JPH07160105A - Developer presence/absence detector - Google Patents

Abstract

PURPOSE:To prevent degradation of detecting accuracy, which is caused by sticking of dust to a detecting means or its change with time, by altering the output or threshold of the detecting means, thereby correcting the degradation of the detecting means which are caused by external or secular factor. CONSTITUTION:When a process cartridge is replaced, a cartridge cover is once closed with the cartridge empty, the output of a photodetector at that time is observed, and the threshold of a judging means is automatically altered according to the value. In this case, the closing of the cartridge cover leaving the cartridge empty and the depressing of a correction switch provided on a device main body are manually performed by an operator, and the actuation of the detecting means after the depression of the correction switch, the observation of the output of the photodetector, and the alteration of the threshold of the judging means are automatically performed. Namely, when a toner container presence/absence sensor judges the process cartridge to be absent and the cartridge cover opening/closing sensor judges the cartridge cover to be closed, it is executed by an incorporated microprocessor only after the correction switch is depressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the presence / absence of a developer in an electrophotographic apparatus, an electrostatic recording apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting the presence or absence of a developer in an electrophotographic apparatus or the like, a light transmission type device for detecting the presence or absence of a developer between a light source and a light receiving element is provided so as to form a photo interrupter. The developer presence / absence detecting device is known.

FIG. 14 shows a conventional example of a light transmission type developer presence / absence detecting device. In the figure, 101 is a light emitting element, and 102 is a light receiving element. Reference numeral 103 denotes a developer container, which is the light emitting element 1 described above.
01 and the light receiving element 102 are provided with windows 104 and 105 for transmitting light.

In this apparatus, while the developer D is sufficiently contained in the developer container 103, the developer container 1 is opened through the window 104.
The light of the light emitting element 101 that has entered into the light source 03 is blocked by the developer D and does not reach the light receiving element 102. On the other hand, when the developer container 103 becomes empty due to consumption of the developer, the light emitting element 10
The light of No. 1 reaches the light receiving element 102 through the windows 104 and 105. In this way, the presence or absence of the developer D is detected by the change in the output of the light receiving element 102.

A window cleaning member 106 is rotated by a drive source (not shown) about a rotating shaft 107 as a center of rotation. Reference numeral 108 denotes a cleaning sheet made of a flexible body, which comes into contact with the inner surfaces of the windows 104 and 105 as the window cleaning member 106 rotates, and the cleaning sheet 108 wipes off the developer D attached to the inner surfaces of the windows 104 and 105. Is configured as follows. This prevents the developer D attached to the window from blocking the light of the light-emitting element 101 even when the developer container 103 is empty, and prevents the developer from being determined to be present.

In such a light transmissive type developer presence / absence detecting device, there is a problem in that the detection accuracy is deteriorated due to adhesion of dust to the light emitting portion and the light receiving portion, aging of the light emitting element and the light receiving element, and the like. For example, in Japanese Unexamined Patent Publication No. 2-284165, since the light emitting portion or the light receiving portion is flexibly held and brought into close contact with the developer container, compared to a type in which the light emitting portion and the light receiving portion are simply fixed. The dust adhesion prevention performance is improved. Further, the publication also proposes a mechanism for cleaning the light emitting portion and the light receiving portion in association with the attachment / detachment of the developer container and the opening / closing of the door.

[0007]

However, in the above-mentioned conventional example, although the method in which the light emitting portion or the light receiving portion is brought into close contact with the developer container is effective in preventing dust adhesion,
If the devices cannot be brought into close contact with each other due to layout restrictions, the effect cannot be expected. The most important constraint on the layout of the apparatus is the recording material conveyance path, which is often located near the developer container in order to downsize the entire apparatus. In particular, when the transport path passes directly below the developer container (just below the vertical direction), the batting is performed on either the light emitting portion or the light receiving portion. This is because the light transmissive developer presence / absence detecting device detects that the developer remaining at the bottom of the developer container is exhausted, and therefore it is necessary to place either the light emitting portion or the light receiving portion immediately below the developer container. Is.

In such a case, the detecting means (the light emitting portion or the light receiving portion) is arranged not obliquely below the developer container but obliquely below, or further below the conveying path (the optical path is formed so as to cross the conveying path. However, in the former case, since the developer remaining on the bottom of the developer container cannot be monitored to the end (until it disappears), a considerable amount of developer remains when "no developer" is detected. It is uneconomical. On the other hand, the latter, unlike the former, has the advantage of being economical because the developer can be used up to the end, but not only can the detection means not be in close contact with the developer container, but the detection means and the developer container There is a demerit that dust is not unavoidable on the detection means, especially paper powder is unavoidably dropped and adhered to the detection means because of a conveyance path between the detection path and the detection path, and the detection accuracy is lowered. To prevent this, a complicated cleaning mechanism is required, resulting in a high manufacturing cost and a device that easily breaks down.

The light-reflecting developer detecting device also has the same problem. Further, in the developer detecting device using a piezoelectric element, the deterioration of the detection accuracy due to the aging of the element cannot be ignored.

The present invention solves the above-mentioned problems and has the advantage that the developer can be used up to the end, and is simple and does not increase the cost, and the detection accuracy due to dust adhesion to the detection means or change with time It is an object of the present invention to provide a developer presence / absence detecting device capable of preventing the deterioration of the developer.

[0011]

According to the present invention, the above-mentioned object is to detect a detector whose output changes according to the remaining amount of the developer, and to detect that the developer is absent when the output exceeds a specified value. In a developer presence / absence detection device for detecting the presence / absence of a developer in a developer container in an image forming apparatus, the deterioration of the detection unit due to an external or temporal factor is detected by the detection unit. This is achieved by having a means for correcting by changing the output or the specified value.

[0012]

According to the present invention, each time the developer is used up, the specified value is changed or the output of the detecting means is adjusted to correct the output disturbance due to the adhesion of dust to the detecting means or the deterioration of the detecting means itself. However, the detection conditions are always kept the same as the initial settings to prevent the detection accuracy from degrading. Further, in the case of a contact type detection method such as a piezoelectric element in which dust adhesion is not a serious problem, the specified value should be changed according to the cumulative use time of the developer presence detection device and the characteristics of the detection means, or the output of the detection means. By adjusting, the output decrease due to the deterioration of the detection means is corrected,
The detection condition is always kept the same as the initial setting to prevent the detection accuracy from decreasing.

[0013]

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

<First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a main sectional view of an LBP recording type facsimile apparatus using the developer presence / absence detecting apparatus of the present invention. In the apparatus of this embodiment, the recording material P fed from the paper feed cassette 1 or 2 is fed.
Passes through the recording material conveyance path 3 or 4, undergoes a predetermined process to form an image, and is discharged to the outside of the apparatus.

In FIG. 1, reference numeral 5 denotes a process cartridge which is detachably attached to the main body of the apparatus, and accommodates a photosensitive drum 6, which is an image carrier, a primary charging device 7, a developing device 8, a cleaning device 9, and a developer T. The developing agent container 10 is stored integrally.

The image forming process in this facsimile apparatus will be described below. After the photosensitive drum 6 is uniformly charged by the primary charger 7, when the photosensitive drum 6 is irradiated with the image light (laser beam) 12 from the light source 11, an electrostatic latent image is formed on the photosensitive drum 6. To be done. The electrostatic latent image is developed by the developing device 8.
Is developed by the developer (toner) T in the inside to be visualized,
Can be converted to a toner image The toner image on the photosensitive drum 6 is
The recording material P, which is transferred onto the recording material P by the transfer charger 13 on the apparatus main body side and further has the toner image fixed by the fixing device 14, is ejected to the outside of the apparatus.
On the other hand, the photosensitive drum 6 after the transfer is finished is cleaned by the cleaning device 9
The residual toner is cleaned by and the preparation for the next electrostatic latent image is completed.

FIG. 2 is an enlarged view of a main part of FIG. 1 and is a vertical sectional view of the developer presence / absence detecting device of the present invention. Reference numerals 15 and 16 denote a light emitting element and a light receiving element, respectively, which are attached so as to face the apparatus main body, and S denotes an optical axis connecting the light emitting element 15 and the light receiving element 16.

Reference numerals 17 and 18 denote an upper wall 19 of the developer container 10.
And a transparent window provided on the bottom wall 20. Among them, the transparent window 18 on the bottom wall side is provided at the lowest position of the developer container 10. The term “transparent” here means that the light of the light emitting element 15 is transmitted, and it does not have to be visibly transparent.

The positional relationship between the light emitting element 15, the light receiving element 16 and the transparent windows 17 and 18 is as follows.
With the device mounted on the apparatus main body, the light emitting element 15 and the light receiving element 16 are positioned so as to sandwich the developer container 10, and the transparent windows 17 and 18 face the light emitting element 15 and the light receiving element 16, respectively. It is configured. The light emitting element 15 is attached to a cartridge cover 21 that can be opened and closed with respect to the apparatus main body, and when the process cartridge 5 is replaced, it retracts upward together with the cartridge cover 21 as shown in FIG. The light receiving element 16 is attached below the conveyance path of the recording material P as described later.

In FIG. 2, reference numeral 22 is a stirring plate provided in the developer container 10, and is reciprocated in the direction of arrow Y by a stirring arm 24 having a pendulum motion around a stirring shaft 23 to develop the developer T. The developer T is prevented from aggregating and unevenly distributed while being sent to the container 8. A cleaning member 25 is supported around a rotating shaft 26 and is reciprocally rotated about 100 degrees by a claw portion 27 on the stirring plate 22. Rotating shaft 26 of cleaning member 25
Are provided at equal distances from the transparent windows 17 and 18, respectively. The cleaning member 25 is provided with a notch window near the center thereof so as not to block the optical axis S. Two
Reference numerals 8 and 29 denote cleaning blades made of a flexible body, which are attached to the front end sides 30 and 31 of the cutout window.

The distance H between the rotary shaft 26 and the window surface 17S (18S) and the tip side 30 (3) of the rotary shaft 26 and the cutout window.
1) the distance I from the rotary shaft 26 and the cleaning blade 28 (2)
The distance J to the tip of 9) has a relationship of I <H <J. Therefore, when the cleaning member 25 reciprocally rotates, the cleaning blades 28 and 29 move the window surface 17S,
The developer that comes into contact with 18S and adheres to the window surfaces 17S and 18S can be wiped off. The optical axis S is blocked only when the tip edges 30, 31 of the cutout window and the cleaning blades 28, 29 cross the optical axis S, and the tip edges 30, 31 of the cutout window and the cleaning blade 28 are the same as in the conventional case. , 29 does not block the optical axis S, the presence or absence of the developer can be detected.

In the image forming process described above, the cleaning member 2 is used.
5 reciprocally rotates, and the cleaning blades 28 and 29 move to the window surface 17
The developer adhering to S and 18S is wiped off, but the cleaning blades 28 and 29 keep the window surface 17 while the developer T is sufficient.
Since the developer T covers the window surface immediately after the developer on S and 18S is wiped off, the light of the light emitting element 15 does not reach the light receiving element 16, or even if it reaches, it is shielded again in a short time. However, when the amount of the developer decreases, it takes a longer time for the developer to cover the window after cleaning the window, and eventually the developer T
When there is no light, the light of the light emitting element 15 reaches the light receiving element 16 except when the front end sides 30 and 31 of the cutout window and the cleaning blades 28 and 29 cross the optical axis S. When the light of the light emitting element 15 reaches the light receiving element 16, the output signal of the light receiving element changes. FIG. 4 shows an output signal from the light receiving element 16 in the above detection process. While the developer T is sufficient, the output is small as shown in (a), and the duration t of the signal receiving the light is short, but when the developer is gone, the output is large as in (b) and the received light is received. The signal duration t becomes longer. Therefore, it is possible to detect that the developer has run out by measuring the light reception signal duration t and comparing it with the specified value by the determination means. Further, in this embodiment, since the one transparent window 18 (bottom wall side) is provided at the lowest position of the developer container 10, the developer T is not supplied to the developing device 8 until just before it is supplied.
It is economical because it is possible to determine the amount of the developer that remains when the determination of "without developer" is made after the determination of "with developer".

In the present embodiment, the recording material P is structured to pass directly under the developer container portion 10 in the process cartridge 5, and the light receiving element 16 is located further below the paper passing surface. The presence / absence of the developer is detected when the recording material is not in the portion of the optical path S of the conveyance path (between recording materials or timing before and after recording). FIG. 5 shows details in the vicinity of the light receiving element 16. The light receiving element 16 is attached to the frame of the facsimile apparatus main body, and a dust adhesion prevention cover 32 is attached so as to cover the frame. The dust adhesion prevention cover 32 is made of a transparent (light transmitting) material. The term “transparent” as used herein means that the light of the light emitting element 15 is transmitted, and it does not have to be visually transparent. The upstream side (the right side in the drawing) of the recording material conveying path of the dust adhesion prevention cover 32 is tapered so that the recording material is not caught.

FIG. 6 shows a cross section taken along the line AA of FIG. Minute protrusions 33 and 34 are provided on the edge of the surface of the dust adhesion prevention cover 32.

From the recording material conveyance path, paper dust generated from the recording material P, dust entering the apparatus when the process cartridge 5 is attached and detached, and the like fall on the light receiving element 16. The dust adhesion prevention cover 32 prevents such paper dust and dirt from adhering to the light receiving element 16, and thus prevents the output of the light receiving element 16 from decreasing and maintains the detection accuracy. Also, a dust adhesion prevention cover 3
The dust that drops on the upper surface of the cover 2 is flushed by the recording material P when the recording material P passes, because the surface of the cover has almost the same height as the paper passing surface. At this time, the small protrusions 33,
Since the recording material P does not come into strong contact with the light transmitting surface of the same cover because of 34, there is no possibility that the light transmitting surface of the cover is scratched and the detection accuracy is adversely affected. It is necessary to find an optimum value for the height of the minute protrusions according to the size of the dust adhesion prevention cover for different types of devices.
In this embodiment, the dust adhesion prevention cover 32 has a diameter of about 15
mm-cylindrical shape, the height of the small protrusions 33, 34 is 0.3 m
m. Further, since the minute protrusions 33 and 34 are formed integrally with the cover, it is advantageous in terms of cost.

However, even with the above configuration,
As time passes, dust and paper dust gradually adhere to the dust adhesion prevention cover 32, and the output of the light receiving element 16 slightly decreases. In addition, the output also decreases due to the change (deterioration) with time of the detection means (light emitting element, light receiving element). This is shown in FIG. In the figure, the horizontal axis represents the years of use of the developer presence / absence detecting device, and the vertical axis represents the raw output of the light receiving element (full output in the absence of the developer). When the number of years of use reaches 5 years, dust adheres,
The raw output of the light receiving element is 10 to 15% due to deterioration of the detection means.
descend. If no correction is made, as shown in FIG. 8, the output when the window is wiped (despite the fact that it is actually wiped) is insufficient for the prescribed value V of the determination means, and the development is performed. It may happen that the disappearance of the agent cannot be detected. The specified value V can be set to a lower value in advance in anticipation of this decrease in output, but even in this case, the detection accuracy is inevitably deteriorated.

Therefore, in the developer presence / absence detection apparatus according to the present invention, when the process cartridge 5 is replaced, the cartridge cover 21 is temporarily closed while the process cartridge 5 is empty, and the output (raw output) of the light receiving element at that time is observed, and the value is measured. The specified value V of the determination means is automatically changed according to the above. This is shown in FIG. It can be seen that what cannot be detected with the specified value V when the correction is not made, can be detected with the corrected specified value V ′. In the developer presence / absence detecting device, the specified value V is lowered in proportion to the rate of decrease of the output from the initial value. Further, in the correction, the process cartridge 5 is taken out from the facsimile apparatus, the cartridge cover 21 is closed while the process cartridge 5 is empty, and the operator manually operates up to the point where the correction switch provided in the facsimile apparatus is pressed. Then, the detection means is operated to observe the raw output of the light receiving element and the specified value V of the determination means is changed automatically (by the microprocessor incorporated in the facsimile apparatus). FIG. 10 shows a block diagram of the correction means of this embodiment, and FIG. 11 shows a correction flowchart. In FIG. 10, a toner container presence / absence sensor detects whether or not the process cartridge 5 is set at a predetermined position of the facsimile apparatus, and a cartridge cover opening / closing sensor detects whether or not the cartridge cover 21 is closed. As shown in FIG. 11, the correction is performed only when the process cartridge 5 is absent and the correction switch is pressed when the cartridge cover 21 is closed.

In the above device configuration, depending on the layout of the detecting means and the shape of the process cartridge, the light of the detecting means when the process cartridge is taken out is too intense as compared with the time of detection, so that proper observation and change of the specified value can be performed. There are things you can't do. In such a case, when the process cartridge is taken out and the raw output is observed, it is advisable to insert a filter or slit between the light emitting element and the light receiving element to attenuate the light. If the configuration is such that these light transmission attenuating means appear in association with the opening / closing operation of the cartridge cover and the presence / absence of the process cartridge, the operator is not forced to perform an extra operation.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the first embodiment, when the process cartridge 5 is replaced, the cartridge cover 21 is temporarily closed while it is empty and the output (raw output) of the light receiving element at that time is observed. Although V is automatically changed, the output of the detection means may be adjusted without changing the specified value V of the determination means. To adjust the output of the detection means, the light output may be changed by changing the current value of the light emitting element, or the amplification factor of the light receiving element may be changed. In any case, the output of the light receiving element after the adjustment is set to the same value as the initial setting. In the adjustment, the process cartridge 5 is taken out from the facsimile apparatus, the cartridge cover 21 is closed while it is empty, and the operator manually operates up to the point where the adjustment switch provided in the facsimile apparatus is pressed. The means for activating the means and observing the raw output of the light receiving element to adjust the sensitivity of the detecting means may be automatically performed (by a microprocessor incorporated in the facsimile apparatus) or provided in the main body of the facsimile apparatus. The volume may be manually operated (this can be applied to the first embodiment). FIG. 12 shows a flow chart of the adjustment of this embodiment.

Further, depending on the layout of the detecting means and the shape of the process cartridge, the light of the detecting means when the process cartridge is taken out is too strong as compared with the time of detection,
It may not be possible to change the sensitivity of appropriate observation and detection means. In such a case, similarly to the first embodiment, when the process cartridge is taken out and the raw output is observed, it is preferable to insert a filter or a slit between the light emitting element and the light receiving element to attenuate the light. If the configuration is such that these light transmission attenuating means appear in association with the opening / closing operation of the cartridge cover and the presence / absence of the process cartridge, the operator is not forced to perform an extra operation.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

It is not necessary to consider the influence of dust, paper dust, etc. when the output decrease due to the adhesion of dust, paper dust, etc. on the detection device is very small, and the contact type detection device using a piezoelectric element, etc. In some cases, it may be adjusted in consideration of only the temporal change (deterioration) of the detection means. In this case, if the state of the change over time of the detecting means is clarified by an experiment in advance, it is possible to automatically adjust it according to the cumulative use time of the developer presence / absence detecting device. That is, the data of the change over time revealed by the experiment is stored in the storage means of the apparatus main body, and the accumulated use time of the developer presence / absence detection device (clocked by the clocking means)
Each time a predetermined time (one step or more) is reached, the specified value V of the determination means is changed by collating with the above data.
Alternatively, the output of the detection means is adjusted. Of course, the series of operations described above can be automatically performed by a microprocessor incorporated in the facsimile apparatus. FIG. 13 shows a flowchart of automatic correction / adjustment of this embodiment.

[0034]

As described above, according to the present invention,
Since the deterioration of the detection means due to external and temporal factors is corrected by changing the specified value of the judgment means or the output of the detection means, the detection means is arranged below the recording material conveying path. Even if the layout is adopted, it is not affected by dust adhesion, and is not affected by a change (deterioration) with time, so that the detection accuracy is not deteriorated. Therefore, while leaving the merit that the developer can be used up to the end, the recording material conveyance path can be freely laid out to downsize the entire device,
The manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a main sectional view of a facsimile apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the developer presence / absence detection device according to the first exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a state in which a cartridge cover of the facsimile apparatus according to the first exemplary embodiment of the present invention is opened.

FIG. 4 is an explanatory diagram of output signals of the light receiving element according to the first embodiment of the present invention.

FIG. 5 is a detailed view of the vicinity of the light receiving element according to the first embodiment of the present invention.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a diagram showing a change (deterioration) with time of the detection means according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram in the case where the output of the light receiving element according to the first embodiment of the present invention is lowered.

FIG. 9 is an explanatory diagram of changing the specified value V of the determination unit according to the first embodiment of the present invention.

FIG. 10 is a block diagram of a correction unit according to the first embodiment of the present invention.

FIG. 11 is a flowchart of correction control according to the first embodiment of the present invention.

FIG. 12 is a flowchart of correction control according to the second embodiment of the present invention.

FIG. 13 is a flowchart of correction control according to the third embodiment of the present invention.

FIG. 14 is a sectional view of a conventional developer presence / absence detection device.

[Explanation of symbols]

 10 Developer Container 17 Light Emitting Section (Detecting Means) 18 Light Receiving Section (Detecting Means) T Developer

Claims (9)

[Claims] 1. A developing device in an image forming apparatus, comprising: a detecting unit that changes an output depending on a remaining amount of the developer; and a determining unit that determines that the developer is absent when the output exceeds a predetermined value. In a developer presence / absence detection device for detecting the presence / absence of a developer in a developer container, there is provided means for correcting deterioration of the detection means due to an external or temporal factor by changing the output of the detection means or the specified value. A developer presence / absence detecting device having. 2. The means for correcting the deterioration of the detecting means includes means for observing the output of the detecting means when the developer container is empty,
The developer presence / absence detection device according to claim 1, further comprising: a unit that changes a specified value of the determination unit based on the observation result. 3. The developer container is arranged so as to be exchangeable, and the means for observing the output of the detection means is set so as to observe when the developer container is replaced. The developer presence / absence detection device according to item 1. 4. The developer according to claim 3, wherein the means for observing the output of the detecting means observes after the output of the detecting means is amplified or attenuated at a constant ratio when the developer container is replaced. Presence detection device. 5. The means for correcting the deterioration of the detecting means comprises means for observing the output of the detecting means when the developer container is empty,
The developer presence / absence detection device according to claim 1, further comprising: a unit that adjusts an output of the detection unit so that the output of the detection unit has a certain value based on the observation result. 6. The developer container is arranged so as to be replaceable, and the means for observing the output of the detection means is set so as to observe when the developer container is replaced. The developer presence / absence detection device according to item 1. 7. The developer according to claim 6, wherein the means for observing the output of the detecting means observes the output of the detecting means after amplifying or attenuating the output of the detecting means at a constant ratio when the developer container is replaced. Presence detection device. 8. The means for correcting the deterioration of the detecting means is set to change the specified value of the judging means according to the cumulative use time of the developer presence detecting device. The developer presence / absence detection device described. 9. The means for correcting the deterioration of the detecting means is a means set to adjust the output of the detecting means in accordance with the accumulated use time of the developer presence / absence detecting device. Developer detection device.