JP2666930B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to an image forming apparatus such as a laser printer and an electronic copier. 2. Description of the Related Art Conventionally, in an image forming apparatus, for example, a laser printer, a developing apparatus having a developer has been developed into a unit which can be inserted (applied) or removed (removed) in a cartridge type. However, the life of the developing unit has not been managed while maintaining the normal developer concentration. Therefore, the developing unit must be replaced before the end of its life, which results in waste. Further, since the developing unit that has been used halfway can be used again, in this case, the life cannot be managed while maintaining a normal developer concentration for the developing unit. Therefore, for the attached developing unit,
There is a drawback that it is not possible to accurately manage the life while maintaining a normal developer concentration. (Problems to be Solved by the Invention) The present invention relates to a mounted developing unit,
It is an object of the present invention to provide an image forming apparatus capable of accurately managing a lifetime while maintaining a normal developer concentration. [Structure of the Invention] (Means for Solving the Problems) An image forming apparatus of the present invention develops a latent image on an image carrier with a developer, and includes a detachable developing unit having a unique identification number. Output means provided in the developing unit for outputting the unique identification number, reading means for reading the identification number output from the output means when the developing unit is mounted, reading by the reading means The stored identification numbers are stored in a plurality, and the number of times of use of the developing unit corresponding to the identification number and the reference value of the developer set for each developing unit are stored in correspondence with the stored identification numbers. Storage means for storing density data; density detection means for detecting the density of the developer in the developing unit; contents detected by the density detection means and stored in the storage means. Based on the reference density data corresponding to each of the identification numbers, controlling the developer concentration to be maintained in a predetermined range, and reducing the number of times the developing unit corresponding to each of the identification numbers is used to a predetermined number. When the number of times is exceeded, the control unit determines that the developing unit has reached the end of its life and disables the output unit provided in the developing unit. (Function) The present invention develops a latent image on an image carrier with a developer, and includes a detachable developing unit having a unique identification number, and an output provided on the developing unit for outputting the unique identification number. Means, reading means for reading the identification number output from the output means when the developing unit is mounted, and a plurality of the identification numbers read by the reading means are stored, and these stored numbers are stored. Storage means for storing the number of times of use of the developing unit corresponding to each identification number, and reference density data of the developer set for each developing unit; Density detection means for detecting the density of the image, and the detection content of the density detection means and the reference density data corresponding to each of the identification numbers stored in the storage means. The control unit controls the developer concentration to be maintained in a predetermined range on the basis of the predetermined number, and when the number of times of use of the developing unit corresponding to each of the identification numbers exceeds a predetermined number, determines that the developing unit has reached the end of its life. Then, the control unit disables the output unit provided in the developing unit. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 and FIG. 3 are an external perspective view and a schematic vertical sectional side view showing an internal structure of an image forming unit apparatus having a laser printer as an image forming apparatus according to the present invention. I have. In FIG. 1, reference numeral 1 denotes a laser printer as an image forming apparatus, which has the following configuration. That is, in the figure, reference numeral 5 denotes a printer main body of the laser printer 1. The upper rear portion of the upper surface of the printer main body 5 is one step higher, and a concave portion 6 as a paper discharge portion is formed at the center of the upper surface. A paper discharge tray 8 movably supported by a jogger 7 is mounted in the recess 6, and an operation panel display 9 and an operation panel switch 10 as an operation panel are provided on the right side of the recess 6. On the left are three
Each of the IC card inserts 11 is arranged. As shown in FIG. 4 (a), the operation panel display section 9
LCD (liquid crystal) display 9a for displaying the number of sheets, mode, etc., and display 9 for lighting and displaying various states with LEDs (emitting diodes)
b,... The indicators 9b,... Are configured to indicate whether or not an external device is connected, that is, an on-line / off-line mode, print ready, during transfer of print data, an operator call, a serviceman call, and a manual operation. As shown in FIG. 4 (b), the operation panel switch unit 10 includes a numeric keypad 10a, an online / offline switching key
b, clear key 10c, yes (YES) key 10d, no (NO)
It comprises a key 10e, an ejection (EXIT) key 10f and the like. Each key of the numeric keypad 10a is also used as a key for setting a copy number setting mode, a paper source paper feed mode, a print suspension paper discharge mode, and the like. The clear key 10c is also used as a reset key, the yes key 10d is also used as an enter key,
The no key 10e is also used as a next key and an increment key, and the ejection key 10f is also used as an ESC key and a decrement key. Further, a paper output tray 12 is provided on the front of the printer body 5,
A manual tray 13 is mounted on the rear side. A drum-shaped photoreceptor (photoreceptor unit) 15 as an image carrier is provided substantially at the center of the printer main body 5, and a charging device 16, as shown in FIG. Laser optical system 17, developing device (developing unit) 18 as developing means, transfer device 19, peeling device 20, cleaning device (cleaner unit) 2 as cleaner means
1, and the static eliminator 22 are sequentially arranged. Further, a photoconductor 15 and a transfer device are provided in the printer body 5.
An image support transport path 24 is formed extending in the forward direction through an image transfer unit 23 between the image transfer unit 19 and the paper feed cassette 28 stored in the bottom of the printer main body 5. The paper P automatically fed through the paper feeder and the paper P manually supplied from the manual tray 13 are guided to the image transfer unit 23. An aligning roller pair 30 is disposed upstream of the image transfer section 23 of the image support transport path 24, and a fixing device 31, a paper discharge selector 32, and a paper discharge roller pair 33 are disposed downstream. I have. At the end of the image support transport path 24, a branch transport path 35 having a pair of paper discharge rollers 34 for guiding the paper P sorted by the paper discharge selector 32 to the concave portion 6 as a paper discharge section.
Are formed. In FIG. 2, 40 is a lower cover, 41 is a front cover, 42
Is an upper cover, 43 is an openable right cover (door), 44 is a left cover, 45 is a right cover open / close lever, 46 is an upper unit open / close lever, and 47, 48 ..., 49 shown in FIG. It is a control board which comprises a part. Thus, in the image forming operation, the photosensitive member 15 is driven and is uniformly charged by the operation of the charging device 16,
Next, exposure corresponding to the image signal is performed on the photoconductor 15 by the laser optical system 17 to form an electrostatic latent image. Next, the electrostatic latent image on the photoreceptor 6 is developed by a developing device 18 using a two-component developer D composed of a toner a and a carrier b, and sent to the image transfer unit 23 as a developer image. On the other hand, in synchronization with this developer image forming operation,
Paper P removed from 25 or manually fed paper P
Is transferred through the aligning roller pair 30, and the developer image previously formed on the photoconductor 15 is transferred onto the sheet P by the operation of the transfer device 19. Then, the paper P is peeled off
20 is peeled off by the photoconductor 15 and is conveyed by the image carrier
It passes through 24 and is sent to the fixing device 31. Here, after the developer image is melted and fixed on the sheet P, the discharge direction is sorted by the sheet discharge selector 32 and discharged onto the upper discharge tray 8 or the front discharge tray 12. After the transfer of the developer image onto the sheet P, the residual toner remaining on the photoreceptor 15 is cleaned by the cleaning device 21 to be ready for the next copying operation. Further, as shown in FIGS. 6 to 9, the photosensitive member 15, the cleaning device 21 as a cleaner, and the developing device 18 as a developing device are each provided with a developing roller 59.
The shaft 201 extending to both ends of the central axis of the photoconductor 15 and the shaft 202 of the photoreceptor 15 are used as guides for the grip handles 87 and 8, respectively.
8 is mounted on a guide frame 51 slidably supported via slide rails 50, 50.
As shown in the figure, by pulling out the guide frame 51 with the right cover 43 open, these can be pulled out to the right side of the printer body 5. Further, the photoconductor 15 and the cleaning device 21 are unitized so that they can be integrally attached to and detached from the guide frame 51, and the developing device 18 can be independently attached and detached. The developing device 18 is mounted horizontally with respect to the printer body 5. The developing device 18 has a configuration as shown in detail in FIG. That is, the developing device 18 includes a developing mechanism section 55 and a developer stirring section 56. The developing mechanism section 55 slides between a developing roller 59 disposed opposite the opening 58 of the developing device main body 57 and the photosensitive member 15 of a developer magnetic brush D ′ formed on the surface of the developing roller 59. A doctor 61 provided at a contact portion, that is, an upstream side of the developing unit 60 to regulate the thickness of the developer magnetic brush D ′;
A scraper 62 is provided on the downstream side of the developing roller 59 and peels off the developer magnetic brush D ′ formed on the surface of the developing roller 59 to guide the developer magnetic brush D ′ to the developer stirring section 56. Also, the developer stirring section 56
The first and second developer stirring bodies 64 and 65 (see FIG. 10) serving as developer augers accommodated in a developer accommodating section 63 formed behind the arrangement section of the developing roller 59. Have. The developing roller 59 includes a magnetic roll 59a having a plurality of magnetic pole portions 89, and a non-magnetic sleeve 59b which is fitted around the magnetic roll 59a and rotates clockwise. Further, a toner receiving portion 66 as a developer receiving portion is formed at a position facing the developer agitating portion 56 of the developing device main body 57, and a toner as a developer replenishing cartridge of a developer replenishing means 150 described later. The toner a supplied from the cartridge 67 and the toner a returned from the cleaning device 21 via the toner return unit 68 serving as a developer return unit
Are accepted. Further, a developer concentration detector 70 for detecting the developer concentration is provided at a position facing the scraper 62, and a voltage conversion value as a detection signal from the developer concentration detector 70 is provided in the toner cartridge 67. The built-in toner supply shaft 71 as a developer supply member is driven as needed (by driving separately from the printer main body 5). Thus, on the surface of the non-magnetic sleeve 59b, the developer D rises due to the lines of magnetic force generated from the respective magnetic pole portions and is attracted in a brush shape to form a developer magnetic brush D '. The toner a in the magnetic brush D 'is sequentially conveyed to the developing unit 60 by the rotation of the sleeve 59b, and the toner a
The toner adheres to the upper electrostatic latent image and is developed. On the other hand, the developer agitator 6 disposed in the developer storage 63
The rotation of 4 and 65 allows the developer D to favorably charge the agitated toner a and the carrier b. FIG. 10 and FIG.
This will be described with reference to FIG. FIG. 10 shows the flow B of the developer D in the developer storage section 63. FIG. 11 shows only the developer stirring bodies 64 and 65. That is, the toner a supplied from the toner supply port 66
Is sent to the stirring body 64 side by the plate-shaped U-turn blade 204, is immediately conveyed by the conveying blade 205, is sufficiently stirred by the stirring blade 69 on the way, and is
It is sent to the stirring body 65 side by 4 '. After that, the flow of the developer D is changed on the blade 74 having a small outer shape at the center. Utilizing this flow, density detection, which will be described later, is performed. The developer agitating bodies 64 and 65 are provided horizontally with respect to the developing device 18, that is, the developing unit, so that the transport of the developer D is not adversely affected (transfer abnormality due to oblique lines). In the vicinity of the developer stirring body 64 corresponding to the toner supply port 66, only a transport blade is provided without a stirring blade in order to prevent delay in toner detection and toner jam. Here, the developer concentration detection and control will be described. First, as shown in FIG. 12, the developing device 18 includes a substrate 39 as a means for recognizing that the device is unusable due to its life and an identification number as a device serial number, and a density detecting device.
70 is connected. The case of a new developing device 18 will be described. The developer D has a predetermined concentration in advance. When the developer D is attached to the main body 5, the new or old is recognized by the substrate 39, and only when the new is recognized, the development is performed by the storage device (not shown) of the main body 5. Reset the usage count in the body of device 18. Thereafter, only the main body starts to be driven while the concentration of the developer D is constant, and the flow of the developer D is stabilized. After about two minutes, the voltage value obtained by the voltage conversion is read from the substrate 39 to a storage device (not shown) of the main body 5. At this time,
This developing device is based on the read voltage value (reference voltage value).
The density control of 18 is started. The cleaning device 21 has a configuration as shown in FIG. That is, reference numeral 75 in the drawing denotes a cleaning device main body having an opening 76 at a portion facing the photoconductor 15, and the cleaning blade 77 is housed in the cleaning device main body 75. The cleaning blade 77 is rotatable by a support shaft 78 and is held at its upper end by a blade holder 80 which is constantly urged counterclockwise in the state of FIG. 5 by a weight 79 as an urging member. , The tip of the lower end is photoconductor 15
In a state of being pressed against the peripheral surface. The remaining toner a adhered to the photoreceptor 15 is scraped off by the cleaning blade 77. Also, a collecting blade is provided at the lower edge of the opening 76.
The toner 81 is scraped off by the cleaning blade 77 and collected in the cleaning device main body 75. Further, a toner collecting auger 82 for transferring the toner a in the cleaning device main body 75 to a toner discharging portion 83 protruding outside to transfer the toner a in the cleaning device main body 75 to a toner returning device 68 as a developer returning device is provided on a bottom portion in the cleaning device main body 75. Is arranged. On the other hand, as shown in FIG.
The toner a collected by the cleaning device 21 is used as a developing device.
In this state, the toner return means 68 for returning to the position 18 is attached. As shown in FIG. 9, on the right cover 43, a driving unit 107 of the toner returning unit 68, a toner replenishing unit 150 as a developer replenishing unit, a guide member 152, a safety switch operating claw 153,
A cover lock claw 154, a guide member 155 for positioning the photosensitive member and the developing device, and the like are attached. Incidentally, 190 shown in FIG. 9 is a toner receiving port 66 of the developing device.
When the right cover 43 is closed, the slide shutter is pushed by the toner discharging section 91 to slide and open the toner receiving port 66. Reference numeral 191 denotes a handle for pulling out a slide rail 51 on which a unit device including the developing device 18, the photoconductor 15 and the cleaning device 21 is detachably mounted. The toner return means 68 and the like are described in Japanese Patent Application No. 61-165666.
Therefore, detailed description is omitted here. FIG. 13 shows a main part of an electric circuit. That is, a control circuit 120 for controlling the entire system, a ROM 121 storing a control program, a personal identification number (ID number) to be collated at the time of data change, a recognition number as data for at least two developing devices 18, and a usage count. , A reference voltage value, and a developing circuit including a storage circuit 122 configured with a nonvolatile RAM, a substrate 39, and a density detecting device 70, in which a top margin, a left margin, a paper type, and the like as data for the paper P are stored. Drive circuit 12 that drives 18
3, print data supplied from an external device (not shown), setting contents of the operation panel switch unit 10, or the board 39
An input port 124 for receiving an identification number from the printer, an output for outputting display contents to the operation panel display section 9 and an output for outputting a drive signal to a drive circuit 125 for driving a toner supply motor (not shown). A port 126, an A / D converter 127 for converting a density signal from the density detector 70 into a digital value, and the control circuit 120, the ROM 121, the storage circuit 122, an input port 124, an output port 126, and an A / D converter
It is composed of a bus 128 connecting 127. The top margin is print start position data of the paper P when printing, the left margin is data for horizontal print position alignment for positioning both sides of the paper P, and the paper type is used. This data indicates the paper size (A4 size, letter type) that differs depending on the country, and is important data that is not changed by the user. Based on the identification number supplied from the substrate 39 of the developing device 18, the control circuit 120 determines whether the developing device 18 to which the developing device has been mounted has been mounted so far or has been mounted before (previous time). Or another new one. That is, the identification numbers supplied from the substrate 39 of the developing device 18 and the storage areas 122a and 122b (the fifteenth
Compare the identification numbers of the two developing devices 18 stored in the storage device (see FIG. 2). If the identification numbers do not match, it is determined that a new (new) developing device 18 is to be mounted, and the storage area is determined. If the identification number 122a matches, the mounting of the developing device 18 that has been mounted is determined, and if the identification number matches the recognition number of the storage area 122a, the mounting of the developing device 18 that was mounted before (previous time) is determined. Judge. The control circuit 120 determines whether or not the mounted developing device 18 has reached the end of life based on a signal indicating whether or not the fuse 133 supplied from the substrate 39 of the developing device 18 has been blown. is there. As shown in FIG. 15, the control circuit 120 sets an identification number for the currently installed developing device 18, a use count number as its life management, and a reference developer concentration set when the developing device is installed. The corresponding reference voltage value (initial voltage value) and the like are stored in the storage area 122a of the storage circuit 122, and the identification number for the developing device 18 mounted last time,
The number of formed images, the reference voltage value, and the like are stored in the storage area 122b of the storage circuit 122.When the developing device 18 is replaced, that is, when a new developing device 18 is mounted, the storage contents of the storage circuit 122 are sequentially updated. That is, the new storage contents are stored in the storage area 122a, and the storage contents of the storage area 122a are stored in the storage area 122b. Further, the control circuit 120 stores a top margin, a left margin, a paper type, and the like set at the time of shipping or the like in the storage circuit 122. Further, when the control circuit 120 determines that the developing device 18 is to be replaced, that is, a new developing device 18 is to be set, the reference voltage value by the storage circuit 122 and the density detecting device 7 of the developing device 18 are used.
Compared with the voltage value from 0, if it is out of the predetermined voltage value range, it is determined that a normal image cannot be formed, and to that effect (that is, the image is read depending on the use environment of the main body 5 and the developing device 18). The operation panel display unit 9 displays a message that the voltage value has remarkably fluctuated and image formation at an appropriate density cannot be performed, and stops the activation of the main body 5. On the substrate 39, as shown in FIG. 14, the diode D1
A recognition number setting unit 132 for setting a 20-bit recognition number (ID code) by connecting or disconnecting to D24, the diode D1
A reading unit 131 constituted by two ICs or the like for reading an identification number by D24, a fuse 133 blown at the end of its life, and a cutting unit 134 for cutting (fusing) the fuse 133. . In such a configuration, data corresponding to the identification number is output by a signal sequentially output from the identification number setting unit 132 in response to the select signal supplied to the reading unit 131. Also, by outputting a signal to the diode D24 in response to the select signal supplied to the reading unit 131, a signal indicating whether or not the fuse 133 has been blown is output. Further, in response to the select signal supplied to the reading unit 131, the cutting unit 1
By operating 34, the fuse 133 is cut (blown).
Is performed. Next, the operation of the above configuration will be described with reference to the flowchart shown in FIG. For example, the developing device 18 is mounted in the printer main body 5 by the setting method described above, and a power switch (not shown) is turned on. Then, the control circuit 120 warms up the engine, that is, the printer main body 5. For example, the heater is warmed up, the main motor is turned on, the charger is detected, the rise of the mirror motor is checked, and the developer D in the developing device 18 is agitated. Next, the control circuit 120 determines that the life-hung (unusable) development apparatus 18 has been mounted, based on a signal indicating whether the fuse 134 supplied from the substrate 39 of the development apparatus 18 has been blown. In this case, the fact is displayed on the operation panel display section 9 and the activation of the main body 5 is stopped. The control circuit 120 also stores the identification number supplied from the substrate 39 of the developing device 18 and the storage areas 122a and 122a of the storage circuit 122.
By comparing the identification numbers for the two developing devices 18 stored in 22b, a new (new) developing device is obtained.
It is determined whether the mounting of the developing device 18, the mounting of the developing device 18 which has been mounted so far, or the mounting of the developing device 18 which has been previously mounted is determined. Accordingly, when the identification number of the mounted developing device 18 does not match the identification number of the storage circuit 122, the control circuit 1
20 judges whether a new (new) developing device 18 is mounted. Based on this determination, the control circuit 120 stirs the developer D in the developing device 18 for 2 minutes. After this stirring, the concentration detection device 70
Are read a plurality of times, the average value is determined as the density level, and it is determined whether or not the density level is within a predetermined reference range. If the result of this determination is outside the range, the control circuit 120 determines that normal image formation is not possible, and to that effect (the read voltage value is not within the appropriate range, so that image formation at an appropriate density is performed. Is displayed on the operation panel display section 9 and the activation of the main body 5 is stopped. Further, when the value is within the predetermined range, the control circuit 120 first stores the identification number, the use count value, the reference voltage value, and the like stored in the storage area 122a in the storage circuit 122 in the storage area 122b.
The memory circuit 12 stores the read voltage value (toner specific density; read value) supplied from the density detecting device 70, that is, the reference voltage value, and the identification number from the developing device 18.
The data is updated and stored in the second storage area 122a. In addition, the control circuit 120
Clears the usage count stored in the storage area 122a of the storage circuit 122. Thereafter, the control circuit 120 turns off the main motor (not shown) and enters a standby state. Thereafter, each time an image is formed, the voltage value (read value) supplied from the density detecting device 70 is compared with the reference value stored in the storage area 122a of the storage circuit 122, and the comparison result is obtained. The corresponding density control is performed. In addition, the use count of the storage area 122a of the storage circuit 122 is counted up for each image formation. In such a state, when the use count number of the storage area 122a of the storage circuit 122 reaches the life number, that is, the count number corresponding to the unusable state, the control circuit 120 supplies a signal to the cutting portion 134 in the substrate 39 every time. By fuse 133
Is cut (fused). Then, the control circuit 120 displays the fact (request for replacement with another developing device because the developing device cannot be used due to its life) on the operation panel display section 9 and
The activation of the main body 5 is stopped. Further, when the power switch is turned on, if the recognition number from the currently mounted developing device 18 matches the recognition number stored in the storage area 122a of the storage circuit 122,
The control circuit 120 is the developing device 18 that was installed before the power was turned on.
It is determined that is attached as is. By this determination, the control circuit 120 uses the storage content stored in the storage area 122a of the storage circuit 122 as it is,
It manages the used count and controls the concentration. Also, when the power switch is turned on, if the recognition number from the currently mounted developing device 18 matches the recognition number stored in the storage area 122b of the storage circuit 122,
The control circuit 120 determines that the developing device 18 that has been mounted before (previous time) before power-on is mounted. By this determination, the control circuit 120 replaces the storage content stored in the storage area 122a of the storage circuit 122 with the storage content stored in the storage area 122b. As a result, the control circuit 120 is stored in the storage area of the storage circuit 122.
The management of the use count number and the density control operation are performed using the contents stored in the previous development device 18 stored in the storage device 122a. As described above, the developing devices are provided with identification numbers, and the life of the plurality of developing devices is managed using the identification numbers. Therefore, the life of the plurality of developing devices can be accurately managed. [Effects of the Invention] As described in detail above, according to the present invention, an image forming apparatus capable of accurately managing the life of a mounted developing unit while maintaining a normal developer concentration is provided. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is a flowchart for explaining the operation, and FIG. 2 is an external perspective view of an image forming unit provided with an image forming apparatus. , FIG. 3 is a schematic vertical sectional side view, FIG. 4 is a diagram showing a configuration of an operation panel display unit, FIG. 5 is a configuration explanatory diagram showing a configuration of a main part of the image forming apparatus, and FIG. 7, FIG. 7 is a diagram for explaining a mounted state of the developing device, FIG. 8 is a diagram for explaining a mounted state of the cleaner device, and FIG. 9 is a schematic diagram of a state in which a cover is opened. Perspective view, 10th
FIG. 11 is a diagram showing a flow of a developer in a developing device and a stirring blade. FIG. 11 is a diagram showing a configuration of a stirring blade in the developing device.
FIG. 12 is an external view of the developing device, FIG. 13 is a block diagram showing a configuration of a main part of an electric circuit, FIG. 14 is a diagram for explaining a configuration of a substrate, and FIG. FIG. 5: Device body, 9: Operation panel display, 9a: LCD display, 10: Operation panel switch, 10a: Numeric keys, 10d
... yes key, 10e ... no key, 18 ... developing device, 39
... board, 70 ... concentration control device, 120 ... control circuit, 122
... Memory circuits, 122a, 122b.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Naoshi Ohara               70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa               Inside the Toshiba Yanagimachi Plant (56) References JP-A-62-95552 (JP, A)                 JP-A-60-229047 (JP, A)                 JP-A-61-252570 (JP, A)                 JP 62-75667 (JP, A)                 JP-A-62-90670 (JP, A)                 JP-A-61-172167 (JP, A)                 JP-A-64-35581 (JP, A)                 JP-A-63-8755 (JP, A)                 JP-A-62-83768 (JP, A)                 JP-A-62-40471 (JP, A)                 JP-A-62-102259 (JP, A)                 JP-A-54-29643 (JP, A)                 Shokai Sho 63-105148 (JP, U)                 63-146451 (JP, U)                 60-120466 (JP, U)                 Japanese Patent Publication 6-42110 (JP, B2)

Claims (1)

(57) [Claims] A developing unit for developing the latent image on the image carrier with a developer; a detachable developing unit having a unique identification number; an output unit provided in the developing unit for outputting the unique identification number; A reading unit that reads the identification number output from the output unit when the device is mounted, a plurality of the identification numbers read by the reading unit are stored, and the identification numbers corresponding to the stored identification numbers are stored. Storage means for storing the number of times of use of the developing unit corresponding to each identification number and reference density data of the developer set for each developing unit; density detection for detecting the density of the developer in the developing unit Means, based on the content detected by the density detection means and the reference density data corresponding to each of the identification numbers stored in the storage means, The control unit controls the developing unit to be maintained within a predetermined range, and when the number of uses of the developing unit corresponding to each of the identification numbers exceeds a predetermined number, it is determined that the developing unit has reached the end of its life and the developing unit is An image forming apparatus, comprising: a control unit that disables an output unit provided in the control unit. 2. The storage unit newly stores the first identification number in the storage unit when the first identification number read by the reading unit does not match the second identification number stored in the storage unit. The image forming apparatus according to claim 1, wherein the information is stored.