JP3049098B2 - A meandering / deviation detecting device for a photoreceptor belt which also serves as a condition detecting unit for detecting deterioration of the photoreceptor belt and peripheral devices. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to detect the meandering / deviation of a photoreceptor belt of an electrophotographic apparatus using the photoreceptor belt, and to detect the deterioration of the photoreceptor belt and its peripheral devices. It relates to a detection device that can be used.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as an electrophotographic copying machine, a laser printer, and a facsimile, an endless belt-shaped photoconductor is often used as a photoconductor due to a space or the like.
If the endless belt-shaped photoconductor is continuously circulated around a plurality of rollers, the belt-shaped photoconductor may meander due to uneven diameter of the rollers or an error in the parallelism between the rollers. Or one side. As a result, if the side edge of the belt-shaped photoreceptor is outside the end of the roller, the belt-shaped photoreceptor is damaged or does not move smoothly. Various corrections are made so that the side edges of the body are within a predetermined range.

Incidentally, it is known that the photoreceptor deteriorates with time due to electrostatic fatigue. In addition, a charger, a static eliminator, and an optical writing system disposed around the photoreceptor deteriorate with time, and need to be replaced when a predetermined state is exceeded.
When the contrast and density of an image obtained by development change, it is necessary to adjust the developing bias and correct the toner density of the developer.

A means for simultaneously detecting the meandering angle and the amount of deviation of the endless photoreceptor belt as a continuous value has been proposed. It is also known to detect the electrostatic fatigue of the photoconductor by measuring the charged position V _D of the photoconductor and the post-exposure potential _VL by a potential measuring means. It is also well known that the deterioration of the charger, the static eliminator, the optical writing system, and the necessity of adjusting the developing bias is performed by detecting the potential of the photoconductor. Further, the density of the toner pattern and the background obtained by developing the reference potential latent image pattern is detected using a density sensor called a P sensor for toner replenishment for adjusting the toner density of the developer, and the output thereof is used. It is also well known to do. However, there is no one detecting means that performs a change in characteristics such as a shift or meander of the photosensitive belt and deterioration of peripheral devices of the photosensitive member, or a shift or meander of the photosensitive belt and correction of the development amount.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described circumstances of detecting a shift or meandering of a photoreceptor belt of a conventional electrophotographic apparatus and detecting deterioration of a photoreceptor and peripheral devices. It is an object of the present invention to provide a detection device that can detect both of them by a detection means and contributes to cost reduction of the device.

[0006]

According to the present invention, there is provided a device for detecting the meandering and deviation of a photoreceptor belt according to the present invention. A straight line is provided, the photosensitive belt is rotated, and scanning is performed across the pair of straight lines by a sensor fixed to the apparatus, and the photosensitive belt is scanned between the pair of straight lines and at least one of the straight lines. In the device for detecting meandering and deviation of the body belt, in the first invention, the pair of wide non-parallel straight lines is formed as an electrostatic image, the sensor is a potential measuring unit, and the pair of non-parallel straight lines is a potential measuring unit. Means for forming an electrostatic latent image by exposure on the photoreceptor in a range which does not overlap with the width non-parallel straight line and which is detected by the sensor, and the potential of the electrostatic latent image formed by the means and the background portion By detecting the potential of the , And performs the status detection of the deterioration of the photosensitive belt and its peripheral devices.

In the second invention, the pair of wide non-parallel straight lines is formed as a grayscale image, the sensor is a density measuring unit, and does not overlap with the pair of wide non-parallel straight lines, and By detecting the density of the toner image formed by developing the electrostatic latent image formed on the photoreceptor by exposure on the photoreceptor in the range detected by the sensor with the developing device and the density of the background portion, the sensor is used. The development amount is detected.

[0008]

According to the first aspect of the present invention, the potential measuring means is used as a sensor for scanning a pair of wide non-parallel straight lines formed as an electrostatic image to detect meandering and deviation of the photosensitive belt. Therefore, it is also used as a sensor for detecting the potential of the electrostatic latent image formed by exposure on the photosensitive belt and the potential of the background portion in order to detect the deterioration state of the photosensitive belt and its peripheral devices. Can be.

According to the second aspect of the present invention, the density measuring means is used as a sensor for scanning a pair of wide non-parallel straight lines formed as a grayscale image in order to detect meandering and deviation of the photosensitive belt. In order to detect the amount of development on the photoreceptor, the density of the toner image obtained by developing the electrostatic latent image formed on the photoreceptor by the developing device and the density of the background portion are detected. Can also be used as a sensor.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing a main part of an endless photosensitive belt 1 to which the first invention is applied. On one side edge of the photoreceptor belt 1, a pair of wide non-parallel straight lines indicated by reference numerals 2 and 3 are formed at intervals in the circumferential direction of the photoreceptor belt 1 indicated by arrows. Further, an electrostatic latent image 4 is formed by exposure at a position that does not fall on the straight line 3 on the upstream side of the photosensitive belt 1 in the circumferential movement direction. The electrostatic latent image may be triggered at the time of passing through a pair of non-parallel straight lines, and written at a position at a predetermined distance from the trigger. The straight line 2 is a thin line extending in a direction perpendicular to the circumferential direction of the photosensitive belt, and the straight line 3 is a wide line extending obliquely to the circumferential direction of the photosensitive belt. In this embodiment, is formed by exposing the photoconductor layer of the photoconductor belt to expose the base. The electrostatic latent image 4 is formed by exposing the photoreceptor layer of the photoreceptor belt 1 by exposure to image writing light or the like. In this embodiment, the non-parallel straight lines 2 and 3 and the electrostatic latent image 4 are formed at one side edge of the photoreceptor belt 1 in the width direction, but the formation positions are not limited thereto. , Anywhere other than the image forming area.

Since the non-parallel straight lines 2 and 3 are formed by exposing the base of the photosensitive belt as described above, the potential is 0V. The potential _VL of the latent image portion of the electrostatic latent image 4 formed by exposing and exposing the photosensitive member belt is -300 V,
The potential V _{D at the} background is −1000 V.

A surface voltmeter is fixedly mounted on the main body of the apparatus at a position along the photoreceptor, after the exposure step and before the development step, and across the non-parallel straight lines 2 and 3 and the electrostatic latent image 4. .

When the photosensitive belt 1 is driven at a predetermined reference position in a predetermined direction without any deviation or meandering, the scanning line by the surface voltmeter becomes a line AA in FIG. However, when the photosensitive belt 1 is driven in a meandering direction to the right, the scanning line becomes like a straight line BB, and when the photosensitive belt 1 meanders to the left, the scanning line becomes like a straight line CC. If the scanning line is shifted to the right from the reference position, the scanning line is a straight line D.
-D.

When the above four scanning lines are scanned by a surface voltmeter, the wide straight line 3 is inclined with respect to the straight line 2, so that the scanning time t between the straight lines 2 and 3 of the scanning lines is changed.
time t crosses _a and the straight line 3 _b is there for the case of four. Therefore, the four scanning lines AA, BB, C
A potential change curve with respect to time when scanning along -C and DD is shown. The potential V _D (-10
(A), (b), (c), and (d) of FIG. 2 due to the difference between the non-parallel straight line potential of the substrate and 0 V).
In the reference state, t _a and t _b are t _a1 and t _b1 as shown in (a), but when meandering rightward, as shown in (b), t a and t b
_a2, t _b2, and the t _a3 as if meandering leftward shown in (c), t _b3, whereas for the closer to the right a t _a4, t _b4 as shown in (d). At any position corresponding to the electrostatic latent image 4, the latent image potential _VL is obtained in any case. _VL is -300 V in the reference state.

Therefore, by processing the values of t _a and t _b using appropriate arithmetic means, the deviation amount and meandering angle of the photoreceptor belt can be obtained. Feedback, the deviation and meandering of the photoreceptor belt can be corrected.

As shown in FIG. 3, as a device for correcting the deviation and meandering of the photosensitive belt, a cam 6 is rotated by a motor 5, and a roller 6 around which the photosensitive belt 1 is wound by the cam 6.
There is well known an apparatus in which one end of the roller 7 is slightly displaced to slightly change the parallelism of the two rollers to correct the deviation or meandering of the photosensitive belt 1. Therefore, the above t
_a, shift amount of the photosensitive belt as determined from the value of t _b, by the meandering angle fed back to the motor 5, more easily, it is possible to correct the meandering.

The background potential V _D of the photoreceptor and the potential V _L of the electrostatic latent image can be measured by the same scanning using the surface voltmeter for detecting the amount of deviation or meandering of the photoreceptor belt. From this detection output, it is possible to detect electrostatic fatigue of the photoconductor, deterioration of the charger, and failure of the laser writing system. V _L
Only abnormally altered deterioration of the photosensitive member when a charger of degradation when only V _D changes abnormally, V _L, If V _D together abnormally altered degradation of both or photoreceptor can be considered. Although not described in detail here, the determination can be made by some arithmetic means. If another extra charger is provided in addition to the charger normally used, it is possible to determine whether the charger has deteriorated or the photoconductor has deteriorated by using the extra charger.

[0019] It is also possible to V _L, by adjusting the developing bias voltage V _B from the V _D for correcting the development potential. That, V _L, if V _D is the degree varies not abnormal, it is also possible that the deterioration of the photosensitive member and the charging device, if falls within the allowable range, the development potential by adjusting the developing bias voltage V _B Is corrected, an image having an appropriate density can be obtained, and background stain can be prevented.

When only the electrostatic latent image potential V _L changes abnormally, the photoconductor is generally considered to be degraded, but sometimes the writing optical system is also degraded. This can be determined by some kind of arithmetic means, but if there is another extra optical writing means, writing with it will determine whether the photoreceptor has deteriorated or the optical system has deteriorated. Can be.

When the surface potential measuring means is provided along the photoreceptor at the positions after charge elimination and before charging, the electrostatic latent image 4 is lost by development, but the potential _Vq as shown in FIG. It can be measured at portions other than the non-parallel wide straight line portions t _a and t _b . From this potential, deterioration of the static eliminator can be detected.

FIGS. 5A and 5B are flow charts showing the control flow for detecting the meandering / deviation of the photoreceptor belt and detecting the deterioration state of the photoreceptor and peripheral devices described above.

FIG. 5A shows a control flow of detection and correction of deviation and meandering of the photoreceptor belt, and FIG. 5B shows a control flow of detection of failure and deterioration of the photoreceptor and its peripheral devices performed thereafter.

The potential is measured by scanning two non-parallel straight lines and the electrostatic latent image with a surface voltmeter (S1: short for step 1).
The times of t _a and t _b are measured (S2).

If t _a > t _a1 , t _b = t _b1 (S3), the photosensitive belt is shifted rightward in the traveling direction, so that T _A = t _a
Gather on the left side depending on the value of -t _a1 (S4).

If t _a <t _a1 and t _b = t _b1 (S5), the photoconductor belt is shifted to the left in the traveling direction, so that T _A = t _a
Corrected Intention to right in accordance with the value of -t _a1 (S6).

When t _b > t _b1 (S7), a comparison of T _B and T _A (S8) indicates that no deviation has occurred, indicating that the vehicle is meandering rightward in the traveling direction. Therefore, T _B = t _b −t
_Correct the meandering to the left according to the value of _b1 (S9) and at the same time T _B
For determining whether the deviation is occurring than the value of T _A = t _a -t _a1, corrected if closer (S10).

If t _b <t _b1 (S11), and if there is no deviation (S12) from the comparison between T _B and T _A , the vehicle is meandering to the left in the traveling direction. T _B = t _b -t correct meandering depending on the value of _b1 to the right at the same time (S13), T for T _{B A} = t _a -
It is determined whether or not a deviation has occurred from the value of t _a1 , and if it is, correction is made (S14).

FIG. 5B is a flowchart showing the processing in S1 of the flowchart of FIG. 5A.
If t _b <t _b1 is determined in 1 is NO, then shall apply in the flow to be performed subsequent to this, the electrostatic latent image portion potential V _L by the photoconductor ground potential V _D and the exposure after charging each -Of reference value
This is a flow for determining whether or not the charging device is defective, the photoconductor is deteriorated, the photoconductor is deteriorated, or the laser writing system is defective, as described above, depending on whether the voltage is 1000 V or −300 V. Note that this flow is complicated because all three of the deterioration of the photoconductor, the failure of the charger, and the failure of the laser writing system are put together, but it becomes simpler if they are separated. Also, the necessity of adjusting the developing bias can be easily determined from the values of _VD and _VL .

Regarding the determination of the defect of the static eliminator, a surface voltmeter is provided at a position between the static elimination and the charging to measure the V _D , and if the measured value is equal to the set value by comparing with the set potential after static elimination. The static eliminator is normal, and if different, it is determined that the static eliminator is defective.

FIG. 6 is a block diagram of a control system for performing the control described in the above flowchart.

Times t _a and t _b for scanning between two non-parallel straight lines and one of the straight line widths measured by a surface voltmeter as the sensor 10, the electrostatic latent image potential _VL , and the background potential V _D. Are input to a computing unit (MPU) 11 and compared with these reference values stored in a database 12, and fed back to a deviation and meandering correction motor 5, whereby deviation and meandering are corrected. If it is determined that the photoreceptor belt or the charger is deteriorated or defective, it is displayed on the component replacement instruction display 13. If it is determined by the computing unit 11 that the developing bias voltage V _B needs to be adjusted, V _B is adjusted.
Adjusting instruction of V _B is indicated on the display 14.

Next, an embodiment of the second invention will be described with reference to the drawings. FIG. 7 is a view showing a main part of the endless photosensitive belt 1 to which the second invention is applied. Also in this embodiment, a pair of wide non-parallel straight lines 2 ′,
3 'and an image 4' formed by optical writing are formed. These arrangement shapes are exactly the same as the non-parallel straight lines 2 and 3 and the electrostatic latent image of the embodiment of the first invention shown in FIG.
However, in this example, the non-parallel straight lines 2 'and 3' are formed on the photoreceptor belt base by applying a paint having the same concentration as that of the photoreceptor, which is developed by a developing device to form a toner image. ing. Image 4 formed by optical writing
'Is a toner image obtained by developing the electrostatic latent image formed on the photoconductor by optical writing with a developing device.

When the potentials of these straight lines 2 'and 3' and the image 4 'after the exposure were measured, the potential V _L of the optically written image was _VL = -3.
00V, the photoconductor background potential V _D = −1000 V, and the non-parallel linear portion substrate potential was 0 V. Therefore, the potential change when scanning with the surface voltmeter along the scanning line AA in the reference state in which the conveyance state of the photosensitive belt 1 is neither shifted nor meandering is exactly the same as that in FIG. .

By developing this with a developing device, the non-parallel straight lines 2 'and 3' and the latent image 4 'are converted into a toner image, and are scanned by a densitometer provided at a position after the development to obtain a toner image as shown in FIG.
(A) is obtained. Similarly, the density curves when meandering rightward, meandering leftward, and rightward are obtained as shown in FIGS. 8B, 8C, and 8D, respectively. Non-parallel 2 in each case from these curves
Times t _a1 and t _b1 between straight lines and 3 ′; t _a2 and t _b2 ;
t _a3 , t _b3 ; t _a4 , t _b4 can be obtained.

The shift amount and meandering angle of the photoreceptor belt are calculated from these measured values, and the shift and meandering are corrected by feeding back to the control means as described in the first embodiment of the present invention.

In this apparatus, since a densitometer is used as a non-parallel linear sensor for detecting the deviation or meandering of the photoreceptor belt, this sensor can also be used for detecting the amount of development on the photoreceptor. it can. FIGS. 9A and 9B show cases where the density of the toner image 4 'is lower and higher than the reference density D, respectively, from which it can be seen that the development amount is too small or too large.

Now, V _L = −300 V, V _D = −1000
V, V _B = -600V, the photoconductor belt base potential = and 0V and initialized. Assuming that the development start voltage V _{K and} the inclination γ of the development amount curve have not shifted, as shown in FIG.
It can be seen that the development amount was further reduced, and it is considered that _VL was increased (the absolute value was increased). Therefore, it is sufficient to increase the value of V _B to be the initial set value V _L -V _B = 300V (increasing the absolute values).

Conversely, when the density of the image 4 'is increased as shown in FIG. 9B, it is known that the development amount has increased.
The value of V _L -V _B may be lower the value of V _B to be the initial set value (small absolute value). However, it is necessary to pay attention to the value of V _D -V _B and take care not to cause reverse bias background contamination.

The development start voltages V _K and γ are not shown in FIGS. 9A and 9B because they may change with the environment and aging. However, the development amount of the two non-parallel straight lines 2 ′ and 3 ′ is not shown. May change. However, since the development amounts of the non-parallel two straight lines 2 'and 3' and the development amount of the image 4 'can be determined from the result of the density measurement, it is possible to know what the development characteristics are. From the results, V _L , V _D ,
By multiplying the feedback to V _B, obtained always proper development characteristics as shown in FIG. 11, no scumming in an appropriate image density can be without wasting toner.

FIGS. 12A, 12B, 12C and 12D are flow charts showing the control flow for detecting and correcting the meandering and deviation of the photosensitive belt, detecting the deterioration of the photosensitive member, and adjusting the developing bias according to the above-mentioned embodiment of the second invention. Are divided and shown in relation to the above. The first part shown in FIG. 12A shows a flow of control of detection and correction of deviation and meandering of the photoreceptor belt, and the "potential measurement" of S1 of the first part of the first embodiment of the first invention in FIG. The description is omitted because it is exactly the same except for the change to “concentration measurement”.

FIGS. 12B, 12C and 12D show the flow of the background soil density after development, the portion corresponding to the non-parallel straight line 3 '(indicated by (B) in the figure), and the light. The density of a portion (represented by (C) in the figure) corresponding to the written image 4 'is measured with a densitometer, and the density is compared with a preset reference value to obtain a bias voltage V.
_The flow for adjusting _B and determining the deterioration of the photoconductor to replace the photoconductor is shown in detail. The contents are clear from the flowchart.

The specific structure and control block diagram of the meandering and deviation correcting device for the photosensitive belt in this embodiment are the same as those in the first embodiment.

[0044]

As described above, according to the present invention, the surface voltmeter or the densitometer for detecting the meandering of the photoreceptor belt is used for detecting the deterioration of the photoreceptor, abnormality detecting means such as a charger, and adjusting the developing bias. Since it can be used also as a means, the number of detecting means can be reduced, and the effect of cost reduction can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a photosensitive belt to which the first invention is applied.

FIGS. 2 (a), (b), (c), and (d) are potentials with respect to time obtained by scanning with a surface voltmeter in a reference state, meandering to the right, meandering to the left, and moving to the right, respectively. FIG.

FIG. 3 is a perspective view illustrating an example of a mechanism that corrects meandering and deviation of the photosensitive belt.

FIG. 4 is a potential curve with respect to time of a measured value of a surface voltmeter when the first invention is used for deterioration measurement of a static eliminator.

FIG. 5A is the first half of the flowchart of the control flow according to the first invention;

FIG. 5B is the latter half of the above flowchart.

FIG. 6 is a control block diagram of the present invention.

FIG. 7 is a plan view showing a main part of the photoreceptor belt of the second invention.

FIGS. 8 (a), (b), (c), and (d) show density versus time obtained by scanning with a densitometer in the reference state, meandering to the right, meandering to the left, and shifting to the right. It is a curve figure.

FIGS. 9A and 9B are density curve diagrams with respect to scanning time by a densitometer when the amount of development is too small and too large, respectively.

FIG. 10 is a curve diagram illustrating an example of a relationship between a development potential and a toner amount on a photoconductor.

FIG. 11 is a curve diagram showing an example of an image density curve and a background stain density curve at the time of proper development characteristics.

FIG. 12A is the first part of the flowchart of the control flow according to the second invention;

FIG. 12B is a part of the flowchart following FIG. 12A.

FIG. 12C is a portion following the flowchart of FIG. 12B.

FIG. 12D is the last part of the above flowchart.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 2, 3 non-parallel straight line 2 ′, 3 ′ non-parallel linear toner image 4 electrostatic latent image of optically written image 4 ′ toner image of optically written image 5 motor for meandering deviation correction 6 cam 10 sensor (surface potential) Meter, concentration meter) 11 Computing unit 12 Database 13 Display

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Claims (7)

(57) [Claims] 1. A pair of non-parallel wide straight lines are provided at intervals in the circumferential direction of the endless photoreceptor belt, and the photoreceptor belt is moved around by a sensor fixed to an apparatus. In an apparatus that scans across a straight line and detects the meandering and deviation of the photoreceptor belt between the pair of straight lines and the time passing at least one of the lines, the pair of wide non-parallel lines is an electrostatic image. The above-mentioned sensor is a potential measuring means, and forms an electrostatic latent image by exposure on a photosensitive member in a range that does not overlap with the pair of wide non-parallel straight lines and is detected by the sensor. Means for detecting the state of the deterioration of the photoreceptor belt and its peripheral devices by detecting the potential of the electrostatic latent image formed by the means and the potential of the background portion of the photoreceptor by the sensor. Meandering and shifting of the photoreceptor belt Detection device. 2. The method according to claim 1, wherein the detecting device is configured to meander the photosensitive belt.
2. The detection device according to claim 1, wherein the detection of the shift is an electrostatic fatigue of the photoconductor. 3. The meandering of the photosensitive belt by the detecting device.
2. The detection device according to claim 1, wherein the detection of the shift is deterioration of the charger. 4. The meandering of the photoreceptor belt by the detecting device.
2. The detection device according to claim 1, wherein an object detected together with the deviation is deterioration of the static eliminator. 5. The meandering of the photosensitive belt by the detecting device.
2. The detecting device according to claim 1, wherein an object detected together with the deviation is a necessity of adjusting a developing bias. 6. The detecting device according to claim 1, wherein said photosensitive device belt is meandering.
2. The detecting device according to claim 1, wherein an object detected together with the shift is deterioration of an optical writing system. 7. A pair of wide non-parallel straight lines are provided at intervals in the circumferential direction of the endless photoreceptor belt, and the photoreceptor belt is moved in a circumferential direction by a sensor fixed to a device. In a device which scans across a straight line and detects the meandering and deviation of the photoreceptor belt between the pair of straight lines and the time passing at least one of the lines, the pair of wide non-parallel straight lines are used as a grayscale image. The sensor is a density measuring means, and forms an electrostatic latent image formed on the photoconductor by exposure in a range not overlapping with the pair of wide non-parallel straight lines and detected by the sensor. A meandering and deviation detecting device for a photoreceptor belt, which detects the amount of development on a photoreceptor by detecting the density of a toner image developed by a developing device and a background portion by the sensor.