JP2014238339A - Optical sensor and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sensor capable of improving the detection accuracy of a light quantity and a position by finely adjusting the deviation of an optical axis caused by the positional deviation of a chip due to the individual difference of a light receiving/emitting element and to provide an image forming apparatus using the optical sensor.SOLUTION: The optical sensor includes light-emitting means 71 for irradiating an image carrier 8 to which toner is adhered with the light of a light-emitting chip 81, a lens 90 irradiating a carrier with the light from the light-emitting means, light-receiving means being a photosensor 70, lenses 91 and 92 condensing the light regularly reflected by the image carrier to the photosensor 70, and a housing 74 in which the light-emitting means, the light-receiving means, and the lenses are stored. In the optical sensor, a positioning projection n3 which is integral with the housing is brought into contact with the lead root part m of the light-emitting means and then, the light-emitting means is fixed to the housing.

Description

  The present invention relates to an optical sensor for detecting an adhesion amount or a powder adhesion position of a powder such as toner on an image carrier provided in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, and a facsimile machine, The present invention also relates to an image forming apparatus including the optical sensor.

An image forming apparatus including an optical sensor uses, for example, a two-component developer containing toner as a powder and magnetic particles, and the toner is formed on the surface of an image carrier such as a photoreceptor or an intermediate transfer belt included in the image forming apparatus. Is attached to form a toner image. An image is formed by transferring the toner image onto transfer paper.
In such an image forming apparatus, in order to obtain a desired image density, for example, a density detection toner patch having a gradation pattern is formed on the surface of the image carrier. Then, the density of the toner patch, that is, the toner adhesion amount is detected by an optical detection means, and based on the detection result, the laser light intensity for forming a latent image on the photosensitive member, the charging bias, the developing bias, etc. Adjustment is made to adjust the density of the image to be formed.

  A full-color image forming apparatus generally forms a plurality of color toner images such as yellow, magenta, cyan, and black on an image carrier such as an intermediate transfer belt and superimposes the toner images of the respective colors on each other. A color image is formed. In such an image forming apparatus that forms a color image, for example, an intermediate transfer belt may be expanded or contracted due to a temperature change in the apparatus, and the position of the toner image may be shifted. Therefore, in order to detect the amount of positional deviation of the toner image, a position detection toner patch made up of each color toner image of a predetermined shape is formed on the surface of the image carrier, and the position of the position detection toner patch is optically determined. The position deviation amount is obtained by detection by the detection means. Based on this misregistration amount, laser beam irradiation timing for forming a latent image, the rotational speed of the image carrier, and the like are adjusted to correct misregistration of the toner image.

As described above, in the optical sensor used in the image forming apparatus, incident light is emitted from a light emitting element to an object on an irradiation object, for example, a toner image, reflected light from the toner image is received by the light receiving element, and the light receiving element is photoelectrically converted. In accordance with the change in output, toner image density adjustment and toner image positional deviation correction are performed. In such density adjustment and positional deviation correction, in order to increase the detection accuracy of the optical sensor itself, the optical path position accuracy, which is the support position accuracy and the relative position accuracy of the light emitting element and the light receiving element of the optical sensor, is increased. It is important.
In particular, the optical sensor appropriately irradiates incident light on an object, for example, a toner image, from a light emitting element attached and supported on the sensor housing body, and receives light reflected and attached to the sensor housing body on the sensor housing body. Lead to the element. At this time, it is necessary to appropriately and stably hold the incident path, the reflection path, and the opposing angle between the virtual reference plane including both paths and the irradiation surface of the irradiation target.

Accordingly, Patent Documents 1, 2, and 3 disclose support structures for mounting a light emitting element used as a light emitting unit of an optical sensor on a circuit board, and an object that absorbs light or diffusely reflects, for example, toner adheres to an irradiation target. Patent Documents 4 to 8 propose examples of optical sensors that are used to detect the amount of adhesion and the position of adhesion.
Here, Patent Document 1 supports a mold part (lens) and a lead wire, which are sealing members, for the purpose of improving positional accuracy when mounting a light emitting element on a circuit board and improving vibration resistance. An LED holder is disclosed. The LED holder not only supports the sealing member, but also fixes the bent part of the lead wire to the main body with a flap, which eliminates instability in positional accuracy when mounted on a circuit board and enhances vibration resistance The structure to perform is disclosed.
In Patent Document 2, an insulating plate is attached in a state where a plate surface is raised on a circuit board, and the insulating plate is supported through a connection pin of an optical element, and the pin is soldered to the circuit board side.
In Patent Document 3, an encoder body that supports a light emitting unit and a light detection unit so as to face each other is provided on a substrate, and each connection portion of the light emitting unit and the light detection unit is extended through a hole in the substrate.

  On the other hand, in Patent Document 4, ultraviolet light is emitted from a light emitting diode onto the surface of a conveyance belt to which color toner is adhered, and a toner density signal corresponding to the amount of ultraviolet light is optically received by a photodiode that receives the regular reflection light. The sensor detects it. Here, the reflectance of the ultraviolet light is low in the color toner, the regular reflection from the color toner can be suppressed from being received by the light receiving unit, and the regular reflection light according to the surface ratio of the transport belt can be received. An appropriate toner density signal is obtained.

The optical sensor of Patent Document 5 receives regular reflection light obtained by regular reflection of incident light emitted from a light emitting means by an irradiation object by the first light receiving means, and the incident light is irregularly reflected by an object attached on the irradiation object. The irregularly reflected light is received by the second light receiving means. Here, the angle formed by the center line of the incident optical path and the center line of the regular reflection optical path is 25 ° or less. As a result, the optical path lengths of incident and reflected light are made relatively short to increase the amount of light received, so that even if the amount of adhesion of the object increases, it can be detected in a sufficient sensitivity range, and the amount of adhesion can be detected with high sensitivity. ing.
Furthermore, the reflection type sensor which is an optical sensor of Patent Document 6 includes a plurality of light emitting elements and light receiving elements that are built in a rectangular resin package at a predetermined interval in a plan view and extend from the light emitting elements and the light receiving elements, respectively. Leads protrude from the side wall of the resin package. Moreover, the ends of each lead are bent and held on a flat substrate, and each lead is bonded to the substrate by melting the solder components in the cream solder using a solder reflow method. ing.

Furthermore, in the optical element mounting structure provided in the optical detection device of Patent Document 7, an optical element that emits and receives light is attached in the vicinity of the edge of the surface of the substrate using a connector. The connector here is arranged so that the insertion hole faces in the direction along the board surface, and the lead of the optical element is inserted and connected to the insertion hole from the direction along the board surface. The thickness is relatively reduced and thinner.
Further, Patent Document 8 discloses an optical connector having a coupling structure of an optical semiconductor element used in an optical communication system and an optical fiber. Here, a rectangular cubic optical semiconductor element is bonded to the stem, the stem is welded to the cap, and the optical fiber is adjusted to the optical axis so that the optical axis is aligned, and then fixed to the cap. Is disclosed.

  By the way, it is desirable for the optical sensor to further improve the detection performance when detecting the toner adhesion amount of the four color toners (yellow, cyan, magenta, black) and the color misregistration amount. Further, such an optical sensor has a light emitting / receiving element, and there is an individual difference in the light receiving / emitting element, and it is already known that the detection performance changes due to the individual difference.

  Here, when the light-emitting element is a bullet-type LED as shown in Patent Documents 1 to 5 and 7, a configuration as shown in FIGS. 11A and 11B is adopted. The light emitting element 100 includes a bullet-shaped sealing member 101, a light emitting chip 102 sealed therein, and a pair of lead frames 103 connected to the light emitting chip 102. These are supported on the main body side of the image forming apparatus via a sensor housing (not shown). The light emitting chip 102 is integrally attached to the tip bulging portion of one lead frame 103, and emits the irradiation light Lc1 to the irradiation surface at the detection position along the irradiation axis. The optical axis of the irradiation light Lc1 is set to coincide with the central axis Lb of the sealing member 101.

By the way, when a bullet-type LED (light-emitting element) 100 is manufactured, the light-emitting chip 102 is die-bonded to the lead frame 103 and finally is sealed with a resin. At this time, the positional relationship between the lead frame 103 and the light emitting chip 102 is the accuracy of die bonding, and is said to be about ± 0.1 mm. Next, resin sealing is performed on the lead frame 103 on which the chip is placed. At this time, the alignment accuracy between the lead frame 103 and the resin is said to be about ± 0.1 mm. As for the positional relationship between the light emitting chip 102 and the resin, tolerances accumulate and become as large as ± 0.2 mm.
For such manufacturing reasons, for example, as shown in FIG. 10, the position of the light emitting chip 102 (the optical axis position of the irradiation light Lc1) is shifted from the center line Lb of the sealing member 101 by a width d2 (enlarged display). There is a case where the light emitting chip 102 ′ is manufactured with a deviation, and a description of this case is added.

  Here, as one of the individual differences that affect the detection characteristics of the light emitting / receiving elements, it is assumed that the position of the light emitting chip 102 has a deviation d2 with respect to the center line Lb of the sealing member 101 as shown in FIG. To do. Then, the optical axis P0 of the light emitting chip 102 is affected by the light condensing characteristic imparted by the hemispherical head 104 of the sealing member 101, and the optical axis is refracted to P01, for example. In this state, the irradiation light of the optical axis P01 is shifted with respect to the designed irradiation position, and the reflected light from the shifted position is received with the reflected optical axis shifted, and the amount of light received by the light receiving element is reduced. However, the accuracy of light quantity and position detection is reduced.

As described above, when the position of the light emitting chip 102 (the optical axis P0 position) is deviated from the center line Lb of the sealing member 101 for manufacturing reasons, the direction of the optical axis P01 is inclined, so that this bullet type. Individual differences of the LEDs (light emitting elements) 100 are reflected as variations in the detection performance of the sensor. Therefore, in order to avoid such a problem, there has conventionally been a problem that an element having a small individual difference between light receiving and emitting points has to be selected and used.
Patent Document 1 discloses an LED holder that supports a mold part (lens) that is a sealing member and a lead wire, and this LED holder eliminates instability in positional accuracy of the light emitting / receiving element with respect to the circuit board. And it is mounted with enhanced vibration resistance. However, the positional deviation of the chip in the light emitting / receiving element cannot be eliminated by fine adjustment.
Furthermore, Patent Document 6 only discloses a configuration in which a light receiving / emitting element or the like is held in a heat resistant resin and a lead is soldered to a flat substrate using a heating furnace, and is fixed in Patent Document 8. Only a coupling structure in which the optical axis is aligned by finely adjusting the support position of the optical fiber with respect to the optical semiconductor element is disclosed. As described above, the techniques of Patent Documents 6 and 8 cannot eliminate the optical axis shift caused by the positional deviation of the chip in the light emitting / receiving element by fine adjustment.

  The present invention has been made in view of the above-described problems of the prior art. In addition to eliminating the need for selecting elements with small individual differences in light receiving and emitting points, it is possible to eliminate chip misalignment due to individual differences in light receiving and emitting elements. It is an object of the present invention to provide an optical sensor and an image forming apparatus using the optical sensor that finely adjusts the accompanying optical axis shift to suppress the influence thereof and improve the accuracy of light quantity and position detection.

The present invention has the following configuration in order to achieve the above object.
The present invention comprises a light emitting means for irradiating light of a light emitting chip toward an image carrier to which toner is attached, a lens for condensing the light from the light emitting means and irradiating the carrier, and a light receiving means, A toner adhering amount and a toner adhering position including a lens for condensing the light regularly reflected by the image carrier onto the light receiving means, the light emitting means, the light receiving means, and a housing in which the lens is accommodated are detected. In this optical sensor, the light emitting means is fixed to the housing after a positioning protrusion integral with the housing is brought into contact with the lead base portion of the light emitting means.

  According to the present invention, since the light emitting means is fixed to the housing after the positioning projection is brought into contact with the lead root portion of the light emitting means, the position of the light emitting chip of the light emitting means is determined, and the chip due to the individual difference of the light receiving and emitting elements. Therefore, it is possible to easily perform fine adjustment to an appropriate position that suppresses the influence of the positional deviation, and it is possible to provide an optical sensor that can improve the accuracy of light quantity and position detection.

1 is an overall schematic configuration diagram of a printer as an image forming apparatus in which an optical sensor according to an embodiment of the present invention is provided in an image forming unit. FIG. 2 is a main part sectional view of a process cartridge used in the image forming apparatus of FIG. 1. FIG. 2 is an enlarged longitudinal sectional view of an optical sensor used in the image forming apparatus of FIG. 1. FIG. 4 is an enlarged front sectional view of the optical sensor of FIG. 3. The positioning function part of the optical sensor of FIG. 3 is shown, (a) is a principal part expanded plane sectional view, (b) is the BB line principal part expanded sectional view of (a). 3A is a main part enlarged view of the optical sensor of FIG. 3, FIG. 3A is a main part enlarged front view of a pair of leads and a front view, and FIG. . It is explanatory drawing of the displacement by the position shift of the light emitting chip of the optical sensor of FIG. 3, and its optical axis. FIG. 2 is an enlarged plan view of a main part of a density detection toner patch having a gradation pattern formed on a conveyance belt of the image forming apparatus of FIG. 1. FIG. 2 is a characteristic explanatory diagram of the sensor output ratio of the optical sensor with respect to a change in the angle of the surface to be examined which is irradiated with light irradiated by the optical sensor used in the image forming apparatus of FIG. It is explanatory drawing of the optical path bending of the light emitting / receiving element used with the conventional optical sensor. It is a figure of the light emitting / receiving element used with the conventional optical sensor, (a) is a principal part enlarged front view which becomes a pair of lead and front view, (b) is a principal part enlarged side view which becomes a side view of a pair of lead. is there

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments and modifications, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description thereof is omitted.
FIG. 1 shows an image forming apparatus using an optical sensor according to an embodiment of the present invention.
As shown in FIG. 1, the image forming apparatus 1 records a color image composed of each color of yellow (Y), magenta (M), cyan (C), and black (K) as a sheet of transfer material 7. (Shown in FIG. 1). Note that units corresponding to yellow, magenta, cyan, and black colors are indicated by Y, M, C, and K at the end of the reference numerals.
The image forming apparatus 1 includes an apparatus main body 2, a plurality of paper feeding units 3, a registration roller pair 10, a transfer unit 4, a fixing unit 5, and a plurality of laser writing units 22Y, 22M, 22C, and 22K (hereinafter, referred to as “image forming apparatus 1”). When not distinguishing colors, it is referred to as “laser writing unit 22”), a plurality of process cartridges 6Y, 6M, 6C, 6K (hereinafter referred to as “process cartridge 6” when not distinguishing colors), and reflection type photo. And at least a sensor 70.

  A plurality of paper feed units 3 are provided in the lower part of the apparatus main body 2. The paper feeding unit 3 includes a paper feeding cassette 23 that can accommodate the recording paper 7 described above in a stacked manner and can be taken in and out of the apparatus main body 2 and a paper feeding roller 24. The paper feed roller 24 is pressed against the uppermost recording paper 7 in the paper feed cassette 23. The paper feed roller 24 feeds the above-described uppermost recording paper 7 between a transfer belt 29 (described later) of the transfer unit 4 and a photosensitive drum 8 (described later) of the process cartridge 6.

  The registration roller pair 10 sandwiches the recording paper 7 between the pair of rollers 10a and 10b, and feeds the recording paper 7 between the transfer unit 4 and the process cartridge 6 at the timing of superimposing the sandwiched recording paper 7 on the toner image.

  The transfer unit 4 is provided above the paper feed unit 3, and includes a driving roller 27, a driven roller 28, a conveyor belt 29, and transfer rollers 30Y, 30M, 30C, and 30K (hereinafter referred to as “transfer roller when colors are not distinguished from each other”). 30 ”). The drive roller 27 is disposed on the downstream side in the conveyance direction of the recording paper 7 and is rotationally driven by a motor or the like as a drive source. The driven roller 28 is rotatably supported by the apparatus main body 2 and is disposed on the upstream side in the conveyance direction of the recording paper 7. The conveying belt 29 has a glossy surface 29a and an endless annular shape. The conveying belt 29 is stretched over both the driving roller 27 and the driven roller 28, and is rotated around the driving roller 27 and the driven roller 28 in the drawing. Circulate clockwise (endless travel).

In FIG. 1, the transfer roller 30 of the transfer unit 4 sandwiches the conveyance belt 29 and the recording paper 7 on the conveyance belt 29 between the photosensitive drum 8 of the process cartridge 6. In the transfer unit 4, the transfer roller 30 presses the recording paper 7 sent out from the paper feeding unit 3 against the outer surface of the photosensitive drum 8 of each process cartridge 6, and the toner image on the photosensitive drum 8 is transferred to the recording paper 7. Transcript to. The transfer unit 4 sends the recording paper 7 onto which the toner image has been transferred toward the fixing unit 5.
In FIG. 1, the fixing unit 5 is provided downstream in the transport direction r of the transfer unit 4 and presses and heats the recording paper 7 sent out from the transfer unit 4 between a pair of rollers 5a and 5b, thereby photosensitive drums. The toner image transferred from 8 to the recording paper 7 is fixed on the recording paper 7.

Each laser writing unit 22 is provided in the apparatus main body 2, corresponds to one process cartridge 6, and irradiates the outer surface of the photosensitive drum 8 with laser light to form an electrostatic latent image.
The process cartridge 6 is provided between the transfer unit 4 and the laser writing unit 22, respectively. The process cartridges 6 are detachable from the apparatus main body 2 and are arranged in parallel along the conveyance direction of the recording paper 7.

  As shown in FIGS. 1 and 2, the process cartridge 6 includes a cartridge housing 11, a charging roller 9 as a charging device, a photosensitive drum 8 as an image carrier (also referred to as a photosensitive member), and a cleaning as a cleaning device. A blade 12 and a developing device 13 are provided.

The charging roller 9 uniformly charges the outer surface of the photosensitive drum 8.
The photosensitive drum 8 is formed in a columnar shape or a cylindrical shape that is rotatable about an axis, and the outer surface thereof is uniformly charged by a charging bias applied to the charging roller 9 (for example, −500 V to −700 V). ) Further, the photosensitive drum 8 is irradiated with laser light by the laser writing unit 22 to form an electrostatic latent image on its outer surface, and the electrostatic latent image is developed with the toner 36 by the developing device 13. The obtained toner image is transferred to the recording paper 7 positioned between the conveyance belt 29. The cleaning blade 12 removes the toner remaining on the outer surface of the photosensitive drum 8 after transferring the toner image to the recording paper 7.
The toner is spherical fine particles produced by an emulsion polymerization method or a suspension polymerization method. This toner may be obtained by pulverizing a lump composed of a synthetic resin mixed and dispersed with various dyes or pigments. The average particle diameter of the toner is 3 μm or more and 7 μm or less.

The magnetic carrier has an average particle size of 20 μm or more and 35 μm or less. The magnetic carrier contains a spherical core material made of ferrite as a magnetic material, a resin component obtained by crosslinking a thermoplastic resin such as acrylic and a melamine resin, and a charge control agent. In addition, a resin coat film covering the outer surface of the core material and spherical alumina particles dispersed in the resin coat film are provided.
As shown in FIG. 2, the developing device 13 includes at least a developer supply unit 14, a case 25, a regulating blade 16 as a regulating member, and a developing roller 15 as a developer carrier.

The developer supply unit 14 includes a storage tank 17 and a pair of stirring screws 18 as stirring members. The storage tank 17 is formed in a box shape whose length is substantially equal to that of the photosensitive drum 8. A partition wall 19 extending along the longitudinal direction of the storage tank 17 is provided in the storage tank 17. The partition wall 19 partitions the storage tank 17 into a first space 20 and a second space 21. Further, both ends of the first space 20 and the second space 21 communicate with each other.
The storage tank 17 stores the developer 26 in both the first space 20 and the second space 21. The developer contains toner as a powder and a magnetic carrier. A supply hole 37 is opened at one end of the first space 20 on the side away from the developing roller 15 in the first space 20 and the second space 21. The toner 36 is appropriately supplied through a supply hole 37 by a developer supply device 35 described later.

The developing device 13 includes a cylindrical cored bar 34, a cylindrical magnet roller (also referred to as a magnet body) 33, and a developing sleeve 32 as a nonmagnetic cylindrical body. The developing device 13
The developer 26 stirred by the pair of stirring screws 18 is attracted to the outer surface of the developing sleeve 32 by the magnetic force of the magnet roller 33, and the developing sleeve 32 rotates to cause the developer to be attracted to the photosensitive drum 8. The developer that rises on the outer surface of the developing sleeve 32 is regulated by the doctor blade 16 to an appropriate amount of rising, and is carried on the developing roller 15, transported to the developing area, and on the photosensitive drum 8. The electrostatic latent image is developed to form a toner image.
As shown in FIG. 2, the developing device 13 is provided with a developer supply device 35. The developer supply device 35 includes a toner container 40 and a transport tank 41 that are connected to each other. The developer supply device 35 loosens the toner stored in the toner container 40 in the transport tank 41 according to the amount (concentration) of the toner in the developing device 13, and then supplies the toner to the developing device 13. .

The image forming apparatus 1 shown in FIG. 1 forms an image on the recording paper 7 as described below.
First, the image forming apparatus 1 rotates the photosensitive drum 8 so that the outer surface of the photosensitive drum 8 is uniformly charged (−500 V to −700 V) by the charging roller 9 to which a charging bias is applied. When a laser beam corresponding to the image formed on the outer surface of the photosensitive drum 8 is irradiated, the potential of the portion irradiated with the laser beam becomes about −50 V, and an electrostatic latent image developed with toner is formed. It is formed. Assume that the electrostatic latent image is positioned in the development area 31. Then, the toner 36 of the developer 26 adsorbed on the outer surface of the developing sleeve 32 of the developing device 13 is a low potential portion of the photosensitive drum 8 by the developing bias (−300 V to −500 V) applied to the charging roller 9. The electrostatic latent image is developed by being attracted to the electrostatic latent image. The toner image is formed on the outer surface of the photosensitive drum 8.

  Then, the image forming apparatus 1 waits for the recording paper 7 to be conveyed by the paper feed roller 24 of the paper feed unit 3 or the like. When the recording paper 7 is positioned between each photosensitive drum 8 of the process cartridge 6 and the conveyance belt 29 of the transfer unit 4, the toner image formed on the outer surface of each photosensitive drum 8 is transferred to the recording paper 7. . The image forming apparatus 1 fixes the toner image on the recording paper 7 with the fixing unit 5. Thus, the image forming apparatus 1 forms a color image on the recording paper 7.

In the image forming apparatus 1 described above, apart from the image forming operation as described above, a process control operation (hereinafter referred to as a process control operation) for optimizing the image density of each color when the power is turned on or after a predetermined number of sheets have passed. ) Is executed.
In this process control operation, the density detection toner patches 91 are formed on the surface 29a of the transport belt 29 so as not to overlap each other for each color (Y, M, C, K). That is, the conveyance belt 29 corresponds to an image carrier. The density detection toner patch 91 formed on the surface 29a of the transport belt 29 is formed into a pattern having a continuous tone by sequentially switching the charging bias and the developing bias. In this embodiment, as shown in FIG. 8, for each toner, a rectangular density detection toner patch 91 whose toner adhesion amount changes in gradation is placed in the center of the conveyance belt 29 in the width direction in the surface movement direction. Create in a line along.

  In the image forming apparatus 1, the photosensor 70 detects the toner adhesion amount of the density detection toner patch 91 whose toner density changes in gradation. The photodiode 72 of the photosensor 70 outputs a voltage corresponding to the toner adhesion amount (that is, toner density), and this output voltage is sent to a control unit (not shown) of the image forming apparatus 1. The control unit functions as an image density control means, and continuously grasps the toner adhesion amount of the density detection toner patch 91 based on the amount of reflected light obtained from the output voltage of the photodiode 72, and the grasped toner adhesion amount. And a predetermined target adhesion amount. Thereafter, based on the comparison result, the laser light intensity of the laser writing unit 22, the charging bias of the charging roller 9, the developing bias applied to the developing roller 15, the amount of developer supplied from the developer supplying device 35, and the like are appropriately set. The image density is changed and adjusted so that the image density becomes a desired density.

  In this process control operation, toner image positional deviation correction is also performed. In this positional deviation correction process control operation, a position detection toner patch 92 is formed on the surface 29 a of the transport belt 29. The position detection toner patches 92 are a plurality of rectangular toner images formed with high density (so-called solid) with each color toner, and are arranged at equal intervals along the surface movement direction of the conveyance belt 29. In this embodiment, as shown in FIG. 8, rectangular toner images having the same density formed by the respective toners are arranged in a row along the surface movement direction at three locations in the width direction center and both ends of the conveyance belt 29. Create sequentially so that they line up.

  In the image forming apparatus 1, the positions of the plurality of rectangular toner images included in the position detection toner patch 92 are detected by the photo sensor 70. The photodiode 72 of the photosensor 70 outputs a voltage corresponding to the positions of a plurality of toner images, and this output voltage is sent to a control unit (not shown) of the image forming apparatus 1. This control unit functions as a positional deviation amount control means. Here, based on the amount of reflected light obtained from the output voltage of the photodiode 72, the positions of the plurality of toner images are grasped, and the interval between the toner images is obtained from the grasped positions of the toner images. After comparing this interval with a predetermined reference value, the laser light irradiation timing for forming the latent image, the rotation speed of the image carrier, and the like are adjusted as appropriate based on the comparison result. Is adjusted to match the reference value.

Next, a reflective photosensor that is an embodiment of the optical sensor according to the present invention will be described with reference to FIGS.
A reflective photosensor 70 (hereinafter simply referred to as a photosensor), which is an optical sensor, is disposed in the vicinity of the driving roller 27 of the conveyor belt 29. Thus, the toner adhesion amount and toner adhesion position of the density detection toner patch formed on the surface of the conveyor belt 29 are detected, that is, the position of the detection toner patch is detected.

  As shown in FIG. 3, the photo sensor 70 is attached to a support member 95 or the like, and is disposed to be opposed to the conveyance belt 29 as an image carrier at an interval. As a result, the density (toner adhesion amount) of the density detection toner patch 91 (see FIG. 8) formed on the glossy surface 29a of the transport belt 29 and the position (toner adhesion) of the position detection toner patch 92 are detected. Used to detect the position).

  The density detection toner patch 91 uses each toner (yellow Y, magenta M, cyan C, black K), and the density gradually decreases from upstream to downstream in the surface movement direction r (see FIG. 8) of the transport belt 29. These are a plurality of rectangular toner images formed in a gradation pattern. The pattern portions are arranged at equal intervals along the surface movement direction of the conveyor belt 29. The position detection toner patches 92 are a plurality of rectangular toner images formed with high density (so-called solid) using each toner, and are arranged at equal intervals along the surface movement direction of the conveyor belt 29. ing.

  In FIG. 8, symbols Y, M, C, and K indicate toner images formed with yellow, magenta, cyan, and black toners, respectively, and numerical values in parentheses added to these symbols indicate toner density. Yes. Further, a photosensor 70 used for detecting the density of the density detection toner patch 91 is indicated by reference numeral 70A, and a photosensor 70 used for detecting the position of the position detection toner patch 92 is indicated by reference numeral 70B.

  In FIG. 4, a photosensor (optical sensor) 70 includes a light receiving element (light receiving means) 72 that receives specularly reflected light from the image carrier and a light receiving element (light receiving means) 73 that receives diffusely reflected light from the image carrier. It is a type that has been added. The photosensor (optical sensor) 70 includes a light emitting diode 71 as ultraviolet light emitting means, photodiodes 72 and 73 as ultraviolet light receiving means, an element holder (hereinafter referred to as a housing) 74, and a substrate 95. Prepare.

  The light emitting diode 71 (hereinafter referred to as LED 71) is a well-known optical semiconductor component that emits ultraviolet light when an electric current is passed. As shown in FIGS. 3 and 6, the LED 71 is connected to a sealing member 83 made of a transparent or translucent synthetic resin, a light emitting chip 81L sealed in the sealing member 83, and the light emitting chip 81L. And a pair of lead wires 82 of a resin mold type. The sealing member 83 of the LED 71 has a rectangular cube-shaped body portion 85, a head portion at the tip of the body portion 85 is formed in a substantially flat surface, and is formed integrally with a mirror-like end wall surface 84 and the other end of the body portion 85. And is formed in a rectangular cubic shape.

  For example, an element made of a gallium nitride (GaN) compound that emits ultraviolet light having a peak emission wavelength of 365 nm is used for the light emitting chip 81L of the LED 71. In the present invention, ultraviolet light means light having a wavelength of 300 nm or more and less than 400 nm. One end of each of the pair of lead wires 82 of the LED 71 is connected to the light emitting chip 81 </ b> L, and the other end of each lead wire 82 protrudes from the other end of the flange portion 86. That is, the lead wire 82 (lead) extending from the light emitting chip 81L extends from the lead root portion m. In this embodiment, the rectangular cube-shaped LED 71 is used in terms of miniaturization and cost reduction. However, the present invention is not limited to this, and a bullet-shaped LED may be used as long as it irradiates ultraviolet light.

  The light receiving element 72 that receives specularly reflected light and the photodiodes 72 and 73 that are light receiving elements 73 that receive diffusely reflected light (hereinafter, only 72 will be described in the case of a representative description) have a voltage (that is, according to the amount of received light (that is, , Signal) is a known optical semiconductor component. The photodiode 72 has the same configuration as the light-emitting diode 71 described above, and is sealed with a sealing member 83 made of a transparent synthetic resin and the sealing member 83 as shown in FIGS. This is a resin mold type comprising a light receiving chip 81R and a pair of lead wires 82 connected to the light receiving chip 81R. The sealing member 83 of the photodiode 72 is formed in the same rectangular cubic shape as the LED 71 described above.

  For the light receiving chip 81R of the photodiode 72, for example, a silicon (Si) element having a sensitivity wavelength range of 320 nm to 1000 nm is used. The light receiving chip 81R only needs to include the wavelength of ultraviolet light emitted from the light emitting chip 81L of the LED 71 in the sensitivity wavelength range. One end of each of the pair of lead wires 82 of the photodiode 72 is connected to the light receiving chip 81 </ b> R, and the other end protrudes from the other end of the flange portion 86.

  In this embodiment, a photodiode is used as the ultraviolet light receiving means. However, the present invention is not limited to this, and a device that generates a voltage or current according to the amount of received ultraviolet light, such as a phototransistor or photodarlington. If so, the shape and configuration of the ultraviolet light receiving means are arbitrary.

  The housing 74 is made of a non-translucent synthetic resin and is formed in a rectangular shape as shown in FIG. 2, and a surface (hereinafter referred to as a lower surface 741) located below the housing 74 in the drawing is conveyed. It arrange | positions so that it may oppose and parallel to the surface 29a of the belt 29 at intervals. As shown in FIG. 4, the housing 74 is a pair of first and second members as viewed in a direction perpendicular to the surface movement direction r of the intermediate transfer belt (see FIG. 5A: a cross-sectional view taken along line AA in FIG. 4). The second housing halves 742 and 743 are overlapped with each other in the thickness direction Y of the housing 74 and integrally joined. The integrated first and second housing halves 742 and 743 provide a first accommodation hole 75, a second accommodation hole 76, and a third accommodation hole 77 each having a circular cross section.

  Here, as shown in FIG. 3, the optical path hole n2 of the 1st accommodation hole 75, the 2nd accommodation hole 76, and the 3rd accommodation hole 77 is opening in the lower surface 741 of the housing 74, Each optical path hole n2 Lenses 90, 91, and 92 are respectively provided in the opening portions of the lens. Thereby, the lens 90 of the first accommodation hole 75 stops and collects the light flux in the optical path R0 of the LED 71. Further, the specularly reflected light from the irradiation point Q where the lens 91 of the second accommodation hole 76 is directed to the photodiode 72 is converged to the light receiving position p1 of the light receiving chip 81R, and the lens 92 of the third accommodation hole 77 is directed to the photodiode 73. The diffused reflected light from the irradiation point Q is converged on the light receiving position p2 of the light receiving chip 82R. With such lenses 90, 91, and 92, the input light amounts of both sensors are increased, and the decrease in the sensor output ratio (S / N) is suppressed.

As shown in FIGS. 3 and 4, the first accommodation hole 75 is formed larger than the outer diameter of the body portion 85 and the flange portion 86 of the LED 71 and fits so as to be minutely displaceable, and the optical path at the tip thereof. A hole n2 and a positioning protrusion n3 integral with the housing protruding in the center of the hole n1 are formed.
As shown in FIGS. 5A and 5B, the positioning projection n3 protrudes from the first and second housing halves 741 and 742 to the center of the hole n1, respectively, and a pair of lead wires is formed by the ends of the positioning abutment. 82, and can be brought into contact with the rear surface f1 of the flange portion 86 of the LED 71.

  Here, the positioning projection n3 is clamped by the first and second housing halves 741 and 742 in a state where the positioning projection n3 is in contact with the back surface f1 of the flange portion 86 of the LED 71 of the first accommodation hole 75 and the pair of lead wires 82. Is done. For this reason, the LED 71 fitted to the first housing half 741 is in a state where the lead root m is supported at three points. In this state, it is assumed that after fine adjustment of the optical path R1 of the irradiation light from the light receiving chip 81R, the other second housing half 742 is overlapped and the two housing halves 741 and 742 are integrally joined. In this case, since the LED 71 after the deviation correction is in a state where the lead root portion m is supported at three points, further deviation can be easily prevented and the positional accuracy is improved. In some cases, after the first and second housing halves 741 and 742 are integrally joined, a work hole (not shown) that opens to the outside is provided behind the hole n1 of the first accommodation hole 75. The deviation of the LED 71 can be finely adjusted. Even in that case, further deviation of the LED 71 after the deviation correction can be easily prevented.

  Further, both the housing halves 741 and 742 and the positioning projection n3 of the position fixing portion are both or at least one is formed of a heat resistant resin. With this configuration, when the lead wire 82 is soldered to the circuit board, problems due to heat being transmitted to the housing halves 741 and 742 and the positioning projection n3 are prevented. That is, it is possible to obtain an effect of preventing the element positions from being fixed (displaced) due to melting and preventing displacement.

  The second accommodation hole 76 and the third accommodation hole 77 of the housing 74 have basically the same configuration as the first accommodation hole 75, and the photodiode 72 for specular reflection light is inserted into the second accommodation hole 76 in the third accommodation. A diffused reflected light photodiode 73 is accommodated in the hole 77. In this case as well, a positioning projection n3 integral with the housing is formed in the hole n1 of the second accommodation hole 76 and enters between the back surface of the flange portion 86 of the photodiode 72 and the pair of lead wires 82. Also in this case, since the lead root portion m of the photodiode 72 is supported at three points, the positioning of the photodiode 72 can be performed accurately and stably. Similarly, a positioning projection n3 integral with the housing is formed in the hole n1 of the third accommodation hole 77, and enters between the rear surface of the flange portion 86 of the photodiode 73 and the pair of lead wires 82. Also in this case, since the lead root portion m of the photodiode 73 is supported at three points, the positioning of the photodiode 73 can be performed accurately and stably.

The optical path R0 of the irradiation light of the LED 71 of the first accommodation hole 75 formed in this way passes through the optical path at the design position, and enters the target irradiation point Q on the surface 29a of the transport belt 29 at an appropriate incident angle. To do. Further, the regular reflection light from the irradiation point Q passes through the optical path R1 at the designed position and enters the light receiving position p1 of the light receiving chip 81R of the photodiode 72, and enters the photodiode 72 in the second accommodation hole 76. A voltage corresponding to the amount of specularly reflected light is sent to a control unit (not shown) of the image forming apparatus 1.
Further, the diffuse reflected light from the irradiation point Q passes through the optical path R2 at the designed position and enters the light receiving position p1 of the light receiving chip 82R of the photodiode 73 to diffuse into the photodiode 73 in the third accommodation hole 73. A voltage corresponding to the amount of the reflected light R is sent to a control unit (not shown) of the image forming apparatus 1.

In this way, the irradiation light of the LED 71 that enters the irradiation point Q of the surface 29a of the transport belt 29 at an appropriate incident angle can secure an appropriate light amount. The regular reflected light passing through the optical path R1 at the designed position at the light receiving position p1 of the light receiving chip 81R of the photodiode 72 can secure an appropriate amount of light. Similarly, the diffusely reflected light passing through the optical path R2 at the designed position at the light receiving position p2 of the light receiving chip 81R of the photodiode 73 can secure an appropriate amount of light.
As described above, in the optical sensor of the present invention, the positioning projection n3 can be brought into contact with the lead root portion m of the light emitting means to maintain the three-point support state, and the light emitting means is fixed to the housing in this state. Thereby, fine adjustment to an appropriate position that suppresses the influence of the positional deviation of the chips 81L and 81R due to individual differences of light emitting and receiving elements is facilitated. In addition, since the positions of the chips 81L and 81R of the light emitting / receiving means can be accurately positioned and subsequent positional deviation can be easily prevented, the accuracy of light quantity detection and position detection can be improved.

  In the first embodiment described above, the LED 71 of the first accommodation hole 75 is sandwiched between the first and second housing halves 741 and 742 and stably supported with the lead root portion m in contact with the three-point position. Has been.

As shown in FIG. 7, the LED 71 has a rectangular cubic body 85, a distal end surface 84 at the distal end of the trunk 85, and a flange 86 at the other end of the trunk 85. The light emitting chip 81L is supported in the center of the inside. The light emitted from the light emitting chip 81L passes through the tip surface 84 from the light emitting point Pc at the center of the body 85, passes through the designed optical path, and enters the target irradiation point Q on the surface 29a of the conveyor belt 29. .
Thus, the irradiation light L1 of the light emitting chip 81L passes through the tip surface 84 vertically from the light emitting point Pc. For this reason, it is assumed that the light emission point Pc of the irradiation light of the light emitting chip 81L has a manufacturing error d1. In the case of the light emitting chip 81L ′ that indicates the optical path with such a broken line, the irradiation light L1 ′ passes vertically through the tip surface 84 from the light emitting point Pc and travels in parallel with the irradiation light L1 of the light emitting chip 81L. That is, the irradiation light L1 ′ of the light emitting chip 81L ′ is shifted from the irradiation light L1 of the light emitting chip 81L by only the manufacturing error d1 at the irradiation point Q.

  Therefore, in consideration of manufacturing error d1 in advance, when the LED 71 ′ is mounted in the first accommodation hole 75, the position of the light emitting chip 81L ′ of the LED 71 ′ overlaps the light emitting point Pc of the irradiation light of the light emitting chip 81L. Such misalignment correction is performed. At this time, the positioning protrusion n3 is brought into contact with the lead root portion m (see FIG. 5B) of the light emitting chip 81L ′ (light emitting means), and the three-point support state is maintained. 1 It fixes to the accommodation hole 75. FIG. Thereby, the optical path of the irradiation light of the LED 71 ′ overlaps the optical path of the irradiation light L 1 of the appropriate light emitting chip 81 L in the first accommodation hole 75, and can enter the target irradiation point Q, and then the regular reflection light and diffuse reflection light Can be prevented, and the accuracy of subsequent light quantity detection and position detection can be improved.

  Thus, since the tip surface 84 of the light emitting chip 81L is a flat surface, the direction of the optical axis of the light emitting means is not changed by the sealing member, so that the optical axis of the optical sensor can be easily adjusted. That is, it is easy to adjust the deviation while maintaining the three-point support state of the light-emitting chip 81L ′ (light-emitting means), and it works more effectively and can prevent a decrease in the amount of regular reflection light and diffuse reflection light. The accuracy of subsequent light quantity detection and position detection can be further improved.

Next, instead of the rectangular cube-shaped LED 71, as a comparative example, for example, a light emitting element 100 (LED) including a bullet-shaped sealing member 101 as shown in FIG. 10 and having a light emitting chip 102 sealed therein. Is adopted.
In the case of this bullet-type LED 100, as shown in FIG. 10, when the position of the light-emitting chip 102 in the sealing member 101 is in an appropriate position, the center position of the bullet-type LED 100 coincides with the center position of the light-emitting chip 102. Therefore, the irradiation light Lc1 of the light emitting chip 102 is appropriately irradiated. However, it is assumed that the light emitting chip has a deviation d2 with respect to the center line Lb of the sealing member as in the light emitting chip 102 ′ of FIG.

In this case, the irradiation light Lc1 of the light emitting chip 102 ′ is affected by the lens characteristics of the hemispherical head 104 of the sealing member 101, and for example, the optical axis Lc1 is refracted to P01. The refractive optical axis Lc1 is incident on a position shifted from the designed irradiation point Q, and the reflected light from the shifted position is received in a further shifted state. In such a case, the amount of light received by the light receiving element decreases, and the accuracy of light amount detection and position detection decreases. Thus, when the light emitting element 100 (LED) as a comparative example is employed, the effect of the present invention cannot be effectively obtained.
In the case of a bullet-type LED 100 as a comparative example, it is assumed that the bullet-type LED 100 is mounted in the accommodation hole 75 (see FIG. 4), for example, in consideration of a manufacturing error d2. In this case, it is assumed that the position of the light emitting chip 102 ′ of the bullet-type LED 100 is corrected and mounted so as to overlap the regular light emitting point Pc. In this case, the positioning projection n3 is brought into contact with the lead root portion m (for example, see FIG. 5B) of the light emitting chip 81La (light emitting means), and the three-point support state is maintained. It is assumed that the first housing hole 75 is fixed.

However, the irradiation light Lc1 of the bullet-type LED 100 as a comparative example remains refracted by the hemispherical head 104, and is also deviated from the target irradiation point Q. As described above, even if the deviation of the light emitting chip 102 ′ is adjusted and used, the state where the optical axis is refracted with P01 is not resolved. For this reason, the amount of light received by the light receiving element decreases, and the accuracy of light amount detection and position detection decreases.
When the deviation of the bullet-shaped LED 100 from the center line of the sealing member of the light emitting chip 102 ′ is very small, the irradiation light Lc 1 passes near the center of the hemispherical head 104. For this reason, the refraction of the irradiation light Lc1 is very small. In such a case, if accuracy is not a problem, the position adjustment is performed so as to cancel a small amount of refraction state after securing the three-point support of the lead root portion m of the light emitting chip 102 ′. The bullet-type LED 100 can be used.

As described above, in order not to cause erroneous detection in toner adhesion amount detection and toner position deviation amount detection, a sensor that is resistant to fluctuations in the angle α of the detected surface (intermediate transfer belt) is desirable.
That is, as shown in FIG. 3, the optical axis L0 of the light emitting chip 81L that is incident on the target irradiation point Q on the surface 29a of the conveyor belt 29 is orthogonal to the surface 29a, but actually the detected surface angle α varies. ing.
Therefore, the characteristics of the sensor that is resistant to angular fluctuations were examined by taking the detected surface angle α on the horizontal axis and the sensor output on the vertical axis, as shown in FIG.

Here, a sensor that is resistant to the angle fluctuation α of the surface 29a of the conveyor belt 29 is a sensor that has little change in output even when α changes. That is, it is clear that the LED chip position in the graph located at the center of the LED has less output change than the sensor shifted from the center position.
From this, it is clear that the sensor characteristics vary depending on the LED chip position, and it is important for the sensor characteristics to accurately determine the LED chip position. That is, by holding the light emitting / receiving element in a state where the lead root m is supported at three points as in the present invention, further deviation of the light receiving / emitting element can be easily prevented, and the positional accuracy of the LED chip position is improved. It is effective to do.
Furthermore, since the above-described photosensor 70 is provided, it is assumed that the amount of color toner attached to the surface 29a of the conveyor belt 29 is large. In such a case, that is, even when the color toner density is high, the photodiode 72 can correctly detect the amount of specularly reflected light (that is, specularly reflected light from the surface 29a) that changes according to the color toner density. The density of the color toner can be detected.

  In the above-described embodiment, the photo sensor 70 is disposed relative to the surface 29 a of the transport belt 29. Instead of such an arrangement of the photosensors 70, for example, as shown by a two-dotted line in FIG. 2, the photosensors 70a are secondly arranged relative to the photosensitive drums 8 in the process cartridges 6 of the respective colors. The embodiment may be configured. In this case, the photosensor 70a detects the toner adhesion amount of the density detection toner patch formed along the surface movement direction of the photosensitive drum 8 and the position of the position detection toner patch. In the case of an image forming apparatus provided with an intermediate transfer belt as an intermediate transfer member, a density detection toner formed on the surface of the intermediate transfer belt by disposing a photo sensor (not shown) relative to the intermediate transfer belt. The toner adhesion amount of the patch and the position of the position detection toner patch may be detected.

Furthermore, although the above-mentioned optical sensor has been described as a type having two light receiving elements of regular reflection light and diffuse reflection light as the light receiving element, the present invention is also applied to an optical sensor having only one of the light receiving elements. It can be applied in the same manner, and the same effect can be obtained.
Furthermore, although a color image forming apparatus has been described as an image forming apparatus provided with a photosensor, the present invention can also be applied to a monochrome image forming apparatus. The present invention can also be applied to image forming apparatuses such as copying machines and facsimile machines.

70, 70a Photosensor (optical sensor)
71 LED
72, 73 Photodiode (light receiving element)
74 Housing (element holder)
81L Light emitting chip 82 Lead wire 83 Sealing member 84 End wall surface 85 Body 86 Flange 90, 91, 92 Lens 95 Substrate m Lead root n3 Positioning projection

JP 2007-189104 A Japanese Utility Model Publication No. 04-015861 JP 2009-174890 A JP 2011-141509 A JP 2004-309292 A Japanese Patent Laid-Open No. 11-330537 Japanese Utility Model Publication No. 06-069872 Japanese Patent Publication No. 61-014678

Claims (8)

Light emitting means for irradiating light from a light emitting chip toward an image carrier to which toner is attached, a lens for condensing light from the light emitting means and irradiating the carrier, a light receiving means, and the image carrier A lens for condensing the light regularly reflected by the light receiving means;
In an optical sensor for detecting a toner adhesion amount and a toner adhesion position, comprising: the light emitting means; the light receiving means; and a housing in which the lens is accommodated.
An optical sensor characterized in that a positioning protrusion integral with the housing is brought into contact with a lead base portion of the light emitting means, and the light emitting means is fixed to the housing. The light emitting means irradiates light of a light emitting chip sealed by the sealing member toward the image carrier, and a lead extending from the light emitting chip extends from the lead root portion.
The optical sensor according to claim 1, wherein the light emitting unit is positioned on the housing by abutting the positioning protrusion on the lead base portion and the lead. Light emitting means for irradiating light toward the image carrier to which toner is attached, a lens for condensing the light from the light emitting means to irradiate the carrier, a light receiving means, and regular reflection by the image carrier A lens that collects the collected light on the light receiving means;
In an optical sensor for detecting a toner adhesion amount and a toner adhesion position, comprising: the light emitting means; the light receiving means; and a housing in which the lens is accommodated.
An optical sensor characterized in that a positioning protrusion integral with the housing is brought into contact with a lead root portion of the light receiving means, and the light receiving means is fixed to the housing. The light receiving means irradiates light of the light emitting chip sealed by the sealing member toward the image carrier, and extends a lead extending from the light emitting chip from the sealing member,
The optical sensor according to claim 3, wherein the light receiving means is positioned in the housing by contacting the positioning protrusions with the lead base portion of the sealing member and the lead.   The optical sensor according to claim 1, wherein the head of the sealing member of the light emitting means is substantially flat.   The optical sensor according to claim 3 or 4, wherein a head of the sealing member of the light receiving means is substantially flat.   The optical sensor according to any one of claims 1 to 6, wherein at least one of the housing and the positioning protrusion is made of a heat-resistant resin.   An image forming apparatus using the optical sensor according to claim 1.

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