JPH02275477A - Image forming device - Google Patents

Abstract

PURPOSE:To detect a latent image data speedily with a low noise by providing moving means which move a detecting means in the direction of the rotary shaft of an electrostatic latent image carrier when the electrostatic latent image is at a stop. CONSTITUTION:When the electrostatic latent image carrier (photosensitive drum) 1 is at a stop, a sensor begins to detect the surface potential of the photosensitive drum 1 at some timing. The moving means 20 - 25 of the sensor 3 moves a wire 25 as a driving-side pulley 23 rotates by the rotation of an STM20 through a worm gear 21 and a driving gear 22. The sensor 3 which is fixed to the wire 25 moves in the rotation-axis direction A of the photosensitive drum 1 to read potentials at respective parts on the surface of the photosensitive drum 1. Further, when the sensor 3 reaches a driven-side pulley 24, the STM20 reverses to move the sensor 3 toward the driving-side pulley 23. Consequently, the latent image state can be detected without operating the photosensitive drum 1 and the low-noise, speedy detection of the latent image state is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

[Conventional technology]

In conventional image forming apparatuses, in order to stabilize image quality, the potential of the photoreceptor is measured while rotating the photoreceptor, which is an electrostatic latent image carrier, using a detection means such as a surface electrometer or an optical sensor.
There are devices that detect latent image conditions such as toner adhesion amount and correct image forming conditions.

[Problem to be solved by the invention]

In the above conventional technology, the photoreceptor is rotated to detect the state of the latent image on the circumference of the drum, so the noise level is almost the same as that during normal image forming operation, even though no image forming process is performed. Furthermore, the detection time also requires a rotation time set for the photoreceptor, which poses a problem in workability.

An object of the present invention is to provide an image forming apparatus that can quickly detect a latent image state with low noise.

[Means to solve the problem]

The above object is to provide a rotatable electrostatic latent image carrier on the surface of which an electrostatic latent image corresponding to a document image is formed, a detection means for detecting the state of the latent image on the electrostatic latent image carrier, and a developer. In the image forming apparatus, the image forming apparatus includes a developing means for developing the electrostatic latent image onto a transfer member using a moving means for moving the detecting means in the direction of the rotation axis of the electrostatic latent image carrier when the electrostatic latent image carrier is stopped. This is achieved by creating a configuration with

[Effect]

The state of the latent image on the electrostatic latent image carrier is detected by moving the detection means in the direction of the rotation axis of the electrostatic latent image carrier using the moving means without rotating the electrostatic latent image carrier.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing an outline of a copying machine which is an embodiment of an image forming apparatus according to the present invention, in which 1 is a rotatable photosensitive drum which is an electrostatic latent image carrier, and la is a photosensitive drum. 2 is a rotating shaft; 2 is a charger; 3 is a sensor that is a detection means for detecting the surface potential of the electrostatic latent image carrier 1; 4 is an eraser; 5 is a developing sleeve; 6 is a pre-transfer static elimination lamp; 7 is a transfer charger; 8 is a fur brush, 9 is a cleaning blade, 10 is a static elimination lamp, 11 is a dustproof glass, ■2
13, 14, and 15 are reflecting mirrors, 16 is a lens, 17 is an irradiation lamp, 18 is a white pattern, 19 is a contact glass, and B is a light beam that exposes the photosensitive drum 1.

In the figure, an original placed on a contact glass 19 is placed between an irradiation lamp 17 and a reflecting mirror 12°13.14.1.
5 and a lens 16, the surface of the photoreceptor drum 1 is exposed to the light beam B, an electrostatic latent image corresponding to the original image is formed, and the charged area around the photoreceptor drum 1 is Charger 2° Developing sleeve 5. The operation of developing the transfer paper using a developer (not shown) by a developing means such as the transfer charger 7, the static elimination operation using the pre-transfer static elimination lamp 6 and the static elimination lamp 10, and the photosensitive drum I using the fur brush 8 and cleaning blade 9. A cleaning operation is performed in a known manner.

FIG. 1 is a front view showing the configuration of a moving means for a sensor 3 which is a detection means, and 3 is disposed between the charger 2 and the eraser 4 as shown in FIG. , 20 is a stepping motor (STM), 21 is 3
A worm gear provided on the rotating shaft of 7M20, 22 a drive gear meshing with the worm gear 21, 23 a drive gear 2
2 is a drive pulley provided coaxially with 2, 24 is a driven pulley, and 25 is a wire that is installed between the two boobies IJ 23 and 24 and has the sensor 3 fixed to a part thereof.

FIG. 3 is a plan view of the moving means for the sensor 3,
Reference numeral 6 is a key-shaped actuator that moves in contact with a part of the sensor 3, 27 is a spring that presses the actuator 26, and 28 detects the presence of one end of the actuator 2G to set the home position of the sensor 3. This is a home position sensor that detects return.

In FIGS. 1 and 3, when the photosensitive drum 1 is stopped (non-rotating), the sensor 3
The surface potential detection operation on the photoreceptor drum 1 starts. The position of the sensor 3 shown by the solid line in FIG.
3 rotates and moves the wire 25. The sensor 3 fixed to the wire 25 moves in the direction A of the rotation axis of the photoreceptor drum 1, and reads the potential of each part on the surface of the photoreceptor drum 1, as will be described later.

37M20 when sensor 3 reaches driven side boo IJ24
rotates in the opposite direction, and moves the sensor 3 in the direction of the drive side boob IJ23. At this time, the sensor 3 pushes back the actuator 26 that has been pushed out by the spring 27, and when the sensor 3 returns to the home position, the home position sensor 28 detects the presence of one end of the actuator 26. One cycle of operation is completed. This cycle can be made shorter than the time required for one normal rotation of the photoreceptor drum 1, and the operation is less noisy than the rotation of the photoreceptor drum 1.

Figure 4 (al is an explanatory diagram showing the position of sensor 3, Figure 4 (
b) is an explanatory diagram showing the potential of each part in FIG. 4(a), and the sensor 3 between the charger 2 and the eraser 4 The potential of the valley portion E between the peak potential portion C of the charger 2 portion and the peak potential portion of the eraser 4 portion is measured.

FIG. 5 is a plan view showing the aperture limiting mechanism, in which 11 is a dustproof glass extending in the direction A of the rotation axis of the photoreceptor drum 1;
0.31 is the opening stepping motor (STM), 3
2.33 is an aperture worm gear provided on the rotating shaft of the aperture STM 30°31; 34.35 is an arm that is an aperture limiting means that rotates to limit the amount of light beam B incident on the dustproof glass 11 portion; Reference numerals 36 and 37 denote opening driving gears fixed to the ends of the arms 34 and 35 and meshing with the opening worm gears 32 and 33, and 38 and 39 the ends F of the opening portions of the arms 34 and 35.

This is an opening home position sensor that detects G.

In the same figure, arms 34 and 35 are used to limit the amount of light beam B that exposes the charged surface of the photoreceptor drum 1 based on the detection result of the surface potential of the photoreceptor drum 1 by the sensor 3. Dustproof glass 1 in the optical path of B
A slit for limiting the amount of light is formed in one portion. Further, the arms 34 and 35 are arranged on the front side (referred to as the F side) and the rear side (referred to as the R side) of the photosensitive drum 1 in FIG.

The arms 34 and 35 receive an actuation signal from an opening ST.
M30.31 rotates, and the opening STMs 30 and 31 connect the opening worm gear 32.33 and the opening drive gear 3.
6. Through 37, rotate by a certain angle and remove the dustproof glass 1.
A part of 1 is shielded from light. And when inactive, arm 3
4.35 does not shield the dustproof glass 1 from light and is waiting at a position detected by the opening home position sensor 38.39.

Figure 6 (a), Figure 7 (a), Figure 8 (a), Figure 9 (
al is an explanatory diagram showing the light amount before correction, Fig. 6(b), Fig. 7
Figure (b).

Fig. 8(b), Fig. 9(b) are explanatory diagrams showing changes in light amount after correction, Fig. 6(C), Fig. 7(C), Fig. 8(C),
FIG. 9(C) is a configuration diagram showing the operation of the arms 34, 35 during light amount correction.

FIG. 6(a) shows a case where the potential on the photosensitive drum 10F side (front side) is high, and at this time, the arm 34 on the R side (back side) of the photosensitive drum 1 as shown in FIG. is rotated to increase the amount of light on the R side as shown in FIG. 6 (bl) to equalize the potential on the photosensitive drum 1.

FIG. 7(a) shows when the potential on the R side of the photosensitive drum 1 is high, and at this time, the arm 35 on the F side of the photosensitive drum 1 is rotated as shown in FIG. 7(e). The amount of light on the F side is increased as shown in FIG. 7(b).

Figure 8 (al) shows when the potential at the center of the photoreceptor drum 1 is high; in this case, as shown in Figure 8 (C), both arms 34 and 35 are rotated to the R side and F side. The amount of light is increased as shown in FIG. 8 (bl).

FIG. 9(a) shows when the potential on the R side and F side of the photosensitive drum 1 is high. At this time, both arms 34 and 35 are rotated greatly as shown in FIG. 9th light amount
Raise as shown in figure (bl).

By correcting the amount of light using the arms 34 and 35 as described above, it is possible to equalize the surface potential of the photoreceptor drum l and prevent the occurrence of background smear during image formation.

FIG. 10 is a block diagram of the control system, where 40 is a main control unit (CPU), 41 is a RAM which is a non-volatile memory built into the CPU 40, 42 is a charging power pack, 43 is a fixing thermistor, and 44 is a Optical system control unit, 45 is an operation/AC control unit, 46 is an AC drive circuit, 47 is various position sensors, 48 is a scanner drive circuit, 49 is a variable magnification drive circuit, 50 is a key manual unit, 51 is a display means, 52 53 is a fixing heater, and 53 is a drive motor.

In the figure, the CPU 40 includes an eraser 4, a charging power back 42 of the charging charger 2, and each STM 20.30.3.
1, and also receives detection signals from the fixing thermistor 43, sensor 3, and home position sensors 28, 38, and 39. Furthermore, the CPU 40 exchanges signals with an optical control section 44 and an operation/AC control section 45. In the optical control section 44, a scanner drive circuit 48 and a variable magnification drive circuit 49 brake the optical system, and control the operation/AC control section 44.
The control section 45 receives the signal from the key power section 50, causes the display means 51 to display, and also controls the AC drive circuit 46 and the CP
Send signal to U40. The AC drive circuit 46 turns on and off the fixing heater 52, various drive motors 53, and irradiation lamp 17.

FIG. 11 is a flowchart showing the overall operation of the above embodiment. When the operation starts in the figure, the system enters an initial mode (step 1l-1), which will be described later, and turns on the charger 2 for a certain period of time while the photosensitive drum l is stopped to charge the photosensitive drum 1 (step 1l-1). 2
), the sensor 3 is moved in the direction A of the rotation axis of the photoreceptor drum l, and the potential (Vo) is measured (step 1l-3). At the potential of the photoreceptor drum 1, only the residual potential of the photoreceptor drum 1 is left by turning on the eraser 4 (step 1).
l-4), the residual potential vR is measured by moving the sensor 3 in the rotation axis direction A (step l-5). Step 1l-6) to calculate the potential V0 and residual potential (8);
The obtained data is fed to the CPU 40, the state of the photosensitive drum 1 is prepared for the copy state, and various control flags are cleared (step 1l-7).
.

FIG. 12 is a flowchart showing the operation in the initial mode, in which a temporary copying operation is performed to stabilize the state of the photosensitive drum 1. When the mode starts, if it is necessary depending on the condition of the photosensitive drum 1 (Y in step 12-1), a drum break-in operation (forming operation) is performed (step 12-2), and the forming operation is performed for 20 copies. and (step 12-3),
The forming operation is turned off (step 12-4), and a copy inhibited state is entered (step 125). If forming is not necessary (N in step 12-1), the process directly shifts to the normal copy mode (step 12-6).

FIG. 13 is a flowchart showing the operation during charging. In this embodiment, since the photosensitive drum 1 is charged without rotating, the relationship between the charging potential of the photosensitive drum 1 and time is as shown in FIG. 14. The predetermined charging potential (Vo)
The on-time of the charging power back 42 required to become 0
．． It will be 5 seconds.

In Figure 13, first the 0.5 second timer is cleared (
Step 13-1), the timer start flag becomes 0 (Step 13-2). If the timer start flag is not on (N in step 13-3), set the start flag (step 13-4), turn on the charging power back 42 (step 13-5), and start the 0.5 second timer. When the time is up (step 13-7), the charging power back 42 is turned off (step 13-8), and the 0.5 second timer is reset and cleared (step 13-9).

FIG. 15 is a flowchart showing the operation of the eraser 4, and in this embodiment, the charging voltage V of the photosensitive drum 1 is determined as shown in FIG. After 0.4 seconds, the eraser 4 causes the residual potential to reach the level ①8.

In FIG. 15, first, the eraser 4 is reset (step 15-1), the data of all lighting modes is set to serially light up (step 15-2), the 4ms timer is cleared (step 15-3), and the eraser 4 is reset. On (all lit)
(Step 15-4). At this time, the 4ms timer starts (step 15-5), and when it counts up (step 15-6), the eraser 4 is turned off (step 15-7), and the 4ms timer and eraser 4 are reset.
Cleared (step 15-8).

FIG. 17 is a flowchart for sampling the potentials Vo and VR, in which the sensor 3 is moved in the rotation axis direction A of the photosensitive drum 1 in synchronization with a step angle of 37M20, and the potential V is sampled. ,■8 is measured, but first 37M20
When the step angle of rises (step 17-1) and the sensor 3 moves, the measurement result of the sensor 3 is input to the register of the CPU 40 via the AN board (step 17-1).
2). This input is sent from the register to the memory 41 within the CPU 40 (step 17-3), and the memory address of the memory 41 is set to +1 (step 17-4).

As shown in FIG. 18, the memory 41 internally has 256 memories (1) to (256), and the memories (1) to (256) are
As shown in the figure, it is divided into 16 parts and serves as an average value memory for phases 1 to [phase].

FIG. 20 is a flowchart showing the operation of the memory 41, in which first the counter of the average value memory is cleared (Step 2O-1), the memory address and the average value memory address are set (Step 2O-2), and the values are added. Clear the number of times counter and memory addition register (Step 20-3)a, and add +1 to the memory data and addition register of the memory address respectively.Step 20-4
), if the number of additions is less than 16 (N in step 20-5), further additions are made to the memory address and the addition register, and when the number of additions reaches 16 (Y in step 20-5).
), divide the memory addition register into 16 equal parts (step 2O
-6). The measured data is stored in the average value memory address (Step 2O-7), and the average value memory counter increases in sequence.
1 is added (step 2O-8), and when the count number of the average value memory counter becomes larger than 16 (step 2O-8),
0-9 Y), clear the various counters and registers, step 2O-10), and if the count number is less than 16, enter the step (20-3) (step 20-10).
9 N).

In the average value memory ■~[phase], the average value (data A) of Φ~[phase] is the potential average (potential V., VR) of the entire photoreceptor drum 1, and the average value (data F) is the potential average on the front side of the photoreceptor 1, the average value of ■~[phase] (data C) is the potential average at the center of the photoreceptor drum 1, and the average value of @~[phase] (data R) is processed to be the average potential on the back side of the photoreceptor 1.

Figure 21 shows the potential ■. +VII is a flowchart showing the operation of calculating Vo-VR, step 2l-
1), the developing bias is corrected based on the calculation result (step 2l-2), and the charging potential is corrected (
Step 2l-3).

FIG. 22 is an explanatory diagram showing the relationship between the potential of the photosensitive drum 1 and the number of copies; as shown in the figure, the charged potential v0 and residual potential 8 of the photosensitive drum 1 increase over time, ■.

-V and I ranges become narrower, which causes deterioration in image quality such as background smearing, and therefore requires the above-mentioned correction.

Figures 23 (Part 1) and (Part 2) are flowcharts for determining the correction value, in which the absolute value ΔA of the difference between the set value and the measured data is calculated (step 23-1), and ΔA is less than the set value. If it is larger (Y in step 23-2), a lamp voltage correction routine is entered (step 23-3). Data F
is larger than data C (Y in step 23-4), calculate the difference as ΔFC (step 23-5), data F
is smaller than data C (N in step 23-4), the difference is output as ΔCF (step 23-6).

Compare data R and data C in the same way.Step 2
3-7), calculating the difference ΔCR (step 23-8), and calculating the difference ΔRC (step 23-9). Further data R
and data F (Step 23-10), the difference ΔF
R is calculated (step 23-11), and the difference ΔRF is calculated (step 23-12).

If the ΔCF is larger than the set value (step 23-13
), STM-F on the front side of STM30 and 31 for opening
31 (step 23-14), and similarly if ΔFC≧set value (step 23-1)
5) Set a minus flag on the STM-F31 (step 23-16), and if ΔRC≧setting value (step 23-17), set a plus flag on the STM-R30 on the back side (step 23-18), If ΔCR≧setting value (step 23-19>), a minus flag is set in the STM-R 30 (step 23-20).

The above steps (23-14), (23-16).

(23-18), (23-20) are STM3 for opening
A step of setting a flag for correction of 0.31,
If you use this as a data table, you can also adjust the amount of correction.

The opening home position 38°39 shown in Fig. 5 is
The front side is HP, F39, and the back side is HP.

If R2O, HP, F39, HP, and R38 are not on (N in step 23-21), STM-F31 and STM-R30 are driven to return arm 34.35 to the home position (HP) (step 23 -22).

Here, the reference position of arms 34 and 35 is when they return to HP, but in FIG.
The position where Hz is parallel is the position where no light amount correction is performed by the arms 34 and 35. Therefore, for control, the arm 34 is always controlled once by STM-F31 and STM-R30.
．． 35 to HP, then set the STM-F plus (minus) flag or STM-R plus (minus) for the position where the surfaces H3 and R2 without correction are parallel.
The width of the opening (slit) created by the arms 34 and 35 is corrected using the flag.

When the STM-F plus flag is raised (step 23-23
), increment the STM-F data (steps 23-24), and when the STM-F minus flag is set (
Steps 23-25) and decrements the STM/F data (Steps 23-26). Also, when the STM-R plus flag is set (steps 23-27), the STM-
Increment R data (Steps 23-28)
, when the STM・R minus flag is raised (step 23-
29) Decrement the STM-R data (steps 23-30). and the plane HI of arm 34.35,
sTM-F2O and STM-R3 so that the Hz is parallel
1 (step 23-31). However, in order to correct the opening width of the arms 34 and 35, the irradiation lamp 17
It is necessary to correct the absolute amount of illuminance (up or down) by changing the lamp voltage.

Irradiation lamp 1 based on the data table according to the above ΔA
Step 23-3: Increase or decrease the lamp voltage of 7.
2) If the positive flags of STM-F and STM-R are set (Y in step 23-33), increase the lamp voltage (step 23-34), and
M-R(7)? If the negative flag is set (Y in step 23-35), the lamp voltage is lowered (step 23-36).

FIG. 24 is a flowchart showing the nuclear data reset operation, and when the above correction is completed, the potentials V, , V, I
each memory data is cleared (step 24-1),
The main drive motor is turned on (step 24-.2),
A bias is applied to the developing sleeve 5 (step 24-3
), the cleaning means such as the cleaning blade 9 is activated (Step 24-4), the static elimination lamp 10 is turned on (Step 24-5), and the photosensitive drum 1 is activated.
When the motor rotates five times (Y in step 24-6), the start flag becomes O (step 24-7).

When the start flag becomes 0, the main drive motor
Bias, cleaning means9. The static eliminating means 10 and the like are turned off (step 24-8), the copy prohibition flag becomes 0 (step 24-9), and the process shifts to normal copy mode (step 24-10).

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide an image forming apparatus that can detect a latent image state without operating an electrostatic latent image carrier, and can quickly detect a latent image state with low noise.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the moving means in the detection means of the image forming apparatus according to the present invention, FIG. 2 is a configuration diagram of a copying machine, and FIG. 3 is a plan view of the moving means stage of FIG. 1. Figure 4 (
a) is an explanatory diagram showing the position of the sensor, FIG. 4(b) is an explanatory diagram showing the potential of each part, FIG. 5 is a plan view showing the opening restriction mechanism, FIGS. 6(a) and 7( a), Fig. 8(a), Fig. 9 (al is an explanatory diagram showing the light amount before correction, Fig. 6(b)
, Fig. 7(b), Fig. 8(b), Fig. 9 (bl is an explanatory diagram showing the change in light amount after correction, Fig. 6(C). Fig. 7(C), Fig. 8 [C] ), Fig. 9 (C1 is a configuration diagram showing the operation of the arm, Fig. 10 is a block diagram of the control system, Fig. 11 is a flowchart showing the overall operation, Fig. 12 is a flowchart showing the operation in the initial mode, Fig. 13 Figure 14 is a flow chart of charging operation, Figure 14 is an explanatory diagram showing the relationship between charging potential and time, Figure 15 is a flow chart showing eraser operation, Figure 16 is an explanatory diagram explaining residual potential, and Figure 17 is an explanatory diagram showing the relationship between charging potential and time. Flowchart of potential sampling, FIG. 18 is an explanatory diagram showing internal memory, FIG. 19 is an explanatory diagram showing division of memory, FIG. 20 is a flowchart showing memory operation, FIG. 21 is a flowchart showing potential calculation operation, Fig. 22 is an explanatory diagram showing the relationship between the potential and the number of copies, Fig. 23 is a flowchart showing the correction value determining operation, and Fig. 24 is a flowchart showing the reset operation. 1... Electrostatic latent image carrier; 2,5.7...Developing means, 3
...Detection means, 20, 21, 22, 23.24.25
...Moving means, A...Rotation axis direction. Figure 5 Funeral diagram (a) Figure (b) Figure (c) Figure (a) Figure rb funeral diagram [a] Figure (b) Funeral diagram (a) C) ++ Figure 14 Funeral diagram Figure 17 Figure 18 0 times mail 256 Funeral diagram Figure 22

Claims (1)

[Claims] A rotatable electrostatic latent image carrier has an electrostatic latent image formed thereon corresponding to the original image, a detecting means detects the state of the latent image on the electrostatic latent image carrier, and a developer is used to detect the electrostatic latent image. In an image forming apparatus having a developing means for developing an electrostatic latent image onto a transfer member, a moving means is provided for moving the detecting means in the direction of the rotation axis of the electrostatic latent image carrier when the electrostatic latent image carrier is stopped. An image forming apparatus characterized by: