JP2886695B2 - Sensor mounting device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, in which a latent image carrier such as a photosensitive drum and a peripheral device such as a cleaning device are unitized. The present invention relates to a device for mounting a sensor for automatically adjusting image density, which is applied to a system which enables the sensor.

[0002]

2. Description of the Related Art Recently, a latent image carrier such as a photosensitive drum and peripheral devices such as a charger and a cleaning device are unitized, and a copying machine, a printer, etc. of a system in which this photosensitive unit can be replaced after a predetermined number of copies are made. Image forming apparatuses have been widely used due to their good maintainability. In this replacement system, there are a system in which the crocodile cover of the apparatus is opened to take out the photoconductor unit from above the apparatus, and a system in which the cover in front of the apparatus is opened and the photoconductor unit is pulled out in the horizontal direction.

On the other hand, there is known a system in which a photo sensor is provided in proximity to a photosensitive drum to automatically adjust the image density. This will be described with reference to FIG. 3. 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 attached to an image area on a photosensitive drum every predetermined number of copies. Projected and developed, the density of the developed target image is detected by a photo sensor, and when the detected density of the target image is higher than a specified value, the supply of toner to the developing device is stopped and the illumination lamp is turned off. The current is increased to increase the amount of light, and the density of the target image is set to a specified value. Conversely, when the detected density of the target image is lower than the specified value, the supply of toner to the developing device is started and the developing device is started. The developing bias voltage to the developing roll is lowered to bring the density of the target image to a specified value.

[0004]

In the case of employing the automatic image density adjusting device, a photosensor is usually arranged at a lower portion (upstream side) of the cleaning device to adjust the position between the photosensor and the photosensitive drum. By the way, below the cleaning device, a belt transport device that transports the paper after transfer is arranged, and the gap between the belt transport device and the cleaning device is narrow, and when the copy paper jams around the sensor. When removing jammed paper, there were problems such as scratching the photosensitive drum, making the position of the sensor itself defective, and dropping toner adhering to the cleaning device and soiling the sensor surface. . More importantly, when the image density automatic adjustment device is adopted in a system in which the photoconductor unit can be attached to and detached from the apparatus main body, when the photoconductor unit is attached to and detached from the apparatus main body for replacement or the like,
There is a problem that the sensor and the photosensitive drum collide and damage one or both of the sensor and the photosensitive drum.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem. In an image forming apparatus in which a photoreceptor unit can be attached to and detached from an apparatus main body, a sensor for automatically adjusting image density can be removably attached. An object of the present invention is to provide a sensor mounting device that can prevent a failure of a sensor and a photosensitive drum.

[0006]

For this purpose, a sensor mounting device in an image forming apparatus according to the present invention is an image forming apparatus in which a photosensitive unit in which a photosensitive drum and its peripheral devices are unitized is detachably mountable to an apparatus body. A sensor for automatically adjusting the density, a sensor mounting lever rotatably disposed on the apparatus main body so that the sensor can be separated from and connected to the photosensitive drum, and a rotatable mounting apparatus mounted with a belt conveying device mounted thereon. A transfer frame provided, a sensor moving plate fixed to the transfer frame, and a plate spring fixed to the sensor transfer plate and capable of pressing the sensor mounting lever. The image density automatic adjustment sensor is retracted from the photosensitive drum in conjunction with the retraction of the image.

In addition, a transfer device rotatably provided on the transport frame may be provided, and the transfer device may be retracted from the photosensitive drum in conjunction with the retraction of the transport frame from the photosensitive drum. Good.

[0008]

In the present invention, the sensor for automatically adjusting the image density is retracted from the photosensitive drum in conjunction with the retraction of the transport frame from the photosensitive drum. Remove the jammed paper around the photosensitive drum when pulling it out of the main body of the device, damage the surface of the photosensitive drum when attaching or detaching the photosensitive unit, change the position of the sensor with respect to the photosensitive drum, There is no danger that the toner adhering to the cleaning device falls on the sensor and stains its surface.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are side views showing one embodiment of a sensor mounting device in the image forming apparatus of the present invention. FIG. 1 shows a state in which a sensor for automatic image density adjustment is retracted from a photosensitive drum, and FIG. The state where the same sensor is arranged on the photosensitive drum is shown.

The overall configuration of an example of a copying machine to which the present invention is applied is composed of a photoreceptor unit including a photoreceptor drum and a cleaning device, a charger unit, a developing unit, a transfer unit, in addition to an exposure unit fixed to the apparatus. Unit, fuser unit, and paper tray, each of which can be independently pulled out toward the front of the machine, and which can be removed from the machine for maintenance and replacement such as paper jams and cleaning. Is available. The photoreceptor unit is configured to be replaced with a new one every 100,000 copies, for example.

In FIG. 1, a photoreceptor unit 1 has a photoreceptor drum 2 and a cleaning device 3 and is removably disposed on a support rail 6 fixed to a main body of the device by bolts 5. A pivot 7 is fixed to the apparatus main body, and a sensor mounting lever 10 is rotatably provided on the pivot 7 via a spring 9. Sensor mounting lever 1
0, a sensor 11 for automatic image density adjustment consisting of a photo sensor and a tracking roll 12 for positioning the sensor 11 for automatic image density adjustment and the photosensitive drum 2 are provided. In 10,
The locking portion 13 is provided, and the sensor driving circuit portion 15 is provided.
Is installed.

Below the photoreceptor unit 1, a belt transport device 16 and a transfer device 17 are provided. The belt transport device 16 includes a transport frame 19 rotatable about a shaft 18.
And a belt transport mechanism 20 provided on the transport frame 19
And a rotating lever 2 for rotating the transport frame 19.
1 and a locking lever 22 connected to the rotating lever 21. The rotating lever 21 is connected to gears 23 and 25 attached to the apparatus main body. Also, the transport frame 19
, A sensor moving plate 26 is attached, and a leaf spring 27 and a stopper member 29 are fixed to the tip of the sensor moving plate 26.

The transfer device 17 includes a transfer device 30 and a static eliminator 3
1 has a transfer frame 32 attached thereto, and the transfer frame 32 is rotatably attached to the transport frame 19 via a shaft 33. A locking piece 35 is formed at one end of the transfer frame 32, and the locking piece 35 can be fitted into a locking hole 36 formed in the transport frame 19.

The operation of the present invention having the above configuration will be described. FIG. 1 is a diagram when a copy paper jam occurs or when the photoconductor unit 1 is pulled out of the apparatus main body. The belt transport device 16, the transfer device 17, and the image density automatic adjustment sensor 11 are retracted from the photoconductor drum 2. It shows the state where it was turned on. When the locking lever 22 and the rotating lever 21 are rotated counterclockwise from this state, the transfer frame 19 rotates around the shaft 18 and the transfer frame 32 rotates the shaft 33 as shown in FIG. It rotates about the center, and the belt conveying device 16
And the transfer device 17 moves in the direction of the photosensitive drum 2, and the locking pieces 35 of the transfer frame 32
6, the belt conveying device 16 and the transfer device 17 are set at the copyable position. At the same time, the sensor movement plate 26 attached to the transport frame 19 also rotates counterclockwise, and the stopper member 29 is disengaged from the locking portion 13 of the sensor attachment lever 10. Is pressed against the spring 9, and the image density automatic adjustment sensor 11 is set at the position shown in FIG.

When the locking lever 22 and the rotating lever 21 are rotated clockwise from the state shown in FIG. 2, the transport frame 19 rotates about the shaft 18 and the transfer frame 32 as shown in FIG. Is rotated about a shaft 33, and the locking pieces 35 of the transfer frame 32 are locked by the locking holes 3 of the transport frame 19.
6, the belt conveyance device 16 and the transfer device 17 move in a direction away from the photosensitive drum 2. At the same time,
The sensor movement plate 26 and the plate spring 27 attached to the transport frame 19 also rotate clockwise, the sensor attachment lever 10 is urged by the spring 9, and the image density automatic adjustment sensor 11 is moved to the position shown in FIG. And the stopper member 29 is locked by the locking portion 13 of the sensor mounting lever 10.

The present invention is not limited to the above embodiment, and various modifications can be made by those having ordinary knowledge in the technical field to which the present invention belongs. For example, in the above-described embodiment, an example of the photoconductor unit including the photosensitive drum and the cleaning device is described. However, for example, a charging device, a developing device, and the like may be added to the photoconductor unit.

[0017]

As described above, according to the present invention, the sensor for automatically adjusting the image density can be retracted from the photosensitive drum when a jam occurs or when the photosensitive unit 1 is pulled out from the apparatus main body. When removing jammed paper around the photosensitive drum, or when attaching or removing the photosensitive unit, the surface of the photosensitive drum is damaged, the position of the sensor with respect to the photosensitive drum is changed, or the sensor is attached to the cleaning device. There is no danger of toner dropping onto the sensor and soiling its surface.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a sensor mounting device in an image forming apparatus of the present invention, showing a state in which a sensor for automatically adjusting image density is retracted from a photosensitive drum.

FIG. 2 is a side view showing a state where the sensor is arranged on a photosensitive drum from the state of FIG. 1;

FIG. 3 is a diagram for explaining the principle of an image density automatic adjustment sensor;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photoreceptor unit, 2 photosensitive drum, 3 peripheral device (cleaning device), 10 sensor mounting lever, 11
... Sensor for automatic adjustment of image density, 16 ... Belt transporter,
19: transport frame, 26: sensor moving plate, 2
7 ... leaf spring.

Claims (2)

(57) [Claims] An image forming apparatus in which a photosensitive unit in which a photosensitive drum and its peripheral device are unitized is detachably mountable to an apparatus main body, a sensor for automatically adjusting image density, and the sensor is detachable from the photosensitive drum. A sensor mounting lever rotatably disposed on the apparatus main body, a transport frame on which a belt transport apparatus is mounted and rotatably disposed on the apparatus main body, and a sensor moving plate fixed to the transport frame And a leaf spring fixed to the sensor moving plate and capable of pressing the sensor mounting lever, and retreating the image density automatic adjustment sensor from the photosensitive drum in conjunction with the retreat of the transport frame from the photosensitive drum. A sensor mounting device in an image forming apparatus, wherein: 2. The image forming apparatus according to claim 1, further comprising a transfer device rotatably provided on said transport frame, wherein said transfer device is retracted from said photosensitive drum in conjunction with retreat of said transport frame from said photosensitive drum. 2. A sensor mounting device in the image forming apparatus according to claim 1.