured on the measurement surfaces of the condenser lenses L1 and L2. If it adheres to the side, the cleaning property is extremely poor, and dust and toner easily remain around the condenser lenses L1 and L2.

Therefore, as shown in FIG. 11, a transparent dustproof plate B is attached in front of the condenser lenses L1 and L2 so that the toner and dust can be easily cleaned.

However, if the dustproof plate B is attached in front of the condenser lenses L1 and L2 as described above, the amount of irradiation light or the amount of received light may be reduced, or the irradiation light focused by the lens L1 may be diffused. There is a risk of

Further, since the light is focused by using the condensing lenses L1 and L2, the requirements for the mounting accuracy of these lenses L1 and L2 become strict, and the assembling property of the sensor deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical density sensor in which the cleaning property of the condenser lens on the measurement surface side is improved.

Another object of the present invention is to provide an optical density sensor in which the assembling precision and the assemblability of the condenser lens are improved.

[0014]

To achieve the above object, the invention according to claim 1 comprises a light emitting part, a light receiving part and a holder for supporting them, and irradiates the object with light from the light emitting part, It is a sensor that detects the density of the object by receiving the reflected light from the light receiving part, in front of the light emitting part a condenser lens for narrowing the irradiation light, and in front of the light receiving part the reflected light. In an optical density sensor including condenser lenses for squeezing, one surface of each condenser lens is a flat surface.

A second aspect of the present invention is characterized in that, in the first aspect of the invention, the flat surface of each condensing lens is a measurement surface side surface.

According to a third aspect of the present invention, in the first aspect of the invention, the flat surface of each of the condenser lenses is on the same plane as the measurement surface of the holder, or the measurement of the holder is performed. It is characterized in that it protrudes from the surface.

A fourth aspect of the invention is characterized in that, in the first aspect of the invention, a transparent protective member is attached to a flat surface of each of the condenser lenses.

A fifth aspect of the present invention is characterized in that, in the first aspect of the invention, a cleaning member is arranged on a flat surface of each of the condenser lenses.

According to a sixth aspect of the present invention, in the first aspect of the invention, each condensing lens has a fitting portion and is fitted and held on the outer periphery of the holder. Is characterized by.

According to a seventh aspect of the present invention, there is provided a light emitting portion, a light receiving portion, and a holder for supporting them. The object is irradiated with light from the light emitting portion, and the light receiving portion receives reflected light from the object. A sensor for detecting the concentration of
In an optical density sensor including an irradiation light condensing lens for narrowing the irradiation light in front of the light emitting unit and a reflected light condensing lens for narrowing the reflection light in front of the light receiving unit, The irradiation light condensing lens and the reflected light condensing lens are integrated.

An eighth aspect of the invention is characterized in that, in the seventh aspect of the invention, one surface of the integrated condenser lens is a flat surface.

A ninth aspect of the present invention is characterized in that, in the eighth aspect of the invention, the flat surface of the integrated condenser lens is a measurement surface side surface.

According to a tenth aspect of the present invention, in the invention of the eighth aspect, the flat surface of the integrated condenser lens is flush with the measurement surface of the holder, or It is characterized in that it protrudes from the measurement surface of the holder.

An eleventh aspect of the invention is characterized in that, in the eighth aspect of the invention, a transparent protective member is attached to the flat surface of the integrated condenser lens.

According to a twelfth aspect of the present invention, in the eighth aspect of the invention, the cleaning member is arranged on the flat surface of the integrated condenser lens.

According to a thirteenth aspect of the invention, in the seventh aspect of the invention, the integrated condenser lens has a fitting portion and is fitted and held on the outer periphery of the holder. It is characterized by

According to a fourteenth aspect of the invention, in the seventh aspect of the invention, the size of the integrated condenser lens is the same as the measurement surface of the holder.

[0028]

According to the first to third aspects of the present invention, even when the surface of the condenser lens (the surface on the measurement surface side) is soiled with toner, dust or the like, the surface of the condenser lens is covered with the cloth. Since it can be easily wiped off with, for example, highly accurate concentration measurement can always be stably performed.

According to the invention described in claim 4,
In addition to the effect according to the invention described in 3, the protective member can prevent the surface of the condenser lens from being scratched by cleaning.

According to the invention of claim 5, claims 1 to
In addition to the effect of the invention described in 3, it is possible to obtain an effect that it is not necessary to bother the user to clean the lens, and it is possible to prevent a decrease in sensor detection accuracy due to forgetting to clean the lens.

According to the invention described in claim 6,
In addition to the effect of the invention described in 3, the effect that the assembling property of the condenser lens to the holder is enhanced can be obtained.

According to the seventh aspect of the present invention, the positional relationship between the irradiation light condensing lens and the reflected light condensing lens is always constant, the mounting accuracy of the integrated lens with respect to the holder is improved, and the assembly is performed. The property is also improved.

According to the inventions of claims 8 to 10, in addition to the effect of the invention of claim 7, there is a case where the surface of the integrated lens (the surface on the measurement surface side) is soiled by toner, dust or the like. However, since the surface of the integrated lens can be easily wiped off with a cloth or the like, it is possible to obtain an effect that high-precision concentration measurement can always be stably performed.

According to the invention of claim 11, claim 8 is provided.
In addition to the effects of the invention described above, it is possible to obtain the effect of preventing the surface of the integrated lens from being scratched by cleaning by the protective member.

According to the invention of claim 12, claim 8 is provided.
In addition to the effects of the invention described above, there is no need to bother the user for cleaning the integrated lens, and it is possible to prevent the sensor detection accuracy from decreasing due to forgetting to clean.

According to the invention of claim 13, claim 7
In addition to the effects of the invention described above, the effect that the assemblability of the integrated lens to the holder is enhanced can be obtained.

According to the invention of claim 14, claim 7
In addition to the effects of the invention described above, since the gap between the integrated lens and the holder is eliminated, toner etc. can be reliably cleaned,
The effect that high-precision concentration measurement can always be stably performed is obtained.

[0038]

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

<First Embodiment> FIG. 1 is a vertical sectional view of an optical density sensor according to a first embodiment of the present invention. The optical density sensor includes a light emitting element E such as an LED and a photodiode C.
A light receiving element D such as dS, an irradiation light focusing lens L1 for narrowing down the irradiation light from the light emitting element E, a reflected light focusing lens L2 for narrowing down the reflected light from the object to be measured, and these light emitting elements E. And a holder H that supports the light receiving element D and the condenser lenses L1 and L2.

In this embodiment, the shape of each of the condenser lenses L1 and L2 on the measurement surface side is a flat surface, and the flat surface is made to coincide with the measurement surface M of the holder H.

Therefore, the lens L for condensing the toner or dust is used.
Even when the measurement surface side of 1, 1 is soiled, the toner, dust or the like adhering to the surfaces of the condenser lenses L1, L2 (the surface on the measurement surface side) can be easily wiped off with a cloth or the like. Highly accurate density measurement can always be stably performed using the optical density sensor.

By the way, the condenser lenses L1 and L2 have fitting portions, which are fitted to the outer circumference of the holder H (measurement surface M in this embodiment).
Held in.

The measuring surfaces of the condenser lenses L1 and L2 may be projected from the measuring surface M of the holder H as shown in FIG. 2, but the amount of projection is 0 in order not to deteriorate the cleaning performance. It is desirable that it is about 0.2 to 1 mm.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. 3 is a vertical cross-sectional view of the optical density sensor according to the present embodiment, and in FIG.
The same elements as those shown in are given the same reference numerals.

In the first embodiment, the condenser lenses L1,
The cleaning property is improved by making the measurement surface side of L2 a flat surface. However, when the condensing lenses L1 and L2 are made of a material such as methacrylic acid resin, the toner or dust is wiped off with a cloth or the like. There is a possibility that the surfaces of the condenser lenses L1 and L2 may be slightly scratched to deteriorate the performance of the lenses L1 and L2.

Therefore, in this embodiment, as shown in FIG. 3, by attaching a transparent dustproof sheet T of PET, PTFE or the like on the surfaces of the condenser lenses L1 and L2, the condenser lenses L1 and L2 are cleaned by cleaning. Protects the surface of the.
If a dust-proof sheet T having a transparent electrode attached thereto is used and a bias having the same polarity as that of the toner is applied to the dust-proof sheet T, the toner is less likely to adhere to the dust-proof sheet, and the cleaning property is further improved.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. 4. FIG. 4 is a perspective view of the optical density sensor according to this embodiment.

In the first and second embodiments, the user has to clean the condenser lenses L1 and L2, which is troublesome for the user.

Therefore, in this embodiment, as shown in FIG. 4, the cleaning member C is provided on the lens surface of the sensor. The cleaning member C reciprocates several times in a direction indicated by an arrow in the drawing by a driving unit (not shown) to clean the lens surface at a predetermined timing according to the number of measurements, operation time, user's instruction, and the like. As a result, it is not necessary to bother the user to clean the lens, and it is possible to prevent a decrease in sensor detection accuracy due to forgetting to clean the lens.

In FIG. 4, H is a holder and T is a dustproof sheet similar to that of the second embodiment.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG. 5 is a vertical cross-sectional view of the optical density sensor according to the present embodiment, and in FIG.
The same elements as those shown in are given the same reference numerals.

In each of the above-described embodiments, the two lenses L1 and L2, that is, the irradiation light collecting lens L1 for narrowing down the irradiation light and the reflected light collecting lens L2 for narrowing down the reflected light are used. In the present embodiment, as shown in FIG. 5, the irradiation light condensing lens L1 for narrowing down the irradiation light from the light emitting element E and the reflected light collection for narrowing down the reflected light incident on the light receiving element D from the object to be measured. The light lens L2 is integrated into one integrated lens L. As a result, the positional relationship between the irradiation light focusing lens L1 that narrows down the irradiation light and the reflected light focusing lens L2 that narrows down the reflected light is always constant, and the lens L when the integrated lens L is incorporated into the holder H is used. The installation accuracy of is improved. Furthermore, 1
Assembling the single lens L also improves its assemblability.

In this embodiment as well, as in the first embodiment, the surface of the integrated lens L on the measurement surface side is a flat surface to improve the cleaning performance of the integrated lens L. In this case, the measurement surface side of the integrated lens L may be projected from the measurement surface of the holder H, but the projection amount is preferably about 0.2 to 1 mm so as not to deteriorate the cleanability.

By the way, also in this embodiment, the second
Similarly to the embodiment, PET, PT are formed on the surface of the integrated lens L.
A transparent dustproof sheet such as FE may be attached to prevent the surface of the integrated lens L from being scratched by cleaning. Further, as in the third embodiment, a cleaning member is arranged on the surface of the integrated lens L in order to prevent the sensor detection accuracy from being lowered due to forgetting the cleaning without bothering the user to clean the integrated lens L. You may.

Further, the integrated lens L according to the present embodiment has a fitting portion, and the lens L is fitted to the outer periphery of the holder H (in this embodiment, the measurement surface) to hold the holder. It is held at H.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIGS. 6 and 7. 6 is a cross-sectional view showing a stray light entrance path in the integrated lens, and FIG. 7 is an exploded cross-sectional view of the optical density sensor according to the present embodiment.
In FIG. 5, the same elements as those shown in FIG.

In the fourth embodiment, two condenser lenses L are used.
1 and L2 are integrated, but lenses L1 and L2 are
6, the stray light of the irradiation light condensing lens L1 that narrows down the irradiation light is circulated to the reflected light condensing lens L2 that narrows down the reflected light, which lowers the detection accuracy of the optical density sensor. May cause

Therefore, in this embodiment, as shown in FIG. 7, a groove R is formed between the two condenser lenses L1 and L2, and a partition S is provided at a position corresponding to the groove R of the holder H.
The integrated lens L is incorporated in the holder H so that the groove R fits into the partition S on the holder H side.

Thus, due to the partition S, the stray light of the irradiation light condensing lens L1 that narrows down the irradiation light does not go to the reflected light condensing lens L2 that narrows down the reflected light, and the detection of the optical density sensor is performed. It is possible to eliminate the possibility that the accuracy is lowered, and always perform highly accurate concentration measurement. <Sixth Embodiment> Next, a sixth embodiment of the present invention will be described with reference to FIG. 8 is an exploded perspective view of the optical density sensor according to this embodiment.

In each of the above embodiments, the condenser lenses L1 and L
2 or L, the toner enters the gap between the lens L1, L2 or L and the holder H, the entered toner is scraped out during the cleaning, and the lens L1, L2 or L again.
There is a risk of soiling the surface.

Therefore, in this embodiment, as shown in FIG. 8, the integral lens L has the same size as the measurement surface of the holder H, and the fitting portion A is further provided on the lens L to provide the fitting portion A.
Is adopted in the holder H.

Thus, according to this embodiment, since the gap between the holder H and the integrated lens L is eliminated, the toner can be reliably cleaned. Of course, if the dustproof sheet T (see FIG. 3) as described in the second embodiment is attached to the integrated lens L, even better results can be obtained.

[0063]

As is apparent from the above description, claim 1
According to the inventions described in (1) to (3), even when the surface of the condenser lens (the surface on the measurement surface side) is soiled with toner, dust, etc., the surface of the condenser lens can be easily wiped off with a cloth or the like. As a result, it is possible to obtain an effect that high-precision concentration measurement can always be stably performed.

According to the invention of claim 4, claim 1
In addition to the effect according to the invention described in 3, the protective member can prevent the surface of the condenser lens from being scratched by cleaning.

According to the invention described in claim 5,
In addition to the effect of the invention described in 3, it is possible to obtain an effect that it is not necessary to bother the user to clean the lens, and it is possible to prevent a decrease in sensor detection accuracy due to forgetting to clean the lens.

According to the invention described in claim 6,
In addition to the effect of the invention described in 3, the effect that the assembling property of the condenser lens to the holder is enhanced can be obtained.

According to the seventh aspect of the present invention, the positional relationship between the irradiation light condensing lens and the reflected light condensing lens is always constant, and the mounting accuracy of the integrated lens with respect to the holder is improved, and the assembling is improved. The property is also improved.

According to the inventions of claims 8 to 10, in addition to the effect of the invention of claim 7, the surface of the integrated lens (the surface on the measurement surface side) is soiled by toner, dust or the like. However, since the surface of the integrated lens can be easily wiped off with a cloth or the like, it is possible to obtain an effect that high-precision concentration measurement can always be stably performed.

According to the invention of claim 11, claim 8 is provided.
In addition to the effects of the invention described above, it is possible to obtain the effect of preventing the surface of the integrated lens from being scratched by cleaning by the protective member.

According to the invention of claim 12, claim 8 is provided.
In addition to the effects of the invention described above, there is no need to bother the user for cleaning the integrated lens, and it is possible to prevent the sensor detection accuracy from decreasing due to forgetting to clean.

According to the invention of claim 13, claim 7
In addition to the effects of the invention described above, the effect that the assemblability of the integrated lens to the holder is enhanced can be obtained.

According to the invention of claim 14, claim 7
In addition to the effects of the invention described above, since the gap between the integrated lens and the holder is eliminated, toner etc. can be reliably cleaned,
The effect that high-precision concentration measurement can always be stably performed is obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an optical density sensor according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a modified example of the optical density sensor according to the first embodiment of the invention.

FIG. 3 is a vertical sectional view of an optical density sensor according to a second embodiment of the present invention.

FIG. 4 is a perspective view of an optical density sensor according to a third embodiment of the present invention.

FIG. 5 is a vertical sectional view of an optical density sensor according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view showing an ingress path of stray light in the integrated lens.

FIG. 7 is an exploded sectional view of an optical density sensor according to a fifth embodiment of the present invention.

FIG. 8 is an exploded perspective view of an optical density sensor according to a sixth embodiment of the present invention.

FIG. 9 is a vertical sectional view of a conventional optical density sensor.

FIG. 10 is a vertical cross-sectional view of a conventional optical density sensor using a condenser lens.

FIG. 11 is a vertical sectional view of a conventional optical density sensor in which a dustproof plate is arranged in front of a condenser lens.

[Explanation of symbols]

 C Cleaning member D Light receiving element (light receiving portion) E Light emitting element (light emitting portion) H Holder L Integrated lens L1 Irradiation light focusing lens L2 Reflected light focusing lens M Measurement surface T Dustproof sheet (protection member)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Ishibe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A sensor comprising a light emitting unit, a light receiving unit and a holder for supporting them, which detects the concentration of the object by irradiating the object with light from the light emitting unit and receiving reflected light from the object at the light receiving unit. In the optical density sensor, a condenser lens for narrowing the irradiation light is arranged in front of the light emitting portion, and a condenser lens for narrowing the reflected light is arranged in front of the light receiving portion. An optical density sensor, wherein one surface of each of the condenser lenses is a flat surface. 2. The flat surface of each condenser lens is
The optical density sensor according to claim 1, wherein the optical density sensor is a surface on the measurement surface side. 3. The flat surface of each condenser lens is
The optical density sensor according to claim 1, wherein the optical density sensor is on the same plane as the measurement surface of the holder or protrudes from the measurement surface of the holder. 4. The optical density sensor according to claim 1, wherein a transparent protective member is attached to a flat surface of each of the condenser lenses. 5. The optical density sensor according to claim 1, wherein a cleaning member is arranged on a flat surface of each of the condenser lenses. 6. Each condensing lens has a fitting portion,
The optical density sensor according to claim 1, wherein the optical density sensor is fitted and held on the outer circumference of the holder. 7. A sensor comprising a light emitting portion, a light receiving portion and a holder for supporting them, which detects the concentration of the object by irradiating the object with light from the light emitting portion and receiving reflected light from the object at the light receiving portion. In addition, an illuminating light condensing lens for converging the irradiating light is arranged in front of the light emitting unit, and a reflected light condensing lens for converging the reflected light is arranged in front of the light receiving unit. In the density sensor, an optical density sensor in which the irradiation light focusing lens and the reflected light focusing lens are integrated. 8. The optical density sensor according to claim 7, wherein one surface of the integrated condenser lens is a flat surface. 9. The optical density sensor according to claim 8, wherein the flat surface of the integrated condenser lens is a surface on the measurement surface side. 10. The flat surface of the integrated condenser lens is flush with the measurement surface of the holder,
Alternatively, the optical density sensor according to claim 8, wherein the optical density sensor projects from the measurement surface of the holder. 11. The optical density sensor according to claim 8, wherein a transparent protective member is attached to a flat surface of the integrated condenser lens. 12. The optical density sensor according to claim 8, wherein a cleaning member is arranged on a flat surface of the integrated condenser lens. 13. The optical density sensor according to claim 7, wherein the integrated condenser lens has a fitting portion and is fitted and held on the outer periphery of the holder. 14. The optical density sensor according to claim 7, wherein the integrated condenser lens has the same size as the measurement surface of the holder.