JP2889368B2 - Target image density sensor mounting device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention develops an electrostatic latent image formed on a photoreceptor such as an electrophotographic copying machine, a facsimile, and a printer with a toner, and converts the toner image into a toner image. Attaching a density sensor that detects the density of the target image formed on the photoreceptor of an image forming apparatus that transfers to a copy sheet.Especially, it can be retracted from the vicinity of the photoreceptor when clearing jams or replacing the photoconductor unit. The present invention relates to a device for mounting a target image density sensor that can be accurately positioned with respect to a photoconductor.

[Conventional technology]

Conventionally, an electrostatic latent image formed on a photosensitive drum or a photosensitive belt is developed with a toner charged to a polarity opposite to that of the latent image to form a toner image, and the toner image is formed at a peripheral speed of the photosensitive drum or the photosensitive belt. In a toner image transfer type image forming apparatus that forms an image by transferring an image on a copy sheet sent at the same speed as that of the copy sheet, the copy sheet is disposed horizontally to facilitate jam removal around a photosensitive drum or the like. The image forming apparatus is configured to be separable into an upper part and a lower part with the paper transport path as a boundary, and both are pivotally mounted at one end, so that the upper part can be opened upward in a crocodile or bivalve shape. It is known to

Further, as shown in FIG. 8, a target having a density of about 0.4 to 0.7 gray solid is attached under a platen support for supporting a platen glass, and the target is placed on an image area on a photoreceptor every predetermined number of copies. The image is developed by projecting it onto the inter-image section between the two, and the density of the developed target image is detected by a photo sensor, for example. If the detected density of the target image on the photosensitive drum is higher than a specified value, When the supply of toner is stopped, the current of the illumination lamp is increased to increase the amount of light, and the density of the target image on the photosensitive drum is set to a specified value. If it is too thin, start supplying toner to the developing unit and lower the developing bias voltage to the developing roll of the developing unit to regulate the density of the target image on the photosensitive drum. Image density automatic adjustment apparatus that are known.

[Problems to be solved by the invention]

By the way, when the image density automatic adjusting device for forming the target image on the inter-image portion as described above is employed, the sensor is usually provided below (upstream) the cleaning device.
To adjust the positioning. By the way, a belt conveying device that conveys the sheet after the transfer is disposed below the cleaning device. The gap between the belt conveying device and the cleaning device is small, and copy paper is jammed around the sensor (jam). When removing jammed paper, problems such as scratching the photoreceptor, making the position of the sensor itself defective, and dropping toner adhering to the cleaning device and contaminating the sensor surface may occur. there were. Further, when the photosensitive drum or the photosensitive member unit is attached to or detached from the image apparatus for replacement or the like, the sensor may collide with the photosensitive member and damage one or both of the sensor and the photosensitive member.

The present invention has been made in view of such a situation, and an object of the present invention is to solve the above-described problems, to configure the apparatus to be separable into an upper portion and a lower portion, and to connect both at one end. In an image forming apparatus in which the upper portion is pivotally mounted so that the upper portion can be opened upward and the photosensitive drum or the photosensitive belt is detachably attached to the upper portion, the vicinity of the photosensitive drum or the photosensitive belt when the upper portion of the device is opened in one direction The present invention provides a target image density sensor mounting device in which a target image density sensor is mounted so as to be retractable from a photoconductor. Also, this mounting device includes
A paper-conveying gear wheel is provided to cooperate with a belt-conveying device provided on the lower part of the apparatus to help transfer the paper after transfer, so that the paper-conveying gear wheel with the target image density sensor is attached simultaneously. You can also

[Means for solving the problem]

A target image density sensor mounting apparatus in an image forming apparatus according to the present invention that achieves the above object is configured such that the apparatus is separable into an upper part and a lower part, both of which are pivotally mounted at one end, and the upper part is separated upward. An image forming apparatus in which a photosensitive drum or a photosensitive belt-shaped photosensitive member is detachably attached to an upper portion so as to be openable, and includes a target image density sensor for detecting a density of a toner image of a target formed on the photosensitive member. In the image forming apparatus, the target image density sensor located near the photoconductor when the upper portion of the apparatus is opened halfway is attached so as to be retractable from the photoconductor.

In this case, a lever-shaped sensor support member having a target image density sensor attached to one end is rotatably attached to the upper part of the apparatus at the other end, and the sensor is supported by the weight of the sensor support member when the upper part of the apparatus is partially opened. The member rotates and the target image density sensor is arranged to retreat from the photoreceptor, and when the upper part of the device is closed, the lower part of the device abuts on the sensor support member and puts the sensor support member under its own weight. When the target image density sensor is positioned against the photoreceptor at a predetermined position where the density can be detected by pressing against the stopper member of the upper part, the upper part of the apparatus is opened, and any other operation is performed. Instead of this, the target image density sensor automatically retracts from the photoconductor in conjunction with it, and closes the upper part of the device. , The sensor support member since it is positioned pressed against the stopper member, the position of the sensor is set correctly, a desired form.

In addition, a gear-shaped wheel that assists in sheet conveyance in cooperation with the sheet conveyance belt on the lower part of the apparatus when the upper part of the apparatus is closed is rotatable at any position of the lever-shaped sensor support member. In this case, a single supporting member can support a target image density sensor and a gear-shaped wheel that assists in transporting a sheet.

Further, as another form, a lever-shaped sensor support member having a target image density sensor attached to one end is rotatably attached to the upper portion of the apparatus at the other end, and the sensor support member is elastically stable across the middle point. It is urged by a spring member so as to take two positions. At one stable position, the target image density sensor is arranged so as to be positioned at a predetermined position where the density can be detected with respect to the photoconductor, and the other is positioned. In a stable position, the target image density sensor is disposed so as to retreat from the photoconductor, and one of the above two stable positions can be selected by an operating member integrally attached to the sensor support member, so that the present invention is possible. An apparatus for mounting a target image density sensor according to the present invention can be realized.

In this case, when the sensor support member is selected to take one stable position by the operation member, the operation member is disposed at a position where the photosensitive member cannot be attached or detached, and the sensor support member is moved to the other stable position by the operation member. When the position is selected, if the operating member is arranged at a position where the photoconductor can be detached, the sensor is always separated from the photoconductor when the photoconductor is removed or attached from the apparatus. It has the advantage of not damaging the body and the sensor.

[Action]

In the present invention, the target image density sensor, which was located near the photoconductor when the upper part of the apparatus was opened halfway, was attached so as to be able to retract from the photoconductor, so that jammed paper jammed around the photoconductor could be removed. When attaching or removing the photoconductor, the surface of the photoconductor may be damaged, the position of the sensor with respect to the photoconductor may be disturbed, and toner adhering between the cleaning device and the photoconductor may fall on the sensor and be removed. There is no danger of soiling the surface.

〔Example〕

Hereinafter, an apparatus for mounting a target image density sensor according to the present invention will be described based on embodiments.

1 and 2 are views showing a schematic configuration of an electrophotographic copying machine to which a target image density sensor mounting device according to the present invention is applied. The copying machine 1 includes an upper portion 1a and a lower portion 1b. , Which are attached to each other so as to be pivotable about a pivot shaft 2 at one end. In the upper part 1a of the apparatus, among the components constituting the copying machine 1, a photosensitive unit 5 in which a cleaning device 4 for a photosensitive drum 3 is integrated, a rail 6 for mounting the photosensitive unit 5, an exposing device 7, a color developing device Device 8a, black developing device 8b, platen 9, target 10, etc. are attached (main charger,
An inter-image lamp and the like are also attached, but are not shown. ), And the lower part 1b of the apparatus includes a transfer charger 11, a paper removing and erasing device 12, a belt conveying device 13, a fixing device.
14, a paper cassette 15, a registration gate 16, a discharge tray 17, and the like are mounted (other paper transport systems are also mounted). FIG. 1 does not show a photosensor for detecting the density of the developed toner image on the target 10 formed on the inter-image portion on the surface of the photosensitive drum 3, and a mounting device therefor.

In the copying machine 1, a portion 1a above a line shown by a dotted line in FIG. 1 is turned upward around a turning shaft 2 as shown in FIG. Photosensitive drum 3
Is exposed, so that paper jammed around the paper transport path 18 and the photosensitive drum 3 can be easily removed. In this open state, the photoconductor unit 5 is attached and detached back and forth along a rail 6 attached to the machine frame of the upper portion 1a.

Incidentally, a photo sensor for detecting the density of the target image formed on the surface of the photosensitive drum 3 is mounted below the cleaning device 4 in the upper portion 1a.
When the copy paper jammed around the sensor is removed by opening 1a, the surface of the photosensitive drum 3 may be damaged, or the position of the sensor with respect to the photosensitive drum 3 may be changed.
There is a possibility that the toner adhering to the cleaning device 4 falls on the sensor and stains its surface. Therefore,
In one embodiment of the present invention, as shown in FIG. 3, there is provided a lever-shaped sensor support member 20 for supporting the photosensor 22 at one end, and the other end of this support member 20 is supported on a support shaft below the rail 6. Attach it freely around 21. Therefore, when the upper part 1a of the device 1 is open,
The support member 20 is suspended from the support shaft 21 at the other end by its own weight, and the photo sensor 22 at one end is at a position away from the photosensitive drum 3. In this state, the support member
The clockwise rotation of 20 in the drawing of FIG. 3 is limited by the abutment of the abutment surface 28 at the other end with the lower surface of the rail 6. Further, in the drawing, the counterclockwise rotation of the support member 20 is limited by the contact between the abutting portion 27 provided near one end thereof and the stopper member 29 provided below the cleaning device 4. In the contact state, the photo sensor 22 enters a detection state in which the photo sensor 22 approaches the photosensitive drum 3 (described later). Incidentally, a long hole 25 intersecting the axial direction is provided in the middle of the support member 20, and a shaft 30 for rotatably supporting the sheet conveying gear wheel 26 is freely movable in the long hole 25 direction in the long hole 25. Attached to. The support member 20
At one end opposite to the support shaft 21, a butting piece is formed extending toward the near side from the drawing of FIG. 3 and bent downward at the tip.
23 is provided integrally, and a spring portion 24 for giving elasticity to the abutting piece 23 is provided in the middle of a portion bent below the abutting piece 23. The photo sensor
The attachment piece 22 may be attached to a portion of the attachment piece 23 extending toward the front side from the drawing in FIG. 3 so that the side view is as shown in FIG. 3 (actually, the attachment piece is attached in this manner). .
Further, a belt conveying device 13 located below the cleaning device 4 includes a belt 13a stretched between two rollers.
And a roller support member 13b extending on both sides thereof (in the front-back direction of the drawing), and when the upper part 1a is closed (FIG. 4),
The tip of the abutment piece 23 of the support member 20 is a roller support member 13b.
, The paper transport gear wheel 26 rides on the belt 13a by its own weight, and is in a positional relationship of rotating following the movement of the belt 13a.

In the sensor mounting device having such an arrangement, when the upper part 1a of the device 1 is closed (FIG. 1), first, as shown in FIG. 13, the support member 20 is rotated in a counterclockwise direction until the abutting portion 27 provided near the tip of the roller support member 13 b abuts against a stopper member 29 provided at a lower portion of the cleaning device 4. Further rotation of the upper portion 1a is absorbed by a spring portion 24 provided on the abutment piece 23, and the support member 20 is
At 27, the stopper member 29 is reliably kept in contact. In this abutting position, the photo sensor 22 attached to the tip of the support member 20 is accurately oriented toward the center of the photosensitive drum 3, is positioned at a predetermined fixed distance from the surface, and is formed on the surface. The density of the target image can be reliably detected. In this position, the paper transport gear wheel 26 movably mounted in the long hole 25 rides on the belt 13a by its own weight, and has passed the positions of the transfer charger 11 and the paper peeling and removing device 12. And the like is transported in cooperation with the belt 13a.

When a sheet is jammed around the photosensitive drum 3 or in the sheet transport path 18 (FIG. 2), or in order to attach / detach the photosensitive unit 5 to / from the apparatus 1, as shown in FIG. When opened around the pivot 2, the support member 20 rises together with the upper portion 1 a and separates above the belt conveying device 13, and rotates by its own weight until the contact surface 28 at the other end abuts against the lower surface of the rail 6. The photo sensor 22 at the leading end of the photo sensor 22 is separated from the photosensitive drum 3 and spread between them as shown. Therefore, when removing jammed paper jammed around the photosensitive drum 3 or attaching / detaching the photosensitive unit 5,
The surface of the photosensitive drum 3 may be damaged, the position of the sensor 22 with respect to the photosensitive drum 3 may be deviated, and the toner adhering between the cleaning device 4 and the photosensitive drum 3 may fall on the sensor 22 to remove the surface. There is no risk of soiling. When the upper portion 1a is closed again, the abutting portion 27 abuts against the stopper portion 29, the photo sensor 22 is accurately positioned, and the density of the target image can be correctly detected.

3 and 4, the sensor 22 and its support member 20 are automatically separated from the photosensitive drum 3 when the upper portion 1a of the device 1 is opened upward. However, even when the upper portion 1a of the apparatus 1 is opened upward, the sensor 22 and the support member 20 do not automatically separate from the photosensitive drum 3 but separate only by rotating the lever. This will be described with reference to FIGS. 5 to 7. In this embodiment, the sensor support member 20
Is a rail 6 which is rotatable about a shaft 21 'integrated therewith.
And a lever 31 is fixed to an end on the near side of the shaft 21 '. Therefore, by rotating the lever 31 clockwise, the support member 22 can be rotated in the same direction, and the photo sensor 22 can be separated from the photosensitive drum 3 (FIG. 5). By rotating the support member 22 in the same direction, the abutting portion 27 abuts against the stopper member 29 so that the photosensor 22 is brought close to the photosensitive drum 3 to accurately determine its position (the sixth position). Figure). Two stable holding positions of the support member 20 which are switched by operation of the lever 31;
That is, the position where the contact surface 28 of the sensor support member 20 abuts against the lower surface of the rail 6 and the position where the abutment portion 27 abuts on the stopper member 29 are obtained by the action of the over-center spring 32. Figure 7 shows this spring
32 is a view of the vicinity of the sensor support member 20 viewed from the rear side to explain the operation of the sensor support member 32. In the position of the angle between the separated position in FIG. The over center spring 32 is stretched between the rail 6 and the support member 20 so as to straddle the rotation axis of the support member 20,
When this point is set as a middle point and the support member 20 is rotated to the upper side, the separated position shown in FIG. 9A is stably taken by the force of the spring 32, and conversely, the support member 20 is slightly shifted to the lower side beyond the middle point. When it is turned, the position shown in FIG.
Therefore, when the upper portion 1a of the apparatus 1 is opened from the state shown in FIG. 6 and the lever 31 is rotated clockwise, as shown in FIG.
Separate from. Conversely, when the lever 31 is rotated in the counterclockwise direction in the state of FIG.
22 approaches the photosensitive drum 3 and a desired position is determined.
Thereafter, when the upper portion 1a is closed, the state shown in FIG. 6 is obtained. By the way, the fixing position of the lever 31 with respect to the support member 22 prevents the removal of the photoconductor unit 5 from the rail 6 to the near side when the photosensor 22 is close to the photoconductor as shown in FIG. As shown in FIG. 5, if the photosensor 22 is selected at a position where the photoconductor unit 5 is allowed to be removed for the first time when the photosensor 22 is separated from the photoconductor, the photosensor 22 must be removed when the photoconductor is removed or attached from the apparatus. Has an advantage that the photoconductor 3 and the sensor 22 are not damaged.

Although two embodiments have been described above, the present invention is not limited to these embodiments, and various modifications are possible. For example, the present invention can be applied to an image forming apparatus in which only a photosensitive drum or a photosensitive belt is detachable, instead of using a detachable photosensitive unit in which a photosensitive drum and a cleaning device are integrated. In this case, for example, a lever
What is necessary is just to make it disturb the removal of the photoreceptor.

〔The invention's effect〕

In the target image density sensor mounting device in the image forming apparatus of the present invention, the target image density sensor, which was located near the photoconductor when the upper part of the device was half-opened, was removably mounted from the photoconductor. When removing jammed paper around the body, removing or attaching the photoconductor, it may damage the surface of the photoconductor, change the position of the sensor with respect to the photoconductor, or adhere to the gap between the cleaning device and the photoconductor. This eliminates the risk that the toner falling on the sensor and contaminate the surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are views showing a schematic configuration of an electrophotographic copying machine to which a target image density sensor mounting device of the present invention is applied, and FIG. FIG. 2 shows a closed state, FIG. 2 shows an open state, and FIGS. 3 and 4 are front views of the vicinity of a target image density sensor mounting apparatus according to an embodiment of the present invention, and FIG. FIG. 4 shows a closed state of the upper part of FIG. 5, and FIGS. 5 and 6 are similar to FIGS. 3 and 4 of another embodiment of the present invention. FIG. 7 is a view from the rear side near the sensor support member in the case of FIGS. 5 and 6, and FIG. 8 shows the image density by forming an image of the target in the inter-image part and detecting the density. It is a figure showing the principle of the device which adjusts. DESCRIPTION OF SYMBOLS 1 ... Electrophotographic copying machine, 1a ... Upper part, 1b ... Lower part, 2 ... Swivel axis, 3 ... Photosensitive drum, 4 ... Cleaning device, 5 ... Photoconductor unit, 6 ... Rail , 7 ...
Exposure device, 8a ... Color developing device, 8b ... Black developing device, 9 ... Platen, 10 ... Target, 11 ... Transfer charging device, 12 ... Paper separation static eliminator, 13 ... Belt transport device,
13a belt, 13b roller support member, 14 fixing device, 15 paper feed cassette, 16 register gate, 17 discharge tray, 18 paper transport path, 20 sensor support member, 21 ... shaft, 21 '... shaft, 22 ... photo sensor,
23… Abutment piece, 24… Spring part, 25 …… Long hole, 26 ……
Paper-conveying gear wheel, 27 abutment, 28 contact surface, 29 stopper member, 30 shaft, 31 lever, 32 overcenter spring

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/08 115 G03G 21/00 520 21/00 520 B41J 29/12 C

Claims (5)

(57) [Claims] An apparatus is constituted so as to be separable into an upper part and a lower part, and both are pivotally mounted at one end so that the upper part can be opened to one side upward, and a photosensitive drum or photosensitive belt-shaped photosensitive member is provided on the upper part. In an image forming apparatus having a target image density sensor for detecting the density of a toner image of a target formed on a photoreceptor, wherein the upper part of the apparatus is partially opened, Wherein the target image density sensor, which is located near the photoconductor, is removably mounted on the photoconductor. 2. A lever-shaped sensor support member having a target image density sensor attached to one end thereof is rotatably attached to an upper portion of the apparatus at the other end, and the weight of the sensor support member is increased when the upper portion of the apparatus is opened halfway. The sensor support member is rotated so that the target image density sensor is retracted from the photoconductor, and when the upper portion of the device is closed, the lower portion of the device abuts the sensor support member and removes the sensor support member. 2. The target according to claim 1, wherein the target image density sensor is positioned so as to be positioned at a predetermined position where the density of the target image can be detected with respect to the photosensitive member by pressing the stopper against the stopper member of the upper portion against its own weight. Mounting device for image density sensor. 3. A gear-shaped wheel which cooperates with a sheet conveying belt on a lower portion of the apparatus when the upper section of the apparatus is closed at any position of the lever-shaped sensor support member to assist in sheet conveyance. 3. The apparatus for mounting a target image density sensor according to claim 2, wherein the apparatus is rotatably mounted. 4. A lever-like sensor support member having a target image density sensor attached to one end thereof is rotatably attached to an upper portion of the apparatus at the other end, and the two elastically stable sensor support members sandwich the middle point. It is urged by a spring member so as to take a position, and in one stable position, the target image density sensor is arranged so as to be positioned at a predetermined position where the density can be detected with respect to the photoconductor, and the other stable position In the position, the target image density sensor is disposed so as to retreat from the photoconductor, and one of the two stable positions can be selected by an operation member integrally attached to the sensor support member. Item 2. A mounting device for a target image density sensor according to Item 1. 5. A sensor supporting member which is disposed at a position where the photosensitive member cannot be attached or detached when the sensor supporting member is selected to take one of the stable positions by the operating member. 5. The target image density sensor mounting apparatus according to claim 4, wherein the operation member is disposed at a position where the photosensitive member is detachable when the other is selected to take the other stable position.