JPS6073558A - Presence/absence detector of developer - Google Patents

Abstract

PURPOSE:To control a device so that the detection state is ignored till the time when the developer presence state is assumed, by putting a developer between an arm and the side face of a storage part to interfere with shake of the arm when the developer is supplied to the storage part. CONSTITUTION:When a motor is rotated, an arm 65 is shaked in the direction of an arrow (d) at a prescribed period by a disc 64. This motion is transmitted to a shaft 60, and an arm 61 with a magnet 62 which turns on and off a lead switch 59 is shaked in the direction of the arrow (d) similarly. If the toner exists between the arm 61 and the side face of a toner hopper 52, the tip of the arm 65 is only brought into contact with the disc 64 and is hardly shaked, and therefore, the magnet 62 at the tip of the arm 61 does not approach the side face of the hopper 52. That is, the lead switch 59 is not turned on. If the toner does not exist between the arm 61 and the side face of the hopper 52, the magnet 62 approaches and gets off the lead switch 59, and the switch 59 is turned on and off repeatedly. Thus, the mechanism which moves the arm 61 is unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developer presence/absence detection device for detecting the presence or absence of developer in a developer storage section, for example, in a developing unit of an electronic copying machine.

[Technical Background of the Invention] Conventionally, as this type of developer presence/absence detection device, toner (
An arm that is installed in a toner hopper (developer storage section) that stores developer (developer) and swings at a predetermined period; a magnet that is installed on the free end side of this arm; and when this magnet approaches the side of the toner hopper. Some devices include a detector installed outside the toner hopper facing the magnet and detecting the magnet, and when the detector detects the magnet, it is determined that there is no toner.

[Problems with the Background Art] However, in the past, the toner supply state was established when the detector detected the magnet, which caused the following problems. In other words, when it is detected that there is no toner, the toner replenishment state is entered and toner is replenished into the toner hopper, but at this time the arm has stopped swinging, so there is no toner between the arm and the side of the toner hopper. does not enter. Therefore, even if toner is replenished, the detector continues to detect the magnet (no toner).

Therefore, when toner is replenished, there is a problem in that a mechanism is required to move the arm so that the magnet is separated from the detector and the toner is present.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to move an arm for detecting the presence or absence of developer so that the developer is present when the developer is replenished. An object of the present invention is to provide a developer presence/absence detection device that does not require a mechanism.

[Summary of the Invention] The present invention includes a swinging arm provided in a storage section that stores developer, and a detector that detects the presence or absence of developer based on the position of the arm that changes depending on the amount of developer in the storage section. In a developer presence/absence detection device comprising:
When replenishing the developer into the storage section, it is assumed that the swinging of the arm is hindered due to the developer entering between the arm and the side surface of the storage section, resulting in a state where the developer is present.

The present invention is characterized in that a control means is provided for ignoring the developer-free detection state of the detector.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an electronic copying machine as an example of an image forming apparatus according to the present invention. That is, reference numeral 1 designates a housing of a copying machine, and a photosensitive drum 2 that rotates in the direction of arrow a in the figure is provided approximately at the center of the housing.

Further, in the upper part of the housing 1, a document table 3 for supporting a document is provided so as to be able to reciprocate in the direction indicated by the arrow in the figure. By moving the document table 3 in synchronization with the rotation of the photoreceptor drum 2, the light emitted from the exposure lamp 4 is reflected by the document on the document table 3, and the reflected light is transmitted through convergent light transmission. An image is formed on the photoreceptor drum 2 by the body 5, and is reflected on the photoreceptor drum 2 as an inverted image of the document. At this time, by charging the photoreceptor drum 2 with the charging device 6, an inverted image of the document is formed on the photoreceptor drum 2 as an electrostatic latent image, and this electrostatic latent image is formed according to the present invention. The 1-toner is deposited by a developing device 7 equipped with a developer presence/absence detecting device to be visualized.

On the other hand, below the developing device 1, a paper feeding mechanism 8 is provided that supplies the paper P to below the photoreceptor drum 2 (image transfer section 12). The paper feeding mechanism 8 is detachably attached to the side of the housing 1 and can feed a plurality of sheets of paper P.

..., and a paper feed roller 1° that feeds sheets of paper P one by one from this paper feed cassette 9, and further positions the leading edge of the paper P that is fed by the paper feed roller 10. A pair of aligning rollers 11 for aligning and conveying the paper are provided. The paper feed roller 10 has a contact portion 10a that contacts the paper P in the paper feed cassette 9, and a non-contact portion 10b that does not contact the paper P in the paper feed cassette 9.
It is a half-moon-shaped roller that has a rotating spring clutch (not shown), which transmits the driving force of the motor, rotates a predetermined angle (for example, 210 degrees), and then stops. It has become.

Thus, the paper P conveyed by the aligning roller 11 is sent to the image transfer section 12. The paper P sent to the image transfer section 12 comes into close contact with the surface of the photoreceptor drum 2 at the transfer charger 13, and at this time, the paper P is charged by the charger 13, causing the paper P to be charged onto the photoreceptor drum 2. toner image is transferred. After the transfer, the photosensitive drum 2 is configured such that residual toner on the surface is removed by a cleaner 14, and afterimages are erased by a static elimination lamp 15, so that the photosensitive drum 2 returns to its initial state. On the other hand, the paper P after the transfer is electrostatically peeled off from the photoreceptor drum 2 by the action of the peeling charger 16, and then guided along the conveyance path 17 and passed through a pair of heat rollers 18 as a fixing device. By passing through, the transferred image is heated and fixed. Then, paper P after fixing
The tray 2 outside the housing 1 is moved by a pair of paper ejection rollers 19.
It is configured to be discharged at 0. The photosensitive drum 2, document table 3, developing device 7, paper feed roller 10, aligning roller 11, heat roller 18, and paper discharge roller 19 are operated using a motor 21 as a driving source.

Further, a switch (hereinafter referred to as a paper feed switch) 22 as a detector for detecting the paper feeding state is provided near (in front of) the aligning roller 11, and a paper ejection roller 19
A switch (hereinafter referred to as a paper ejection switch) 23 as a detector for detecting the paper ejection state is provided near (on the front side). Each of these switches is provided primarily to detect paper jams (also referred to as jams).

The housing 1 is divided into two parts, an upper housing 1a and a lower housing 1b, with the transport path 17 as a border, as shown by the two-dot chain line, and both cylinders 1a and 1b are provided at one end. The upper casing 1a is pivoted at a fulcrum (not shown), and can be opened at a predetermined angle in the direction of arrow C in the drawing. Here, the upper housing 1a includes a photosensitive drum 2 and a document table 3.
, an exposure lamp 4, a focusing light transmitter 5, a charger 6, a developer 7, a paper feed roller 10, an upper roller of an aligning roller 11, a cleaner 14, a static elimination lamp 15, etc., are provided in the lower housing 1b. The paper feed cassette 9, the lower roller of the aligning roller 11, the charger 13.16, the transport path 17, the heat roller 18, the paper ejection roller 19, and the tray 20
, motor 21, etc. are provided respectively.

FIG. 2 shows the document table drive mechanism. That is,
The driving force of the gear 31 directly connected to the motor 21 is transmitted to the electromagnetic clutch 36 via gears 32, 33, 34, 35 for transmitting the driving force. This electromagnetic clutch 36 can be used in three cases according to the control signal: when it does not transmit the driving force to the pulley 37, when it transmits it in the forward direction, and when it transmits it in the reverse direction.
It is designed to perform two switchings. And pulley 3
The driving force transmitted to the document table 7 is transmitted to the document table 3 by a wire 38 whose both ends are fixed to the document table 3, and moves the document table 3. The pulley 39 is provided to ensure that the path of the wire 38 is approximately parallel to the document table 3 so that it does not come into contact with other parts.

3 to 6 show the document table position detection mechanism. That is, as shown in FIG. 3, -
Three magnets i~41.42 at predetermined intervals on a straight line
．． 43 is attached, and two magnets 44 and 45 are attached to both ends thereof with a phase shift. In addition, as shown in FIG. 4, the housing 1 includes the magnet 41.
Reed switches 46 and 47 are installed to detect . This reed switch 46 is connected to the magnet 41~
Similarly to the magnets, the reed switch 47 is arranged out of phase so as to detect that the reed switch 43 is placed above it, and the reed switch 47 is arranged so as to detect that the magnet 44, 45 is placed above it.

In FIGS. 4 to 6, the position of the magnet detected by the reed switch 46 is shown on p41. P42゜Pd2
and the position of the magnet detected by the reed switch 47 is p44. Let it be Pd2. FIG. 4 is a diagram when the document table 3 is located at the home position. The home position is the position where the document table 3 is stopped at the end of the copying operation, and as shown in FIG. When it is at the movement stop position (hereinafter referred to as the original platen limit position) where it can be detected by
6 is turned on for the first time, that is, the reed switch 46 is turned on by the magnet 43. Further, FIG. 5 is a diagram when the original platen 3 is located at the bank word movement stop position (hereinafter referred to as the original platen start position).

The original platen start position is detected by simultaneously turning on reed switches 46 and 47 by magnets 41 and 44. Further, the document table 3 starts moving forward from the document table start position, and the document table star I~
The first time the reed switch 46 is turned on after the reed switch 46 is out of position, that is, the magnet 42 causes the reed switch 4
6 is turned on, the aligning roller start position is detected.

As mentioned above, since the photosensitive drum 2 and document table 3 are driven in synchronization, the aligning roller 11 is rotated so that the leading edge of the image on the photosensitive drum 2 and the leading edge of the paper P are aligned. The timing to start is when photoconductor drum 2
It can be removed from the document table 3 without removing it from the original plate. The position at which the aligning roller 11 starts rotating is the aligning roller start position.

FIG. 7 schematically shows the structure of the developing device 7. As shown in FIG. That is, 51 is a developing unit main body, which houses a developing roller (not shown). A toner hopper 52 is provided upright at the upper rear end of the main body 51 to store toner as a developer. When the toner in the toner hopper 52 is consumed by development, a predetermined amount of toner is replenished into the main body 51 by a toner replenishment mechanism (not shown). The upper part of the toner hopper 52 is opened to form a toner replenishment port 53, and a lid body (JJ, referred to as a lower hopper cover) 54 is pivotally attached to the toner replenishment port 53 so as to be openable and closable. The toner supply port 53 and the hopper cover 54 are exposed on the upper surface of the housing 1 corresponding to the movement path of the document table 3, as shown in FIG.
When the toner in the toner hopper 2 runs out, the user can open the hopper cover 54 from the top outside the housing 1 to replenish the toner in the toner hopper 52. On the other hand, an arm 55 having a curved shape as shown in the figure is attached to one end of the back surface of the hopper cover 54, and a magnet 56 is attached to the tip of the arm 55. . Further, when the hopper cover 54 is closed, a reed switch 57 is provided at the end of the arm 55 at a portion facing the magnet 56, and this reed switch 57 is mounted on a printed circuit board 58. When the hopper cover 54 is opened, the magnet 56 separates from the reed switch 57, and the reed switch 57 is turned off, making it possible to detect that the hopper cover 54 has been opened. Further, a reed switch 59 is mounted on the printed circuit board 58 as a detector for detecting the presence or absence of i-toner in the toner hopper 52. Further, in the toner hopper 52 corresponding to this reed switch 59, a shaft 6 is provided while the motor 21 is rotating by a swinging mechanism to be described later.
A plate-shaped arm 61 for detecting the presence or absence of developer is provided, which swings at a fixed angle imaging width with 0 as a fulcrum, and a magnet 62 is attached to the tip of this arm 61.

As the magnet 62 approaches or moves away due to the swinging of the arm 61, the reed switch 59
is set to turn on and off.

FIG. 8 schematically shows the swinging mechanism of the arm 61. That is, 63 is a gear, and the rotational force of the motor 21 is transmitted via a driving force transmission mechanism (not shown). A disk 64 is fixed to the rotating shaft of the gear 63 with an offset from the center, and this disk 64 plays the role of a cam. Further, 65 is a rod-shaped arm, one end of which is fixed to the shaft 60, and the other end (free end) is in contact with the circumferential surface of the disc 64. This results in
When the motor 21 rotates and the gear 63 rotates, the arm 6
5 is swung by a disc 64 at a predetermined period in the direction of arrow d in the figure.

This motion is transmitted to the shaft 60, and the arm 61 equipped with the magnet 62 that turns the reed switch 59 on and off is similarly swung in the direction of arrow d at a predetermined period.

Therefore, when there is toner between the arm 61 and the side surface of the toner hopper 52, the tip of the arm 65 is connected to the disk 64.
The magnet 62 at the tip of the arm 61 does not come close to the side surface of the toner hopper 52 because it is merely in contact with the toner hopper 52 and hardly swings. That is, the read switch 59 is not turned on. On the other hand, when there is no toner between the arm 61 and the side surface of the toner hopper 52, the arm 65 swings as the disc 64 rotates, so the magnet 1-62 at the tip of the arm 61 approaches the reed switch 59. The reed switch 59 repeats on and off while the motor 21 is rotating.

FIG. 9 schematically shows the overall control circuit.

That is, 71 is a microprocessor as a main control section, which controls the entire copying machine.

The microprocessor 71 is connected to the paper feed switch 22 and the paper ejection switch 23 via an interface circuit 72.
, the reed switch 57 (hereinafter referred to as the hopper cover switch), and the reed switch 59 (hereinafter referred to as the hopper cover switch).
Each signal from a toner empty switch (hereinafter referred to as a toner empty switch) is input. Then, the microprocessor 71
It judges and processes input signals, and outputs various control signals to each control device via the interface circuit 73 according to a pre-stored program. Each control device includes the exposure lamp 4, the motor 21, an electromagnetic clutch (hereinafter referred to as a document platen clutch) 36, and a paper feed roller 1.
Paper feed roller solenoid 74 for transmitting driving force to
, a high-voltage power supply 75 that supplies power to the charging charger 6, an aligning roller solenoid 76 that transmits driving force to the aligning roller 11, a transfer charger 13, and a peeling charger 16. High voltage power supply for 77
, a blade solenoid 18 for pressing the blade of the cleaner 14 against the photoreceptor drum 2, and the like, each of which is operated by a control signal.

The microprocessor 71 is configured as shown in FIG. 10, for example. That is, the main processor 11 is a one-chip microprocessor having an architecture as shown in FIG. In the figure, 81 is an arithmetic unit (ALU) having an arithmetic determination function, 82 is a read-only memory (ROM) for storing processing programs, and 83
is random access memory (RAM) for data storage.
), 84 is an input/output port and input/output control unit (IOC>) for transmitting and receiving signals with external devices, 85 is a program counter (PC), 86 is a flag (FLAG), 8
7 is an accumulator (ACC), 88 is a stack register (STACK), and 89 is an interrupt control unit (INC).

Here, to briefly explain the operation of the microprocessor 71, the address of the processing program stored in the ROM 82 is specified by the PC 85, and the ROM 82
The instruction read from is decoded and executed. FLAG 86 stores the carry/borrow status of the result of the calculation. The calculation result is A
RAM via CC87 or ACC87 by instruction
83.

STA CK 8B specifies the depth of the subroutine, stores the return address of the main routine, and is also used to save the contents of the PC 85 at the time of an interrupt. I
When an internal interrupt or an interrupt from an external terminal (1NT) is requested, the NTC 89 terminates the instruction being executed at that point and enters interrupt processing. When entering interrupt processing, PC85
The contents of are saved in the STA CK 88, the program jumps to a specific address for interrupt processing, executes the interrupt processing program, and then returns to the main program.

FIG. 11 is a general flowchart of a general copying machine. The initial check is a routine for checking whether or not the copying state is possible. For example, it is checked whether the heat roller 18 is at a temperature that allows heat fixing. After this initial check is completed, if copying is possible, the process moves to a copying standby routine. Here, the routine sets the number of copies and continues until the copying switch is turned on and the copying operation is started. When the copying operation is started, the above-described copying process including charging, exposure, transfer, neutralization, fixing, etc. is sequentially executed to make a copy, and the copying operation is repeated until the set number of copies is completed. Also, during copying operations, checks are made for abnormalities such as paper jams.

Furthermore, control during copying operation will be explained using flowchart 1 shown in FIG. When the copying operation is started, the process advances to step S1, where the blade solenoid 78, motor 21, static elimination lamp 15, high voltage N source 77 (charger 13.1
6) are turned on, and the process proceeds to step S2. In step S2, it is determined whether or not the document table 3 is at its start position based on the signal from the document table switch 46 and 47. If it is not at the start position, the process advances to step S3 and a control signal is sent to the document table clutch 3G. Then, the document table 3 is moved by the bank word, and the process proceeds to step S4. In step S2 above, if the document table 3 is at the start position, step S3
Jump to step S4. In step S4, the document table 3 is moved until it reaches the document table start position,
When the original platen switches 46 and 47 are both turned on and the original platen start position is detected, the process advances to step S5. Step S
In step S5, a control signal is sent to the paper feed roller solenoid 74 to rotate the paper feed roller 10, and the exposure lamp 4 is turned on, and the process proceeds to step S6. In step S6, a control signal is sent to the document table clutch 36 to move the document table 3 forward, and the process proceeds to step $7. In step S7, the high voltage power supply 75 (charger 6) is turned on, and in step S8
Proceed to. In step S8, the above-mentioned aligning roller start position is determined, and the process proceeds to step S9. In step S9, a control signal is sent to the aligning roller solenoid 76 to rotate the aligning roller 11, and the process proceeds to step S10. In step 810, it is determined whether or not the document table 3 has moved to the document table limit position, which is detected when only the document table switch 41 is turned on, and if it has moved, the process proceeds to step 811. In step S11, the high voltage power supply 75 is turned off, and the process proceeds to step 812. In step S12, a control signal is sent to the document table clutch 3G to move the document table 3 by the bank word, and the process proceeds to step S13.

In step 813, the exposure lamp 4 is turned off, and the process proceeds to step S14. In step S14, it is determined whether or not the document table 3 has moved to the home position detected by the document table switch 46, and if it has moved, the process proceeds to step 815.

In step 815, it is determined whether or not copying of the set number of sheets has been completed. If not, the process returns to step S4 and the above-described copying operation is repeated; if it has been completed, step 81
Proceed to step 6. In Stella 1816, a control signal is sent to document table clutch 36 to stop document table 3, and step 817 is performed.
Proceed to. In step 817, it is determined based on the signal from the paper ejecting switch 23 whether or not the copied paper P has been completely ejected, and when the ejecting has been completed, the process advances to step S18.

In step 818, the high-voltage electricity [77, the static elimination lamp 15,
The motor 21 and the blade solenoid 78 are turned off to complete the copying operation and enter the copying standby state shown in FIG. 11.

In addition, in controlling the copying machine of the present invention, the microprocessor 7
1 internal interrupt is used. This interrupt processing is set to be repeated at regular intervals. To explain this using FIG. 13, when the power is turned on, normally R
The main program among the programs stored in O-182 is being executed. However, for example, by setting INTC89 so that an internal interrupt is generated every 12m5ec from the start of the copying operation, the main program is temporarily interrupted and the interrupt program is executed when 12m5ec has elapsed from the start of the copying operation. , and the main program is executed again after the interrupt program ends. Further, the flow of the program is such that the interrupt program is executed when 12 m5 ec has elapsed, that is, 24 m5 ec has elapsed from the start of the copying operation.

Incidentally, in the developing device 7 having the above-described structure, even if the hopper cover 54 is opened to replenish toner when the toner is empty, the arm 61 approaches the side surface of the toner hopper 52 when the motor 21 stops. When the toner empty switch 59 is on, toner does not enter between the arm 61 and the side of the toner hopper 52. Even if the toner empty switch 59 is turned on, it is ignored until the toner empty switch 59 enters between the toner hopper 52 and the side surface of the toner hopper 52.

Further, when the hopper cover switch 57 detects that the hopper cover 54 has been opened and then closed again, it is determined that toner has been replenished, and the toner replenishment state is canceled. In this case, the reason why the state returns to 1 to toner replenishment state when toner is not replenished is because toner has entered between the arm 61 and the side of the toner hopper 52 after the motor 21 started rotating for the reason mentioned above. This is when the toner empty switch 59 is turned on after a period of time has elapsed.

The above control is performed by a program shown in a flowchart shown in FIG. This program is executed by interrupt processing that is repeated at regular intervals, and will be described in detail below. First, in step S1, it is determined whether the motor 21 is rotating. When the motor 21 is not rotating, the process proceeds to step S2, where a certain address in the RAM 83 is called a timer and its value is cleared to "0". On the other hand, if the motor 21 is rotating, the process advances to step S3. Here, since the motor 21 is not rotating when the power is turned on, "1" is added to the cleared timer. Since the interrupt is generated every fixed time t, when the timer value exceeds T/, it means that time T has elapsed since the motor 21 was turned on. This time T is longer than the time required for toner to enter between the arm 61 and the side surface of the toner hopper 52. therefore,
Determine whether or not time T has elapsed in step S4,
If the time has not elapsed, nothing is done, and if the time has elapsed, the process proceeds to step S5, where it is determined whether the toner empty switch 59 is turned on. As mentioned above, in the toner empty state, the toner empty switch 59 repeats on and off, so once the toner empty switch 59 is turned on and the toner empty state is displayed in step S6, the display is not performed regardless of whether the toner empty switch 59 is on or off. continue. This toner empty state is canceled by the program in steps 87 to S12. here,
The flag (FLAG) refers to the 1 bit in the RAM 83 that allows you to determine which state it has passed through on the flowchart by setting 1 bit at a certain address in the RAM 83 to ``1'' or ``0''. That's it. First, in step S7, it is determined whether or not the hopper cover switch 57 is turned on. If it is not turned on, it is determined that the hopper cover '54 is opened, and the process proceeds to step S8, where the flag is set to "1". do. This memorizes the open state of the hopper cover 54.

In step S7 above, the hopper cover switch 57
If the hopper cover 54 is on, the process advances to step S9, and it is determined using a flag whether or not the previous state was the open state of the hopper cover 54. In other words, when the flag is "1", it means that it has been released once. In this case, the process advances to step S10, and the toner empty state is canceled. This is because when the hot spring cover 54 is opened and then closed again, it can be determined that toner has been replenished while the hot spring cover 54 is opened. Next, the flag is set to 10'' in step S11. This is to remember that the hopper cover 54 is in the open state. When the toner empty state is released in this way, the process proceeds to step 812, in order to perform the next detection after a time T has elapsed since the rotation of the motor 21.
Clear the timer to "0".

By carrying out the control described above, a mechanism is created which moves the arm 61 so that the magnet 62 separates from the toner empty switch 59 and enters the toner present state each time when toner is replenished into the toner hopper 52. No longer needed.

In the above embodiment, a case has been described in which the presence or absence of developer is detected in a developing device of an electronic copying machine, but the present invention is not limited to this. It can also be applied to detecting the presence or absence of developer.

[Effects of the Invention] As detailed above, according to the present invention, when replenishing the developer, it is possible to remove the developer without requiring a mechanism to move the arm for detecting the presence or absence of the developer so that the developer is present. A presence detection device can be provided.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view schematically showing an electronic copying machine, FIG. 2 is a side view showing the document table drive mechanism, and FIGS. Figure 7 is a perspective view schematically showing the structure of the developing unit, Figure 8 is a side view showing the swinging mechanism of the arm for detecting the presence or absence of developer. Fig. 9 is a block diagram schematically showing the overall control circuit, Fig. 10 is a configuration diagram of the microprocessor, Fig. 11 is a general flowchart of a general copying machine, and Fig. 12 is during copying operation. FIG. 13 is a flowchart of a program including microprocessor interrupt processing, and FIG. 14 is a flowchart showing control of toner presence/absence detection. 2... Photosensitive drum, 3... Document table, 4... Exposure lamp, 7... Developing device, 8... Paper feeding mechanism, P...
paper, 51... developer body, 52... toner hopper, 53... toner supply port, 54... hopper cover,
57... Hopper cover switch, 59... Toner empty switch (detector), 61... Arm, 62
...Magnet, 64...Disc, 65...Arm, 71...Microprocessor (main control section). Figure 7 Figure 8 Figure 4 Figure 11 Figure 12

Claims (1)

[Claims] A developer comprising: a swinging arm provided in a storage section that stores developer; and a detector that detects the presence or absence of the developer based on the position of the arm, which changes depending on the amount of developer in the storage section. In the presence/absence detection device, when replenishing the developer into the storage section, the point in time when it is assumed that the swinging of the arm is obstructed by the developer entering between the arm and the side surface of the storage section and a state where the developer is present is assumed. A developer presence/absence detecting device characterized in that a control means is provided for ignoring the developer absence detection state of the detector.