JP2008058355A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect a developer detection time and a developer replenishing ending time by one sensor etc. <P>SOLUTION: An upper limit detecting member 31 is stored in each developing device 221, extends from one window hole 221a up to the upper limit toner position showing the prescribed upper limit amount of toner in the developing device 221, shields the light emitted from a light emitting part so that a light receiving part 182 may not receive the light when the toner amount in the developing device 221 reaches the upper limit, and when the toner amount in the developing unit 221 does not reach the upper limit, guides the light emitted from the light emitting part 181 so that it may be received by the light receiving part 182. A lower limit detecting member 32 is stored in each developing device 221, extends from the other window hole 221a up to the lower limit position, that is, a position where the prescribed toner amount in the developing device 221 is below the lower limit, reflects the light emitted from the light emitting part 181 toward the light receiving part 182 so that the light may be received by the light receiving part 182 when the toner amount in the developing device 221 is below the lower limit, and when the toner amount in the developing device 221 is equal to or exceeding the lower limit, shields the light emitted from the light emitting part 181 so that it may not be received by the light receiving part 182. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of forming a color image based on image information.

  An electrophotographic image forming apparatus is an apparatus that forms an image based on image information, and includes an electrostatic latent image carrier on which an electrostatic latent image is formed and a developer inside. A developing device for supplying a developer to the latent image carrier. In this image forming apparatus, an electrostatic latent image is formed on the electrostatic latent image carrier based on the image information, and a developer is applied from the developer onto the surface of the electrostatic latent image carrier on which the electrostatic latent image is formed. Supplied. In this way, an image based on the image information is formed.

  Here, when the developer in the developing device decreases, it is necessary to replenish the developer or replace the developing device. A sensor having a light emitting part and a light receiving part, and a light emitting part for guiding the light of the light emitting part to a predetermined location and reflecting it to a member on the light receiving part side in order to detect the time of replenishment of developer or replacement of the developing device There is an image forming apparatus including a side light guide member and a light receiving part side light guide member that reflects light reflected by the light emitting part side light guide member toward the light receiving part and guides the light to the light receiving part (see Patent Document 1). .

  In the image forming apparatus described in Patent Document 1, when a developer exists between a portion of the light emitting unit side light guide member that reflects to the light receiving unit side light guide member side and the light receiving unit side light guide member, development is performed. The light of the light emitting part is blocked by the agent, and it is determined that it is not time to replenish the developer or replace the developer. On the other hand, when there is no developer between the portion of the light emitting unit side light guide member that reflects toward the light receiving unit side light guide member and the light receiving unit side light guide member, the light from the light emitting unit is received by the light receiving unit. It is determined that it is time to replenish the developer or replace the developer.

On the other hand, there is an image forming apparatus in which the developer is replenished from the outside when the developer decreases due to an image forming operation or the like. In such an image forming apparatus, a sensor for detecting the developer replenishment time, the light emitting unit side light guide member, and the light receiving unit side light guide member are necessary, and further, the developer replenishment end time is detected. A light emitting unit side light guide member and a light receiving unit side light guide member are necessary. In addition, when the sensor for detecting the end timing of developer replenishment, the light emitting unit side light guide member, and the light receiving unit side light guide member are not arranged, the developer replenishment is performed according to the replenishment time from the developer replenishment time. The end time is detected.
JP 2000-221768 A

  A space for arranging two sensors or the like when detecting the developer replenishment timing and the developer replenishment end timing using two sensors, two light-emitting portion-side light guide members, and two light-receiving portion-side light guide members. Becomes necessary and the cost becomes high. Further, when the developer replenishment end time is detected from the replenishment time from the developer replenishment time by using the sensor, the light emitting part side light guide member, and the light receiving part side light guide member one by one, depending on the replenishment time. Since the developer replenishment end time is detected, the detection accuracy of the amount of developer at the end of replenishment deteriorates.

  An object of the present invention is to accurately detect the developer detection timing and the developer replenishment end timing using one sensor or the like.

  An image forming apparatus according to a first aspect includes an electrostatic latent image carrier, a rotary developing device, a sensor, a developer upper limit detecting member, a developer lower limit detecting member, and a developer supply device. The electrostatic latent image carrier is a member capable of forming an electrostatic latent image on the surface. The rotary developing device stores therein a developer to be supplied to the surface of the electrostatic latent image carrier, and includes a plurality of developing units having at least two window portions through which light can pass, and a plurality of developing units. And a rotatable rotating frame. The sensor can receive light from a light emitting unit that can irradiate light inside the developing unit through a window when the rotating frame rotates and positions the developing unit at a predetermined position, and light from the light emitting unit through the window. And a light receiving portion. The developer upper limit detection member is housed in each developer unit, and extends from one window to the upper limit position of the developer when the amount of developer in the developer unit reaches a predetermined upper limit. When the amount of the developer reaches the upper limit, the light from the light emitting part to the light receiving part is blocked, and when the amount of the developer in the developing unit does not reach the upper limit, the light from the light emitting part is received. The light from the light emitting unit is guided to the light receiving unit so as to be received by the unit. The developer lower limit detection member is housed in each developer unit, and extends from the other window to the developer lower limit position when the amount of developer in the developer unit is less than a predetermined lower limit, and develops in the developer unit. When the amount of the developer is less than the lower limit, the light from the light emitting portion is reflected to the light receiving portion so as to be received by the light receiving portion, and when the amount of the developer in the developing device is equal to or more than the lower limit, the light emitting portion Blocks light to the light receiver. The developer replenishment control device replenishes the developer when the amount of the developer is less than the lower limit, and stops the developer replenishment when the amount of the developer reaches the upper limit.

  In this image forming apparatus, when light is irradiated from the light emitting unit to the inside of the developing device through the other window when the rotating frame rotates and positions the developing device at a predetermined position, the light is transmitted through the lower limit detection member. Is guided. Here, when the amount of the developer in the developing device is less than the lower limit, light is received by the light receiving unit, and when the amount is greater than the lower limit, the light cannot be received by the light receiving unit. When light can be received by the light receiving unit, that is, when the amount of the developer is less than the lower limit, the developer is supplied by the developer supply device. On the other hand, when the light from the light emitting portion is incident on the developer upper limit detecting member through the window portion, the supply of the developer is terminated when the light is not guided to the light receiving portion side by the developer upper limit detecting member. Here, the developer lower limit position refers to a height position (empty state) where the developer in the developing device is replenished, and the developer upper limit position is after a predetermined developer replenishment. The height position (full state).

  Here, it is possible to accurately detect the state in which the developer is replenished and the state in which the replenishment of the developer is terminated by one sensor (light emitting unit and light receiving unit). Further, space can be saved and the apparatus can be downsized as compared with the case where two or more sensors are arranged. And since it does not use two sensors, it becomes cheap.

  An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the rotary developing device is a cylindrical device, and the sensor is disposed radially outside the rotary developing device, and the developer The upper limit detection member and the developer lower limit detection member are arranged inside each developer along the radial direction of the rotary developing device.

  Here, the distance between each developing device and the sensor becomes equal, and the detection accuracy is improved.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, wherein the developer upper limit detecting member includes a first light guide section that guides light from the light emitting section to an upper limit position; A first reflecting surface that is disposed at an upper limit position of one light guide unit and reflects light from the light emitting unit; a second reflecting surface that reflects light reflected by the first reflecting surface toward the light receiving unit; and second reflection And a second light guide unit that guides light reflected by the surface to the light receiving unit. A first developer entry space into which the developer can enter is formed between the first reflective surface and the second reflective surface so that the developer blocks an optical path from the first reflective surface to the second reflective surface. ing. The developer lower limit detection member includes a third light guide part that guides light from the light emitting part to a lower limit position, a third reflection surface that is disposed at a lower limit position of the third light guide part, and reflects light from the light emitting part, A fourth reflecting surface that reflects the light reflected by the third reflecting surface to the light receiving unit side and a fourth light guide unit that guides the light reflected by the fourth reflecting surface to the light receiving unit are provided. A second developer entry space into which the developer can enter is formed between the third reflecting surface and the fourth reflecting surface so that the developer blocks an optical path from the third reflecting surface to the fourth reflecting surface. ing.

  In this image forming apparatus, when light is emitted from the light emitting portion to the developer upper limit detecting member, the light from the light emitting portion is incident on the first light guide portion through the window portion, and the light receiving portion is received by the first reflecting surface. Reflected by the side member. When the developer does not enter the first developer entry space, that is, when the developer has not reached the upper limit position, the light reflected by the first reflecting surface is reflected by the second reflecting surface and is guided by the second light guide. To the light receiving unit. When the developer is present in the first developer entry space, the light reflected by the first reflecting surface is blocked by the developer and cannot be received by the light receiving unit. In addition, when light is emitted from the light emitting unit to the developer lower limit detection member, the light from the light emitting unit is incident on the third light guide unit through the window unit and is incident on the light receiving unit side member at the third reflecting surface. Reflected. When the developer does not enter the second developer entry space, that is, when the amount of the developer is less than the lower limit, the light reflected by the third reflecting surface is reflected by the fourth reflecting surface, and the fourth light guide unit Is guided to the light receiving unit. When the developer is present in the second developer entry space, the light reflected by the third reflecting surface is blocked by the developer and cannot be received by the light receiving unit.

  Here, it is possible to detect whether or not the developer exists at the upper limit position and the lower limit position, that is, the amount of the developer in the developing device. In addition, the amount of the developer (the developer is present at the lower limit position and the upper limit position with high accuracy in order to measure whether the developer is present in the first developer entry space and the second developer entry space by transmitting light). Whether or not) can be detected.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, wherein the rotary developing device supplies a developer to the electrostatic latent image carrier from any one of the developing devices. It is possible to position the developing device at a possible developing position and a replenishment position at which any developer can be replenished with developer, and the sensor is located when any developing device is located at the developing position. The developer lower limit detection member housed in the developer unit is incident on the developer upper limit detection member housed in the developer unit when light is incident on the developer lower limit detection member and one of the developer units is located at the replenishment position. Light enters from the light emitting section.

  Here, when the developing device is located at the developing position, it is detected whether or not the amount of the developer in the developing device is less than the lower limit, and when the developing device is located at the replenishing position, the amount of the developer in the developing device is It is detected whether the upper limit has been reached.

  In the present invention, it is possible to accurately detect the developer detection time and the developer replenishment end time using one sensor or the like.

1. Overall Configuration FIG. 1 shows a color printer 1 as an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a schematic diagram for illustrating the arrangement of each component, and details of each part are omitted.

  The color printer 1 is connected to a computer (not shown) or the like, and is a device that can print a color image on paper based on image information sent from an external computer or the like. The color printer 1 includes an image forming unit 2, a fixing unit 4, a paper storage unit 5, a discharge unit 6, a paper transport unit 3, and a toner supply device 7. The toner supply device 7 will be described in detail later.

  The image forming unit 2 includes a photosensitive drum 21, a rotary developing device 22, a charging device 23, a laser unit 24, a cleaning device 25, a drive mechanism 26 (see FIG. 3), and a rotation stop mechanism 27 (FIG. 3). Reference). The rotation developing device 22, the drive mechanism 26, and the rotation stop mechanism 27 will be described in detail later. Here, FIG. 3 is a diagram showing the rotary developing device 22, the drive mechanism 26, and the like.

  The photosensitive drum 21 is a member on which an electrostatic latent image is formed, and is disposed at the approximate center of the color printer 1. The photosensitive drum 21 is a drum-shaped member, and a rotation shaft is provided in a direction orthogonal to the paper surface of FIG. An intermediate transfer belt 211 for transferring a toner image on the photosensitive drum 21 to a sheet is disposed below the photosensitive drum 21 in the vicinity of the photosensitive drum 21. The charging device 23 is a device for charging the surface of the photosensitive drum 21, and is disposed on the upper side of the photosensitive drum 21. The laser unit 24 is a member arranged on the right side of the rotary developing device 22 in FIG. 1 and irradiates a laser beam to form an electrostatic latent image on the photosensitive drum 21 based on image data. It is a part for. The cleaning device 25 is a device for removing deposits such as residual toner remaining on the photosensitive drum 21. In the color printer 1, the cleaning is performed on the entire axial direction of the photosensitive drum 21 above the photosensitive drum 21. A blade is provided.

  The paper transport unit 3 has a transport path that continues from the paper storage unit 5 through the image forming unit 2 and the fixing unit 4 to the discharge unit 6.

  The fixing unit 4 is disposed below the rotary developing device 22 and has a heating roller 41 and a pressure roller 42. The heating roller 41 is a member for melting toner that forms an image formed on a sheet by heat, and is disposed on the upper side of the pressure roller 42.

  The paper storage unit 5 is a part disposed at the lower part of the color printer 1 and has a paper feed cassette 51.

  The discharge unit 6 is disposed on the upper surface of the color printer 1 and discharges a sheet on which an image is formed.

2. Rotating developing device, driving mechanism, rotation stopping mechanism, sensor The rotating developing device 22 is a member disposed adjacent to the photosensitive drum 21 and is a cylindrical device as a whole. The rotary developing device 22 includes four developing units 221 and a frame 222 that supports the four developing units 221.

  The developing device 221 includes a container body 223 (see FIG. 4), a developing roller 224, a toner upper limit detection member 31 (see FIGS. 4 and 5), and a toner lower limit detection member 32 (see FIG. 5). . The container main body 223 has a shape in which a cylinder is divided into four in the circumferential direction, and has an opening extending in the longitudinal direction on the outer peripheral portion. As shown in FIG. 5, a window hole 221 a for allowing light from the sensor 18 to enter the inside of the developing device 221 is formed on the side surface of the container main body 223, and a toner upper limit detection member 31 and a toner lower limit detection member 32 are formed. Is arranged. The four container main bodies 223 store yellow, cyan, magenta, and black toners, respectively.

  As shown in FIG. 3, the developing roller 224 extends in the direction of the rotation axis of the rotary developing device 22 and is disposed at the opening of the container body 223. The developing roller 224 is a member for supplying toner to the surface of the photosensitive drum 21. At both ends of the developing roller 224, distance regulating rollers 225 for maintaining a distance between the photosensitive drum 21 and the developing roller 224 are disposed. The distance regulating roller 225 is a disk-like member having a larger radius than the developing roller 224.

  As shown in FIG. 5, the toner upper limit detection member 31 includes a first light guide 311, a first reflection surface 312, a second reflection surface 313, a second light guide 314, and a first toner entry space 315. And have. Further, the toner upper limit detection member 31 is a member disposed along the radial direction in the vicinity of the frame 222 inside the developing device 221. The first light guide unit 311 is a part that guides the light emitted from the light emitting unit 181 of the sensor 18 to the first reflecting surface 312. The first reflecting surface 312 is a part for reflecting the light guided by the first light guide unit 311 toward the second reflecting surface 313, and is inclined with respect to the light irradiation direction of the light emitting unit 181 of the sensor 18. Slope. The second reflecting surface 313 is a part for reflecting the light reflected by the first reflecting surface 312 to the light receiving unit 182 side of the sensor 18. The second light guide part 314 is a part for guiding the light reflected by the second reflecting surface 313 to the light receiving part 182. The first toner entry space 315 is provided between the first reflection surface 312 and the second reflection surface 313 and allows toner to enter. When the toner enters the first toner entry space 315, the optical path from the first reflecting surface 312 to the second reflecting surface 313 is blocked, and the light from the light emitting unit 181 of the sensor 18 is not received by the light receiving unit 182.

  As shown in FIG. 5, the toner lower limit detection member 32 includes a third light guide unit 321, a third reflection surface 322, a fourth reflection surface 323, a fourth light guide unit 324, and a second toner entry space 325. And have. The toner lower limit detection member 32 is a member disposed along the frame 222 inside the developing device 221. The third light guide unit 321 is a part that guides the light emitted from the light emitting unit 181 of the sensor 18 to the third reflecting surface 322. The third reflection surface 322 is a part for reflecting the light guided by the third light guide unit 321 toward the fourth reflection surface 323, and is inclined with respect to the light irradiation direction of the light emitting unit 181 of the sensor 18. Slope. The fourth reflection surface 323 is a portion for reflecting the light reflected by the third reflection surface 322 to the light receiving unit 182 side of the sensor 18. The fourth light guide unit 324 is a part for guiding the light reflected by the fourth reflection surface 323 to the light receiving unit 182 of the sensor 18. The second toner entry space 325 is provided between the third reflection surface 322 and the fourth reflection surface 323, and allows toner to enter. When toner enters the second toner entry space 325, the optical path from the third reflection surface 322 to the fourth reflection surface 323 is blocked, and the light from the light emitting unit 181 of the sensor 18 is received by the light receiving unit 182 of the sensor 18. Disappear.

  The frame 222 is a member in which four plate-like members 226 (see FIG. 1) extending in the same direction as the rotation axis of the photosensitive drum 21 are arranged at equal intervals. Four spaces are formed. Developers 221 are arranged in these four spaces, respectively. In addition, disk-shaped members 222 a are disposed at both ends of the frame 222 in the axial direction. The disc-shaped member 222a is provided with an annular portion 22b.

  As shown in FIG. 3, the drive mechanism 26 is a mechanism for rotating the rotary developing device 22, and includes a drive mechanism side input gear 261, a second gear train 262 that rotates the drive mechanism side input gear 261, and A motor (not shown) to which the second gear train 262 is coupled. The drive mechanism side input gear 261 is a member that transmits the transmitted power to the frame 222, and includes a pair of disk-like members 26a and a shaft member 26b. The pair of disk-shaped members 26a are members in which gear teeth that mesh with the gear teeth of the annular portion 22b are formed on the outer periphery. The shaft member 26b is a portion that connects a pair of disk-shaped members 26a. The second gear train 262 is a part for transmitting power from the motor and transmitting the power transmitted from the motor to the drive mechanism side input gear 261. The motor shaft is fixed to one of the gears constituting the second gear train 262.

  As shown in FIG. 3, the rotation stopping mechanism 27 includes an input cam 271 that is coaxially connected to the drive mechanism side input gear 261, and a locking member 273 that has a protrusion 272 that locks the input cam 271. Have. The input cam 271 is a member attached to one end of the shaft member 26b of the drive mechanism side input gear 261, and is disposed outside one disk-shaped member 26a. The input cam 271 is a disk-shaped member, and includes a first locking portion 271a and a second locking portion 271b that are locked to the protruding portion 272 of the locking member 273. The first locking portion 271a is a portion for stopping the rotation of the frame 222 in a state where any one of the developing units 221 is located at the developing position (position where toner can be supplied to the photosensitive drum 21). The second locking portion 271b is a portion for stopping the rotation of the frame 222 in a state where any one of the developing devices 221 is located at a toner replenishing position (a position where toner can be replenished from the toner replenishing device 7 to the developing device 221). is there. The locking member 273 includes a support portion 277 supported by the outer frame of the color printer 1, a protruding portion 272 that locks the first locking portion 271a and the second locking portion 271b of the input cam 271, and a solenoid ( And a connecting portion 278 connected to the terminal (not shown). Further, the protruding portion 272 is biased toward the input cam 271 by an elastic member (not shown).

3. Toner replenishing device The toner replenishing device 7 is a portion for replenishing toner into the developing device 221, and is disposed on the upper side of the photosensitive drum 21. The toner replenishing device 7 is connected to the sensor 18, and replenishes toner into the developing device 221 located at the replenishing position when any of the developing devices 221 is located at the replenishing position (see FIG. 2). When the light from the light emitting unit 181 cannot be received by the light receiving unit 182 via the toner upper limit detecting member 32, the replenishment is stopped. Here, the developing position of the developing unit 221 (position facing the photosensitive drum 21 in FIG. 1) and the toner replenishing position (position facing the photosensitive drum 21 in FIG. 2) are different positions. The toner supply device 7 includes four toner containers 71 and four toner supply pipes 72 provided corresponding to the toner containers 71. Each of the four toner containers 71 is a box-like member that stores toner to be replenished in the developing device 221, and is arranged in a direction perpendicular to the paper surface of FIG. The toner replenishment pipe 72 is a member that replenishes the toner in the toner container 71 into the developing device 221 and is a pipe-shaped member that extends in one direction. Further, the toner replenishment pipe 72 can take an upper retracted position and a supply position where the tip of the toner replenishment pipe 72 enters the inside of the developing device 221 below. Further, the toner supply pipe 72 has an opening at the tip, and the tip is inserted into the developing device 221 to supply toner into the developing device 221.

4). Operation When image information is sent from an externally connected computer, the surface of the photosensitive drum 21 is charged by the charging device 23. The laser unit 24 irradiates the surface of the photosensitive drum 21 with laser light based on the image information. In this way, an electrostatic latent image is formed on the surface of the photosensitive drum 21. Thereafter, the frame 222 is rotated, and when the developing device 221 that stores toner of a predetermined color is positioned at the developing position, the protruding portion 272 is locked to the first locking portion 271a. The developing unit 221 storing the first color toner is positioned at the developing position, and the toner is supplied to the photosensitive drum 21. After supplying the first color toner to the photosensitive drum 21, the developing unit 221 that stores the toner for the second and subsequent colors by rotating the frame 222 is the same as in the case of supplying the first color toner to the photosensitive drum 21. The toner is sequentially supplied to the photosensitive drum 21 by being positioned at the development position. A color image is formed on the photosensitive drum 21, and the color image is transferred to the transfer belt 211. The color image transferred to the transfer belt 211 is transferred from the transfer belt 211 to a sheet. The sheet on which the color image is transferred is conveyed to the fixing unit 4, and the color image is fixed on the sheet by the fixing unit 4. The sheet on which the color image is fixed is discharged from the discharge unit 6.

  Next, the toner supply operation will be described.

  When the developing device 221 is located at the developing position, the sensor 18 irradiates light from the window hole 221a of the developing device 221 located at the developing position to the toner lower limit detecting member 32. When toner is present in the second toner entry space 325 of the toner lower limit detection member 32, the light from the light emitting unit 181 is blocked by the toner and cannot be received by the light receiving unit 182. In this state, a predetermined amount or more of toner is present in the developing device 221, and it is not necessary to supply toner. When the toner in the developing device 221 decreases and no toner is present in the second toner entry space 325, the light from the light emitting unit 181 is received by the light receiving unit 182. The developing device 221 that has received the light from the light emitting unit 181 by the light receiving unit 182 is positioned at the toner replenishment position. Specifically, the frame 222 is rotated and the protrusion 272 is locked with the second locking portion 271b, and the developing device 221 stops at the toner supply position. The toner is supplied to the developing device 221 located at the toner supply position by the toner supply device 7. At this time, light is emitted from the light emitting portion 181 of the sensor 18 to the toner upper limit detecting member 31 at the same time. When the light from the light emitting unit 181 cannot be received by the light receiving unit 182, the toner supply operation of the toner supply device 7 is stopped.

  Here, it is possible to detect the toner replenishment timing by detecting the toner replenishment timing of all the developing units 221 using one sensor 18 (light emitting unit 181 and light receiving unit 182). At this time, since both the toner supply timing and the toner supply completion timing are measured and detected, the detection accuracy is improved. Further, since only one sensor 18 is disposed, space can be saved and the size can be reduced. Further, since the sensors 18 are arranged on the outer side in the radial direction of the rotary developing device 22, the distances between the respective developing units 221 and the sensors 18 are substantially equal. Therefore, the variation due to the developing device 221 can be suppressed in the timing detection accuracy.

5. Other Embodiments (a) In the above embodiment, the color printer 1 has been described. However, the present invention is not limited to this and may be a copying machine, a multifunction machine, or the like.

  (B) Moreover, the upper limit detection member 31 and the lower limit detection member 32 are not limited to the above shapes, and may be another shape or two members.

1 is an overall cross-sectional view showing an entire color printer 1 according to the present invention. FIG. 3 is an overall cross-sectional view of the color printer 1 when toner is supplied. FIG. 3 is a perspective view showing a rotation developing device 22, a drive mechanism 26, and a rotation stop mechanism 27. FIG. 4 is a diagram illustrating a toner upper limit detection member 31 and a sensor 18; The figure which shows arrangement | positioning of the rotation developing device 22, the sensor 18, the upper limit detection member 31, and the lower limit detection member 32. FIG.

Explanation of symbols

1 Color printer (image forming device)
7 Toner supply device (Developer supply device)
18 Sensor 21 Photosensitive drum (electrostatic latent image carrier)
22 Rotating developing device 31 Upper limit detecting member 32 Lower limit detecting member 181 Light emitting unit 182 Light receiving unit 221 Developer 221a Window hole (window)
222 frames (rotating frames)
311 1st light guide part 312 1st reflective surface 313 2nd reflective surface 314 2nd light guide part 315 1st toner approach space 322 3rd reflective surface 324 4th light guide part 325 2nd toner approach space

Claims (4)

An electrostatic latent image carrier capable of forming an electrostatic latent image on the surface;
A developer supplied to the surface of the electrostatic latent image carrier is housed therein, and supports a plurality of developers having at least two windows through which light can pass, and the plurality of developers. A rotating developing device having a rotatable rotating frame;
A light emitting unit capable of irradiating light through the window when the rotating frame rotates and positions the developing unit at a predetermined position, and light from the light emitting unit through the window A sensor having a light receiving portion capable of receiving light;
A developer housed in each of the developing devices and extending from one of the windows to the upper limit position of the developer when the amount of the developer in the developing device reaches a predetermined upper limit, When the amount of the toner reaches the upper limit, the light from the light emitting portion to the light receiving portion is blocked, and when the amount of the developer in the developing device does not reach the upper limit, the light from the light emitting portion is blocked. An upper limit detecting member that guides light from the light emitting unit to the light receiving unit so as to be received by the light receiving unit;
The amount of developer stored in each of the developing devices and extending from the other window portion to the lower limit position of the developer when the amount of developer in the developing device is a predetermined lower limit, and the amount of developer in the developing device Is less than the lower limit, the light from the light emitting portion is reflected to the light receiving portion so as to be received by the light receiving portion, and when the amount of developer in the developer is not less than the lower limit, A lower limit detection member that blocks light from the light emitting unit;
A developer replenishing device that replenishes the developer when the amount of the developer falls below the lower limit, and stops the replenishment of the developer when the amount of the developer exceeds the upper limit;
An image forming apparatus. The rotary developing device is a cylindrical device,
The sensor is disposed radially outside the rotary developing device,
The developer upper limit detection member and the developer lower limit detection member are respectively arranged inside the developing devices along the radial direction of the rotary developing device.
The image forming apparatus according to claim 1. The developer upper limit detection member is disposed at a first light guide part that guides light from the light emitting part to an upper limit position and at the upper limit position of the first light guide part, and reflects the light from the light emitting part. A first reflecting surface; a second reflecting surface that reflects light reflected by the first reflecting surface toward the light receiving portion; and a second light guiding portion that guides light reflected by the second reflecting surface to the light receiving portion. And
Between the first reflecting surface and the second reflecting surface, the first developer enters the developer so that the developer can block an optical path from the first reflecting surface to the second reflecting surface. A space is formed,
The developer lower limit detecting member is disposed at the lower limit position of the third light guide unit and the third light guide unit that guides light from the light emitting unit to the lower limit position, and reflects the light from the light emitting unit. A third reflecting surface, a fourth reflecting surface that reflects the light reflected by the third reflecting surface toward the light receiving portion, and a fourth light guide portion that guides the light reflected by the fourth reflecting surface to the light receiving portion. And
Between the third reflecting surface and the fourth reflecting surface, the second developer enters the developer so that the developer can block an optical path from the third reflecting surface to the fourth reflecting surface. A space is formed,
The image forming apparatus according to claim 1. The rotary developing device is located at a developing position where a developer can be supplied from any of the developing units to the electrostatic latent image carrier, and a replenishment position where a developer can be replenished to any of the developing units. Can be positioned,
When one of the developing units is located at the developing position, the sensor makes light incident on the developer lower limit detection member housed in the developing unit from the light emitting unit, and is disposed at the replenishing position. When the developing unit is positioned, light is incident on the developer upper limit detection member housed in the developing unit from the light emitting unit.
The image forming apparatus according to claim 1.

Images