JP2001005276A - Image forming device and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device constituted in a way that the residual quantity of developer can be accurately and stably detected. SOLUTION: A light shielding member 80 having a prescribed-sized light shielding surface is integrally formed at a rotary shaft 55 together with an agitator 53 and a cleaning member 54 so that it is positioned at a more downstream side in a rotating direction than the agitator 53 and at a more upstream side in the rotating direction than the cleaning member 54. By the shielding member 80, a light transmitting window 56b is shielded so that an optical path is prevented from being formed between the windows 56 in response to the behavior of the agitator 53 when it is not the detection timing of the residual quantity of toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a developer remaining amount detecting means for optically detecting the remaining amount of a developer in a developer chamber, and a developing device used in the image forming apparatus. It belongs to the technical field of equipment.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, the remaining amount of developer in a developing device is detected, and when the remaining amount falls below a predetermined value, the developer is urged to be replenished. Things are common. There are various types of methods for detecting the remaining amount of the developer, but, as an example, a pair of light transmission windows are arranged opposite to each other in a developer chamber of a developing device.
A light-emitting element and a light-receiving element are arranged so as to face the light-transmitting window outside the developing device, and light is emitted from the light-emitting element and transmitted through the light-transmitting window so that light having substantially parallel optical axes is received by the light-receiving element. Accordingly, there is a method of detecting the remaining amount of the developer in the developer chamber.

In a developing apparatus employing such a method, a cleaning member for a light transmitting window and a stirring and conveying member are rotatably provided inside a developer chamber, and the surface of the light transmitting window is wiped off by the cleaning member. The time from when the developer is again covered by the developer stirred by the stirring and conveying member is measured based on the output of the light receiving element, and when this time becomes longer than a predetermined value, the remaining amount of the developer is supplied. It was judged that it had decreased to an appropriate level.

[0004]

However, in the conventional developing device, after the stirring / conveying member scrapes the developer in the developer chamber, the optical path from the light emitting element to the light receiving element passes, and the light is transmitted from the light receiving element to the light receiving element. May be obtained. In order to prevent such a phenomenon, the stirring / conveying member is configured to be separated from the light transmitting window so as not to come in contact with the light transmitting window. If it changes depending on the conditions, the developer near the light transmission window may be transported together with the developer scraped off by the stirring and transporting member. for that reason,
Sometimes, when it is not the light receiving timing, the light receiving element receives the light, and the detection of the remaining amount of the developer becomes unstable.

Accordingly, the present invention solves such a problem, and in an image forming apparatus which includes a light transmission window on a side wall of a developer chamber and detects the remaining amount of developer, the detection of the remaining amount of developer is improved. It is an object of the present invention to provide an image forming apparatus that can be stably performed with high accuracy, and a developing device used in the image forming apparatus.

[0006]

According to an aspect of the present invention, there is provided an image forming apparatus, comprising: a developer accommodating chamber for accommodating a developer therein; and a light provided in the developer accommodating chamber. A light-transmitting window, a light-emitting element and a light-receiving element provided at positions corresponding to the light-transmitting windows outside the developer accommodating chamber, and radiated from the light-emitting elements and transmitted through the light-transmitting windows to reach the light-receiving elements A developer remaining amount detecting means for detecting a developer remaining amount in the developer accommodating chamber based on a light receiving state of the light receiving element at the time of forming an optical path; and a rotatable light source provided inside the developer accommodating chamber; A cleaning member for cleaning the transmission window at a predetermined cycle; a developer stirring and conveying member rotatably provided inside the developer storage chamber for stirring the developer in the development storage chamber; and a cleaning cycle for the cleaning member. The optical path is closed for a predetermined time with a period equal to Characterized by comprising a light blocking member.

According to the first aspect of the present invention, when the light transmitting window is cleaned by the cleaning member, an optical path radiated from the light emitting element and transmitted through the light transmitting window to the light receiving element is formed. The light receiving state of the element changes. When the developer stirring and conveying member stirs the developer in the developing chamber,
The light transmitting window is again covered with the developer, the light path is blocked, and the light receiving state of the light receiving element changes again. When the developer stirring / conveying member passes through the position of the light transmitting window, the developer around the light transmitting window may change the behavior of the developer stirring / conveying member depending on the use period of the image forming apparatus or environmental conditions. The optical path may be formed irrespective of the timing of detecting the remaining amount of the conveyed developer. However, according to the present invention, since the light blocking member closes the optical path for a predetermined time at a cycle equal to the cleaning cycle of the cleaning member, the formation of the optical path at a time other than the timing of detecting the remaining amount of the developer is prevented. As a result, the light receiving state of the light receiving element does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer is performed.

According to a second aspect of the present invention, there is provided an image forming apparatus according to the first aspect, wherein the cleaning member and the light shielding member are rotatably supported by a common rotation shaft. It is characterized by having been done.

According to the image forming apparatus of the present invention, when the rotating shaft is driven to rotate, the cleaning member and the light shielding member attached to the rotating shaft also rotate. Accordingly, light is blocked by the light blocking member at a cycle equal to the cleaning cycle of the cleaning member, and the formation of the optical path when the timing of detecting the remaining amount of the developer is not reached is reliably prevented.

According to a third aspect of the present invention, there is provided an image forming apparatus according to the first or second aspect, wherein the cleaning member comprises a light transmitting window on the light emitting element side and the light receiving element. The light-blocking member is a member that cleans the light-transmitting windows at substantially the same time, and the light-blocking member is divided into two when the cleaning member cleans the light-transmitting windows on both sides from the start of one cycle to the start of the next cycle. The optical path is closed in the latter half of the period.

According to the image forming apparatus of the present invention, the cleaning member cleans the light transmitting window on the light emitting element side and the light transmitting window on the light receiving element side substantially simultaneously, and repeats this cleaning at a predetermined cycle. At this time, the light blocking member closes the optical path in the latter half of the period from when the cleaning member cleans the light transmission windows on both sides, the period from the start of one cycle to the start of the next cycle. As a result, in the first half period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the optical path is properly formed, but the optical path at this time is blocked by the light shielding member. Nothing. On the other hand, during the latter half of the period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the light path is blocked by the light blocking member, and this is not the timing of developer remaining amount detection. Nevertheless, the formation of the optical path is reliably prevented.

According to a fourth aspect of the present invention, there is provided an image forming apparatus according to the second or third aspect, wherein the developer agitating and conveying member is common to the cleaning member and the light shielding member. Around the rotation axis, the cleaning member is disposed at a predetermined rotation angle separated from the cleaning member, the light shielding member is further downstream in the rotation direction than the developer stirring and conveying member, and the light shielding member is more than the cleaning member. It is characterized in that it is arranged upstream in the rotation direction.

According to the image forming apparatus of the present invention, since the developer agitating and conveying member and the cleaning member are arranged at a predetermined rotation angle separated from each other, before and after the cleaning member wipes the light transmitting window. Then, the developer is pushed out by the developer stirring and conveying member. The remaining amount of the developer is detected satisfactorily. Moreover, the light shielding member is located downstream of the developer stirring and conveying member in the rotation direction, and even if the developer near the light transmission window is conveyed in accordance with the behavior of the developer stirring and conveying member, the light path is immediately changed. Since the block is closed for a predetermined time, the formation of the optical path when the timing of detecting the remaining amount of the developer is not reached is prevented. As a result, the light receiving state of the light receiving element does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer is performed. Furthermore, since the light-blocking member is disposed upstream of the cleaning member in the rotational direction, the light-shielding member does not block the optical path that is appropriately formed after the light-transmitting window is cleaned by the cleaning member.
The detection of the remaining amount of the developer is appropriately performed.

According to a fifth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to fourth aspects, wherein the developer is stored in the developer storage chamber. The light shielding member is provided at both end positions of the opening or at positions outside the both end positions in the longitudinal direction of the opening. .

According to the image forming apparatus of the present invention, the light-shielding member is located at both ends of the opening provided in the developer accommodating chamber or at positions outside the both ends in the longitudinal direction of the opening. It does not affect the circulation of the developer through the opening between the inside and outside of the developer storage chamber. Therefore, the light-shielding member does not act as a barrier to cause the bias of the developer.

According to a sixth aspect of the present invention, there is provided a developing device including a light emitting element and a light receiving element, wherein the remaining amount of the developer is detected based on a light receiving state of the light receiving element. A developer accommodating chamber for accommodating a developer therein, and the developer corresponding to an optical path formed between the light emitting element and the light receiving element. A light transmitting window provided in the storage chamber; a cleaning member rotatably provided inside the developer storage chamber for cleaning the light transmission window at a predetermined cycle; and a rotatable inside the developer storage chamber. And a developer stirring and conveying member that stirs the developer in the developing chamber storage, and a light blocking member that closes the optical path for a predetermined time at a cycle equal to the cleaning cycle of the cleaning member.

According to the developing device of the present invention, when the light transmitting window is cleaned by the cleaning member, the light is emitted from the light emitting element provided in the image forming apparatus, passes through the light transmitting window, and is transmitted to the image forming apparatus. The light path reaching the light receiving element is formed, and the light receiving state of the light receiving element changes. When the developer stirring and conveying member stirs the developer in the developing chamber, the light transmitting window is again covered with the developer, the light path is interrupted, and the light receiving state of the light receiving element changes again. When the developer stirring / conveying member passes through the position of the light transmitting window, the developer around the light transmitting window may change the behavior of the developer stirring / conveying member depending on the use period of the image forming apparatus or environmental conditions. The optical path may be formed irrespective of the timing of detecting the remaining amount of the conveyed developer. However, according to the present invention, since the light blocking member closes the optical path for a predetermined time at a cycle equal to the cleaning cycle of the cleaning member, the formation of the optical path at a time other than the timing of detecting the remaining amount of the developer is prevented. As a result, the light receiving state of the light receiving element does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer is performed.

According to a seventh aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the sixth aspect, the cleaning member and the light shielding member are rotatably supported by a common rotation shaft. It is characterized by being.

According to the image forming apparatus of the present invention, when the rotating shaft is driven to rotate, the cleaning member and the light shielding member attached to the rotating shaft also rotate. Accordingly, light is blocked by the light blocking member at a cycle equal to the cleaning cycle of the cleaning member, and the formation of the optical path when the timing of detecting the remaining amount of the developer is not reached is reliably prevented.

According to an eighth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the sixth or seventh aspect, the cleaning member comprises a light transmitting window on the light emitting element side and a light transmitting window on the light receiving element side. A member that cleans the light transmission window almost simultaneously,
The light blocking member is characterized in that the light blocking member closes the optical path in the latter half of the period when the period from the start of one cycle of cleaning the light transmitting windows on both sides to the start of the next cycle is bisected. .

According to the developing device of the present invention, the cleaning member makes the light transmitting window on the light emitting element side provided in the image forming apparatus and the light transmitting window on the light receiving element side provided in the image forming apparatus substantially simultaneously. Cleaning is performed and this cleaning is repeated at a predetermined cycle. At this time, the light blocking member closes the optical path in the latter half of the period from when the cleaning member cleans the light transmission windows on both sides, the period from the start of one cycle to the start of the next cycle. as a result,
In the first half period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the optical path is properly formed, but the optical path at this time is not blocked by the light shielding member. . On the other hand, during the latter half of the period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the light path is blocked by the light blocking member, and this is not the timing of developer remaining amount detection. Nevertheless, the formation of the optical path is reliably prevented.

According to a ninth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the seventh or eighth aspect, the developer stirring / conveying member includes a common rotation of the cleaning member and the light shielding member. Around the shaft, the cleaning member is disposed at a predetermined rotation angle separated from the cleaning member, the light shielding member is further downstream in the rotation direction than the developer stirring and conveying member, and is disposed in the rotation direction more than the cleaning member. It is characterized by being located upstream.

According to the developing device of the present invention, since the developer agitating / conveying member and the cleaning member are arranged at a predetermined rotation angle separated from each other, before and after the cleaning member wipes the light transmitting window. Then, the developer is pushed out by the developer stirring and conveying member. The remaining amount of the developer is detected satisfactorily. Moreover, the light shielding member is located downstream of the developer stirring and conveying member in the rotation direction, and even if the developer near the light transmission window is conveyed in accordance with the behavior of the developer stirring and conveying member, the light path is immediately changed. Since the block is closed for a predetermined time, the formation of the optical path when the timing of detecting the remaining amount of the developer is not reached is prevented. As a result, the light receiving state of the light receiving element on the image forming apparatus side does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer is performed. Further, since the light blocking member is disposed upstream of the cleaning member in the rotation direction, the light path does not obstruct the optical path formed properly after the cleaning of the light transmitting window by the cleaning member. Will be performed appropriately.

According to a tenth aspect of the present invention, in order to solve the above problem, in the developing device according to any one of the sixth to ninth aspects, the developer is conveyed to the outside of the developer accommodating chamber. The light shielding member is provided at both ends of the opening or at a position outside the both ends in the longitudinal direction of the opening.

According to the tenth aspect of the present invention, the light shielding members are provided at both ends of the opening provided in the developer accommodating chamber or at positions outside the both ends in the longitudinal direction of the opening. This does not affect the circulation of the developer through the openings between the inside and outside of the developer storage chamber. Therefore, the light-shielding member does not act as a barrier to cause the bias of the developer.

[0026]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The following description is an embodiment in which the present invention is applied to an image forming apparatus including a developing device. First, an overview of the entire image forming apparatus according to the present embodiment will be described.

(Overview of Overall Image Forming Apparatus) FIG. 1 is a sectional view showing a schematic configuration of a laser beam printer 1 as an image forming apparatus to which the present invention is applied. In FIG. 1, the laser beam printer 1 includes a feeder unit for feeding paper (not shown) at the bottom of a main body case 2.
The feeder unit includes a paper pressing plate 10 that is pressed by a spring (not shown), a paper feeding roller 11, and a friction separating member 14. The uppermost sheet is separated between the feed roller 11 and the friction separating member 14 by the rotation of the roller, and the sheet is supplied at a predetermined timing.

A pair of registration rollers 12 and 13 are rotatably supported on the downstream side in the sheet transport direction by the rotation of the sheet supply roller 11 rotating in the direction of the arrow in FIG. The sheet is conveyed to a transfer position formed by the transfer roller 21 at a predetermined timing.

The photosensitive drum 20 is made of a positively chargeable material, for example, an organic photoreceptor mainly composed of positively chargeable polycarbonate. More specifically, the photosensitive drum 20 has, for example, a cylindrical aluminum sleeve as a main body, and has a predetermined thickness (for example, about 20 μm) in which a photoconductive resin is dispersed in polycarbonate on an outer peripheral portion thereof. It is composed of a hollow drum on which a conductive layer is formed, and is rotatably supported by the main body case 2 with the cylindrical sleeve grounded. Further, the photosensitive drum 20 is driven to rotate in a direction indicated by an arrow by driving means (not shown).

The charger 30 is, for example, a scorotron type charger for positive charging for generating corona discharge from a charging wire made of tungsten or the like.

The laser scanner unit 40 includes a laser generator (not shown) for generating a laser beam L for forming an electrostatic latent image on the photosensitive drum 20, and a polygon mirror (pentahedral mirror) 41 that is driven to rotate. , A pair of lenses 42 and 4
5 and reflection mirrors 43, 44 and 46.

In the developing device 50, a toner storage chamber 52 as a developer storage chamber is formed in a case 51. In the toner storage chamber 52, an agitator 53 as a developer stirring and conveying member, a cleaning member 54, A light-blocking member 80 provided therebetween is rotatably provided around the rotation shaft 55. The toner accommodating chamber 52 accommodates a positively chargeable nonmagnetic one-component developer having electrical insulation. The rotation shaft 55 of the toner storage chamber 52
Light transmitting windows 56 are provided on the side walls located at both ends of the light emitting element. On the photosensitive drum 20 side of the toner accommodating chamber 52, a developing chamber 57 for performing development by communicating with the toner accommodating chamber 52 through an opening A is formed, and a supply roller 58 and a developing roller 59 are rotatably supported. . The toner on the developing roller 59 is a thin plate-shaped elastic layer regulating blade 64 having elasticity.
Is regulated to a predetermined layer thickness, and is subjected to development.

The transfer roller 21 is rotatably pivotally supported,
It is made of a conductive foamed elastic body made of silicone rubber or urethane rubber. The transfer roller 21 is configured to reliably transfer the toner image on the photosensitive drum 20 to the paper by the applied voltage.

The fixing unit 70 includes the registration roller 12
The heating roller 71 and the pressing roller 72 are provided on the further downstream side in the sheet conveyance direction from the sheet feeding roller 13 to the pressure contact portion between the photosensitive drum 20 and the transfer roller 21. The toner image transferred to the sheet is heated and pressed while being conveyed by the heating roller 71 and the pressing roller 72 and is fixed on the sheet.

A pair of transport rollers 73 and a discharge roller 74 for transporting the paper are provided on the downstream side of the fixing unit 70 in the transport direction, and a discharge tray 75 is provided on the downstream side of the discharge roller 74. Have been.

The above-described photosensitive drum 20, transfer roller 21, charger 30, and developing device 50 are housed in a drum cartridge 2a, and the drum cartridge 2a is detachably attached to the laser beam printer 1. Is provided. Further, the developing device 50 is provided detachably as a developing device cartridge with respect to the drum cartridge 2a.

In the laser beam printer 1 of the present embodiment as described above, the surface of the photosensitive drum 20 is
When the laser beam L modulated according to image information is emitted from the laser scanner unit 40, an electrostatic latent image is formed on the surface of the photosensitive drum 20.
This electrostatic latent image is visualized with toner by the developing device 50, and the visible image formed on the photosensitive drum 20 is transported by the photosensitive drum 20 to a transfer position. At the transfer position, the paper is supplied via the paper feed roller 11 and the registration rollers 12 and 13, and the visible image is transferred to the paper by a transfer bias applied by the transfer roller 21. The toner remaining on the photosensitive drum 20 after the transfer is collected in the developing chamber 57 by the developing roller 59.

Next, the sheet is conveyed to the fixing unit 70, and is nipped and conveyed by the heating roller 71 and the pressing roller 72 of the fixing unit 70. The visible image on the sheet is pressed and heated to be fixed on the sheet. You. Then, the sheet is discharged to the discharge tray 75 above the laser beam printer 1 by the pair of transport rollers 73 and the discharge rollers 74, and the image forming operation is completed.

(Structures of Developing Apparatus and Developer Remaining Detecting Means) According to the laser beam printer 1 of the present embodiment, the toner in the toner accommodating chamber 52 is consumed with the image forming operation as described above. In order to prevent a decrease in image quality due to a shortage of toner, it is necessary to detect a decrease in the remaining amount of toner at an appropriate timing and supply toner as needed. Therefore, in the present embodiment, the developing device 50 is configured as described below, and includes the following developer remaining amount detecting means. Hereinafter, a detailed configuration of the developing device 50 and the developer remaining amount detecting unit according to the present embodiment will be described with reference to FIGS.

FIG. 2 is a cross-sectional view of the developing device 50 of the present embodiment taken along line YY ′ shown in FIG. 3, and FIG. 3 is a cross-sectional view of the developing device 50 of the present embodiment taken along line XX ′ of FIG. FIG. However, FIG. 3 is a diagram when the agitator 53 and the cleaning member 54 are at positions shown by two-dot chain lines in FIG. Also, in FIG. 3, the frame 2b, the light emitting means 60, the light receiving means 61, and the substrates 60b, 61b are illustrated as cross sections, but these are cross sections along the line ZZ 'in FIG.

The developing device 50 in this embodiment is similar to the developing device shown in FIG.
As shown in FIG. 5, the case 51 is detached from the drum cartridge 2a shown in FIG. 3 or mounted on the drum cartridge 2a in a state where other components are provided in the case 51. Accordingly, the case 51 forms the toner storage chamber 52 and the developing chamber 57 and also functions as a frame that supports each component.

Next, components other than the case 51 will be described. First, a developing roller 5 as a developer carrier
9, a cylindrical base 59b formed of conductive silicone rubber containing fine particles of conductive carbon is provided on a cored bar 59a formed of stainless steel or the like. A coat layer 59c of a resin or rubber material containing fluorine is formed on 59b. In addition,
The base of the developing roller 59 does not necessarily have to be made of conductive silicone rubber, and may be made of conductive urethane rubber. A predetermined voltage is applied to the developing roller 59 by a power supply (not shown).
Are configured to have a predetermined potential difference between them.

Layer thickness regulating blade 6 as layer thickness regulating member
4 is made of stainless steel or the like, and has a developing device 50 at its base end.
A support portion 64a fixed to the case 51 of the above, and an insulating or conductive silicone rubber, an insulating or conductive fluorine-containing rubber, or an insulating or conductive urethane rubber provided at the tip of the support portion 64a. And a contact portion 64b formed by the above. The contact portion 64b is a support portion 64
It is pressed against the developing roller 59 by the elastic force a. In the present embodiment, the contact portion 64b is formed to have a substantially half-moon-like convex shape in cross section as shown in FIG. 2, but may be formed in a plate shape.

The supply roller 58 is a roller in which a cylindrical base member 58b formed of a conductive sponge is formed on a metal core 58a formed of stainless steel or the like. They are arranged so as to be pressed by elastic force. In addition, as the supply roller 58, an appropriate member such as conductive silicone rubber or urethane rubber can be used.

The toner accommodated in the toner accommodating chamber 52 is a positively charged non-magnetic one-component developer, and a styrene-acrylic resin formed into a spherical shape by a suspension polymerization method, such as carbon black or the like. The toner base particles have a particle diameter of 6 μm to 10 μm and an average particle diameter of 8 μm to which a well-known coloring agent and a charge control agent such as nigrosine, triphenylmethane, and quaternary ammonium salt are added. The toner is configured by adding silica as an external additive to the surface of the toner base particles. The silica as the external additive is subjected to a well-known hydrophobic treatment using a silane coupling agent or the like, has an average particle diameter of 10 nm, and is added in an amount of 0.6% by weight (wt)% of the toner base particles. It is. in this way,
The toner is a suspension-polymerized toner having an extremely spherical shape.
Since 6% by weight (wt) is added as an external additive, it is extremely excellent in fluidity. As a result, a sufficient charge amount can be obtained by frictional charging, so that an image with high transfer efficiency and extremely high image quality can be formed.

Agitator 53 as a developer stirring and conveying member
A sheet-like sliding contact portion 53b made of PET (polyethylene terephthalate) is attached to the tip of a support member 53a made of a resin such as ABS (acrylonitrile-butadiene-styrene) resin. As shown in FIG. 3, the support member 53a is formed integrally with a rotating shaft 55 supported by both side walls 51a and 51b of the case 51. A gear 63 is attached to the shaft end of the rotating shaft 55. ing. Further, as shown in FIG. 2, the sliding contact portion 53b has at least a cylindrical bottom portion 52a of the toner storage chamber 52.
Has a width (length in the direction of the radius of rotation) so as to bend when sliding. Therefore, when the rotational driving force from the motor (not shown) is transmitted to the gear 63, the agitator 53 including the support member 53a and the sliding portion 53b is provided.
Rotates in the direction of the arrow shown in FIG. 2, and the sliding contact portion 53b slides against the bottom surface 52a of the toner storage chamber 52 in a bent state, and pushes the toner to the opening A by the transport surface. Note that FIG.
In FIG. 7, the opening A is painted black. As shown in FIG. 3, the sliding contact portion 53b is provided with cuts 53d corresponding to both end positions of the opening A, and the main transport portion of the sliding contact portion 53b sandwiched between the two cuts 53d has an opening. The toner enters the portion A so as to be elastically repelled, and repels the toner toward the developing chamber 57 side. Further, not only the sliding contact portion 53b but also the surface of the support member 53a pushes up the toner. Therefore, as shown in FIG. 3, an opening 53c is formed in the support member 53a, and the surface of the support member 53a is formed. Is configured to reduce the resistance received from the toner during rotation. Further, the longitudinal lengths of the support member 53a and the sliding contact portion 53b are set to be shorter than the longitudinal length of the case 51, and as shown in FIG. The sides are light-transmitting windows 5 on both sides.
6a and 56b are arranged so as to have a predetermined interval so as not to contact.

The cleaning member 54 includes a support member 54a formed integrally with the support member 53a of the agitator 53, and wipers 54b attached to both ends of the support member 54a as shown in FIG. Wiper 54b
Are formed of urethane rubber, and the supporting members 54a
The surface of the light transmitting windows 56a and 56b is rubbed with the rotation of the light transmitting window 56a, and the light transmitting windows 56a and 56b are attached at positions where the toner on the surfaces can be wiped off. As an example, the support member 54a is set so as to be parallel to the support member 53a of the agitator 53 in the opposite direction, that is, so that the phase angle of the support member 53a with the support member 53a is 180 degrees.

The light transmission window 56 is a transparent or translucent member made of acrylic, polycarbonate, polypropylene, or the like. As shown in FIG. 3, the light transmission window 56 is attached to the side wall 51a of the case 51 on the light emitting means 60 side. Window 5
6a and a light transmitting window 56b attached to the side wall 51b on the light receiving means 61 side. The light transmitting windows 56a and 56b are provided so as to protrude into the toner storage chamber 52 as shown in FIG.
The wiper 54b of the cleaning member 54 is securely connected to the light transmitting window 5
The surfaces of 6a and 56b can be wiped off. Further, as shown in FIG. 2, the light transmission window 56b (56a) is a plane including the rotation center line of the agitator 53 and the cleaning member 54, and is larger than a plane G (hereinafter referred to as a vertical plane) extending in the vertical direction. It is provided at a position on the opening A side.
Furthermore, the light transmission windows 56a, 56 of the drum cartridge 2a
In the position corresponding to b, as shown in FIG.
a and 62b are formed, the opening 62a allows light to enter the light transmitting window 56a, and the opening 62b allows light to exit from the light transmitting window 56b.

As shown in FIG. 3, on both sides of the developing device 50 corresponding to the positions where the light transmission windows 56a and 56b are provided, as shown in FIG. Light receiving means 61 is provided.

The light emitting means 60 includes a holder 60a attached to the frame 2b, a substrate 60b supported by the holder 60a, and a light emitting element 60 provided on the substrate 60b.
c. The holder 60a is formed of plastic, and the light transmitting window 5 of the holder 60a is formed.
On the side facing 6a, a plastic lens 60d is formed by integral molding.

Similarly, the light receiving means 61 also includes a holder 61a attached to the frame, a substrate 61b supported by the holder 61a, and a light receiving element 61c provided on the substrate 61b. Also, the holder 61a
Is formed of plastic, and a plastic lens 61d is formed by integral molding on the side of the holder 61a facing the light transmission window 56b. Note that a phototransistor is used as an example of the light receiving element.

The light emitting element 60c, the plastic lens 60d, the opening 62a of the drum cartridge 2a,
The light transmitting window 56a, the light transmitting window 56b, the opening 62b of the drum cartridge 2a, the plastic lens 61d, and the light receiving element 61c are set so as to be substantially aligned as shown in FIG. Is irradiated by the plastic lens 60d to be converted into substantially parallel light, and enters the light transmitting window 56a through the opening 62a. Therefore, in a state where no toner exists between the light transmitting window 56a and the light transmitting window 56b, the light transmitting window 56a
Is incident on the opposite light transmission window 56b, passes through the light transmission window 56b, passes through the opening 62b, and is incident on the plastic lens 61d. The incident light is collected by the plastic lens 61d and received by the light receiving element 61c.

As shown in FIG. 4, the light receiving element 61c is an element whose output voltage value changes according to the amount of received light.
In this embodiment, when the amount of received light is minimum, the voltage value is approximately 5V.
And the voltage value is almost 0 when the amount of received light is maximum.
It becomes a value close to V. In this range, the voltage value changes according to the amount of received light. In the present embodiment, the output of the light receiving element 61c is read by a control unit (not shown) including a microprocessor or the like, a predetermined voltage value is set as a threshold, and an output voltage value higher than the threshold is high. Level, an output voltage value lower than the threshold value is determined to be low level, and the sum of the low level period (hereinafter referred to as low level period) T1 in the measurement unit period T2 is determined by the measurement. The remaining amount of toner is detected by calculating the ratio of the toner in the unit period T2.

Next, the light shielding member 80 will be described. As shown in FIG. 2, the light shielding member 80 is a plate-shaped member provided between the support member 53a of the agitator 53 and the support member 54a of the cleaning member 54 and made of a resin such as ABS resin. And the rotating shaft 5 together with the cleaning member 54
5 and is configured to rotate around a rotation shaft 55. In addition, in the axial direction of the rotation shaft 55, as shown in FIG. 3, it is provided only on the light emitting means 60 side.

The light-shielding member 80 starts moving immediately after the agitator 53 passes the position of the light transmission window 56b (56a).
As shown in FIG. 6, the light to the light transmitting window 56b is blocked,
4 has a light-shielding surface large enough to release the light blocking immediately before the cleaning of the light transmitting window 56b (56a).

With this configuration, while the light shielding member 80 blocks the optical path, even if the toner around the light transmitting window 56b (, 56a) is scraped off by the scraping operation by the agitator 53. , Light receiving element 60
Since the output from c is not obtained, accurate detection of the remaining amount of the developer can be performed regardless of the environmental conditions or the usage period.

Further, since the light shielding member 80 is rotated around the rotation shaft 55 common to the cleaning member 54 and the agitator 53, the configuration can be simplified.

In the present embodiment, the cleaning member 5
4 is configured to simultaneously clean the two light transmitting windows 56b (, 56a), and the light blocking member 80 blocks the optical path only when the cleaning member 54 is closed by the two light transmitting windows 56b (, 56a).
The period between the simultaneous cleaning of a) and the next simultaneous cleaning is limited to the latter half. This configuration is shown in FIGS.
This will be described in detail below.

FIG. 5 shows that the cleaning member 54 has two light transmitting windows 56.
b (, 56a) is being cleaned at the same time. From the state shown in FIG. 5, the cleaning member 54 rotates 360 degrees, returns to the state shown in FIG. 5, and a period until the next cleaning is performed is T0. When the period T0 is divided into the first half period T0 / 2 and the second half period T0 / 2, the first half period T0 / 2 is changed from the state shown in FIG. 5 to the one shown in FIG. Until the passage, the light blocking member 80 does not block the optical path. However, the light shielding member 80 blocks the optical path from the state shown in FIG. 7 until the period T0 / 2 of the latter half portion elapses as shown in FIG.

In this embodiment, the time from when the light transmitting window 56b (56a) is cleaned by the cleaning member 54 to when the light transmitting window 56b (56a) is closed with toner is measured. , The remaining amount of toner is detected. In the above-described first half period T0 / 2,
If something other than the toner blocks the light transmission window 56b (56a), accurate detection of the remaining amount of toner cannot be performed.
On the other hand, in the above-described second half period T0 / 2, the agitator 53 passes through the light transmitting window 56b (, 56a), but the agitator 53 transmits the light through the light transmitting window 56b (, 5).
6a) so that they do not come into contact with each other.
b (, 56a), and the light transmission window 5 is normally provided in the latter half of the period T0 / 2.
If there is a change in the light blocking state or the light transmitting state of 6b (, 56a), it is impossible to accurately detect the remaining amount of toner. Therefore, in the present embodiment, the period T of the first half is
At 0/2, the light-blocking member 80 does not block the optical path. By configuring the light-blocking member 80 to block the optical path in the latter half of the period T0 / 2, accurate toner remaining amount detection is possible. .

The agitator 53, the light shielding member 80, and the cleaning member 54 are arranged on the same rotating shaft 55 with a certain phase difference, and the positional relationship in the rotating direction around the rotating shaft 55 is as follows. The light shielding member 80 is an agitator 5
3 on the downstream side in the rotation direction and the light shielding member 80
Is located upstream of the cleaning member 54 in the rotation direction.

Therefore, the agitator 53 is moved to the light transmitting window 56b.
After passing through the position of (, 56a), the agitator 53
Since the light shielding member 80 provided on the downstream side in the rotation direction covers the light transmitting window 56b (56a), the state of the toner after the agitator 53 has passed the position of the light transmitting window 56b (56a). Regardless, a change in the output of the light receiving element 61c can be reliably prevented. When the cleaning member 54 cleans the light transmission window 56b (56a),
Since the light blocking member 80 has already passed through the position of the light transmitting window 56b (, 56a), the light transmitting window 56b (, 56
It does not affect the transmission state or the light shielding state of a). Therefore, it is possible to accurately detect the amount of remaining toner.

The positional relationship of the rotary shaft 55 in the axial direction is such that the light shielding member 80 is located at the end of the opening A as shown in FIG.

As described above, since the light shielding member 80 is provided in an area that does not affect the circulating conveyance of the toner, the light shielding member 80 acts as a barrier to interrupt the conveyance of the toner, and the toner conveyance amount is shifted. Can be prevented.

The light shielding member 80 may be provided at a position outside the end of the opening A in the longitudinal direction of the opening A.

(Operation Example) Hereinafter, an operation example of the present embodiment will be described with reference to the detection of the remaining amount of toner, the agitator 53 and the cleaning member 5.
4 will be described in detail.

First, the uppermost surface of the toner (hereinafter, referred to as the toner surface) is connected to the light transmitting window 56 as shown by the dotted line in FIG.
a, 56b, which is much higher than
A case where a sufficient amount of toner is stored in the printer will be described. In this case, the rotation of the agitator 53 causes the sliding contact portion 53b to agitate the toner in the toner storage chamber 52 while slidingly contacting the wall surface of the toner storage chamber 52.
As the sliding contact portion 53b reaches the opening A and further passes through the opening A as shown in FIG.
The toner inside is transported to the developing chamber 57. On the other hand, the wiper 54b of the cleaning member 54 performs an operation of wiping the surfaces of the light transmitting windows 56a and 56b.
6b, a sufficient amount of toner is stored, so that the light transmitting windows 56a, 56 wiped by the wiper 54b are removed.
The surface of b is immediately again covered with the surrounding toner. Therefore, the light emitted from the light emitting element 60c does not pass through the inside of the toner storage chamber 52, and the output of the light receiving element 61c does not change.

Next, the period for measuring the remaining amount of toner as described above ends, and the agitator 53 moves to the position shown in FIG. 7 and further passes through the positions of the light transmission windows 56a and 56b. When the use period is long, or depending on environmental conditions, the toner near the light transmission windows 56a and 56b may be conveyed when passing through the agitator 53. However, in this embodiment, when the agitator 53 moves from the position shown in FIG. 7 to the position shown in FIG. 2, as shown in FIG.
a and the light transmission window 56b. Therefore, even if the toner near the light transmitting windows 56a and 56b is conveyed when passing through the agitator 53, the output of the light receiving element 61c keeps the high level, and the noise-like output signal as seen in the conventional apparatus is obtained. Does not cause any change in

Next, a case where the remaining amount of toner decreases and the toner surface approaches the positions of the light transmitting windows 56a and 56b as shown by the solid line in FIG. 5 will be described. In such a case, the light transmission windows 56a and 56b will not be covered with the toner immediately after wiping by the wiper 54b.
When the wiper 54b rotates from the position shown in FIG. 5 to the position shown in FIG. 6, the sheet member 53b of the agitator 53 also rotates.
Is pushed out in the direction of arrow B shown in FIG. 6 to cover the light transmitting windows 56a and 56b. The time in which the light transmitting windows 56a and 56b are covered by the toner pushed out by the sheet member 53b in this way depends on the amount of toner. That is, as the amount of toner increases, the light transmitting windows 56a and 56b are blocked for a longer time, and as the amount of toner decreases, the time of blocking the light transmitting windows 56a and 56b decreases. Therefore, as the toner amount increases, the light receiving element 6 shown in FIG.
The low-level period T1 of the output of 1c becomes shorter, and the lower the toner amount, the longer the low-level period T1 of the output of the light receiving element 61c shown in FIG. In the present embodiment, the control unit (not shown) controls the light receiving element 61 at a predetermined sampling cycle.
The output voltage value of c is sampled and stored, and when the ratio of the total of the low-level periods T1 within the predetermined measurement unit period T2 exceeds the predetermined ratio, it is determined that the toner is in the empty state. did.

Next, the period for measuring the remaining amount of toner as described above ends, and the agitator 53 moves to the position shown in FIG. 7 and further passes through the positions of the light transmitting windows 56a and 56b. In this case, the light transmission windows 56a and 56b
The transmission state has been reached before the agitator 53 arrives. However, in the present embodiment, when the agitator 53 moves from the position shown in FIG. 7 to the position shown in FIG. 2, as shown in FIG. 2, the light blocking member 80 moves the light path between the light transmitting window 56a and the light transmitting window 56b. Block out. In this embodiment, the light-shielding member 80 is always in the same cycle as the cleaning cycle of the cleaning member 54 regardless of the position of the toner surface.
Since the optical path between 6a and 56b is blocked, the output of the light receiving element 61c maintains the high level period even in this case, and the separation between the measurement period and the non-measurement period of the remaining amount of toner becomes clear.

As described above, the developing device 50 of this embodiment
In the above, the surfaces of the light transmitting windows 56a and 56b are wiped by the wiper 54b of the cleaning member 54 and the agitator 5
3, the toner in the toner storage chamber 52 is pushed out, thereby transmitting and blocking light between the light transmitting window 56a and the light transmitting window 56b. Further, the agitator 53 passes through the light transmitting windows 56a, 56b. Immediately after this, the light path between the light transmitting window 56a and the light transmitting window 56b is blocked by the light blocking member 80, thereby preventing the output of the light receiving element 61c from being changed due to the behavior of the agitator 53. Detection can be performed.

In the above description, the developing device 5
Although the example in which the light shielding member is provided in 0 is described, the present invention is not limited to such a configuration, and the light shielding member may be provided on the image forming apparatus main body side.
In this case, a shutter that blocks the light transmitting window may be provided on the image forming apparatus main body side, and the shutter may be opened and closed at the same cycle as the cleaning cycle of the cleaning member.

In the above description, the light emitting element 6
Although the case where the optical path formed between the light receiving element 0c and the light receiving element 61c is substantially horizontal has been described, the present invention is not limited to this, and may be applied to any mode, for example, when the optical path is vertical. be able to.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. Can easily be inferred.

[0075]

According to the image forming apparatus of the first aspect,
A cleaning member rotatably provided inside the developer accommodating chamber and cleaning the light transmitting window at a predetermined cycle; and a developing member rotatably provided inside the developer accommodating chamber and agitating the developer in the developing accommodating chamber. A developer stirring / conveying member, and a light shielding member that closes an optical path formed between the light transmitting windows for a predetermined time at a cycle equal to the cleaning cycle of the cleaning member. The formation can be prevented, and the light receiving state of the light receiving element does not change when it is not the timing for detecting the remaining amount of the developer, so that the accurate detection of the remaining amount of the developer can be performed.

According to the second aspect of the present invention, since the cleaning member and the light shielding member are rotatably supported by the common rotation shaft, the light shielding by the light shielding member is performed at a period equal to the cleaning period of the cleaning member. And the formation of the optical path when the timing of detecting the remaining amount of the developer is not reached can be reliably prevented. Further, the configuration can be simplified.

According to the image forming apparatus of the third aspect, a member for cleaning the light transmitting window on the light emitting element side and the light transmitting window on the light receiving element side substantially simultaneously is used as the cleaning member, and the cleaning member is used as the light shielding member. Since the optical path is closed in the latter half of the period when the period from the start of one cycle for cleaning the light transmission windows on both sides to the start of the next cycle is bisected, the cleaning member is provided on both sides of the light transmission windows. Can be prevented from being blocked by the light shielding member in the first half period from the start of one cleaning cycle. Also, in the latter half of the period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the light path is blocked by the light blocking member, and this is not the timing of the developer remaining amount detection. Regardless, the formation of the optical path can be reliably prevented.

According to the image forming apparatus of the fourth aspect, the developer agitating and conveying member is disposed around the common rotation shaft of the cleaning member and the light shielding member and separated by a predetermined rotation angle from the cleaning member. As a light shielding member, a member disposed downstream of the developer stirring and conveying member in the rotation direction and upstream of the cleaning member in the rotation direction is used, so that the developer remaining amount can be detected satisfactorily. Can be. Further, it is possible to prevent the formation of the optical path when the light shielding member is not at the timing of detecting the remaining amount of the developer. As a result, the light receiving state of the light receiving element does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer can be performed. Furthermore,
Since the light-blocking member is arranged upstream of the cleaning member in the rotation direction, the light-path formed appropriately after the cleaning of the light transmission window by the cleaning member is not blocked, and the developer remaining amount is appropriately detected. be able to.

According to the image forming apparatus of the present invention, the developer accommodating chamber is provided with an opening for transporting the developer outside the room, and the light shielding member is provided at both ends of the opening or the length of the opening. Since it is provided at a position outside the both end positions in the hand direction, the circulation of the developer through the openings between the inside and outside of the developer storage chamber is not affected. Therefore, it is possible to prevent the developer from being offset due to the light blocking member acting as a barrier.

The developing device according to claim 6 is provided rotatably inside the developer accommodating chamber, and provided with a cleaning member for cleaning the light transmission window at a predetermined cycle, and rotatably provided inside the developer accommodating chamber. A developer stirring / conveying member that stirs the developer in the developing chamber housing; and a light blocking member that closes the optical path for a predetermined time at a cycle equal to the cleaning cycle of the cleaning member. Therefore, it is possible to prevent the formation of the optical path when the remaining amount of the developer is not detected, and to accurately detect the remaining amount of the developer without changing the light receiving state of the light receiving element in the image forming apparatus when the timing of the remaining amount of the developer is not detected. it can.

According to the seventh aspect of the present invention, since the cleaning member and the light shielding member are rotatably supported by the common rotary shaft, the light shielding by the light shielding member is performed at a period equal to the cleaning period of the cleaning member. Therefore, it is possible to reliably prevent the formation of the optical path when it is not the timing of detecting the remaining amount of the developer.

According to the developing device of the present invention, the cleaning member is provided so that the light transmitting window on the light emitting element side provided in the image forming apparatus and the light transmitting window on the light receiving element side provided in the image forming apparatus are substantially simultaneously. As a member to be cleaned, the light-blocking member may block the optical path in the latter half of the period when the cleaning member cleans the light transmitting windows on both sides and the period from the start of one cycle to the start of the next cycle is bisected. Therefore, it is possible to reliably prevent the appropriately formed optical path from being blocked by the light blocking member in the first half period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides. On the other hand, during the latter half of the period from the start of one cycle in which the cleaning member cleans the light transmitting windows on both sides, the light path is blocked by the light blocking member, and this is not the timing of developer remaining amount detection. Nevertheless, it is possible to reliably prevent the optical path from being formed.

According to the developing device of the ninth aspect, a member arranged at a predetermined rotation angle and separated from the cleaning member around the common rotation shaft of the cleaning member and the light shielding member is used as the developer stirring and conveying member. As the light-shielding member, a member disposed in the rotational direction downstream of the developer stirring and conveying member and disposed in the rotational direction upstream of the cleaning member was used.
Before and after the cleaning member wipes the light transmitting window, the developer is pushed out by the developer stirring and conveying member. The developer remaining amount can be detected satisfactorily. Moreover, the light blocking member is located downstream of the developer stirring and conveying member in the rotation direction,
Even if the developer in the vicinity of the light transmission window is transported in accordance with the behavior of the developer stirring and transporting member, the optical path is immediately closed for a predetermined time, thereby preventing the formation of the optical path when it is not the timing for detecting the remaining amount of the developer. can do. As a result, the light receiving state of the light receiving element on the image forming apparatus side does not change when it is not the timing for detecting the remaining amount of the developer, and the accurate detection of the remaining amount of the developer can be performed. Further, since the light shielding member is arranged upstream of the cleaning member in the rotation direction, the light shielding member does not obstruct the optical path formed properly after the cleaning of the light transmitting window by the cleaning member, and the detection of the remaining amount of the developer is appropriately performed. Can be done.

According to a tenth aspect of the present invention, in the developer accommodating chamber, an opening for transporting the developer to the outside of the chamber is provided, and the light shielding member is provided at both ends of the opening or in the longitudinal direction of the opening. Since it is provided at a position outside the both end positions, it reliably prevents the developer from circulating through the openings between the inside and outside of the developer storage chamber, and the light shielding member becomes a barrier. As a result, it is possible to reliably prevent the developer from being biased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a developing device in the image forming apparatus of FIG.

FIG. 3 is a view showing a cross section taken along line XX in FIG. 2;

FIG. 4 is a diagram for explaining an output voltage waveform of a light receiving element and a method of detecting a remaining amount of a developer in the image forming apparatus of FIG. 1;

FIG. 5 is a diagram for explaining the operation of an agitator and a cleaning member of the developing device and the operation of detecting the remaining amount of developer in the image forming apparatus of FIG. 1 (part 1);

FIG. 6 is a view for explaining an operation of an agitator and a cleaning member of a developing device and an operation of detecting a remaining amount of developer in the image forming apparatus of FIG. 1 (part 2);

FIG. 7 is a view for explaining the operation of the agitator and the cleaning member of the developing device and the operation of detecting the remaining amount of the developer in the image forming apparatus of FIG. 1 (part 3);

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam printer 50 Developing device 51a, 51b Side wall 52 Toner storage chamber 53 Agitator 54 Cleaning member 54b Wiper 56 Light transmission window 57 Developing room 59 Developing roller 60 Light emitting means 61 Light receiving means 80 Light shielding member

Claims (10)

[Claims] 1. A developer accommodating chamber for accommodating a developer therein, a light transmitting window provided in the developer accommodating chamber, and a light transmitting window provided outside the developer accommodating chamber at a position corresponding to the light transmitting window. And a light-emitting element and a light-receiving element that are irradiated with light from the light-emitting element and pass through the light-transmitting window to reach the light-receiving element. A developer remaining amount detecting means for detecting the amount, a cleaning member rotatably provided inside the developer accommodating chamber, and cleaning the light transmission window at a predetermined cycle; and a rotating member inside the developer accommodating chamber. A developer stirring / conveying member that is freely provided and stirs the developer in the developing storage chamber; and a light blocking member that blocks the optical path for a predetermined time at a cycle equal to a cleaning cycle of the cleaning member. Image forming device. 2. The image forming apparatus according to claim 1, wherein the cleaning member and the light shielding member are rotatably supported by a common rotation shaft. 3. The cleaning member is a member that cleans the light transmitting window on the light emitting element side and the light transmitting window on the light receiving element side substantially at the same time. 3. The image forming apparatus according to claim 1, wherein the optical path is closed in a latter half of a period obtained by dividing a period from the start of one cycle of cleaning the window to the start of the next cycle. 4. The developer stirring / conveying member is disposed around a common rotation axis of the cleaning member and the light blocking member and separated by a predetermined rotation angle from the cleaning member. The image forming apparatus according to claim 2, wherein the image forming apparatus is arranged downstream of the developer stirring and conveying member in the rotation direction and upstream of the cleaning member in the rotation direction. 5. The developer accommodating chamber is provided with an opening for transporting the developer to the outside of the chamber, and the light blocking member is provided at both ends of the opening or in the longitudinal direction of the opening. 5. The semiconductor device according to claim 1, wherein said first and second end portions are provided at positions outside said both end portions.
The image forming apparatus as described in the above. 6. A developing device which has a light emitting element and a light receiving element and is attached to an image forming apparatus having a developer remaining amount detecting means for detecting a remaining amount of the developer based on a light receiving state of the light receiving element. A developer accommodating chamber for accommodating a developer therein; a light transmitting window provided in the developer accommodating chamber corresponding to an optical path formed between the light emitting element and the light receiving element; A cleaning member rotatably provided inside the chamber and cleaning the light transmitting window at a predetermined cycle; and a developing member rotatably provided inside the developer storage chamber and agitating the developer in the development storage chamber. A developing device comprising: an agent stirring and conveying member; and a light blocking member that closes the optical path for a predetermined time at a cycle equal to a cleaning cycle of the cleaning member. 7. The developing device according to claim 6, wherein the cleaning member and the light shielding member are rotatably supported by a common rotation shaft. 8. The cleaning member is a member for substantially simultaneously cleaning the light transmitting window on the light emitting element side and the light transmitting window on the light receiving element side. The developing device according to claim 6, wherein the optical path is closed in a latter half of a period when a period from the start of one cycle of cleaning the window to the start of the next cycle is divided into two. 9. The developer stirring / conveying member is disposed around a common rotation axis of the cleaning member and the light shielding member and separated by a predetermined rotation angle from the cleaning member. The developing device according to claim 7, wherein the developing device is disposed downstream of the developer stirring and conveying member in the rotation direction and upstream of the cleaning member in the rotation direction. 10. The developer accommodating chamber is provided with an opening for transporting the developer to the outside of the chamber, and the light blocking member is provided at both ends of the opening or in the longitudinal direction of the opening. 10. The developing device according to claim 6, wherein the developing device is provided at a position outside the both end positions.