JP2003091108A - Mounting structure for reflection type photosensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the mounting structure of a reflection type photosensor by which space-saving is attained and the cost of parts is reduced because a base plate to support the photosensor is not used in the image forming device of an electrophotographic type using the reflection type photosensor as a density detecting means to detect the density of a reference pattern image on a photoreceptor so as to control toner density. SOLUTION: In the image forming device of the electrophotographic type in which the reflection type photosensor 20 is used as the density detecting means to detect the density of the toner image formed by developing the electrostatic latent image of a specified pattern formed on the photoreceptor 1 by a developing means 4 and the reflection type photosensor is arranged on a downstream side from the developing means, the reflection type photosensor is constituted by directly mounting a light-emitting element 21 to emit and reflect detecting light by the toner image of the specified pattern and a light- receiving element 22 to receive reflected light from the toner image without having the base plate at an appropriate position where they face to the surface of the photoreceptor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to density detection in an electrophotographic image forming apparatus using density detection means for detecting the density of a toner image formed of a reference pattern on a photoconductor in order to control the toner density. When a reflective photosensor is used as the means, the sensor can be arranged in the minimum required space without increasing the occupied space by using a substrate for supporting the sensor. The present invention relates to a mounting structure for a photo sensor.

[0002]

2. Description of the Related Art An electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile machine has a charging means, an exposing means, a developing means, a transferring means, a cleaning means, a discharging means around a photosensitive member which is rotatably supported. An image forming unit in which means and the like are sequentially arranged is provided. In the image forming unit, an electrostatic latent image is formed by irradiating optical image information such as reflected light from an original document by the exposing unit while the photosensitive member is preliminarily uniformly charged by the charging unit. The toner image developed with the toner from the developing means is transferred onto the transfer paper by the transfer means, and then the toner image is fixed onto the transfer paper by the fixing means. After the toner image is transferred from the photoconductor, the toner remaining on the photoconductor is removed and collected by the cleaning unit. Further, conventionally, in order to appropriately control the density of a toner image to be developed, a toner image having a fixed pattern is formed on a photoconductor, and the density of this toner image is detected by a reflective photosensor. That is, when the patterned toner image is irradiated with the detection light from the light emitting element that constitutes the reflection type photo sensor, the toner density is controlled based on the amount of the reflected light received by the light receiving element. By the way, in an electrophotographic image forming apparatus using a reflection type photo sensor as a density detecting means, a light emitting element and a light receiving element forming the reflection type photo sensor are mounted on one surface of one wiring board, and this substrate is It has been generally arranged at a suitable position during the process from developing means around the photosensitive drum unit to cleaning. Although the size of the reflection type photo sensor itself in which the light emitting element and the light receiving element are integrated can be extremely reduced to about 5 × 12 mm, by mounting both elements on a substrate having a large area, it is possible to obtain 3 to 5 mm. The size is about twice as large, resulting in a large occupied space and a cause of increasing the cost of parts.

That is, FIG. 4 is a view showing a mounting structure of a conventional reflection type photosensor (density sensor), which has a structure in which a reflection type photosensor 102 is mounted on a wiring board 101. The reflective photosensor 102 has a light emitting element 104 and a light receiving element 105 fixed on a support base 103,
Further, the lead terminal 106 is projected from the support base 103. The lead terminal 106 is connected to a connector 107 fixed to another portion of the substrate 101 via a wiring pattern on the substrate. The connector 107 is connected to the external connector 109 via the harness 108. A resistor or the like is further mounted on the substrate 101. The length of the substrate in the longitudinal direction is about 40 to 70 mm, and the length in the lateral direction is 10.
It is generally about 30 mm. As is clear from this figure, the area of the substrate 101 is several times larger than the size of the reflection type photosensor, and the layout of other parts can be freely set in order to install the substrate at a proper position around the photoconductor. Is decreasing. Also, parts costs are increasing.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and a reflection type photo sensor as a density detecting means for detecting the density of a reference pattern image on a photoconductor in order to control the toner density. It is an object of the present invention to provide a mounting structure of a reflection type photo sensor capable of saving space and reducing component cost without using a substrate supporting the sensor in an electrophotographic image forming apparatus using And

[0005]

In order to solve the above-mentioned problems, the invention of claim 1 provides a toner image formed by developing an electrostatic latent image of a specific pattern formed on a photoconductor by a developing means. In an electrophotographic image forming apparatus in which a reflective photosensor is used as a density detecting unit for detecting the density, and the reflective photosensor is arranged on the downstream side of the developing unit, the reflective photosensor is the specific pattern. A light emitting element that emits and reflects detection light on the toner image of, and a light receiving element that receives the reflected light from the toner image,
It is characterized in that it is directly attached to an appropriate position facing the surface of the photoconductor without using a substrate. The invention of claim 2 uses a photodiode having at least one lead terminal drawn out as the light emitting element, and uses a phototransistor having at least one lead terminal drawn out as the light receiving element. Each of the lead terminals has a structure capable of being directly inserted and connected to a socket of a harness connector to be connected. According to a third aspect of the present invention, the reflective photosensor is
The cleaning unit is attached to a mounting plate provided in a cleaning unit located on the downstream side of the developing unit disposed around the photoconductor and faces the surface of the photoconductor, and the mounting plate of the cleaning unit has a highly insulating mold material. Each of the lead terminals penetrates through the mounting plate and projects to the back surface side thereof to be connected to the harness connector.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a schematic view showing an example of an image forming unit to which the density detecting means of the present invention is applied, and FIG. 2 is an external view of a reflective photosensor used as the density detecting means according to an embodiment of the present invention. , Fig. 3 (a)
And (b) are perspective views showing the mounting state. Figure 1
In the image forming section shown in FIG. 3, along the outer periphery of the drum-shaped photosensitive member 1 which is rotationally driven in the direction of the arrow, the charging unit 2, the writing unit 3, the developing unit 4, the transfer unit 5, the separating unit 6,
Separation claw 7, cleaning unit 8, and static eliminator 9 are sequentially arranged. Reference numeral 10 is a pair of registration rollers, and 11 is a fixing means. In the image forming operation, the charging unit 2
By irradiating image information by laser light from a writing optical system (not shown) onto the photoconductor from the writing means 3 while the photoconductor 1 is uniformly charged in advance,
An electrostatic latent image is formed on the photoconductor 1. This electrostatic latent image is developed by the transfer and adhesion of the toner on the developing roller 4a of the developing means 4 when passing through the developing means 4, and becomes a toner image, and this toner image is transferred to the transfer means 5. When passing, it is transferred onto the transfer paper fed to the transfer position by the registration roller pair 10 by the transfer bias from the transfer means 5. The transfer paper on which the toner image has been transferred is fixed by the fixing means 11 and is discharged to the outside of the apparatus.
The separating means 6 is means for electrostatically peeling off the transfer paper to be adsorbed on the surface of the photoconductor, and the separating claw 7 is means for physically peeling off similar transfer paper. The toner remaining on the surface of the photoconductor 1 after the toner image is transferred onto the transfer paper is removed by the cleaning blade 16 constituting the cleaning unit 8 and collected in the casing 15. A cleaning inlet seal 17 made of an elastic sheet is arranged at the upstream end 15a of the cleaning unit 8, and the cleaning blade 1 is arranged at the downstream end 15b.
6 is fixed.

A characteristic construction of the present invention is that the reflection type photosensor 20 as a density detecting means is arranged in a region up to the developing means 4 and the cleaning unit 8 as a single sensor without a wiring board. is there. That is, in the present embodiment, the reflective photosensor 20 is attached to the attachment plate 15c that projects further from the upstream end 15a of the casing 15 of the cleaning unit than the upstream end 15a. FIG. 2 is an enlarged view of the reflective photosensor 20 used in the present invention. A light emitting element (for example, a photodiode) 21,
The light receiving elements (for example, phototransistors) 22 are arranged in the concentration sensor case 23, respectively, and have a predetermined emission angle,
It is installed with a reflected light receiving angle, and is installed in a state where the pattern density on the surface of the photoconductor can be optimally measured. One or more pin terminals (lead terminals) 21a and 22a are respectively provided from the light emitting and light receiving elements 21 and 22 for energization.
Is pulled out of the sensor case. Further, a positioning pin 24 is projectingly provided on the bottom surface of the sensor case 23. Each of the pin terminals 21a and 22a has a configuration that can be directly inserted and connected to a socket of a harness connector as a connection target.

FIG. 3 is a configuration diagram of a main part as seen from the opening side of the casing of the cleaning unit, showing a mounting state of the reflection type photo sensor. The casing 15 of the cleaning unit is made of a molding material such as ABS, PC, PS or the like, and has excellent insulating properties. A concentration sensor mounting plate 15c integrally projects from a proper place of the casing 15, and the reflection type photosensor 20 shown in FIG. 2 is mounted on the surface of the mounting plate 15c facing the photoconductor. When attaching the reflective photosensor 20 to the mounting plate 15c, the pin terminals 21a, 22 extending from the sensor 20 when the reflective photosensor 20 is brought into contact with the surface side of the mounting plate 15c.
The a is inserted into an insertion hole formed through the mounting plate 15c in advance so as to project from the rear surface side of the mounting plate. After that, a harness connector to be described later is attached to each pin terminal. The reflection-type photosensor 20 of the present invention is not mounted on the wiring board as in the conventional case, but is arranged on the side of the main body of the device when a resistance circuit which is conventionally arranged side by side on the wiring board is required. By arranging the resistors on the side of the power supply board, the characteristic of reducing the occupied space is not impaired. In addition, this reflection type photo sensor 20 is
It is located directly below the cleaning unit 8 and both elements 21 and 22 are embedded in the density sensor case 23, and only the emitting portion and the light receiving portion of each element are in the case 23.
Since the toner is exposed through the openings 23a and 23b provided in the machine, the toner floating inside the machine emits light and receives light from both the light receiving elements 21 and 2
It may adhere to the surface of No. 2, but the cleanability is poor. Therefore, in order to prevent toner contamination on the surface of each element, a dustproof case 25 is attached to the outer surface of the density sensor case 23 so that the openings 23a and 23b are closed. Further, it is necessary to select a material and structure for the dustproof case 25 so that light is not diffusely reflected. That is, it has high transparency and is 100 to 30.
It should have a transparency of about 00 decibels. In the present invention, PC is used as the material of the dustproof case 25, but cellophane tape or the like can be used instead.

FIG. 3 (b) is a view seen from the back side of FIG. 3 (a). The pin terminals 21a and 22a extending from both the light emitting and light receiving elements 21 and 22 shown in FIG. It becomes possible to receive power supply. Each element 2
Since only a weak current (about 1 to 100 mA) is applied to Nos. 1 and 22, no consideration is required to enhance safety, such as shielding the surroundings. Further, once the harness connector 30 is inserted into the pin terminal, it is less necessary to remove it except when the sensor unit is broken, so there is no fear of breaking the pin terminal other than assembling and maintenance. The reflection type photo sensor 20 as the density sensor is the photosensitive member 1
Is very important, and an accuracy of ± 0.5 mm or more is required for the distance from the surface of the photoconductor 1 (site to be detected). It is important that the above distance is within this dimensional tolerance, and the concentration sensor mounting plate 15c is accurately manufactured, and pins or ribs for positioning the sensor case 23 or the mounting plate 15c side are set up or buried. It is necessary to devise such as to dent. In the present invention, positioning is performed by raising a pin on the back side of the density sensor case 23. The mounting structure of the density sensor of the present invention can be applied not only to general machines for copying and printing using an electrophotographic process but also to general equipment using a reflective photosensor.

[0010]

As described above, according to the present invention, the electrophotographic image using the reflection type photosensor as the density detecting means for detecting the density of the reference pattern image on the photoconductor in order to control the toner density. In the forming apparatus, it is possible to provide a mounting structure for a reflective photosensor that can save space and reduce component costs without using a substrate that supports the sensor. That is, the invention of claim 1 is
In an electrophotographic image forming apparatus in which a reflective photo sensor is arranged on the downstream side of the developing unit, the reflective photo sensor includes a light emitting element that emits and reflects detection light to a toner image of a specific pattern, and a toner image. A light-receiving element for receiving the reflected light from was attached directly to an appropriate position facing the surface of the photoconductor without using the substrate. Therefore, a space-saving layout can be easily realized, the margin can be increased, and the cost can be reduced. Claim 2
The invention uses a photodiode and a phototransistor in which at least one lead terminal is drawn out to the outside as a light emitting element and a light receiving element, and each lead terminal is
It is provided with a structure that can be directly inserted and connected to the socket of the harness connector to be connected. Therefore, the number of parts can be reduced, and the cost can be reduced without impairing the function of the conventional concentration sensor. According to a third aspect of the present invention, the reflection type photo sensor is attached to a mounting plate provided in a cleaning unit located on the downstream side of the developing unit arranged around the photoconductor so as to face the surface of the photoconductor. , Which is made of a highly insulating mold material, each lead terminal penetrates through the mounting plate and projects to the back surface side thereof to be connected to the harness connector. Therefore, the mounting plate as a part of the casing of the cleaning unit realizes the same insulating property as that of the wiring board, the number of parts can be reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an image forming section to which a density detecting means of the present invention is applied.

FIG. 2 is an external view of a reflective photosensor used as a density detecting unit according to an embodiment of the present invention.

FIG. 3A and FIG. 3B are perspective views showing a mounting state thereof.

FIG. 4 is a diagram showing a configuration of a conventional density sensor.

[Explanation of symbols]

1 Photoconductor, 2 Charging Means, 3 Writing Means, 4 Developing Means, 5 Transfer Means, 6 Separation Means, 7 Separation Claws, 8
Cleaning unit, 9 static eliminator, 10 registration roller pair, 11 fixing means, 15 casing, 15
a, 15b end part, 15c mounting plate, 20 reflection type photo sensor (density sensor), 21 light emitting element, 22 light receiving element, 21a, 22a pin terminal (lead terminal), 2
3 density sensor case, 24 positioning pins, 30 harness connector.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G059 AA01 BB20 DD12 EE02 KK01                 2H027 DA10 DA32 DD07 DE02 DE10                       EA06 EC04 ED10 EF09 ZA07                       ZA09                 2H071 BA03 BA20 BA27 BA29 BA34                       DA08 DA13 DA15 DA32                 2H077 AD02 AD06 DA04 DA47 DA63                       DA86                 2H134 GA01 GB02 HD01 KF01 KF04                       KG03 KH03 KH09

Claims (3)

[Claims] 1. A reflection type photosensor is used as a density detecting means for detecting the density of a toner image formed by developing an electrostatic latent image of a specific pattern formed on a photoconductor with a developing means. In an electrophotographic image forming apparatus in which a photo sensor is arranged on the downstream side of the developing unit, the reflective photo sensor includes a light emitting element that emits and reflects detection light to a toner image of the specific pattern, and a toner image. A reflection-type photosensor mounting structure, wherein a light-receiving element for receiving reflected light from is directly mounted at a proper position facing the surface of the photoconductor without a substrate. 2. A photodiode having at least one lead terminal extended to the outside is used as the light emitting element, and a phototransistor having at least one lead terminal extended to the outside is used as the light receiving element, The mounting structure for a reflective photosensor according to claim 1, wherein each lead terminal has a structure capable of being directly inserted and connected to a socket of a harness connector as a connection target. 3. The cleaning device is mounted on a mounting plate provided in a cleaning unit located on the downstream side of the developing unit arranged around the photoconductor, the reflection type photosensor facing the surface of the photoconductor. The mounting plate of the unit is made of a highly insulative molding material, and each of the lead terminals penetrates through the mounting plate and protrudes to the back surface side to be connected to the harness connector. Attachment structure for the reflective photosensor described.