JP2002096943A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect, using one and same sensor, whether or not there is a storage medium in a cassette and the time when the end of the storage medium passes. SOLUTION: This image forming device includes a cassette storing sheets of recording paper; two contact hands, that is, a first contact hand 6b for making contact with the sheets of recording paper in the cassette, and a second contact hand 6a for making contact with the sheets of recording paper upon rotation of the first contact hand 6b when the sheets of recording paper are fed from within the cassette; and a common sensor having a light shield plate 4 provided in such a manner as to be rotatable about a rotating shaft 5 for shielding a photointerruptor 2 against light only when the first contact hand 6b is in contact with the recording paper, the common sensor detecting whether or not there is recording paper in the cassette and the time when the end of the recording paper passes.

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 for forming a toner image on a recording medium using an electrophotographic process, and more particularly, to the presence or absence of a recording medium in a cassette and the passage of a leading end of a recording medium supplied from the cassette. The present invention relates to a technology that is effective when applied to a technology for detecting timing.

[0002]

2. Description of the Related Art Conventionally, various image forming apparatuses have been proposed as output terminals of personal computers and workstations.

Here, an image forming apparatus using an electrophotographic process includes a charging step, an exposing step, a developing step, a transferring step,
An image is formed by sequentially executing processes such as a fixing step.

Hereinafter, the configuration and operation of a conventional image forming apparatus will be described. FIG. 4 is a schematic diagram showing a configuration of a conventional image forming apparatus.

As shown in FIG. 4, an image forming apparatus comprises a photosensitive drum (photosensitive member) 101 having an organic photoconductive substance attached on an electrode thin film on the surface of a metal drum such as aluminum and rotating in the direction of arrow A. A charging device (charging means) 102 configured by a wire 113 made of tungsten, etc., and a grid plate 114 having a mesh shape, and performing a charging step of uniformly charging the surface of the rotating photosensitive drum 101 to a predetermined potential; A lens (not shown) and a polygon mirror (not shown) for scanning the semiconductor laser light are provided therein, and the semiconductor laser light 120 obtained by optically modulating the image data is irradiated onto the surface of the charged photosensitive drum 101. An exposure optical system (exposure means) 105 for executing an exposure step for forming an electrostatic latent image, and toner 116 on a photosensitive drum 101 on which the electrostatic latent image is formed are developed by a developing roller 115. A developing device (developing means) 103 for performing a developing process for visualizing an electrostatic latent image by feeding, and the developing device 10
3 includes a transfer roller (transfer unit) 106 for executing a transfer step of transferring a toner image formed on the surface of the photosensitive drum 101 to a recording paper (recording medium) 117, and a plurality of light emitting diodes (not shown). And the transfer roller 106
Eliminator 107 for removing the potential remaining on the surface of the photosensitive drum 101 after the toner image has been transferred onto the recording paper 117, a heating roller 118 including a heat source such as a halogen lamp (not shown), and a heating roller 118. And a fixing unit 108 configured to perform a fixing step of fixing the transferred toner image to the recording paper 117, and a discharge tray for discharging the recording paper 117 on which the toner image is fixed. 1
11 is formed in the upper part.

The recording paper 117 is conveyed at a constant speed by rotating the photosensitive drum 101, the developing roller 115, the heating roller 118, the pressure roller 119, and the like at a constant speed via a gear or a belt (not shown). Drive motor 112 is provided. As the drive motor 112, a known DC servo motor or stepping motor is used.

Then, the photosensitive drum 101, the charger 10
2. The developing unit 103 and the electricity removing unit 107 are provided as a unit in a detachable process cartridge (process unit) 104.

The image forming apparatus shown in FIG.
A recording paper cassette (cassette) 109 in which the recording papers 17 are stored is provided below, and a paper feed roller 110 for taking out the recording papers 117 in the recording paper cassette 109 one by one and guiding the recording papers 117 to a transport path is provided. I have.

In such an image forming apparatus, a recording paper presence / absence detection sensor 121 for detecting the presence / absence of recording paper 117 in the recording paper cassette 109, the recording paper 1 traveling on the conveyance path,
Sheet feed sensor 12 for detecting the timing of passage of the front end of the sheet feeder 17
2. The discharge tray 111 for the recording paper 117 after the toner image is fixed
Each sensor of the paper discharge sensor 123 for detecting paper discharge to the paper is disposed.

Next, the printing operation of the image forming apparatus having such a configuration will be described.

Control means (hereinafter, referred to as control means) for controlling a printing operation in accordance with a printing request from a host computer (not shown)
It is called “CPU”. ) Is a recording paper presence / absence detection sensor 121
, The presence or absence of the recording paper 117 is detected. Then, when it is detected that all the devices are equipped and normal printing can be performed, the process waits for a printing operation. On the other hand, when it is detected that the recording paper 117 is not installed and printing cannot be performed normally,
An error message is transmitted to the user via a control panel (not shown) or the like.

When a printing request is input from the host computer while waiting for a printing operation, the CPU rotates the drive motor 112 to perform a charging process, an exposing process, a developing process, a transferring process, a fixing process, and the like. Controls the printing operation.

In the printing operation, first, the CPU feeds the recording paper 117 by the paper feed roller 110,
The timing at which the leading end of the recording paper 117 fed by the printer 2 is passed is detected and used as a reference timing for the printing operation.

Further, it is determined whether the leading edge passage timing detected by the paper feed sensor 122 is a predetermined time from the start of rotation of the paper feed roller 110, and if it is the predetermined time, the printing operation is continued. Otherwise, the recording paper 117 is not normally fed due to a paper jam or the like, so an error message is transmitted to the user via a control panel (not shown) or the like.

Photosensitive drum 101 rotating in the direction of arrow A
In the charging step, the wire 113 in the charger 102 is
A high voltage is applied in a DC manner to cause a corona discharge to generate a voltage of about −700 V on the grit plate 114, thereby uniformly charging the surface of the photosensitive drum 101 to about −700 V.

Next, in the exposure step, the paper feed sensor 12
The exposure optical system 1 according to characters and image pattern data transmitted from an image processing unit (not shown) at a predetermined timing based on the reference timing of the printing operation detected by the
The semiconductor laser beam 120 irradiated from step 05 is modulated, and the semiconductor laser beam 120 is irradiated on the surface of the photosensitive drum 101. Then, since the portion irradiated with the semiconductor laser light 120 has increased electric conductivity, the electric charge disappears only in that portion, and an electrostatic latent image is formed on the surface of the photosensitive drum 101.

In the developing step, the developing device 103 charges the toner 116 to about -300V. Then, the toner 116 charged to about -300 V is adsorbed on the surface portion of the photosensitive drum 101 where the charge has been eliminated by the irradiation of the semiconductor laser light 120, and the development is performed by the negative-positive process.

In the transfer step, the toner adsorbed on the surface of the photosensitive drum 101 is transferred to the recording paper 117 by the electrostatic Coulomb force of the transfer roller 106 to which a voltage of about +1000 V is applied to the surface. The residual potential on the surface of the photoconductor drum 101 after the transfer is removed by the neutralizer 107.

In the fixing step, the toner image transferred to the recording paper 117 is fixed by the holding pressure of the pressure roller 119 in the fixing device 108 and the heat of the heating roller 118.

Then, the recording paper 11 on which the toner image is fixed
7 is discharged onto a discharge tray 111. At this time, the paper discharge sensor 123 detects the leading edge passage timing of the discharged recording paper 117, and the CPU determines whether the detected timing is a predetermined time from the reference timing of the printing operation detected by the paper feed sensor 122. Determine whether And
If it is a predetermined time, it waits for the next printing operation.If it is not the predetermined time, the printing operation has not been completed normally due to a paper jam or the like, so through the control panel or the like,
Communicate the error message to the user.

As described above, the CPU controls the timing of the printing operation, the passage timing of the recording paper 117 during the printing operation,
The timing of the entire apparatus is controlled while detecting the presence or absence of the recording paper 117 in the recording paper cassette 109 by a sensor. The operation of these sensors will now be described with reference to FIG.

FIG. 5 is an explanatory diagram showing a detection operation of a sensor using a photo interrupter in a conventional image forming apparatus.

In the sensor shown in FIG. 5, a light emitting diode (not shown) as a light emitting element and a phototransistor (not shown) as a light receiving element are incorporated in one unit so as to face each other. (Hereinafter referred to as “light shield plate”) 126 is a transmission type photointerrupter 124 for detecting the presence or absence of an object 126. Note that reference numeral 12
5 is a light shielding plate 126 and a contact hand 128 that contacts the detection target.
Is an actuator rotatable about a rotation shaft 127.

Such a photo interrupter 124 is
Light shielding plate 1 that is moved by rotation of actuator 125
26, the presence or absence of the recording paper presence sensor 12
1. It can be applied to the paper feed sensor 122, the paper discharge sensor 123, and the like. That is, the recording paper 117 is
When the contact is not made, the contact 128 is at the position A, and the photo interrupter 124 detects the light shielding plate 126. On the other hand, when the recording paper 117 comes into contact with the contact hand 128, the contact hand 128 is pushed up to the position B by the recording paper 117, and the photo interrupter 124 does not detect the light shielding plate 126. As described above, by detecting the presence or absence of the light shielding plate 126 by the photo interrupter 124, it is possible to detect the presence or absence of the recording paper 117 that contacts the contact hand 128.

Therefore, the photo interrupter 124 and the actuator 125 are arranged at predetermined positions where the contact hand 128 is rotated depending on the presence or absence of the recording paper 117 in the recording paper cassette 109, so that the recording paper presence / absence detection sensor 1 is provided.
21. Further, by disposing the photo interrupter 124 and the actuator 125 at predetermined positions where the contact hand 128 is rotated by the passage of the recording paper 117 in the paper feeding unit or the paper discharging unit, the paper feeding sensor 12
2 and the paper ejection sensor 123.

[0026]

However, the above-described recording paper presence / absence detection sensor is provided above the recording paper cassette, and the paper supply sensor is provided at a predetermined position in the recording paper transport path of the paper supply unit.
Since they are arranged independently of each other, a board for mounting each sensor is required.

Therefore, the conventional image forming apparatus involves an increase in cost due to an increase in the number of parts, a poor connection due to the connection of an electric cable to a connector, an increase in man-hours at the time of assembling the apparatus, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of detecting the presence or absence of a recording medium in a cassette and the timing at which the leading end of the recording medium passes by the same sensor.

[0029]

In order to solve this problem, an image forming apparatus according to the present invention comprises a photosensitive member, charging means for uniformly charging the surface of the photosensitive member, and Exposure means for irradiating light corresponding to image data to form an electrostatic latent image, developing means for visualizing the electrostatic latent image formed on the photoreceptor with toner, and a developing means formed on the photoreceptor Transfer means for transferring the toner image to the recording medium; fixing means for fixing the transferred toner image to the recording medium; a cassette containing the recording medium; a first contact hand for contacting the recording medium in the cassette; When the recording medium is fed from the cassette, the first contact is rotated to contact the recording medium by rotating the first contact and the two contacts and the first contact come into contact with the recording medium. The light shielding plate that shields the light shielding plate detector only when Rotatably provided at the center, it is obtained by a configuration having a common sensor for detecting the passage timing of the presence and the sheet tip of the recording medium in the cassette.

With this configuration, the light-shielding plate detecting section detects the light-shielding plate rotating by the first and second contacts that are rotated depending on the presence or absence of the recording medium, so that the presence or absence of the recording medium in the cassette and the cassette during image formation. It is possible to detect both the passage timing of the leading end of the recording medium fed from the same sensor by the same sensor.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a photosensitive member, a charging means for uniformly charging the surface of the photosensitive member, and a light corresponding to image data on the charged photosensitive member. Exposure means for forming an electrostatic latent image by irradiating the toner, developing means for visualizing the electrostatic latent image formed on the photoconductor with toner, and a toner image formed on the photoconductor on a recording medium. Transfer means for transferring, a fixing means for fixing the transferred toner image to the recording medium, a cassette containing the recording medium, a first contact hand for contacting the recording medium in the cassette, and the recording medium from the cassette. The light-shielding plate is turned on only when the first contact hand is in contact with the recording medium by rotating the first contact hand when the sheet is fed and the second contact hand that contacts the recording medium. A light-shielding plate that shields the detector is provided so as to be rotatable around the rotation axis. An image forming apparatus having a shared sensor for detecting the presence / absence of a recording medium and the passage timing of the leading end of the recording medium in a cassette, wherein the light-shielding plate is rotatably moved by first and second contacts that rotate depending on the presence / absence of the recording medium. Is detected by the light-shielding plate detecting section, the same sensor can detect both the presence or absence of the recording medium in the cassette and the passage timing of the leading end of the recording medium fed from the cassette during image formation. Having.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted. Further, since the overall configuration and operation of the apparatus are the same as those of the conventional image forming apparatus described above, the repeated description is omitted here.

FIG. 1 is an explanatory view showing a shared sensor using a photo interrupter mounted on an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a detection operation of the shared sensor in FIG. 3 is a flowchart showing a detection process by the shared sensor of FIG.

In the shared sensor shown in FIGS. 1A and 1B, a light-emitting diode (not shown) as a light-emitting element and a phototransistor as a light-receiving element are incorporated in one case in parallel, so that a The transmissive photo-interrupter (light-shielding plate detection unit) 2 that detects the presence or absence of an object (hereinafter, referred to as “light-shielding plate”) 4 located directly on the substrate 1 is mounted on the substrate 1. Reference numeral 3 denotes an actuator in which the light shield plate 4 and the second contact hand 6a and the first contact hand 6b that directly contact the detection target are rotatable about the rotation shaft 5, and The length of the rotating shaft 5 and the second contact hand 6 are set so that the contact hand 6a and the first contact hand 6b contact the detection target.
a, the shape such as the length of the first contact 6b is adjusted, and the shape of the light shielding plate 4 is arranged so that the photo interrupter 2 can detect the light shielding plate 4.

The photo-interrupter 2 detects the presence or absence of the light-shielding plate 4 which is rotated by the second contact hand 6a and the first contact hand 6b which rotate depending on the presence or absence of the detection object, thereby detecting the recording paper cassette. Recording paper 1 in 109
17 and the recording paper cassette 1 when forming an image.
09 and the passage timing of the leading end of the recording paper 117 fed from the printer.

More specifically, as shown in FIG. 2, the second contact hand 6a comes into contact with the recording paper 117 fed from the recording paper cassette 109 at the time of image formation, and detects the passage timing of the leading end. The first contact 6b is the recording paper cassette 109
Then, the presence or absence of the recording paper 117 is detected by contacting the recording paper 117 in the inside.

FIG. 2B shows the recording paper cassette 1
9 shows a state in which the recording paper 117 is mounted in the recording paper 09. In this state, the first contact hand 6b is pushed up by the recording paper 117, the actuator 3 rotates, and the photo interrupter 2 detects the light shielding plate 4. (Light shielding state). On the other hand, FIG. 2C shows a state in which there is no recording paper 117 in the recording paper cassette 109.
The contact hand 6b is located below and the photo interrupter 2 does not detect the light shielding plate 4 (transmission state).

As described above, the presence or absence of the light shielding plate 4 (light shielding or transmission state) is detected by the photo interrupter 2 so that the recording paper cassette 109 which comes into contact with the first contact 6b.
The presence or absence of the recording paper 117 is detected. If it is detected that there is no recording paper 117 in the recording paper cassette 109 and printing cannot be performed normally, an error message is transmitted to the user via a control panel (not shown) or the like, and the user receives the recording paper 117. Recording paper 117 in cassette 109
Replenish.

That is, before the image is formed, the recording paper 117 is mounted in the recording paper cassette 109, and as shown in FIG. 2B, the recording paper 117 comes into contact with the first contact 6b. I have. At this time, as described above, the photo interrupter 2 is in a state of detecting the light shielding plate 4.

When the image formation is started, the recording paper 117 fed from the recording paper cassette 109 comes into contact with the second contact 6a, and as shown in FIG. When the light 6a is depressed, the light-shielding plate 4 rotates out of the detection area of the photo-interrupter 2, and the photo-interrupter 2 does not detect the light-shielding plate 4. Therefore, by detecting the timing at which the light shielding plate 4 is detected (FIG. 2B) and the light shielding plate 4 is not detected (FIG. 2A), the passage timing of the leading end of the recording paper 117 is detected. can do.

Now, the flow of the detection process in the image forming apparatus using the shared sensor operating as described above will be described with reference to FIG.

First, when the power is turned on (S1), CP
U rotates the drive motor 112 to rotate the photosensitive drum 101
And the heating roller 118 and the like in the fixing unit 108 are rotationally driven,
Initial processing such as cleaning of the surface of the photosensitive drum 101 and generation of heat from an internal heat source to heat the heating roller 118 are performed, and the process shifts to a standby state (S2).

Next, the photo-interrupter 2 of the shared sensor
Is detected in a light-shielded state (S3). If the light-shielded state is detected, it is determined that the recording paper 117 is installed in the recording paper cassette 109, and a host computer (not shown) is used.
If a print request is input from (S6), the printing process is started (S7). If a print request is not input from the host computer (S6), the process returns to the standby state (S2).

On the other hand, in S3, the photo interrupter 2
Is in a transparent state, it is determined that the recording paper 117 is not installed in the recording paper cassette 109, and a normal printing operation cannot be performed. Therefore, an error message is transmitted to the user via a control panel (not shown) or the like. (S4). Then, the recording paper 117 is stored in the recording paper cassette 109 by the user.
Is supplied and the photointerrupter 2 enters a light-shielding state (S5), the process shifts to a standby state (S2). If it is in the transparent state, an error message is continuously transmitted to the user via the control panel or the like (S4).

When the printing process is started in S7, the recording paper 117 is fed from the recording paper cassette 109, and when the photo-interrupter 2 shifts from the light shielding state to the transmitting state (S8), the timing of the fed recording is determined. It is detected as the passage timing of the leading edge of the paper 117 (S9). And
Using the detected passage timing of the leading end of the recording paper 117 as the reference timing of the printing process, the subsequent printing process is continued (S10), and when the printing process ends normally, the standby state is resumed (S2).

On the other hand, in S8, the photo interrupter 2
In the light-shielded state, it is determined whether a predetermined time has elapsed since the start of the printing process (S11). If it is within the predetermined time, the printing process is continued (S7). Thus, it is determined that the recording paper 117 is not normally fed, and a paper feed error message is displayed via a control panel or the like to inform the user (S12). Then, it is determined whether or not the user has performed a predetermined process to recover from the sheet feeding error (S13). If the recovery process is performed, the process returns to the standby state (S2). If the recovery process is not performed, the control is continued. A paper feed error message is displayed via a panel or the like (S12).

As described above, according to the image forming apparatus of the present embodiment, the light shielding plate 4 that is rotated by the second contact 6a and the first contact 6b that rotate with or without the recording paper 117 is provided. Is detected by the photo interrupter 2, the same sensor detects both the presence or absence of the recording paper 117 in the recording paper cassette 109 and the passage timing of the leading end of the recording paper 117 fed from the recording paper cassette 109 during image formation. It becomes possible.

As a result, parts such as a plurality of sensors, a board for mounting the sensors, electric cables, and the like are reduced, and it is possible to prevent a cost increase, a contact failure at the time of wiring, an increase in man-hours at the time of assembly, and the like. .

[0049]

As described above, according to the present invention, the light-shielding plate detecting section detects the light-shielding plate which is rotated by the first and second contact hands which rotate depending on the presence or absence of the recording medium. And the passage of the leading edge of the recording medium fed from the cassette during image formation can be detected by the same sensor.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a shared sensor using a photo interrupter mounted on an image forming apparatus according to an embodiment of the present invention;

FIG. 2 is an explanatory diagram showing a detection operation of the shared sensor of FIG. 1;

FIG. 3 is a flowchart showing detection processing by the shared sensor of FIG. 1;

FIG. 4 is a schematic diagram illustrating a configuration of a conventional image forming apparatus.

FIG. 5 is an explanatory diagram showing a detection operation of a sensor using a photo interrupter in a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 2 photointerrupter (light-shielding plate detection unit) 4 light-shielding plate 5 rotating shaft 6a second contact hand 6b first contact hand 117 recording paper (recording medium)

Claims (1)

[Claims] A photosensitive member; a charging means for uniformly charging the surface of the photosensitive member; and an exposure device for irradiating the charged photosensitive member with light corresponding to image data to form an electrostatic latent image. Means, developing means for visualizing the electrostatic latent image formed on the photoconductor with toner, transfer means for transferring the toner image formed on the photoconductor to a recording medium, Fixing means for fixing the toner image to the recording medium, a cassette containing the recording medium, a first contact hand for contacting the recording medium in the cassette, and feeding of the recording medium from the cassette. When the first contact hand is rotated, the first contact hand is rotated only when the two contact hands and the first contact hand that contact the recording medium are in contact with the recording medium. The light shield plate that shields the light shield detector rotates An image forming apparatus, comprising: a shared sensor rotatably provided around an axis, and detecting presence / absence of the recording medium in the cassette and detecting passage timing of the leading end of the recording medium.