JPH01250978A - Separation controller for transfer material - Google Patents

Abstract

PURPOSE:To improve an image by calculating the ratio of the number of times of detection of a separated state detecting means and the number of sheets of copy from a copy sheet number detecting means, comparing it with a separated state setting index value, controlling a separated state varying means in accordance with its result and setting a prescribed separated state. CONSTITUTION:A central processing circuit 57 calculates the ratio of the number of sheets of copy and the number of times detected by a photosensor 27, based on the result of detection from the sensor 27, compares this calculated value with an index value for showing a separated state, and executes a control for selecting and setting one of several separated states, based on the result of its comparison. In such a way, an optimum separated state can be set against the kind of paper and the variation of the environment, a stable separating property can always be maintained, and a satisfactory image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention is advantageously used in image forming apparatuses that utilize an electrostatic transfer process, such as electrostatic copying machines and printers, and in particular, when toner images are transferred. The present invention relates to a transfer material separation control device that detects the separation state when the transfer material is separated from the surface of an image carrier and controls the setting of the separation state.

Conventional ■KiW A transferable toner image is formed using charged powder toner on a photosensitive layer on the surface of an image carrier that runs in an endless manner, and a transfer material, mainly paper, is brought into contact with the toner image. After the toner image is electrostatically transferred to the transfer material by applying a charge with opposite characteristics to that of the toner, the transfer material is separated from the image carrier and the toner image is fixed and fixed to the transfer material. residual toner that remains on the
2. Description of the Related Art Image forming apparatuses configured to repeat the process of removing residual charges are conventionally well known.

In such an image forming apparatus, when a toner image is transferred to a transfer material, the transfer material is electrostatically attracted to the image carrier after transfer due to the influence of the electric charge applied to the toner image, so that the separation of the two is made to be like a container. Therefore, in order to perform charging with opposite characteristics to the charging during transfer after transfer, an AC corona discharge is applied to the transfer material to neutralize the charge during transfer. A structure in which this is separated from the image carrier is widely used.

,! ! However, the elasticity and stiffness of paper, which is most commonly used as a transfer material, varies significantly depending on its type, and even with the same type of paper, depending on the environment, especially humidity. It is not always easy for the electrostatic separation method as described above to always provide a stable separation effect by itself.

In addition, separation performance deteriorates when separation is performed using the above-mentioned separation charger, as the number of sheets passing through increases, and scattered toner, paper dust generated from the transfer material, and other foreign matter get onto the discharge wire of the charger. As the discharge current decreases or becomes unstable, the separation function is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer material separation control device that can set an optimal separation state in response to changes in paper type and environment and maintain stable separation performance at all times. .

The present invention includes a means for detecting the number of copies and a means for detecting the separation state when the transfer material to which the toner image is transferred is separated from the surface of the image carrier. a detection means, a separation state changing means capable of changing the state to a different separation state, and an index indicating the separation state setting by calculating a ratio between the number of detections by the separation state detection means and the number of copies from the copy number detection means. The present invention is characterized by comprising a separation control means for comparing the separation state with a predetermined separation state and controlling the separation state changing means according to the comparison result to set a predetermined separation state.

According to the above configuration, the ratio between the number of detections by the separation state detection means and the number of copies from the copy number detection means is calculated, and the ratio is compared with the separation state setting index value, and the separation is performed according to the comparison result. Control the state change means. As a result, the optimum separation state is selected and set from among a plurality of different separation states depending on the deterioration of the separation property.

Fig. 1 is a simplified diagram showing the internal structure of a copying machine equipped with a transfer material separation control device according to the present invention. A plate 80 is provided, and a light 6i2 is arranged below this document placement plate 80. The light from this light source 2 is irradiated onto the document via the document placement plate 80, and this reflected light is is slit-exposed onto the surface of the photosensitive drum 6 through the reflecting mirror 3, condensing lens 4, and reflecting mirror 5.

Around the photosensitive drum 6, a charging charger 7, a developing device 8, a transfer charger 9, a separation charger 10, a cleaning device W11, and an erase lamp 12 are arranged in this order. Prior to exposure, the surface of the photosensitive drum 6 is charged by a charging charger 7, and the photosensitive drum 6 is rotated in the direction of the arrow to expose the exposure area to form an electrostatic latent image corresponding to the original. Further, when the photosensitive drum 6 is driven to rotate and reaches a position where the electrostatic latent image faces the developing device 8, toner is attached to the surface of the photosensitive drum 6 by the electrostatic force of the developing device 8. As a result, a toner image corresponding to the electrostatic latent image is formed on the surface of the photosensitive drum 6.

On the other hand, the transfer material 16 in the paper feed cassettes 1 to 15 is fed by the paper feed roller 17, passes between the conveyance rollers 18, and waits with its leading edge against the position of the registration roller 19. This transfer material 16 is supplied between the transfer charger 9 and the photosensitive drum 6 in synchronization with the rotation of the photosensitive drum 6,
It comes into contact with the toner image on the photosensitive drum 6. At this position, the transfer charger 9 applies a charge of opposite polarity to the toner to the back surface of the transfer material 16, and the toner image on the photosensitive drum 6 is transferred to the transfer material 16.

At this time, the transfer material 16 adheres to the surface of the photosensitive drum 6 due to magnetic adsorption force, so the separation charger 10 applies a charge of opposite polarity to that of the transfer charger 9 to eliminate the previous charge, thereby increasing the stiffness of the transfer material 16 itself. Strength and even separation claws 20
It is separated from the photosensitive drum 6 by. The separated transfer material 16 is transported by an endless transport heald 21, fixed by a heat fixing roller 22, and placed on a paper output tray 23.
is discharged. On the other hand, residual toner on the photosensitive drum 6 is scraped off by a cleaning device 11 and erased by an erase lamp 12.

At the bottom of the cleaning device 11, there is a detection means 25 for detecting the separability of the transfer material 16, as shown in FIG.
is provided. This detection means 25 detects a reflection plate 26 provided at the bottom of the cleaning device 11 and near the photosensitive drum 6, and a reflective optical sensor 27 provided at the bottom of the cleaning device 11 with a space from the reflection plate 26. have

When the separability of the transfer material 16 deteriorates, it is slightly dragged by the photosensitive tram 6 from the normal paper passing path A shown in FIG. 2, resulting in a paper passing path as indicated by reference mark B.

Therefore, under normal conditions, light from the light emitting element of the optical sensor 27 is reflected by the reflecting plate 26 and received by the light receiving element of the optical sensor 27. On the other hand, when the paper passing path B is reached, the light from the optical sensor 27 is blocked, and the optical sensor 27
No reflected light is incident on the light receiving element. In this way, the optical sensor 27 can detect whether the separability of the transfer material 16 is good or bad.

FIG. 3 is a block diagram showing an electrical configuration related to transfer material separation control. The conveyance heald 21 has a pulley 30
．． 31, and a plurality of suction holes (not shown) are formed on the conveying surface thereof. A suction fan 34 is provided in association with the conveyance heald 21, and the suction force of the suction fan 34 draws outside air in the direction of the arrow through the suction hole and through an exhaust duct (not shown). It is discharged. Due to the air flow in the direction of the arrow, the transfer material 16 is brought into close contact with the transport surface of the transport heald 21, and in this state is supplied between the heat fixing rollers 22 and 22.

This suction fan 34 is driven by a suction fan drive circuit 40. The drive circuit 40 includes a power supply 41 and a power supply 41.
The high voltage side output terminal 42a and the normal potential output terminal 42
and a switching circuit 43 that selectively switches between the two.

Further, the separation claw 20 is driven into contact with and away from the photosensitive drum 6 by an electromagnetic solenoid 44 .

The electromagnetic solenoid 44 is driven by a solenoid drive circuit 45. This drive circuit 45 has a power supply 46 and a switching circuit 47 that turns on/off the power from each power supply 46.

Further, the charger 7 is provided with a charger transformer circuit 48, and the separate charger 12 is provided with a separate charger transformer circuit 49.

The charger transformer circuit 48 includes a power supply 50 and a switching circuit 52 that selectively switches between a high voltage side output terminal 51a and a normal potential output terminal 51b of each power supply 50. Similarly, the separate charger transformer circuit 49 includes a power supply 53 and a switching circuit 55 that selectively switches between the high voltage side output terminal 54a of the power supply 53 and the normal potential output terminal 54b. Charger transformer circuit 48,
The solenoid drive circuit 45, the suction fan drive circuit 40, the optical sensor 27, and the separate charger transformer circuit 49 are connected to a central processing circuit (hereinafter referred to as CPU) 57 via a human output port 56. This CPU 57 controls the switching circuits 43, 47, 52° 55 during separation control to be described later.
A switching control signal is output to the switching circuit 43.
47, 52, and 55 switching modes are switched.

In addition, a display section 58 including an LED for displaying a separation deterioration state, which will be described later, is connected to the CPU 57 via an input/output boat 56.
It is connected to the.

A non-volatile memory 59 is connected to this CPU 57, and separate state setting index values Ri (i-0 to 4), which will be described later, are stored in a non-volatile memory 59.
constants and system programs such as are stored. In addition, in FIG. 3, 60 is a commercial AC power supply for driving these circuits, and the type #i41, 46, 50
．． 53 is obtained by converting this power source 60 to high voltage or low voltage.

Based on the detection result from the optical sensor 27, the CPU 57 determines the ratio R=C/of the number of copies N and the number of times C detected by the sensor.
N is calculated, and this calculated value R is combined with an index value R4 indicating the separation state.
(i=o to 4), and control is performed to select and set one of the five separation states to be described later based on the comparison result.

By the way, specific means for restoring the separability include changing the output in the separation charger, switching the contact and separation of the separation claw 20 with the photosensitive drum 6, changing the suction force of the suction fan 34, and It is conceivable to change the output of the charger 7. For example, separate charger 1
When the output of 0 increases, the static elimination function increases accordingly,
Separability is restored. Regarding the separation claw 20, if the separation performance deteriorates, the separation position tends to be dragged a little by the photoreceptor drum 6; The material 16 is separated, and the separation performance is improved.

Furthermore, if the separation property deteriorates, the transfer material 16 may be removed from the photoreceptor drum 6.
As a result, the distance from the transfer material separation position to the conveyance heald 21 becomes longer than in the normal case. Therefore,
Each time the transfer material 16 reaches the conveyance heald 21, the position becomes closer to the end of the conveyance heald 21 than the normal position.
The attraction force of the transfer material 16 to the conveyance heald 21 is weakened,
The transfer material 16 is transported without being in complete contact with the transport surface of the transport belt 21. If the transfer material 16 is conveyed between the heat fixing rollers 22 and 22 in such a state, problems such as jamming, paper wrinkles, or smudges may occur in the transfer material 16. Therefore, by increasing the suction force of the suction fan in the case of poor separation, the transfer material 16 can be transported in complete contact with the transport surface of the transport heald, thereby preventing jams, paper wrinkles, etc. This can be prevented from occurring.

Further, when the output of the electrification charger 7 is lowered, the magnetic adsorption force between the photosensitive drum 6 and the transfer material 16 is weakened, and therefore, the separability can be improved.

On the other hand, regarding changes in the output of these separation chargers and the charging charger 7, switching between press contact and separation of the separation claw 20 with respect to the photoreceptor F ram 6, and changes in the suction force of the suction fan 34,
When actions are taken in the direction of improving separability, side effects occur. That is, when the separation claw 20 is brought into pressure contact with the photosensitive drum 6, there is a risk that scratches may occur on the surface of the photosensitive drum 6, and when the output of the separation charger 10 is increased, an AC mark may occur, and the suction of the suction fan may be damaged. If the power is increased, transfer deviation and noise will occur, and if the output of the charger 7 is decreased, the image density will be decreased. Therefore, as shown in Table 1, by appropriately combining the drives of the electrification charger 7, separation charger 10, separation claw 6, and suction fan 34, five stages of separation state are created. Control is performed to sequentially switch from the first separated state to the fourth separated state.

Table 1 Note that in Table 1, Nor indicates a normal state.

FIG. 4 is a flowchart showing the copying operation routine. Initialization processing is performed in step S1, and step S2
The internal timer starts timer operation. Then, in step S3, a process corresponding to the manual key operation is executed, in step S4, a copy operation process shown in FIG. 5 (described later) is executed, in step S5, other processes are executed, and in step S6, an internal timer A judgment is made, and if the timing is such that the timer times up, the process returns to step S3.

FIG. 5 is a flowchart showing the subroutine of the copying operation.

First, when the print switch is turned on, the on-edge is detected in Sl and the copy start flag is set to 1.

(S2). Next, in step 83, it is determined whether the copy start flag is 1, and if Yes, the process advances to S4, where the main motor,
Turn on the developing motor, charging, and transfer (“1” corresponds to ON), set the copy start flag to O, and
82 timers (TA, TB) are set. Furthermore, the number of copies N is incremented by 1. Next, copy paper is fed. At this time, a judgment is made on the timer (S6), and if the timing is such that the timer times up, the process proceeds to step S7 and the paper feed roller clutch that was turned on earlier is turned off. Next, judge timer B (S8)
, if it is the timing when the timer times up, the scan signal is turned on (S9). In SIO, when the timing signal becomes 1, the timing roller clamper is turned on and timer C is set (Sll).

This drives the timing roller, so that the transfer paper 16 is sent to the transfer section in synchronization with the toner image formed on the photosensitive drum 6, and the toner image is transferred. After the transfer paper 16 in the transfer section is separated from the surface of the photosensitive drum 6, it is sent between fixing rollers 22, 22.

Then, in step S12, the process moves to an abnormality detection routine shown in FIG. 6, which will be described later, and then in step S13, the timer C is judged, and the charging, scan signal, and timing roller clutch are turned off at the timing of time-up (S14). Then, in step 315, when the return signal is 1, that is, when the scanner starts returning,
Unable to determine whether multi-copy copying is complete 51
6) If not yet, the copy start flag is set to 1 again in step S17, the results of the processing up to now are outputted in step S20, and then the same copying operation as above is repeated again. Then, when the copying operation for the multi-copy is completed, the process proceeds from step 316 to step 821 in the flowchart (j). When the scanner returns to the normal position and the normal position SW is turned on, the developing motor and transfer are turned off and timer D is set. (S22).Next, at the timing when one timer times up (S18), the main motor is turned off.
19), output the final result (S20).

FIG. 6 is a flowchart showing the abnormality detection routine. First, in step s23, it is determined whether or not a detection signal is output from the optical sensor 27. If not, the process moves to step s25.

When the detection signal is output from the optical sensor 27 in step S23, the sensor flag is set to 1 in step S52.
4). Then, in step S25, it is determined whether the return signal is 1, and if it is not 1, the process moves to step 328. When the return signal is 1 in step s25, the process moves to step S26, where it is determined whether the sensor flag is 1, and when it is not 1, the process proceeds to step 82.
Move on to 8. When the sensor flag is 1, step s2
7, the number of detections C is incremented by 1, and the sensor flag is reset to 0. Then, the process moves to step 328, and the process moves to the 5"C normal processing routine shown in FIG. 7, which will be described later.

FIG. 7 is a flowchart 1 showing the abnormality processing routine. In step s29, the ratio R=C/N between the number of detections C of the detection signal and the number N of copies is calculated. And step S30
Then, it is determined whether the calculated value R is less than or equal to the 0th separation state setting index value RO, and if so, the separability is determined to be good and the 0th separation state is set in step s31. . That is, the output of the separation charger 10 is in a normal state, the separation claw 20 is in a state separated from the photosensitive drum 6, the suction force of the suction fan 34 is also in a normal state, and the output of the charging charger 7 is also in a normal state.

When the calculated value R is greater than or equal to R0 in step 330, the process moves to step 332, where it is determined whether or not the value R is less than or equal to the first separation state setting index value R1. If so, the process moves to step s33. Set to the first separated state. That is, the outputs of the separation charger 10 and the charging charger 7 are maintained in their normal state, the suction force of the suction fan 34 is maintained in their normal state, and the separation claw 20 is brought into pressure contact with the photosensitive drum 6.

If the value R is equal to or greater than R1 in step s32, the process moves to step S34, where it is determined whether or not the value R is less than or equal to the second separation state setting index value R2. If so, the process moves to step s35, where the second It is set to the second separated state. That is, the separation claw 20, suction fan 34, and charger 7 remain in the first separation state, and the output of the separation charger 10 is increased.

If the value R is equal to or greater than R2 in step S34, the process moves to step S36, where it is determined whether or not the value R is equal to or less than the third separation setting index value R3. If so, in step S37, the third Set to isolated state.

That is, the separation charger 10, the separation claw 20, and the charging charger 7 remain in the second separation state, and the suction fan 34
Increase the suction power of.

When the value R is equal to or greater than R3 in step s36, the process moves to step s38, where it is determined whether or not the value R is equal to or less than the fourth separation state setting index value R4. If so, in step s39, the fourth is set to an isolated state. That is, the separation charger 10, separation claw 20, and suction fan 34 remain in the third separation state, and the output of the electrification charger 7 is reduced. In this way, the index value RO~
By comparing R4 and the calculated value R and setting the separation state to one of the 0th to 4th five separation states depending on the state of deterioration of the separation property, stable separation property can be maintained at all times and the separation property can be improved. The side effects associated with the drug can be selected in descending order of relatively minor side effects. Therefore, when looking at the copying machine as a whole, it is possible to maintain separation, and to prevent image deterioration as much as possible.

Incidentally, when the value R is equal to or greater than R4 in step S38, the process moves to step s40, and a warning is displayed. Thereby, the user can be prompted to perform maintenance and inspection of the separation charger 10, such as cleaning.

In the above-mentioned embodiment, the detection means 25 was composed of the reflection plate 26 and the optical sensor 27, but a mechanical switch such as a limit switch, a sensor using infrared rays or ultrasonic waves, etc. may also be used.

In addition, in the above-mentioned embodiment, the separation charger 10 and the separation claw 2
Although the five separation states are set by the four components, 0, the suction fan 34, and the electrification charger 7, more fractionation states may be set by other devices.

Effect of dust generation As described above, according to the present invention, it is possible to set the optimum condition in response to changes in the type of paper and the environment, and it is possible to maintain stable separation at all times. Therefore, a good image can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a simplified diagram showing the internal structure of a copying machine l to which the transfer material separation state detection device according to the present invention is applied, and FIG. 2 is a diagram showing the separation state of the transfer material 16. 3 is a block diagram of a mechanism related to separation control, FIG. 4 is a flowchart of the copying process, FIG. 5 is a flowchart 1-1 showing the copying operation routine, and FIG. 6 is a flowchart showing the abnormality detection routine. , FIG. 7 is a flowchart showing the abnormality handling routine. DESCRIPTION OF SYMBOLS 1... Copying machine, 6... Photosensitive tram, 7... Charger, 9... Transfer charger, 10... Separation charger, 16... Transfer material, 20... Separation claw, 27
... Optical sensor, 34... Suction fan, 40... Suction fan drive circuit, 44... Solenoid, 45...
Solenoid drive circuit, 48... Charger 1-lance circuit, 49... Separate charger transformer circuit, 5
7...CPU, 59...Memory, RO~R4...
・Indicator value, C...Number of detections, N...Number of copies, A
, B...Paper passing route. Figure 5 σ←--Double rent Figure 6

Claims (1)

[Claims] (1) A means for detecting the number of copies, a detecting means for detecting the separation state when the transfer material to which the toner image has been transferred is separated from the surface of the image carrier, and a separation state that can be changed to a different separation state. a changing means; calculating a ratio between the number of detections by the separation state detection means and the number of copies from the copy number detection means; comparing the ratio with an index value indicating the separation state setting; and changing the separation state according to the comparison result; 1. A transfer material separation control device comprising: separation control means for controlling the means to set a predetermined separation state.