JP3347542B2 - Concentration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a density sensor in a forming device such as a printing machine and a printer.

[0002]

2. Description of the Related Art FIG. 15 shows a conventional example of a density detecting sensor for measuring the density of a toner image on an image carrier such as a photosensitive drum or transfer paper. The concentration detection sensor has an LED 1 as a light emitting element and a photodiode 3 as a light receiving element in a holder 4. In order to irradiate the detection image 9 on the image carrier 8 with a constant amount of light, a constant current flows through the LED 1 by the power supply 61 and the resistor 62. Light emitted from the LED 1 to the detection image 9 on the image carrier 8 reflects reflected light corresponding to the density of the detection image 9 and enters the photodiode 3. A current flows through the photodiode 3 in proportion to the amount of incident light, and this current is amplified by the amplifier 7 to be a density signal. The signal thus obtained is converted into a digital signal by a DA converter (not shown), and the subsequent processing is performed.

The above-described density sensor has the advantages that the configuration is simple and the cost is low. However, since the current-light amount characteristic of the half-side LED 1 tends to fluctuate due to thermal characteristics and the like, the irradiation amount is unstable. The accuracy of density detection is not sufficient . FIG. 16 shows an improvement of this. This is because the LED 1 as a light emitting element has dual emission, one of which is illuminated with the detection image 9, the other is received by the light receiving element 2, and L
The light amount of ED1 is monitored, and the control circuit 6
1 is controlled to be constant. In this method, since the light quantity of the LED 1 is monitored by the light receiving element 2, the light quantity is more stable than that of the density sensor described above.

[0004]

However, in the above-mentioned conventional example, since the light amount of the LED is divided into two for the irradiation side and the monitor side, the irradiation light amount becomes low, and the S / N deteriorates. was there. In order to solve this, an LED having a large output must be used, which leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and includes a light-emitting element, a first light-receiving element for measuring a light amount of the light-emitting element, and light reflected from an object to be measured. In a density sensor comprising a second light receiving element and a holder for supporting the first light receiving element and the second light receiving element, stable and accurate density detection is achieved by providing a light flux regulating member at an irradiation opening of the light emitting element. Is to make it possible.

Further, a shield having an opening for forming an optical path is provided between the light emitting element and the first light receiving element, and a cross section including the optical axis of the incident light from the light emitting element to the second light receiving element is provided. If the angle between the two intersecting lines with the inner peripheral side surface of the portion is 45 degrees or more, the light amount of the light emitting element can be accurately controlled even when an optical path is provided by a shield.

Further, by providing a reflector for reflecting light from the light emitting element to the first light receiving element on the surface of the holder facing the first light receiving element, the light amount of the light emitting element can be further stabilized. It is to enable accurate density detection.

In addition, the irradiation opening of the holder and the entrance opening where the reflected light from the object to be measured enters the second light receiving element,
By providing a lens in which the two lenses and the support member are integrally formed, the detection spot of the second light receiving element can be made smaller, the amount of toner consumed for density detection can be reduced, and the cost can be reduced.

[0009]

According to the present invention, there is provided a light receiving element, a first light receiving element for measuring a light amount of the light emitting element, and a light receiving element for receiving reflected light from an object to be measured. at a concentration sensor having a second light receiving element, and a holder for supporting the first light receiving element and the <br/> second light receiving element, the to be provided to the irradiation opening portion of the light emitting element
And a light flux regulating member provided opposite to the first light receiving element.
The first light receiving element is provided with
Light coming directly from the optical element and reflected from the reflector
It is characterized by receiving both light .

[0010]

A cross-section including an optical axis of incident light from the light-emitting element to the first light-receiving element provided with a shield having an opening for forming an optical path between the light-emitting element and the first light-receiving element; An angle formed by two lines of intersection between the opening and the inner peripheral side surface of the opening is 45 degrees or more.

[0012]

[0013]

A lens in which two lenses and a support member are integrally formed is provided at an entrance opening of the holder where the reflected light from the irradiation opening and the object to be measured enter the second light receiving element. And

[0015] By shining a lens formed integrally with two lenses and a support member on an incident opening where the reflected light from the irradiation opening of the holder and the object to be measured enters the second light receiving element, Irradiation light from the light emitting element and reflected light from the measurement object can be collected.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of the present invention. This will be described below with reference to the drawings. LED as light emitting element
1, a photodiode 2 serving as a first light receiving element and a photodiode 3 serving as a second light receiving element are arranged in a sensor holder 4 as shown in the figure. LED1, photodiodes 2 and 3 are each made of Stanley AN304 (PT
506-1) was used. Here, the LED 1 emits light in one direction, and the amount of light is monitored and controlled by a photodiode 2 provided on a side surface of the LED 1. L
The light emitted from the ED 1 passes through an aperture 5 serving as an optical path regulating member, which will be described later, and is applied to a detection image 9 as a measurement object on the image carrier 8. Next, light corresponding to the density of the detection image 9 is incident on the photodiode 3, and the density is measured. As shown in the figure, the light path around the LED 1 is not formed by the sensor holder 4 and the photodiode 2
A sufficient space is provided between them and there is no obstruction. As shown in FIG. 3, when an optical path is formed from the LED 1 to the photodiode 2 by the shield 41, the amount of light received by the photodiode 2 is reduced, and the LED is accurately detected.
1 cannot be controlled. Therefore, as shown in FIG.
Of the cross section including the optical axis of the incident light to the inner surface of the opening
An angle between the intersection lines of the books, that is, a shield 41 whose angle is changed as indicated by θ1 in the figure is provided,
When the degree of shielding up to 1 was changed, good results were obtained when the angle of the shield 41 was 45 ° or more, preferably 60 ° or more. The above positional relationship between the LED 1 and the photodiode 2 will be further described with reference to FIG. The distance L between the center of the light emitting unit of the LED 1 and the center of the light receiving unit of the photodiode 2 is 3 mm, depending on the LED 1 and the photodiode 2 used.
If the angle θ2 with respect to the irradiation direction of the LED is small, the photodiode 2 receives more intense light, but the light illuminating the detection image 10 is blocked. Since the light received by the diode 2 becomes weak, the angle is preferably 30 ° to 90 °.

Next, the aperture 5 will be described. FIG. 2 shows the aperture 5 viewed from the arrow A in FIG.
The aperture 5 is provided in an LED opening 12 which is an irradiation opening of the sensor holder 4. By not shielding between LED1 and the photodiode 2, the photodiode 2 has already been described to receive sufficient light LED1, anyway, a defect, such as: By providing the LED opening 12 as shown in FIG. 6 Occurs. That is, LED1
The emitted light impinges on the detection image 9 on the image carrier 8 and is irregularly reflected here, and a part of the light is
And the density is measured, but a part returns to the photodiode 2 and the light quantity of the LED 1 cannot be monitored correctly. This phenomenon appears remarkably when the reflectance of the detection image 9 is high and the density is low. Therefore, according to the present invention, the aperture 5 is provided in the LED opening 12 of the sensor holder 4 to prevent light returning to the photodiode 2 which monitors the light amount of the LED 1. That is, as shown in FIG. 7, the return light from the detecting image 9 prevents incoming isosamples blocked by the aperture 5 in the photodiode 2.

In the present embodiment, the aperture is provided as a separate member, but may be formed integrally with the sensor holder.

(Second Embodiment) FIG. 8 shows a second embodiment of the present invention.
It is an embodiment of the present invention. A feature of the present invention is that a reflection portion is provided in a sensor holder 4 in a concentration sensor that uses a light emitting element of one-way light emission, monitors a light amount of the light emitting element by a light receiving element provided on a side surface of the light emitting element, and stabilizes the light amount. Another advantage is that the light intensity stability of the light emitting element is further improved. Hereinafter, description will be made with reference to the drawings. Components having the same configuration and operation as the previous embodiment are denoted by the same reference numerals, and description thereof is omitted.
Reference numeral 10 denotes a reflector as a reflector, and L as a light emitting element
The light of ED1 is reflected, and the light is guided to photodiode 2 which is a light receiving element. According to the present invention, since the photodiode 2 receives both the light coming directly from the LED 1 and the light reflected from the reflector 10, the light amount of the LED 1 can be monitored with a larger light amount, and the accuracy of light amount control, Stability is improved. Further, the influence of the return light from the detection image 9 described in the previous embodiment becomes relatively small, and in this respect, the accuracy and stability of the light amount control are improved. Reflector 10
Any material may be used as long as it reflects the wavelength of the light emitting element 1 to be used. For example, a metal plate of Al or the like or a member on which these are vapor-deposited is preferable. In addition, if vapor deposition is performed directly on the inner wall of the sensor holder, a separate member is not required, and a device with lower cost can be provided.

Further, as shown in FIG.
It is needless to say that the provision of the aperture 5 in 2 further increases the stability and is good.

(Third Embodiment) FIG. 10 shows a third embodiment of the present invention. A feature of the present invention resides in that a lens provided integrally with two lens portions made of a transparent material such as glass and PMMA and a lens support member is provided in the irradiation opening portion 12 and the incidence opening portion 13.

Hereinafter, description will be made with reference to the drawings. Components having the same structure and operation as those of the previous embodiment are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 11 denotes a lens integrally provided with two lens portions 111 and 112 and lens supporting members 113a, b, and c.
By condensing the light reflected from, the use efficiency of light is improved, and the accuracy and stability of density detection are improved, and by providing an aperture 5 described later,
The detection spot of the sensor can be made smaller, whereby density detection can be performed with a smaller detection image, and as a result, the amount of toner consumed for density detection can be reduced.

FIG. 11 is an enlarged view of the lens. Most of the light incident on the lens unit 111 is refracted into a predetermined optical path. However, as shown in the figure, the lens unit 111 and the support units 113b and 113c are provided integrally, and therefore, pass through the support unit. Some light (shown by A in the figure ) and light (shown by B in the figure) that are incident on the periphery of the lens 111 and are reflected inside the lens and leak from the support portion 113 are present. When these lights are present, as shown in FIG. 12B, the shape of the LED 1 illuminating the detection image becomes larger than when there is no lens (FIG. 12A). Becomes bigger. 13 shows the relationship between the detection image 9 and the detection spot of the density sensor, and FIG. 14 shows the output of the density sensor. When the detection spot is smaller than the detection image 9 shown in FIG. As shown in FIG. 14 (A), a constant output is stably obtained while the image is completely included in the detection image 9, and accurate density detection can be performed by using this value. On the other hand, FIG.
If the detection spot is larger than the detection image 9 indicated by, the combined output of the density of the base of the image carrier carrying the detection image 9 and the detection image is detected in any state, As for the output, as shown in FIG. 14 (2), a constant value cannot be obtained, and the accuracy of density detection is poor. Therefore, the detection image 9 to be used must be enlarged,
The amount of toner to be consumed also increases accordingly. This can be solved by using the lens portions 111 and 112 and the support member 113 as separate members, and making the support member 113 opaque, but requires two lenses and a support portion, respectively, and increases costs. Therefore, in the present invention, FIG.
By providing the aperture 5 as shown in (1), the light that goes to the periphery of the supporting member and the lens is blocked, and even if a lens having the lens unit and the supporting unit integrated is used, the spot can be reduced, and the toner consumed for detection can be reduced. Consumption was reduced.

[0024]

According to the present invention, the light emitting element , the first light receiving element for measuring the light amount of the light emitting element, and the second light receiving element for receiving the reflected light from the object are provided. a light receiving element, wherein the first light receiving element and the holder for supporting the second light receiving element, the density sensor having a beam restricting portion provided in the irradiation opening of the light emitting element
Material and a reflector provided to face the first light receiving element
Wherein the first light receiving element is directly connected to the light emitting element.
It receives both the light coming in and the light reflected from the reflector.
Light, the light amount of the first light receiving element is
Can be monitored to improve the accuracy and stability of light quantity control.
Can be up.

Further, a shield having an opening for forming an optical path is provided between the light emitting element and the first light receiving element, and a cross section including the optical axis of the incident light from the light emitting element to the second light receiving element and the opening. The angle between the two intersecting lines with the inner peripheral side surface of the portion is set to 45 degrees or more, and even when an optical path is provided by a shield, the light amount of the light emitting element can be accurately controlled.

[0026]

[0027] Further, the incident opening where the reflected light from the irradiation opening of the holder and the object to be measured enters the second light receiving element is provided.
By providing the lens in which the two lenses and the support member are integrally formed, the detection spot of the second light receiving element can be reduced, and the amount of toner consumed for density detection can be reduced and the cost can be reduced. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram of the aperture 5 viewed from a direction A in FIG.

FIG. 3 is an explanatory diagram of a positional relationship between an LED 1 and a photodiode according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a positional relationship between the LED 1 and the photodiode according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a positional relationship between an LED 1 and a photodiode according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of an aperture 5 according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of an aperture 5 according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a second embodiment of the present invention.

FIG. 9 is a diagram showing a second embodiment of the present invention.

FIG. 10 is a diagram showing a third embodiment of the present invention.

FIG. 11 is a diagram illustrating light passing through a lens.

FIG. 12 is a diagram showing detection spots of a density sensor.

FIG. 13 is a diagram illustrating a relationship between a detection spot of a density sensor and a detection image.

FIG. 14 is a diagram showing an output of a density sensor.

FIG. 15 is a diagram showing a conventional example.

FIG. 16 is a diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 LED (light emitting element) 2 photodiode (first light receiving element) 3 photodiode (second light receiving element) 4 sensor holder 5 aperture (light flux regulating member) 6 light quantity control circuit of light emitting element 7 output amplifier 8 image carrier 9 Detection image (measurement object) 10 Reflector 12 Irradiation opening 13 Incident opening 41 Shield 111, 112 Lens 113a, 113b, 113c Lens support member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takaaki Tsuruya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Sasame 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Masuro Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuya Kobayashi 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Naoki Enomoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Haruo Fujii 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference Document JP-A-3-110450 (JP, A) JP-A-60-64232 (JP, A) JP-A-62-44220 (JP, A) Japanese Utility Model Laid-Open No. 5-66537 (JP, U) (58) Survey The field (Int.Cl. ^7, DB name) G01N 21/00 - 21/01 G01N 21/17 - 21/61 G03G 15/00 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A light-emitting element and a first light receiving element that measures the amount of light of the light emitting element, a second light receiving element for receiving reflected light from the measurement object, the first light receiving element and the second in density sensor having a holder for supporting the light receiving elements, beam restricting member provided in the irradiation opening of the light emitting element
And a reflector provided to face the first light receiving element
Wherein the first light receiving element is directly connected to the light emitting element.
It receives both the light coming in and the light reflected from the reflector.
A concentration sensor that emits light . 2. A shielding member having an opening forming an optical path between the light emitting element and the first light receiving element is provided, and an optical axis of light incident on the first light receiving element from the light emitting element is provided. 2. The concentration sensor according to claim 1, wherein an angle formed by two intersecting lines between a cross section including the opening and an inner peripheral side surface of the opening is 45 degrees or more. 3. 3. The irradiation opening of the holder and measurement.
An entrance opening where reflected light from an object enters the second light receiving element.
In the mouth, a lens in which two lenses and a support member are integrally formed
3. A lens according to claim 1 or 2, wherein
Concentration sensor.