JP3313850B2 - Image forming device detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting device for an image forming apparatus having a contact type charging device.

[0002]

2. Description of the Related Art In a general electrophotographic image forming apparatus represented by the Carlson process, a corona discharge method, which is a non-contact charging method, is used to uniformly charge a photosensitive member. However, since the corona discharge device discharges by applying a high voltage to a 30 to 100 μm tungsten wire called a corona wire, air is ionized and a large amount of ozone and nitric oxide is formed. This ozone and the like is not only harmful to the human body, but also damages the photoreceptor and the machine. In addition, ozone is particularly prominent when negative discharge is performed. In recent years, the photoreceptor has become an organic photoreceptor for negative charging, and environmental standards for generated gas discharged from an image forming apparatus have become strict. This is a serious problem. Therefore, a contact charging system has been proposed in which a charging member is brought into contact with a photosensitive member to perform charging. This method has the advantages of requiring a small voltage to be applied to the charging member and generating a very small amount of ozone, and therefore has already been commercialized as a roller-shaped contact charging member.

The charging process for forming an image is affected by environmental conditions such as temperature. Therefore, in order to always keep the charged state of the photoconductor constant, it is necessary to control, for example, detecting the temperature of the contact charging member and adjusting the applied voltage of the contact charging member according to the detected temperature. is there.

For example, Japanese Patent Laying-Open No. 4-186381 discloses that a charging member is provided with a temperature detecting sensor, the temperature of the charging member is detected, and the applied voltage is controlled based on the detected temperature.

[0005]

Incidentally, in order to detect the temperature of the contact charging member, Japanese Patent Application Laid-Open No. 4-186381 has been proposed.
It is necessary to bring the temperature detecting sensor into contact with the contact charging member, as in the publication. However, since the contact charging member is usually a roller and rotates with the rotation of the photoreceptor, the surface layer portion of the contact charging member is worn by the temperature detecting sensor which is constantly in contact therewith due to aging. Then, the surface layer is destroyed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent a surface layer of a contact charging member from being worn or broken by a temperature detecting sensor or the like.

[0007]

In order to solve the above-mentioned problems, the present invention relates to a detecting device of an image forming apparatus, which is disposed near a photoconductor (1) for forming an image and is in contact with the photoconductor. Contact-type charging means (3) for charging the charged state in a state; charger-supporting means for movably supporting the contact-type charging means between a position in contact with the photoreceptor surface and a position away therefrom ( 9, 11); positioning means (10, 12) for positioning the contact-type charging means at one of a first position in contact with the photoreceptor surface and a second position distant therefrom; Detecting means (5B) installed at a position where the contact-type charging means is in contact with the contact-type charging means when the contact-type charging means is in the second position, and detecting a state such as a temperature of the contact-type charging means in a state where the contact-type charging means is in contact therewith;
Is provided.

The symbols shown in the parentheses indicate the reference numerals of the corresponding elements in the embodiments described later for reference, but each component of the present invention is a specific element in the embodiments. It is not limited to only.

[0009]

The contact type charging means (3) is movably supported between a first position in contact with the photoreceptor surface and a second position distant therefrom, and the detection means (5B) The contact type charging means is installed at a position where it comes into contact with the contact type charging means when it is at the second position. Therefore, the contact type charging unit contacts the detection unit only when the contact type charging unit is not in contact with the photoreceptor, that is, when the contact type charging unit is not rotating, so that deterioration of the surface of the charging unit due to such contact hardly occurs. That is, good image quality can be maintained for a long time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a photoreceptor peripheral portion of a copying machine embodying the present invention. This will be described with reference to FIG. The photoreceptor 1, which is an image bearing member, is driven to rotate at a predetermined peripheral speed in the direction of the arrow in the figure during the image forming process. Charging device 2
In the image forming process, the surface of the photoconductor 1 is uniformly charged to a predetermined potential. The charging device 2 of this embodiment includes a roller-shaped charging roller 3. The charging roller 3 is constantly pressed against the photoreceptor 1 with a predetermined pressure by a pressure spring (not shown), and rotates in accordance with the rotation of the photoreceptor 1. In the image forming process, a voltage is applied to the charging roller 3 from a DC power supply (not shown), whereby the photoconductor 1 that is in contact with the charging roller 3 is charged.

The image forming process other than charging is the same as in a general copying machine. That is, the surface of the charged photoconductor is exposed to image light, and the potential distribution corresponding to the density of the image,
That is, after the electrostatic latent image is formed, the electrostatic latent image is visualized by a toner of a developing device, and the visible toner image on the photoconductor is transferred to a predetermined transfer paper. Foreign matter such as transfer residual toner and paper dust is removed by
Prepare for the next image forming process.

FIG. 2 shows main components near the charging roller 3.
Shown in This will be described with reference to FIG . As shown in FIG. 2, the charging roller 3 is supported so as to be capable of moving toward and away from the photoconductor 1. That is, the charging roller 3 can move between a position away from the photoconductor 1 as shown by a solid line and a position in contact with the surface of the photoconductor 1 as shown by a virtual line. A temperature sensor 5B for detecting the temperature of the charging roller 3 is fixed to the bracket 20, and when the charging roller 3 is at a position away from the surface of the photoconductor 1 (in a solid line), the temperature sensor 5B 5B, the temperature sensor 5B can detect the temperature of the charging roller 3.

Referring to FIG. 3 , a pressure spring 10 is attached to a moving member 9 which is passed through a core bar protruding from both ends of the charging roller 3, and the charging roller 3 is 1
0 presses the photosensitive member 1 with a predetermined force. One end of the moving member 9 is supported by the charging device 2, and the other end is supported by the moving lever 11.

Referring to FIG. 4 , a solenoid 12 is connected to one end of a moving lever 11, and the solenoid 1
When the switch 2 is in the ON operation (b), the moving member 9 is lifted, the charging roller 3 is separated from the photoconductor, and contacts the temperature sensor 5B for temperature detection, so that the temperature can be measured. When the solenoid 12 is OFF (a), the charging roller 3 is pushed down by the force of the pressure spring 10,
Pressure is applied to the photoconductor 1. The charging roller 3 is separated from the temperature sensor 5B .

[0015] (not shown) for implementing control such an image forming process of the copying machine control device (microcomputer - data)
5 is shown in FIG. The operation of the control device will be described with reference to FIG. When the print start key is pressed during the standby operation of the copying machine, the control device outputs a predetermined ON control signal and turns on the solenoid 12 . When a predetermined time T has elapsed since the output of the ON control signal, a predetermined temperature detection process is executed. That is, the temperature sensor 5 B in contact with the charging roller 3 by sampling the signal to be output, and inputs the updated temperature information of the charging roller 3. Based on this temperature information, the value of the charging DC voltage applied to the charging roller 3 is determined. Thereafter, the control device outputs an off control signal to turn off the solenoid 12 . Thus, the temperature sensor 5 B is again moved away from the charge roller 3.

Thereafter, a control signal for driving the photosensitive member 1 is output, and a normal image forming process is performed. That is, it is possible to photoreceptor 1 is completed the work of the temperature detection when the stop before the rotation, since the charging roller 3 does not rotate when the charging roller 3 temperature sensor 5 B are in contact, the temperature sensor 5 B Even if it is in contact, the charging roller 3 is hardly worn.

The charging roller 3 is provided with a pulse generator or the like as rotation detecting means, and controls the timing of turning on / off the solenoid 12 and the timing of starting temperature detection based on a signal output from the pulse generator. Good
No.

[0018] In the above embodiment, the charging roller 3
Although the description has been given of the case where the detection means for detecting the state of the temperature sensor is a temperature sensor, the image forming process is also affected by environmental conditions other than temperature, for example, humidity. Detection means may be installed. Therefore, other detecting means may be provided together with or instead of the temperature sensor.

[0019]

The contact- type charging means (3) is movably supported between a first position in contact with the surface of the photoreceptor and a second position distant therefrom. )
Is installed at a position where it comes into contact with the contact-type charging means when the contact-type charging means is at the second position. Therefore, the contact type charging unit contacts the detection unit only when the contact type charging unit is not in contact with the photoreceptor, that is, when the contact type charging unit is not rotating, so that deterioration of the surface of the charging unit due to such contact hardly occurs. That is, good image quality can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a front view illustrating a configuration of a main part of a copying machine according to an embodiment.

FIG. 2 is a front view showing a configuration near a charging roller 3 of the copying machine shown in FIG.

FIG. 3 is a front view showing details of a part of FIG. 2 ;

4 is a side view of the moving lever 11 shown in FIG.

FIG. 5 is a flowchart showing processing of the control device.

[Explanation of symbols]

 1: Photoreceptor 2: Charging device 3: Charging roller 5B: Temperature sensor 6: Sensor mounting member 9: Moving member 10: Pressure spring 11: Moving lever 12: Solenoid 20: Bracket

──────────────────────────────────────────────────続 き Continued on the front page (72) Kentaro Matsumoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Naoshi Hayakawa 1 Nakamagome, Ota-ku, Tokyo No.3-6, Ricoh Co., Ltd. (72) Inventor Yoshiaki Miyashita 1-3-6, Nakamagome, Ota-ku, Tokyo Incorporation Ricoh Co., Ltd. (72) Inventor Takeshi Tabuchi, Nakamagome, Ota-ku, Tokyo 1-3-6, Ricoh Co., Ltd. (56) References JP-A-6-118770 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/02

Claims (1)

(57) [Claims] 1. A detecting device of an image forming apparatus, comprising: a contact-type charging unit disposed near a photoreceptor for forming an image and charging the photoreceptor while contacting the photoreceptor; Charger support means for movably supporting between a position contacting the photoconductor surface and a position away therefrom; a first position contacting the contact-type charging means with the photoconductor surface; Positioning means for positioning at any one of the separated second positions; and the contact type charging means is provided at a position in contact with the contact type charging means when the contact type charging means is at the second position. Detecting means for detecting a state of the contact type charging means such as temperature; and a detecting device for the image forming apparatus.