JPH07206215A - Sheet detector - Google Patents

Abstract

PURPOSE:To prevent misdetection of whether a paper sheet is present or not, by providing an inclination part having such an inclination face that light from a projection part radiates on parts except a light receiving part, in a position facing to a reflection type sensor across a paper sheet in a sheet storage part. CONSTITUTION:A light reflection type sensor 100 composed of a light projection part 100a and a light receiving part 100b is provided at an upper part of a paper supply cassette 30 of a copying machine to detect whether paper sheets are existed in a paper feed cassette 34 or not. A notch is formed in a load board 70 at a part radiated by the light from the projection part 100a and an inclination part 101 is formed in the bottom of a case main body 32 at the lower part of the notch in such a state that its tip side is positioned downward. The inclination part 101 and its surroundings are coated with black paint so as to adsorb light from the projection part 100a. Even if sensitivity of the sensor 100 is improved, reflection light from parts except a paper sheet is thus restricted to radiate on the light receiving part 100b so as to prevent misdetection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet detecting device, and more particularly to a sheet detecting device for detecting the presence / absence of a sheet stored in a sheet storage portion.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine is provided with a sheet feeding device for feeding a sheet to an image forming section.
The sheet feeding device includes a sheet feeding cassette for storing sheets, a forward feeding roller for feeding the sheets in the sheet feeding cassette, and a double feeding prevention mechanism for sequentially feeding the sheets fed by the forward feeding roller one by one. And have.

In such a paper feeding device, a paper detection device for detecting that there is no more paper in the paper feeding cassette is provided. The paper detection device is composed of a reflection type sensor arranged above the paper feed cassette, and black paint is applied to the bottom surface of the paper feed cassette facing the reflection type sensor. Here, when there is a sheet in the paper feed cassette, the light emitted from the reflection type sensor is reflected by the sheet and returns to the reflection type sensor again to confirm the presence of the sheet. On the other hand, if there is no more paper in the paper cassette,
The light from the reflective sensor is absorbed by the black portion on the bottom of the cassette and does not return to the reflective sensor. As a result, it is detected that there is no more paper in the paper feed cassette.

[0004]

In the paper feed cassette,
Not only white paper but also colored paper is stored. Colored paper has a lower reflection efficiency than white paper, so
When colored paper is stored, it is necessary to increase the sensitivity of the reflective sensor. On the other hand, although black paint is applied to the bottom of the paper feed cassette, it reflects a small amount of light, so if the sensitivity of the reflective sensor is too sensitive to detect colored paper, It detects a small amount of reflected light. In this case, it is erroneously detected that there is paper even though the paper has run out.

An object of the present invention is to reduce false detection of the presence or absence of paper. Another object of the present invention is to reduce erroneous detection of the presence or absence of paper with a simple structure.

[0006]

A sheet detecting device according to the present invention is a device for detecting the presence / absence of a sheet accommodated in a sheet accommodating portion, and comprises a reflection type sensor and an inclined portion. The reflection type sensor is arranged apart from the sheet accommodated in the sheet accommodating section and has a light projecting section and a light receiving section. The inclined portion is arranged at a position facing the reflective sensor with the sheet in the sheet storage portion interposed therebetween, and has an inclined surface such that the light from the light projecting portion is reflected to a portion other than the light receiving portion.

In the sheet detecting device according to another aspect of the present invention, an antireflection film for deteriorating the reflection efficiency is formed on the inclined surface of the inclined portion. In a sheet detecting device according to still another aspect of the present invention, the sheet storage unit is a paper feed cassette mounted in the image forming apparatus, and the inclined portion is formed by inclining a part of a bottom portion of the paper feed cassette. There is.

[0008]

In the sheet detecting apparatus according to the present invention, light is emitted from the light projecting portion of the reflection type sensor. When there is a sheet, the light is reflected on the surface of the sheet and is received by the light receiving portion of the reflective sensor. This confirms the presence of the sheet. On the other hand, when there is no sheet, the light from the light projecting portion is applied to the inclined portion. The inclined portion has an inclined surface, and the light emitted to the inclined portion is reflected by a portion other than the light receiving portion of the reflective sensor.

Here, even if the sensitivity of the reflection type sensor is made sensitive, it is possible to prevent reflected light from a portion other than the sheet from entering the light receiving portion of the sensor, and erroneous detection is reduced. In the sheet detecting device according to another aspect of the present invention, the antireflection film is formed on the inclined surface of the inclined portion. Therefore, the reflected light of the light irradiated on the inclined surface is very small, and the false detection can be further reduced.

A sheet detecting apparatus according to another aspect of the present invention detects the presence / absence of a sheet in a sheet feeding cassette of an image forming apparatus. At this time, since the inclined portion is formed by inclining a part of the bottom portion of the paper feed cassette, erroneous detection can be reduced with a simple structure.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a copying machine as an image forming apparatus in which a paper feeding device according to an embodiment of the present invention is adopted. In FIG. 1, an original placing table 2 on which an original is placed is arranged on the upper surface of the copying machine main body 1. A document holder 3 is provided on the upper surface of the document table 2 so as to be openable and closable. Copier body 1
External paper feed units 4a and 4b are attached to the bottom of the. Further, on the left side of the copying machine main body 1 in the drawing, a paper discharge tray 5 for mounting discharged paper is mounted. Further, on the right side, a paper feed tray 6 for manual paper feed is attached so as to be openable and closable.

Inside the copying machine main body 1, a reading device 10 for reading the image information of the original document on the original document table 2,
An image forming unit 11 is provided below the document reading device 10 to form an image on a sheet, and a sheet feeding device 12 is provided below the image forming unit 11 to feed the sheet to the image forming unit 11. Has been. Further, on the downstream side of the image forming unit 11 in the paper conveyance direction, a paper conveyance device 13, a fixing device 14 for fixing an image formed on the paper, and a discharge for discharging the paper to the discharge tray 5. The roller 15 is provided in order.

The image forming section 11 has a photosensitive drum 16 on the surface of which an electrostatic latent image is formed.
6, a main charging device 17 that charges the photoconductor drum 16 with electric charges, a developing device 18 that develops the electrostatic latent image on the photoconductor drum 16, and a transfer device that transfers the developed toner image to a sheet. A device 19, a separating device 20 for separating the paper from the photosensitive drum 16, and a cleaning device 21 for removing the residual toner on the photosensitive drum 16 are arranged.

The external sheet feeding units 4a and 4b each have a sheet feeding cassette, and each sheet feeding cassette can be pulled out to the front side. As shown in FIG. 2, an opening 25 as an external paper feeding unit mounting portion is provided on the right side of the copying machine main body 1 and below the manual paper feeding tray 6.
When the external paper feeding unit cannot be mounted, the mounting opening 25 is covered by the cover 26.

On the other hand, the external paper feeding units 4a and 4b have
A mounting member 2 for mounting the paper feeding unit in the upper copying machine body 1 or the upper paper feeding unit 4a, respectively.
7 is fixed. Below the mounting member 27, an opening 28 having the same shape as the mounting opening 25 provided in the copying machine main body 1 is provided. The mounting member 27 of the upper sheet feeding unit 4a is fixed to the mounting opening 25 of the copying machine body 1, and the lower sheet feeding unit 4b has the mounting member 27 of the upper sheet feeding unit 4a.
Is attached to the mounting opening 28 of. Here, when the external paper feeding units 4a and 4b are attached, the cover 2 that covers the attachment opening 25 of the copying machine main body 1
6 is an opening 28 for mounting the lowermost sheet feeding unit 4b.
It is designed to be attached to.

Here, the cover 26 covering the mounting opening 25 of the copying machine body 1 can be used also as the cover of the paper feeding unit 4, and the members can be used efficiently. Next, the sheet feeding device 12 will be described. The sheet feeding device 12 includes a sheet feeding cassette 30 for storing sheets.
And a paper feed mechanism 31 for feeding the paper from the paper feed cassette 30 to the image forming unit 11 side.

The paper feed cassette 30 is formed in a box shape as shown in FIGS. 1 and 3, and has a case body 32 having a substantially rectangular parallelepiped shape and a width adjusting mechanism 33 for adjusting the width of the stored paper. And a pressure contact mechanism 34 (see FIG. 4) for pressing the paper against the paper feed mechanism 31 side. As shown in FIG. 5, the case body 32 is movable in the front-rear direction along the guide frames 35a and 35b on the copying machine body side. A plurality of guide rollers 36 are rotatably provided on the guide frames 35a and 35b on the copying machine body side. Further, guide grooves 32a and 32b (see FIG. 6) that fit into the guide rollers 36 are formed on the bottom surface of the bottom of the case body 32. The guide grooves 32a and 32b are formed at both ends of the case body 32 along the front-rear direction. One guide groove 32a is formed in a concave shape so that the upper portion of the guide roller 36 can be fitted therein. Similarly, the guide roller 36 can be fitted into the other guide groove 32b, but the outer side is open.

The guide grooves 32a, 32b having such a structure
By forming the case main body 32, the guide roller 3
6 and the concave guide groove 32a can limit the lateral movement of the paper feed cassette when the paper feed cassette is pulled out,
It is possible to prevent the catching at the time of pulling out, and to smoothly take in and out the paper feed cassette. See also FIG.
As is clear from the above, the guide frame 35 on the copying machine main body side
The side surface of the case main body 32 on the side contacting b is protruded outward from the inner side and the front side compared to the central portion, and these protruding portions abut the guide frame 35b on the guide surfaces 32c and 32d. Has become. A space 32e is formed between the guide surfaces 32c and 32d so as not to contact the guide frame 35b.

As described above, a pair of front and rear guide surfaces 32 are provided.
By forming c and 32d, the contact area between the case main body 32 and the guide frame 35b is reduced, and together with the concave guide groove 32a described above, it is possible to suppress the positional deviation when the sheet cassette is pulled out, and at the same time, supply Smoother loading and unloading of paper cassettes. Next, the width adjusting mechanism 33 will be described.

The width adjusting mechanism 33 provided in the paper feeding cassette 30 has a pair of width adjusting guide members 40 as shown in FIGS. The width adjusting guide member 40 is formed in an L shape, and the side wall 40a extending in the vertical direction abuts the side portion of the sheet to perform the width adjusting. Paper cassette 3
0 on the bottom of the case body 32 along the width direction of the paper 1
A pair of guide grooves 41 are formed. A rack 42 is arranged on the lower surface of the guide groove 41, and the rack 42 is connected to the bottom portion 40 b of the width adjusting guide member 40 through the guide groove 41. Therefore, the width adjusting guide member 40 and the rack 42 can move in the paper width direction along the guide groove 41. As shown in FIG. 8, the rack 42 fixed to each of the pair of width-adjustment guide members 40 has tooth portions 42a formed on the side surfaces facing each other. Further, a pinion gear 43 is arranged on the lower surface of the substantially central portion of the case body 32 of the paper feed cassette 30. The pinion gear 43 meshes with the tooth portions 42 a of the rack 42 fixed to each of the pair of width adjustment guide members 40. An adjustment plate 44 is arranged above the pinion gear 43 and on the upper surface of the bottom of the case body 32. A support shaft 45 is fixed to the lower surface of the central portion of the adjusting plate 44 so as to project downward.
The pinion gear 43 is rotatably supported by the support shaft 45. The hole 46 of the case main body 32 through which the support shaft 45 penetrates is an elongated hole as shown in FIGS. 8 and 9.
A screw 47 for fixing the adjusting plate 44 to the bottom of the case body 32 penetrates an elongated hole 44 a formed in the adjusting plate 44. Therefore, by loosening the screw 47, the pinion gear 43 can be moved in the width direction together with the adjusting plate 44.

Next, the paper feed mechanism 31 will be described. As shown in FIG. 4, the sheet feeding mechanism 31 contacts the uppermost sheet in the sheet feeding cassette 30 to feed the sheet, and the pre-feed roller 5
0, a double feed prevention mechanism 51 provided on the downstream side of the front feed roller 50 in the paper feed direction, and a separation mechanism 53 for separating the feed roller 50 from the paper of the paper feed cassette 30.

The double feed prevention mechanism 51 has a paper feed roller 55 and a friction pad 56 which is pressed against the paper feed roller 55. The paper feed roller 55 is fixed to an intermediate portion of the paper feed shaft 57, and is rotated counterclockwise in FIG. 4 by a drive system (not shown). The paper feed shaft 57 is rotatably supported between the rear frame and the front frame 1a of the copying machine body 1. The friction pad 56 is fixed to the upper surface of the pad housing 58, and the pad surface is located above the upper surface of the housing 58 (on the side of the paper feed roller 55). One end of the pad housing 58 is rotatably attached to the case main body 32 of the paper feed cassette 30, and the upper end portion thereof is rotatable about the fulcrum P. A pressure contact spring 59 is arranged between the pad housing 58 and the case main body 32, and the pad housing 58 is constantly driven by this spring 59.
It is biased to the 5 side.

As shown in FIGS. 10 and 11, the paper feed roller 55 has a collar 55a fixed to the paper feed shaft 57 by a spring pin 61 and an elastic portion made of resin or the like fixed to the outer periphery of the collar 55a. 55b. One end of the paper feeding shaft 57 on the front side of the apparatus is rotatably supported by a bearing 62 mounted on the front frame 1a of the copying machine main body 1. A notch 1c is formed from below in the front frame 1a, and the paper feed shaft 57 can be taken out downward through the notch 1c. Further, a stop ring 63 is attached to the front end of the paper feeding shaft 57, which restricts the movement of the paper feeding shaft 57 in the front-rear direction. Further, a pipe 64 as a paper feed guide is arranged between the collar 55a of the paper feed roller 55 and the front frame 1a. One end of the pipe 64 is fixed to the collar 55a of the paper feed roller 55, and the other end is rotatably supported on the outer periphery of the bearing 62. The outer diameter of the pipe 64 is set smaller than the outer diameter of the paper feed roller 55. On the other hand, a temporary paper feed guide 57 a is fixed to the paper feed shaft 57 on the rear side of the paper feed roller 55. The outer diameter of the paper feed guide 57a is set to be the same as the outer diameter of the pipe 64.

Further, in the pad housing 58, a guide sheet 60 for guiding the fed paper to the nip position between the paper feed roller 55 and the friction pad 56 is fixed upstream of the friction pad 56 in the paper feed direction. Has been done. The guide sheet 60 is arranged so as to cover a part of the friction pad 56 on the upstream side in the sheet conveying direction from above. Then, as shown in FIG. 12, a V-shaped notch 60a is formed in the center portion in the width direction of the friction pad 60.

One end of a support frame 65 is rotatably supported on the paper feed shaft 57. A drive shaft 66 for driving the forward feed roller 50 is supported on the other end of the support frame 65. The paper feed shaft 57 and the drive shaft 66 are transmitted by a belt (not shown).
And the forward feed roller 50 are rotated in the same direction. In addition,
The front end of the support frame 65 on the forward feed roller side has a protrusion 65a.
Is formed, and detects the vertical position of the forward feed roller 50 together with the photo interrupter 67 fixed to the frame on the main body side of the copying machine.

The pressure contact mechanism 34 has a placing plate 70 on which the front end of the sheet is placed, and a lift member 71 for lifting the leading end of the placing plate 70. The mounting plate 70 is shown in FIG.
As indicated by the chain double-dashed line, it is placed on the paper feed direction side of the paper feed cassette 30, and the front end side is vertically rotatable around the rear end side. The lift member 71 is arranged below the front end of the mounting plate 70. The rear end of the lift member 71 is fixed to the lift shaft 72. As shown in FIG. 13, the lift shaft 72 further protrudes rearward from the rear wall of the case body 32 of the paper feed cassette 30, and an engaging pin 73 is attached to the tip thereof. On the other hand, a joint 74 that meshes with the engagement pin 73 is arranged on the copying machine body side. The joint 74 is fixed to the tip of the drive shaft 75 and is rotated by a drive system (not shown). A spring 77 is arranged between the joint 74 and the rear frame 76 of the copying machine body.

In such a structure, the lift shaft 72 is rotated by the drive system via the joint 74 and the engagement pin 73, and the tip of the lift member 71 is rotated counterclockwise in FIG. As a result, the mounting plate 70 moves upward, and the paper placed on the upper part of the mounting plate 70 moves forward.
Pressed to 0. The amount of rotation of the lift member 71 is controlled by a detection signal from the photo interrupter 67.

Next, the mechanism 53 for separating the forward feed roller 50 from the paper will be described. The separating mechanism 53
As shown in FIGS. 14 and 15, a support member 80 fixed to the rear side of the device of a support frame 65 that supports the feed roller 50, and an interlocking mechanism 81 provided between the support member 80 and the paper feed cassette 30. And have. The interlocking mechanism 81 is
It has a cam member 82 that is movable in the front-rear direction of the apparatus and can contact the rear wall surface of the paper feed cassette 30, and an elevating member 83 provided between the cam member 82 and the support member 80.
The cam member 82 is housed in a case 85 fixed to the rear frame 1b of the copying machine main body, and is similarly biased toward the front side of the apparatus (sheet feeding cassette side) by a spring 84 arranged in the case 85. There is. Further, the cam member 82 includes a first cam surface 82a having a small lift amount and the first cam surface 82a.
The second cam surface 82b having a larger lift amount and the inclined surface 8 formed between the first cam surface 82a and the second cam surface 82b
2c and. Then, the lower end of the elevating member 83 is
By contacting the cam surfaces 82a, 82b and the inclined surface 82c,
The cam member 82 moves up and down as it moves.

Next, the paper transport path on the downstream side from the paper feed roller 55 will be described. As shown in FIGS. 1 and 16, a return conveyance guide member 90 for changing the conveyance direction of the sheet sent from the double feed prevention mechanism 51 is provided on the downstream side in the sheet conveyance direction above the sheet feeding roller 55. It is arranged. The return conveyance guide member 90 is provided so as to extend in the front-rear direction of the apparatus as shown in FIG. Further, it has a curved surface guide portion 91 for feeding the paper fed from the lower side to the image forming portion side, and both ends thereof are for attaching the return transport guide member 90 to the frame 1c of the copying machine main body. It has a mounting portion 92. Curved surface guide part 9
Reference numeral 1 denotes a sheet, which is sent from a sheet feeding cassette in the copying machine main body 1, to the image forming section together with the guide members 93 and 94 by the first feeding surface 91a on the side facing the sheet feeding roller 55, and also the first feeding. The sheet sent from the external sheet feeding units 4a and 4b is sent to the image forming unit side by the second carrying surface 91b opposite to the surface 91a. A long hole 92a that is long in the front-rear direction is formed in one of the mounting portions 92, and the return conveyance guide member 90 is mounted to the frame 1d with a minute gap by a screw 95 penetrating the long hole 92a. .

In such a structure, when the return conveyance guide member 90 expands in the front-rear direction due to heat, the expansion portion is absorbed by the elongated hole 92a, so that the curved surface guide portion 91 is prevented from bending in the vertical direction. It can be prevented. Therefore, even if the return conveyance guide member 90 contracts due to heat, the gap between the curved surface guide portion 91 and the guide members 93 and 94 is maintained at a preset gap, and the conveyance of the sheet is not hindered.

As shown in FIG. 4, a light reflection type sensor 100 for detecting whether or not there is a sheet in the sheet feeding cassette 30 is provided above the sheet feeding cassette 30.
The reflective sensor 100 includes a light projecting unit 100a that irradiates the upper surface of the paper with light and a light receiving unit 100b that receives the light reflected from the paper. On the other hand, in the mounting plate 70, a notch 70a is formed in the portion irradiated with the light from the transparent portion 100a, as shown in FIG. Then, an inclined portion 101 as shown in FIG. 18 is formed on the bottom surface of the case body 32 below the cutout 70a. A black paint is applied to the inclined portion 101 and its periphery so as to absorb the light from the light projecting portion 100a. The inclined portion 101 is inclined so that the front end side is located lower than the rear end side. Therefore, even when the light from the light projecting unit 100a is applied to the inclined unit 101 and a small amount of light is reflected, the reflected light is reflected.
The light receiving part 100b of 00 does not enter.

By providing the inclined portion 101 as described above, even when the reflection type sensor 100 is made highly sensitive in order to improve the detection accuracy of the presence or absence of the sheet, the case main body 3
The reflected light from 2 can be prevented from entering the light receiving portion, and erroneous detection of the presence or absence of paper can be avoided. Next, the operation will be described. When an original is placed on the original table 2 and the copy start key is pressed, the internal paper feed cassette 3
0 or an appropriate size of paper is selected from the external paper feed units 4a and 4b and supplied to the image forming unit 11 side.

The operation when paper is supplied from the internal paper feed cassette 30 will now be described. In the state where the paper feed cassette 30 is set at the set position in the copying machine main body 1, as shown in FIG.
The sheet on the mounting plate 70 is in contact with the forward feed roller 50. When the copy start key is pressed, the forward feed roller 50 rotates counterclockwise in FIG. 4, and the uppermost sheet is fed to the double feed mechanism 51 side. The sheet sent to the double feed mechanism 51 side is guided by the guide sheet 60 to the nip position between the sheet feed roller 55 and the friction pad 56. At this time, when two sheets of paper are simultaneously supplied to the nip position between the paper feed roller 55 and the friction pad 56, the friction coefficient between the paper feed roller 55 and the paper is overlapped and the paper is supplied. Since the coefficient of friction is higher than the coefficient of friction, slippage occurs between the upper sheet and the lower sheet, and only the upper sheet is conveyed to the image forming unit 11 side by the sheet feeding roller 55. In this way, double feeding of paper is prevented.

Here, when the paper enters the double feed prevention mechanism 51, the friction pad 56 is arranged so as to project from the upper surface of the pad housing 58 to the paper feed roller 55 side, and moreover the tip of the guide sheet 60 is arranged. It is arranged so as to cover a part of the friction pad 56 on the upstream side in the paper transport direction. Therefore, as compared with the case where the friction pad 56 is embedded inside the pad housing 58, the occurrence of double feeding can be reduced, and the leading edge of the sheet due to the collision between the leading edge of the sheet and the friction pad 56 can be prevented.

Here, since the guide sheet 60 has a notch 60a in its central portion as shown in FIG. 12, when the leading edge of the sheet passes the leading edge of the guide sheet 60, the central portion of the sheet comes first. The friction pad 56. For this reason,
The transport speed S1 at the central portion of the paper is slightly slower than the transport speed S2 at both ends thereof. Therefore, the central portion of the paper is guided to the nip position between the paper feed roller 55 and the friction pad 56 while being pulled on both sides thereof. Here, it is possible to reliably feed the paper while suppressing double feeding and preventing the leading edge of the paper from being turned over.

The sheet sent out from the sheet feeding cassette 30 as described above is the first sheet of the return transport guide member 90.
The conveyance direction is changed along the conveyance surface 91a and is guided to the image forming unit 11 side by the guide members 93 and 94. In the image forming section 11, a toner image corresponding to the image information of the original is transferred onto a sheet, and then the sheet conveying device 13 conveys the toner image to the fixing device 14. In the fixing device 14, the toner image on the paper is fixed, and the paper after the fixing process is discharged onto the paper discharge tray 5 by the discharge roller 15.

When the paper of the external paper feeding units 4a and 4b is selected, the paper is fed from the paper feeding cassette in the same manner as described above, and the paper is fed along the second feeding surface 91b of the return feeding guide member 90. The transport direction can be changed. After that, the same processing as described above is performed. Next, the paper feed cassette 3
The operation of removing 0 from the copying machine main body 1 will be described.

When the paper feed cassette 30 is pulled out to the front side,
The lift member 71 and the drive system on the copying machine body side are separated. That is, by pulling out the paper feed cassette 30 to the front side, the engagement pin 7 fixed to the tip of the lift shaft 72 is pulled out.
3, the joint 74 comes off. As a result, the lift shaft 7
The driving force transmitted to the lift member 71 is released, and the lift member 71 is released.
Rotates clockwise in FIG. 4 due to the weight of the mounting plate 70 or the like. As a result, the paper is lowered together with the placing plate 70 in the paper feed cassette 30. At this time, the forward feed roller 50 descends due to its own weight, but its descending is restricted by a descending limiting member (not shown).
The forward feed roller 50 separates from the upper surface of the sheet above 0.

When the paper feed cassette 30 is set at the set position in the main body of the copying machine, the interlocking mechanism 81
The cam member 82 is housed in the case 85 against the biasing force of the spring 84, as shown by the alternate long and short dash line in FIG. In the state shown by the one-dot chain line, the elevating member 83 is in contact with the first cam surface 82 a of the cam member 82. Therefore, the support member 80 is lowered, and the paper feed roller 50 can contact the paper in the paper feed cassette 30 by its own weight.

On the other hand, when the paper feed cassette 30 is pulled out to the front side, the cam member 82 is pushed out from the case 85 to the front side by the spring 84. Then, the lifting member 83
Is the inclined portion 82c from the first cam surface 80a of the cam member 82.
And comes into contact with the second cam surface 82b having a high lift amount.
In this state, the elevating member 83 rises and pushes the support member 80 upward. Then, the support frame 65 rotates clockwise around the paper feed shaft of the paper feed roller 55, and the forward feed roller 50 rises as shown by the solid line in FIG. For this reason,
The forward feed roller 50 is further separated from the paper in the paper feed cassette 30.

When the paper feed cassette 30 is pulled out to the front side in such a state, the paper and the forward feed roller 50 are reliably separated from each other.
It is possible to prevent it from popping out of the machine or being damaged. Moreover, in this case, since it is not necessary to lower the paper feed cassette 30, the vertical space is small,
It is possible to downsize the entire device.

When the paper feed cassette 30 is pulled out, the supporting portions 32c and 32d at the front and rear of the case body 32 of the paper feed cassette 30 are guided by the guide frame 35b on the body side of the copying machine.
Since the roller 36 on one side is fitted into the concave groove 32a of the case 32, the case body 32 can be smoothly pulled out while suppressing rattling.

When the paper feed cassette 30 is set in the main body of the copying machine, when the paper feed cassette 30 is pushed into the main body 1 of the copying machine and moves to the vicinity of the set position, the rear side wall of the case main body 32. Pushes the cam member 82 of the interlocking mechanism 81 toward the rear side of the apparatus. As a result, the cam member 82 moves rearward of the device against the biasing force of the spring 84. Then, the lifting member 8
3 contacts the first cam surface 82a having a small lift amount from the second cam surface 82b through the inclined portion 82c. As a result, the elevating member 83 descends, and the supporting member 80 also descends to the position shown by the alternate long and short dash line in FIG. In this state, the support frame 65 and the forward feed roller 50 can come into contact with the paper in the paper feed cassette 30 by their own weight.

By setting the paper feed cassette 30 in the main body of the copying machine, the engaging pin 7 at the tip of the lift shaft 72 is set.
3 engages in the groove of joint 74. Here, when the groove of the joint 74 and the engagement pin 73 are not smoothly engaged, the joint 74 is pushed backward, but in this case, the spring 77 absorbs the movement of the joint 74. Since the groove of the joint 74 is formed so as to be inclined in the circumferential direction, when the joint member 74 is pushed forward by the biasing force of the spring 77, the engagement pin 73 engages with the groove of the joint member 74.

Here, the mounting plate 70 is lowered when the paper feed cassette 30 is mounted in the set position. Therefore, the protrusion 65 a of the support frame 65 is located below the photo interrupter 67. In this case, the lift member 7 is moved through the lift shaft 72 by the control unit of the copying machine main body.
1 is increased. As a result, the placing plate 70 and the sheet are raised and brought into contact with the forward feed roller 50. Mounting plate 7
0 is raised by a predetermined amount and the protrusion 65 of the support frame 65 is
When a interrupts the light of the photo interrupter 67, the rotation of the lift member 71 is stopped by the signal from the control unit, and this state is maintained.

Next, the width adjusting operation of the paper in the paper feeding cassette 30 and the center adjustment of the width adjusting mechanism will be described. When the width of the paper is adjusted, the width adjusting guide member 40 is moved along the guide groove 41. The rack 42 is fixed to the width adjusting guide member 40,
Since the rack 42 meshes with the pinion gear 43,
By moving one width adjusting guide member 40, the other width adjusting guide member 40 is also moved inward or outward by the same amount, and width adjustment can be performed according to the width of the paper.

Further, in order to align the center of the image forming unit 11 with the center position of the paper stored in the paper feed cassette 30, the center alignment of the width alignment mechanism 33 is required.
In this case, the position adjustment plate 44 supporting the pinion gear 43 is loosened by moving the screw 47 and moved in the width direction. That is, by moving the adjusting plate 44 in the width direction, the meshing position between the rack 42 fixed to the width adjusting guide member 40 and the pinion gear 43 is changed, and the center position of the width adjusting guide mechanism 33 is adjusted.

Here, the centering of the width adjusting mechanism 33 can be performed only by moving the position adjusting plate 44, and the adjusting work becomes very easy. In addition, the device is inexpensive because the structure is simple. Next, the replacement operation of the paper feed roller 55 will be described. Since the paper feed roller 55 is a consumable item, it needs to be replaced when it is consumed due to long-term use.
In this case, first stop ring 6 from the front side of the device.
3 is removed, and the bearing 62 is pulled out from the front frame 1a. Next, through the notch 1c of the front frame 1a, the pipe 6
4 is lowered to an opening provided below the front frame 1a, and its end face is pulled out to the front side. Since the paper feed roller 55 is fixed to one end of the pipe 64, the pipe 6
By pulling out 4, the paper feed roller 55 can be pulled out at the same time.

In this case, the operator does not need to put his / her hand inside the apparatus, and the paper feeding roller 55 can be easily replaced. Further, since the paper feed guide is constituted by the pipe 64, it is possible to guide the entire area of the paper, and it is possible to suppress jamming due to turning over of the paper or the like. Other Embodiments (a) In the above embodiment, the mechanism for separating the forward feed roller 50 in synchronism with the pulling out of the paper feed cassette 30 is constituted by the separating mechanism 53 including the cam member 82 and the like. It is also possible to electrically detect that the 30 is pulled out and raise the forward feed roller 50 by a solenoid or the like. (B) The central cutout of the guide sheet 60 is not limited to the V-shape, but a U-shape or a rectangular cutout may be formed as shown in FIGS. 19 and 20. (C) In the above embodiment, the pipe-shaped paper feed guide is provided only on the front side of the paper feed roller 55, but a similar pipe may be provided on the rear side.

[0050]

As described above, in the sheet detecting apparatus according to the present invention, the inclined portion is formed so as to face the reflection type sensor. The reflected light can be suppressed from entering the light receiving portion of the sensor, and erroneous detection is reduced.

In the sheet detecting device according to another aspect of the present invention, since the antireflection film is formed on the inclined surface of the inclined portion, the reflected light of the light irradiated on the inclined surface is very small, and the false detection is made. Will be less. A sheet detection device according to another aspect of the present invention is used when detecting the presence or absence of a sheet in a paper feed cassette, and the inclined portion is formed by inclining a part of the bottom portion of the paper feed cassette. Therefore, false detection can be reduced with a simple structure.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional configuration diagram of a copying machine that employs a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a perspective exploded partial view of the copying machine.

FIG. 3 is a plan view of a paper feed cassette.

FIG. 4 is a front partial view of the sheet feeding device.

FIG. 5 is a front view showing a support structure of a paper feed cassette.

6 is an enlarged partial view of the structure shown in FIG.

FIG. 7 is a perspective partial view of a width adjusting mechanism.

FIG. 8 is a partial bottom view of the width adjusting mechanism.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a partial sectional side view of the paper feed roller and the paper feed shaft.

FIG. 11 is a front view showing a mounting structure of a paper feed shaft.

FIG. 12 is a plan view of a friction pad and a guide sheet.

FIG. 13 is a plan view showing a drive system of a lift member 71.

FIG. 14 is a front view of the separating mechanism.

FIG. 15 is a sectional side view of the separating mechanism.

FIG. 16 is a front view of a return conveyance guide member of the sheet feeding device.

FIG. 17 is a perspective partial view of a return conveyance guide member.

FIG. 18 is a perspective view showing an inclined portion on the bottom of the paper feed cassette.

FIG. 19 is a plan view showing another embodiment of the guide sheet.

FIG. 20 is a plan view showing still another embodiment of the guide sheet.

[Explanation of symbols]

 1 Copier main body 30 Paper feed cassette 100 Reflective sensor 100a Light emitting unit 100b Light receiving unit 101 Inclined portion

Claims (3)

[Claims] 1. A sheet detection device for detecting the presence / absence of a sheet stored in a sheet storage portion, the sheet detection device being disposed apart from the sheet stored in the sheet storage portion, and including a light projecting portion and a light receiving portion. A reflection type sensor having, and an inclined surface which is arranged at a position facing the reflection type sensor with the sheet of the sheet storage section interposed therebetween and which reflects light from the light projecting section to a portion other than the light receiving section. A sheet detection device comprising: an inclined portion. 2. The sheet detection device according to claim 1, wherein an antireflection film for deteriorating the reflection efficiency is formed on the inclined surface of the inclined portion. 3. The sheet storage unit is a paper feed cassette mounted in an image forming apparatus, and the inclined portion is formed by inclining a part of a bottom portion of the paper feed cassette.
Alternatively, the sheet detection device according to item 2.