JP2021183523A - Image forming device - Google Patents

Abstract

To provide an image forming device capable of inhibiting a residual amount of recording medium from being erroneously determined.SOLUTION: A residual amount detection unit 18 of an image forming device 100 detects a residual amount of a recording medium P in paper feeding cassettes 11. The residual amount detection unit 18 includes an encoder 20, a photo-sensor 30 and a control unit 5. The encoder 20 rotates so that an inclination angle θ2 to a horizontal plane changes according to a reduction in the residual amount of the recording medium P. The photo-sensor 30 detects a transmitted light amount between a light projection part 31 and a light receiving part 32. The control unit 5 determines the residual amount of the recording medium P based on a change in the transmitted light amount. The encoder 20 includes a plurality of light shield plates 25, 26 and 27 crossing sequentially between the light projection part 31 and the light receiving part 32 according to a change in the inclination angle θ2. The light shield plates 25, 26 and 27 include front edge parts 25a, 26a and 27a and rear edge parts 25b, 26b and 27b inclined to respective moving directions.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image forming apparatus.

The image forming apparatus described in Patent Document 1 includes a paper feed cassette, a paper feed unit, an image forming unit, and a remaining amount detecting unit. The paper cassette contains a recording medium. The paper feed unit presses against the uppermost surface of the recording medium and feeds out the recording media one by one from the paper feed cassette. The image forming unit forms an image on the recording medium fed by the paper feeding unit. The remaining amount detection unit detects the remaining amount of the recording medium in the paper cassette. The paper cassette has a bottom plate and a lift mechanism. A recording medium is placed on the bottom plate. The lift mechanism drives the bottom plate so that the first tilt angle indicating the tilt angle of the bottom plate with respect to the horizontal plane increases as the remaining amount of the recording medium decreases. The remaining amount detection unit includes an encoder, a photo sensor, and a determination unit. The encoder rotates so that the second tilt angle indicating the tilt angle with respect to the horizontal plane changes as the first tilt angle increases. The photo sensor detects the amount of transmitted light between the light projecting unit and the light receiving unit. The determination unit determines the remaining amount of the recording medium based on the change in the amount of transmitted light. The encoder has a plurality of light-shielding plates that sequentially cross between the light-emitting unit and the light-receiving unit according to the change in the second inclination angle. The plurality of shading plates have edges that are orthogonal to each direction of movement.

Japanese Unexamined Patent Publication No. 5-229674

In the image forming apparatus described in Patent Document 1, when the rotation of the encoder stops at the moment when the edge portion of the light shielding plate starts to shield the light projected from the light projecting portion, the light blocking state becomes unstable. It ends up. If vibration is applied to the encoder or the photo sensor in this state, the determination unit erroneously determines the remaining amount of the recording medium.

An object of the present invention is to provide an image forming apparatus capable of suppressing erroneous determination of the remaining amount of a recording medium.

The image forming apparatus of the present invention includes a paper feed cassette, a paper feed unit, an image forming unit, and a remaining amount detecting unit. The paper cassette accommodates a recording medium. The paper feed unit presses against the uppermost surface of the recording medium and feeds out the recording medium one by one from the paper feed cassette. The image forming unit forms an image on the recording medium fed by the paper feeding unit. The remaining amount detecting unit detects the remaining amount of the recording medium in the paper feed cassette. The paper cassette has a bottom plate and a lift mechanism. The recording medium is placed on the bottom plate. The lift mechanism drives the bottom plate so that the first tilt angle indicating the tilt angle of the bottom plate with respect to the horizontal plane increases as the remaining amount of the recording medium decreases. The remaining amount detecting unit includes an encoder, a photo sensor, and a determination unit. The encoder rotates so that the second tilt angle indicating the tilt angle with respect to the horizontal plane changes as the first tilt angle increases. The photo sensor detects the amount of transmitted light between the light projecting unit and the light receiving unit. The determination unit determines the remaining amount of the recording medium based on the change in the amount of transmitted light. The encoder has a plurality of light-shielding plates that sequentially cross between the light-emitting unit and the light-receiving unit in response to a change in the second tilt angle. The plurality of light-shielding plates have edges inclined with respect to each moving direction.

According to the present invention, there is provided an image forming apparatus capable of suppressing erroneous determination of the remaining amount of a recording medium.

It is a schematic diagram which shows an example of the structure of the image forming apparatus which concerns on embodiment. It is sectional drawing which shows an example of the detailed structure of a paper cassette. It is an enlarged front view which shows an example of the structure of an encoder and a photo sensor. FIG. 3 is a sectional view taken along line IV-IV of FIG. It is an enlarged perspective view which shows the detailed structure of an encoder. It is an enlarged plan view which shows the detailed structure of a photo sensor. It is a figure which shows an example of the relationship between the rotation angle of an encoder, and the output of a photo sensor. It is a figure which shows an example of the paper remaining amount determination.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, the same or corresponding parts are designated by the same reference numerals and the description is not repeated.

First, the image forming apparatus 100 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing an example of the configuration of the image forming apparatus 100. In FIG. 1, for convenience, the direction from left to right is the positive direction of the X axis, the direction from the front to the back is the positive direction of the Y axis, and the direction from the bottom to the top is the positive direction of the Z axis. do.

As shown in FIG. 1, the image forming apparatus 100 is a multifunction device. The image forming apparatus 100 includes an image forming unit 1, an image reading unit 2, a document transport unit 3, an operation display unit 4, and a control unit 5.

The image forming unit 1 forms an image on the paper P. The image scanning unit 2 reads an image formed on the original R and generates a scanned image. The document transport unit 3 transports the document R to the image reading unit 2. The operation display unit 4 displays various images and accepts user operations. Paper P corresponds to an example of a “recording medium”.

The control unit 5 includes a processor 5A and a storage unit 5B. The processor 5A includes, for example, a CPU (Central Processing Unit). The storage unit 5B includes a memory such as a semiconductor memory, and may include an HDD (Hard Disk Drive). The storage unit 5B stores the control program.

The image forming unit 1 includes a paper feed cassette 11, a pickup roller 12, a transport roller pair 13, an image forming unit 14, a fixing unit 15, a discharge roller pair 16, and a discharge tray 17. The paper cassette 11 accommodates the paper P. The pickup roller 12 presses against the uppermost surface of the paper P and feeds out the recording medium P one by one from the paper feed cassette 11. The fed paper P is conveyed to the image forming unit 14 by the conveying roller pair 13. The pickup roller 12 corresponds to an example of a “paper feed unit”.

The image forming unit 14 forms an image on the paper P. The image forming unit 14 includes a photoconductor drum, a charging unit, an exposure unit, a developing unit, and a transfer roller.

The paper P on which the image is formed is conveyed to the fixing portion 15. The fixing unit 15 heats and pressurizes the paper P, and fixes the image formed on the paper P to the paper P. The paper P on which the image is fixed is discharged to the discharge tray 17 by the discharge roller pair 16.

Next, the configuration of the paper feed cassette 11 will be described with reference to FIGS. 1 and 2. FIG. 2 is a cross-sectional view showing an example of the detailed configuration of the paper cassette 11.

As shown in FIG. 2, the paper feed cassette 11 includes a lift mechanism 110, a bottom plate 111, a rear end cursor 113, a width matching cursor pair 114, a sheet storage unit 115, a transport roller 117, a feed roller 121, and a handling roller 122. And a support member 123.

The bottom plate 111 is arranged on the inner bottom surface of the sheet storage portion 115 of the paper feed cassette 11, and a plurality of sheets of paper P are placed on the bottom plate 111. The lift mechanism 110 drives the bottom plate 111 so that the first inclination angle θ1 indicating the inclination angle of the bottom plate 111 with respect to the horizontal plane increases as the remaining amount of the paper P decreases. As a result, the uppermost surface of the paper P placed on the bottom plate 111 is pressed against the pickup roller 12.

The lift mechanism 110 includes a push-up member 112, a drive shaft 116, and a support portion 118.

The bottom plate 111 is rotatably supported by the support portion 118 at the upstream end portion (the end portion in the negative direction of the X-axis) of the paper P in the feeding direction. The support portion 118 is provided at both end portions of the sheet storage portion 115 in the width direction (Y-axis direction) of the paper P.

The drive shaft 116 and the push-up member 112 are provided below the bottom plate 111 on the downstream side in the feeding direction of the paper P. The drive shaft 116 extends in a direction intersecting the feeding direction of the paper P (Y-axis direction), and is rotationally driven from the outside of the paper feed cassette 11 by a lift drive motor (not shown). The push-up member 112 includes a base portion fixed to the drive shaft 116 and a tip portion abutting on one main surface of the bottom plate 111.

The rear end cursor 113 aligns the rear edges of the paper P. The rear end cursor 113 is provided so as to be movable in a direction parallel to the feeding direction of the paper P. The width adjustment cursor pair 114 positions the paper P stored in the sheet storage unit 115 in the width direction. The width adjustment cursor pair 114 is provided so as to be movable in the width direction of the paper P along a guide rail (not shown). The rear end cursor 113 and the width adjustment cursor pair 114 are moved according to the size of the loaded paper P, so that the paper P is stored in a predetermined position in the paper feed cassette 11.

The feeding roller 121 feeds the paper P unwound by the pickup roller 12 to the transport roller 117. The feeding roller 121 rotates in the direction of transporting the paper P to the downstream side (positive direction of the X-axis) of the paper P in the feeding direction. The transport roller 117 is provided on the downstream side of the paper P in the feed direction with respect to the feed roller 121. The transport roller 117 transports the paper P to the transport roller pair 13 (see FIG. 1).

The handling roller 122 is provided below the feeding roller 121. Further, the handling roller 122 is in contact with the feeding roller 121. The handling roller 122 rotates in the direction of feeding back the paper P to the upstream side (negative direction of the X-axis) of the paper P in the feeding direction, contrary to the feeding roller 121. Even when the paper P fed by the pickup roller 12 overlaps, the handling roller 122 suppresses the feeding of the paper P other than the uppermost paper P to the transport roller 117. Therefore, only the uppermost paper P is conveyed to the transfer roller 117 by the feed roller 121.

The support member 123 rotatably supports the pickup roller 12 around the rotation axis of the feed roller 121. The pickup roller 12 is configured to be rotatable around the rotation axis of the feeding roller 121.

Next, the configuration of the remaining amount detecting unit 18 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. 3 is an enlarged front view showing an example of the configuration of the encoder 20 and the photo sensor 30. FIG. 4 is a sectional view taken along line IV-IV of FIG. FIG. 5 is an enlarged perspective view showing a detailed configuration of the encoder 20. FIG. 6 is an enlarged plan view showing a detailed configuration of the photo sensor 30.

As shown in FIGS. 3 and 4, the image forming apparatus 100 further includes a remaining amount detecting unit 18. The remaining amount detection unit 18 includes an encoder 20 and a photo sensor 30 on the outer surface of the housing of the paper feed cassette 11 so as to detect the remaining amount of the paper P in the paper feed cassette 11. The encoder 20 rotates so that the second tilt angle θ2, which indicates the tilt angle with respect to the horizontal plane, changes as the first tilt angle θ1 increases. The photo sensor 30 detects the amount of transmitted light between the light projecting unit 31 and the light receiving unit 32. The control unit 5 functions as a determination unit that determines the remaining amount of the paper P based on the change in the amount of transmitted light by executing the control program stored in the storage unit 5B.

As shown in FIGS. 3 and 4, the encoder 20 has a main body portion 21 formed in a fan-shaped plate shape. The main body 21 includes a base fixed to the drive shaft 116.

As shown in FIG. 5, the main body 21 is provided with a circular hole 22 at the base for fixing the encoder 20 to the drive shaft 116. Further, the main body portion 21 includes a tip portion in which the first light-shielding plate 25, the second light-shielding plate 26, and the third light-shielding plate 27 are erected at a certain distance from each other. The first light-shielding plate 25, the second light-shielding plate 26, and the third light-shielding plate 27 sequentially cross between the light-emitting unit 31 and the light-receiving unit 32 in accordance with the change in the second inclination angle θ2. The first light-shielding plate 25 has a leading edge portion 25a and a trailing edge portion 25b inclined with respect to the moving direction of the first light-shielding plate 25. The second light-shielding plate 26 has a leading edge portion 26a and a trailing edge portion 26b that are inclined with respect to the moving direction of the second light-shielding plate 26. The third light-shielding plate 27 has a leading edge portion 27a and a trailing edge portion 27b that are inclined with respect to the moving direction of the third light-shielding plate 27. The leading edge portions 25a, 26a, 27a and the trailing edge portions 25b, 26b, 27b are not limited to linear shapes, but may be formed in a curved shape.

As shown in FIG. 6, the light emitting unit 31 includes a first light emitting element 31a and a second light emitting element 31a arranged along the vertical direction of the first light shielding plate 25, the second light shielding plate 26, and the third light shielding plate 27. The element 31b, the third light emitting element 31c, and the fourth light emitting element 31d are included. The light receiving unit 32 includes a first light receiving element 32a, a second light receiving element 32b, a third light receiving element 32c, and a fourth light receiving element 32d corresponding to the first light emitting element 31a to the fourth light emitting element 31d.

Next, the output of the photo sensor 30 will be described with reference to FIGS. 1 to 7. FIG. 7 is a diagram showing an example of the relationship between the rotation angle of the encoder 20 and the output of the photo sensor 30. Here, it is assumed that the remaining amount of the paper P is approximately 100%, and the first inclination angle θ1 and the second inclination angle θ2 are both approximately 0 degrees.

As shown in FIG. 7, when the rotation angle of the encoder 20 is less than the first angle α1, the light emitted from the first light emitting element 31a to the fourth light emitting element 31d is first without being shielded. Light is received by the light receiving elements 32a to the fourth light receiving elements 32d. That is, since the light receiving unit 32 receives 100% of the transmitted light, the output of the photo sensor 30 is "0". Here, the output "0" is defined as the "Low" state.

When the rotation angle of the encoder 20 is equal to or greater than the first angle α1 and less than the second angle α2 (α2-α1 = γ1), the light emitted from the first light emitting element 31a is the inclined leading edge of the first light shielding plate 25. It is shielded from light by the portion 25a. The light emitted from the second light emitting element 31b to the fourth light emitting element 31d is received by the second light receiving element 32b to the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 75% of the transmitted light, the output of the photo sensor 30 is "1". Here, the output "1" is defined as an "indefinite" state.

When the rotation angle of the encoder 20 is the second angle α2 or more and less than the third angle α3 (α3-α2 = γ1), the light emitted from the first light emitting element 31a and the second light emitting element 31b is the first shading plate. It is shielded from light by the inclined leading edge portion 25a of 25. The light emitted from the third light emitting element 31c and the fourth light emitting element 31d is received by the third light receiving element 32c and the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 50% of the transmitted light, the output of the photo sensor 30 is "2". Here, the output "2" is defined as an "indefinite" state.

When the rotation angle of the encoder 20 is the third angle α3 or more and less than the fourth angle α4 (α4-α3 = γ1), the light emitted from the first light emitting element 31a to the third light emitting element 31c is the first light shielding plate. It is shielded from light by the inclined leading edge portion 25a of 25. The light emitted from the fourth light emitting element 31d is received by the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 25% of the transmitted light, the output of the photo sensor 30 is "3". Here, the output "3" is defined as an "indefinite" state.

When the rotation angle of the encoder 20 is the fourth angle α4 or more and less than the fifth angle β1 (β1-α4 = γ2), the light emitted from the first light emitting element 31a to the fourth light emitting element 31d is the first. The light is shielded by the inclined front edge portion 25a of the light-shielding plate 25. That is, since the light receiving unit 32 receives 0% of the transmitted light, the output of the photo sensor 30 is "4". Here, the output "4" is defined as the "High" state.

When the rotation angle of the encoder 20 is the fifth angle β1 or more and less than the sixth angle β2 (β2-β1 = γ3), the light emitted from the first light emitting element 31a to the third light emitting element 31c is the first shading plate. It is shielded from light by the inclined trailing edge portion 25b of 25. The light emitted from the fourth light emitting element 31d is received by the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 25% of the transmitted light, the output of the photo sensor 30 is in the "3" or "undefined" state.

When the rotation angle of the encoder 20 is the sixth angle β2 or more and less than the seventh angle β3 (β3-β2 = γ3), the light emitted from the first light emitting element 31a and the second light emitting element 31b is the first shading plate. It is shielded from light by the inclined trailing edge portion 25b of 25. The light emitted from the third light emitting element 31c and the fourth light emitting element 31d is received by the third light receiving element 32c and the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 50% of the transmitted light, the output of the photo sensor 30 is in the "2" or "undefined" state.

When the rotation angle of the encoder 20 is 7th angle β3 or more and less than 8th angle β4 (β4-β3 = γ3), the light emitted from the first light emitting element 31a is the inclined trailing edge of the first light shielding plate 25. It is shielded from light by the portion 25b. The light emitted from the second light emitting element 31b to the fourth light emitting element 31d is received by the second light receiving element 32b to the fourth light receiving element 32d without being shielded from light. That is, since the light receiving unit 32 receives 75% of the transmitted light, the output of the photo sensor 30 is in the "1" or "undefined" state.

When the rotation angle of the encoder 20 is the eighth angle β4 or more, the light emitted from the first light emitting element 31a to the fourth light emitting element 31d is not shielded from light, and the first light receiving element 32a to the fourth light receiving element 32a to the fourth light receiving element. The light is received by 32d. That is, since the light receiving unit 32 receives 100% of the transmitted light, the output of the photo sensor 30 is in the "0" and "Low" states.

As the rotation angle of the encoder 20 increases, the output of the photo sensor 30 repeats the state change of "Low"-> "indefinite"-> "High"-> "indefinite"-> "Low" shown in FIG. 7 three times. The number of repetitions is the same as the number of the first light-shielding plate 25 to the third light-shielding plate 27.

Finally, a specific example of determining the remaining amount of paper will be described. FIG. 8 is a diagram showing an example of paper remaining amount determination.

As shown in FIG. 8, the control unit 5 is conditioned on the condition that the output of the photo sensor 30 indicates that the state has changed from the “Low” (transmissive) state to the “High” (light-shielding) state through the “indefinite” state. As a (start-up condition), it is determined that the remaining amount of the paper P has changed. That is, if the number of times the output of the photo sensor 30 transitions from the “Low” state to the “High” state is 0 times, the remaining amount of the paper P is 100%. If the number of times the output of the photo sensor 30 transitions from the “Low” state to the “High” state is once, the remaining amount of the paper P is 75%. If the number of times the output of the photo sensor 30 transitions from the “Low” state to the “High” state is two times, the remaining amount of the paper P is 50%. If the number of times the output of the photo sensor 30 transitions from the “Low” state to the “High” state is three times, the remaining amount of the paper P is 25%.

As shown in FIG. 7, since the “indefinite” state is provided between the “Low” state and the “High” state, even if vibration is applied to the encoder 20 or the photo sensor 30, the remaining paper P remains. Misjudgment of quantity is suppressed. The control unit 5 is conditioned on the condition that the output of the photo sensor 30 indicates that the state has changed from the "High" (light-shielding) state to the "Low" (transmissive) state through the "indefinite" state (falling condition). , It may be determined that the remaining amount of the paper P has changed. Further, the control unit 5 may determine that the remaining amount of the paper P has changed under both the rising condition and the falling condition.

According to the embodiment, as described with reference to FIGS. 1 to 8, an image forming apparatus 100 capable of suppressing erroneous determination of the remaining amount of the paper P is provided.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiment, and can be implemented in various embodiments without departing from the gist thereof. In addition, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, some components may be removed from all the components shown in the embodiments. In order to make the drawings easier to understand, each component is schematically shown, and the number of each component shown may differ from the actual one due to the convenience of drawing. Further, each component shown in the above embodiment is an example, and is not particularly limited, and various changes can be made without substantially deviating from the effect of the present invention.

For example, in the embodiment, the light emitting unit 31 includes the first light emitting elements 31a to the fourth light emitting elements 31d arranged discretely, but the present invention is not limited to this. The light emitting unit 31 and the light receiving unit 32 may be an analog system using slit light whose longitudinal direction is the arrangement direction of the first light emitting element 31a to the fourth light emitting element 31d.

The present invention is available in the field of image forming apparatus.

5 Control unit (judgment unit)
11 Paper cassette 12 Pickup roller (paper feed unit)
14 Image forming unit 18 Remaining amount detection unit 20 Encoder 21 Main body 25 First shading plate 25a Leading edge 25b Trailing edge 26 Second shading plate 26a Trailing edge 26b Trailing edge 27 Third shading plate 27a Leading edge 27b Trailing edge 30 Photosensor 31 Floodlight 31a 1st light emitting element 31b 2nd light emitting element 31c 3rd light emitting element 31d 4th light emitting element 32 Light receiving part 32a 1st light receiving element 32b 2nd light receiving element 32c 3rd light receiving element 32d 4 Light receiving element 100 Image forming device 110 Lift mechanism 111 Bottom plate 112 Pushing member 116 Drive shaft P Paper (recording medium)
θ1 1st tilt angle θ2 2nd tilt angle

Claims (4)

A paper cassette that houses a recording medium and
A paper feeding unit that presses against the uppermost surface of the recording medium and feeds out the recording medium one by one from the paper cassette.
An image forming unit that forms an image on the recording medium fed by the paper feeding unit, and an image forming unit.
A remaining amount detecting unit for detecting the remaining amount of the recording medium in the paper cassette is provided.
The paper cassette is
The bottom plate on which the recording medium is placed and
It has a lift mechanism that drives the bottom plate so that the first tilt angle indicating the tilt angle of the bottom plate with respect to the horizontal plane increases as the remaining amount of the recording medium decreases.
The remaining amount detection unit is
An encoder that rotates so that the second tilt angle indicating the tilt angle with respect to the horizontal plane changes according to the increase in the first tilt angle.
A photo sensor that detects the amount of transmitted light between the light projecting section and the light receiving section,
It has a determination unit that determines the remaining amount of the recording medium based on the change in the amount of transmitted light.
The encoder has a plurality of light-shielding plates that sequentially cross between the light-emitting unit and the light-receiving unit in response to a change in the second tilt angle.
The plurality of light-shielding plates are image forming devices having edges inclined with respect to each moving direction. The lift mechanism is
A drive shaft extending in a direction intersecting the feeding direction below the bottom plate on the downstream side in the feeding direction of the recording medium.
It has a push-up member including a base fixed to the drive shaft and a tip that abuts on one main surface of the bottom plate.
The encoder has a main body portion formed in a fan-shaped plate shape, and has a main body portion.
The image forming apparatus according to claim 1, wherein the main body portion includes a base portion fixed to the drive shaft and a tip portion on which the plurality of light-shielding plates are erected. The light projecting unit includes a plurality of light emitting elements arranged along the erection direction of the plurality of light shielding plates.
The image forming apparatus according to claim 2, wherein the light receiving unit includes a plurality of light receiving elements corresponding to the plurality of light emitting elements. The output of the photo sensor indicates that the output of the photo sensor indicates that the light-transmitting state has transitioned to the light-shielding state through the indefinite state, or that the determination unit has transitioned from the light-shielding state to the light-transmitting state through the indefinite state. The image forming apparatus according to any one of claims 1 to 3, wherein it is determined that the remaining amount of the recording medium has changed.

Images