JPH08137334A - Paper detector for electrophotographic device - Google Patents

Abstract

PURPOSE: To execute writing in a photoreceptor and the detection of a paper width by one light source and to reduce the cost by providing an optical separation means for dividing optical path of the same light source into an optical path for irradiating the photoreceptor and an optical path for irradiating the paper in the width direction in a paper feeding part, and also providing a means for detecting information on a position in the width direction. CONSTITUTION: Laser beams 13 emitted from semiconductor laser 1 are collimated through a collimator lens 2, and then, the laser beams 13 are alternately transferred by a rotary mirror 3 toward a reflecting plate 4 and a reflecting plate 6. When the rotary mirror 3 faces toward the reflecting plate 4, a photoreceptor drum 5 is scanned with the laser beams 13 functioning as write-in light 13a. On the other hand, when the rotary mirror 3 faces toward the reflecting plate 6, a light transmission plate 8 is scanned in the width direction of a paper 14 with the laser beams 13 functioning as illuminating light for detecting a paper 13b. The direction of the illuminating light 13 projected on the light transmission plate 8 is shifted by a blaze, and the light 13 is totally reflected again and again, thereafter, the light is received by photodetectors 9 and 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for irradiating a photoreceptor with light to write information, and in particular, it is possible to optically obtain information such as a paper size supplied to the electrophotographic apparatus. The present invention relates to a paper detection device of an electrophotographic device.

[0002]

2. Description of the Related Art A conventional electrophotographic apparatus is equipped with a paper detection device for detecting the size of a document or copy paper. In such a sheet detecting device, as a detecting means,
A transmissive photointerrupter having a light emitting element 80 and a light receiving element 81 as shown in FIG. 9 and a reflective photointerrupter as shown in FIG. 20 are used. The transmissive photo interrupter detects a sheet by blocking a signal when the sheet passes between the light emitting element 80 and the light receiving element 81, and the reflective type photo interrupter detects the sheet from the light emitting element 82 when the sheet passes above the sheet. The emitted light is reflected by the paper and detected by the light receiving element 83 as a signal.

As an example of a sheet detecting device, Japanese Patent Laid-Open No. 5-3
Japanese Patent No. 36317 discloses a document detection device such as a facsimile device to which the above-mentioned transmission type photo interrupter is applied. As shown in FIG. 21, in the above-described sheet detecting device, the light emitting element 90 has the document passage portion 9 near the document insertion port 92.
3, the reflecting plate 94, the lens 95, and the light receiving element 91 are housed below the document passage portion 93, and are sequentially arranged in the horizontal direction.

As shown in FIG. 22, the document insertion opening 92 is formed.
Document guide members 97a and 97b are provided in the vicinity of both sides of the document in the document transport direction so that the document insertion posture can be appropriately maintained. A plurality of the light emitting elements 90 are provided according to the type of the detected size so that various sizes of the document can be detected. For example, in FIG.
In order to detect three standard sizes of A4, B4 and A3, three light emitting elements 90a, 90b and 90c are sequentially arranged along the width direction of the document. More specifically, the light emitting elements 90a, 90b, 90c are installed at positions having a length approximately equal to the width of each standard size document from the document guide member 97b aligned with the reference position.

In the document detection method in this case, for example, when an A4 document is inserted along the document guide members 97a and 97b from the document insertion port 92, the light emitted from the light emitting element 90a is blocked by the document. Light emitting element 90b / 90
The light from c passes through the window 96, is reflected by the reflecting plate 94, and is condensed on the light receiving element 91 by the lens 95. This allows
It can be detected that the document size is A4. Similarly, B4
-A3 size document can also be detected.

[0006]

However, in the structure of the conventional paper detection device, a reference position for setting the original or copy paper on the paper feed tray or the like is provided, and the paper must be aligned with the reference position. The paper size cannot be detected accurately. Further, in order to adjust the paper to the reference position, a paper feed tray having a structure provided with auxiliary tools such as the document guide members 97a and 97b is required. Further, since detection means such as a transmissive photo interrupter are required for the number of paper sizes to be detected, and since the individual detection means are installed at intervals, nonstandard specifications such as between A4 and B5 are provided. There is a problem that size paper cannot be detected.

Therefore, according to the present invention, it is possible to accurately detect the paper size without placing a paper on the basis of a fixed position, and it is possible to efficiently obtain continuous size information with at least one detecting means. An object is to provide a paper detection device for an electrophotographic apparatus.

[0008]

In order to solve the above-mentioned problems, the paper detection device for an electrophotographic apparatus according to claim 1 of the present invention irradiates light onto a photoconductor (for example, a photoconductive drum) to obtain information. Equipped with an electrophotographic device for writing,
In a paper detection device of an electrophotographic apparatus that detects a paper (for example, a copy paper, a document, or an OHP sheet) conveyed in a paper feeding unit of the electrophotographic apparatus, the same light source (for example,
A semiconductor laser, or a copy lamp), an optical separating unit for separating an optical path for irradiating the photosensitive member and an optical path for irradiating the width direction of the paper in the paper feeding unit, and a light separating unit provided near the paper feeding unit And a light detecting unit (for example, a light guide plate and a light receiving element) that detects a change in the amount of light applied to the sheet feeding unit in the width direction and outputs continuous position information in the width direction. I am trying.

According to a second aspect of the present invention, there is provided a sheet detection device for an electrophotographic apparatus, wherein the light source emits a light beam (for example, a laser beam) (for example, a semiconductor laser). ), The light separating means includes an optical path changing means (for example, a rotating mirror) that changes an optical path of the light beam so that the light beam scans the sheet feeding unit from one end to the other end in the width direction, The light detecting means is disposed at the end portion in the width direction and the light guide means (for example, a light guide plate made of a translucent material) that collects the light beam scanned in the width direction in the width direction at the end portion in the width direction. A light detection signal output unit (for example, a light receiving element) that outputs a signal according to a change in the amount of light applied to the sheet feeding unit is provided.

According to a third aspect of the present invention, there is provided a paper detection device for an electrophotographic apparatus, wherein the light guide means is an incident surface of the light beam.
Has a surface and a second surface opposite to the first surface, and extends in the width direction. The second surface has the light detection signal output disposed at the end of the light guide means. Deflectors that guide the light beam to the means (eg, sawtooth blazes, or reflective scattering surfaces)
Is formed.

According to a fourth aspect of the present invention, there is provided a sheet detection device for an electrophotographic apparatus, which is the sheet detection apparatus for an electrophotographic apparatus according to the first, second or third aspect, wherein the light from the light source is obliquely applied to the surface of the sheet. It is characterized in that the above-mentioned light detecting means is arranged so as to receive the reflected light obtained by the above.

[0012]

According to the structure of the first aspect, by providing the light separating means, the light source for writing on the photosensitive member can also be used as the light source for detecting the sheet in the sheet feeding section. Therefore, it is possible to omit a light emitting element or the like which is conventionally provided separately for detecting the sheet conveyed into the electrophotographic apparatus.
For example, a conventional rotating mirror may be used as the light separating unit, and the rotating surface may be rotated so that the reflecting surface of the rotating mirror faces the optical path for irradiating the photoconductor and the optical path for irradiating the paper feeding unit. As a result,
Since the light emitting element can be omitted while utilizing the conventional configuration, the paper detection device can be constructed at a lower cost than the conventional one.

Further, since the light detecting means detects the light quantity of the light radiated in the width direction of the paper conveyed to the paper feed section, information on the width of the paper can be easily obtained from the change in the light quantity. Further, the presence / absence of paper can be continuously detected at any position in the width direction. As a result, the width of the paper, that is, the paper size can be detected without providing the reference position for setting the paper in the paper feed tray or the like provided in the conventional paper detection device. It does not have to be a standard size.

Further, when the sheet is conveyed in a posture in which the sheet is obliquely inclined with respect to the correct conveying direction, the opposite sides of the sheet are gradually biased to either of the width directions of the sheet, and therefore, the width direction of the sheet. The amount of light changes at the position.
On the other hand, when the paper is conveyed in the correct posture, there is no change in the position of the light amount by the light detecting means. Therefore, in the above configuration, it is possible to easily detect whether or not the posture of the conveyed sheet is appropriate, and the control is performed to correct the posture of the sheet by using the detection result, or the writing on the photoconductor is inclined and conveyed. It is possible to control to match the paper to be used.

According to the second aspect of the invention, the light beam emitted from the light source and scanned by the paper feed portion is guided by the light guide means to the light detection signal output means arranged at the end portion in the width direction. The light detection signal output means detects a change in the amount of received light and outputs a signal indicating the presence / absence of a sheet at the part (scanning position) where the light beam is currently scanning.

By the way, since the scanning position of the light beam in the paper feeding portion is continuously moved from one end to the other end in the width direction by the optical path changing means, the above-mentioned signal has a waveform in which the output at each scanning position is continuous. Will be shown. Therefore, the light amount of the light beam scanning the paper feed portion changes depending on whether or not there is paper in the paper feed portion, and thus signals of different waveforms are output. In addition, the output signal waveform when the paper is present in the paper feed unit indicates the width of the paper and the position of the paper in the width direction of the paper feed unit. Further, as described in the operation of the first aspect, by detecting the change in the position of the sheet, it is possible to detect the attitude of the sheet to be conveyed.

As a result, unlike the conventional case, it is not necessary to provide as many light detecting means as the number of paper sizes to be detected, and at least one light detecting signal output means is provided at the end portion in the width direction of the paper feeding section. Thus, it is possible to accurately detect the paper size, the position of the paper in the width direction of the paper feed unit, and the attitude of the paper.
Further, since the light beam continuously scans the paper feed unit, it is possible to detect an arbitrary size of the paper placed at an arbitrary position in the width direction of the paper feed unit. As a result, claim 1
This can contribute to the simplification of the configuration of the light detection unit in the above.

As the light separating means provided with the optical path changing means, for example, a conventional rotating mirror is used, and the optical path for scanning the photosensitive member by rotating the reflecting surface of the rotating mirror by 360 °, and the paper feeding section. And an optical path for scanning.

According to the structure of claim 3, the second of the light guide means
Since the deflecting surface is formed on the surface, the light beam incident on the first surface is directly irradiated on the deflecting surface and is deflected toward the end portion of the light guide means. Therefore, the light beam can be efficiently guided to the light detection signal output means. Moreover, if the light propagating in the light guide means is configured to utilize the total reflection on the inner surface of the light guide means other than the deflecting surface, the light beam can be guided to the light detection signal output means more efficiently. Further, since the deflection surface is formed on the second surface of the light guide means,
The deflecting surface can be formed at the same time when the light guide means is formed, and the light guide means having the deflecting surface can be mass-produced easily and inexpensively.

According to the structure of claim 4, since the reflected light obtained by obliquely irradiating the light from the light source onto the paper is used, the reflection of light can be achieved in addition to the operation of claim 1 or 2. It is possible to detect not only paper but also a transparent sheet such as an OHP film as a paper from which light can be obtained. That is, when the transparent sheet is irradiated with light, the change in the light amount due to the presence or absence of the paper cannot be obtained in the case of the transmissive paper detection device in which the light source and the light detection means are arranged with the paper sandwiched in the paper feed unit. In the case of the reflection type that uses reflected light, the reflected light is detected only at the portion where the paper is present in the paper feed unit, so the size of the paper and arbitrary position information in the width direction can be obtained by the light detection means. As a result, it becomes possible to detect a transparent sheet such as an OHP film which cannot be detected by the conventional transmissive paper detection device.

[0021]

【Example】

[Embodiment 1] One embodiment of the present invention will be described with reference to FIGS.
The description will be made based on item 2.

In this embodiment, a case where the paper detection apparatus according to the present invention is applied to a laser printer as an electrophotographic apparatus will be described. As shown in FIG. 2, the laser printer of this embodiment includes a semiconductor laser 1, a collimator lens 2,
Rotating mirror 3, reflectors 4, 6, 7, photoconductor drum 5, light guide plate 8, light receiving elements 9, 9 (see FIG. 1) arranged at both ends of the light guide plate 8, paper feed tray 10, conveyance roller 11 and a discharge tray 12.

The semiconductor laser 1 is a light source of a laser printer, and the collimator lens 2 collimates the laser light 13 emitted from the semiconductor laser 1 into a rotating mirror 3 (light separating means.
Optical path changing means). By rotating the rotating mirror 3 at a constant speed, it is possible to irradiate the laser beam on the entire circumference of 360 °. Further, the reflection plates 4 and 6 are located on both sides of the rotary mirror 3, and the light reflected by the rotary mirror 3 is exposed to the photoconductor drum 5 (photoconductor) and the light guide plate 8 (light detection means / light guide means). ) And are arranged to irradiate respectively. The light guide plate 8 extends in the width direction of the paper near the paper feed port (paper feed section) of the paper feed tray 10.

When the rotary mirror 3 is directed toward the reflection plate 4 on the side of the photoconductor drum 5, the laser beam 13 scans the surface of the photoconductor drum 5 as the writing light 13a, while facing the light guide plate 8 side. When the laser light 13 is present, the light guide plate 8 or the paper 14 (paper) passing on the light guide plate 8 is scanned in the width direction as the illumination light 13b for paper detection. Further, since the paper 14 is scanned by the rotating mirror 3 while passing over the light guide plate 8, it is also scanned in the transport direction of the paper 14.

The writing light 13a is reflected by the reflecting plate 4 and is applied to the photosensitive drum 5 located below the reflecting plate 4 to write print information. On the other hand, the illumination light 13b is configured to be guided to the light guide plate 8 located ahead of the paper feed tray 10 via the reflection plates 6 and 7.

Although the light guide plate 8 and the paper feed tray 10 are arranged with an inclination in FIG. 2, the inclination may be horizontal as shown in FIG. 1, for example. Further, since the reflection plates 6 and 7 are for guiding the illumination light 13b to the light guide plate 8, only the reflection plate 6 may be used according to the position and inclination of the light guide plate 8 as shown in FIG. 1, for example.

As shown in FIG. 4, the light guide plate 8 is provided with illumination light 13
It is for guiding b to the light receiving elements 9, 9 (light detecting means, light detecting signal outputting means) arranged in close contact with both end portions 8c, 8c of the light guide plate 8, and therefore illumination as shown in FIG. As a deflecting surface, a sawtooth-shaped surface (hereinafter referred to as a blaze 8b) is formed on the opposing surface (second surface) facing the incident surface 8a (first surface) on which the light 13b is incident. . On the surface of the blaze 8b, a metal film having a high reflectance such as aluminum, gold and silver is formed by sputtering or vapor deposition in order to sufficiently reflect the illumination light 13b. No metal film or the like is added to the surface of the light guide plate 8 other than the blaze 8b.
The reason is that the reflectance due to total reflection is higher than the reflectance due to the reflection film, so that the illumination light 13b reflected by the blaze 8b is totally reflected by the surface of the light guide plate 8 other than the blaze 8b to efficiently receive light. This is because the light can be focused on 9 · 9.

When the blaze 8b is formed, the pitch W ₁ of the blaze 8b shown in FIG. 5 causes ripples in the output of the light receiving elements 9 and 9. Therefore, the pitch W ₁ is desired to be as small as possible. The pitch is limited to about 0.5 to 1 mm because of the forming precision of the molding die. Further, the width W _{2 of the} blaze 8b shown in FIG. 3 is ideally equal to the spot diameter of the laser light, but the width W ₂ is set to about 1 to ₂ mm in consideration of the installation accuracy of the light guide plate 8 and the like. Since the light guide plate 8 is made of a transparent resin such as acrylic or polycarbonate which is a translucent material, the blaze 8b can be formed at the same time when the light guide plate 8 is formed. Therefore, the light guide plate 8 having the blaze 8b formed thereon can be easily mass-produced.

The light receiving elements 9, 9 arranged in close contact with both ends of the light guide plate 8 are the illumination light 1 guided by the light guide plate 8.
The size of the paper 14 is detected by receiving 3b and outputting it as a photoelectric conversion signal according to the change in the light amount of the illumination light 13b.

The paper feed tray 10, the conveyance roller 11 and the paper discharge tray 12 are located below the above-mentioned optical system, and the paper 14 sent from the paper feed tray 10 passes above the light guide plate 8. The sheet is sent to the photosensitive drum 5 while being controlled by the carrying roller 11, where the print information is written, and then the sheet is received by the paper discharge tray 12.

In the above structure, the laser light 13 emitted from the semiconductor laser 1 is collimated by the collimator lens 2, and the laser light 13 is alternately sent by the rotating mirror 3 in the directions of the reflection plate 4 and the reflection plate 6. . Rotating mirror 3 is reflector 4
When facing the direction, the laser light 13 scans the photosensitive drum 5 as the writing light 13a. On the other hand, when the rotating mirror 3 faces the reflecting plate 6, the laser beam 1
3 is a paper 14 on the light guide plate 8 as illumination light 13b for paper detection.
Scan in the width direction. Illumination light 13 applied to the light guide plate 8
5b, the direction of light is changed by the blaze 8b as shown in FIG. 5, and the light receiving elements 9c arranged at both ends 8c of the light guide plate while repeating total reflection several times directly or by the surface of the light guide plate. The light is received at 9.

The paper detection method in this case is as follows.

First, when the illumination light 13b scans the light guide plate 8 in the initial state where the paper 14 is not on the light guide plate 8, the light receiving element 9
As shown in FIG. 7A, the total output of 9 is a dish-shaped output waveform in which the output near the center of the light guide plate 8 is slightly smaller than the outputs at both ends of the light guide plate 8. The reason is that the light receiving element 9
・ Illumination light 13 near the center of the light guide plate 8 with a long optical path to 9
When b is irradiated, the total number of times the light is totally reflected on the surface of the light guide plate 8 increases the reflection loss of the illumination light 13b, and the amount of light received by the light receiving elements 9 and 9 decreases. The total output value of 9 · 9 becomes smaller. on the other hand,
When the illumination light 13b is radiated near both ends of the light guide plate 8 having a short distance to the light receiving elements 9 and 9, the number of total reflections of light on the surface of the light guide plate 8 is small, so that the reflection loss of the illumination light 13b is reduced. There is not much, and the total output value of the light receiving elements 9 and 9 becomes large. The vertical axis of the figure represents the total output value of the light receiving elements 9 and 9,
The horizontal axis of the figure is the time axis, that is, the illumination light 13b is the light guide plate 8.
The position (scanning position) where the upper part is scanned is shown.

Next, when the paper 14 is started to be conveyed from the paper feed tray 10 and the paper 14 passes over the light guide plate 8,
As shown in FIG. 8, while the illumination light 13b scans the part without the paper 14, the output waveforms of the light receiving elements 9 and 9 show the same output waveform as the case without the paper 14, but the part with the paper 14 exists. In this case, since the illumination light 13b is blocked by the paper 14 and does not enter the light guide plate 8, the output of the light receiving elements 9 and 9 becomes very weak.
The output waveform is such that the output sharply drops on the way from both ends of the light guide plate 8 shown in FIG. Therefore, if there is no paper 14 (FIG. 7A), the paper 14
If the output is subtracted (Fig. 7 (b)), paper 14
A detection signal D ₁ having a waveform as shown in FIG. 7C that rises at one end in the width direction and falls at the other end is obtained. That is, the output width L corresponds to the paper size, and the rising and falling positions of the detection signal D ₁ are determined by the light guide plate 8.
The position of the paper in the upper width direction is shown.

Further, since the rotating mirror 3 scans not only in the width direction of the paper 14 but also in the carrying direction thereof, the paper 14 is scanned with respect to the light guide plate 8 as shown in FIG. 9, for example. When the paper is conveyed with an inclination, the detection signal D
_With respect to the waveform of 1, the position of the output waveform changes as shown in FIG. 10 every time the paper 14 is scanned by the illumination light 13b. That is, the output is initially obtained, but the position where the paper 14 blocks the light guide plate 8 gradually shifts, so the position of the output waveform sequentially moves to. Therefore, by detecting the position change of this output, it is possible to detect the state in which the paper 14 is inclined and is improperly conveyed, and the conveyance roller 11 is controlled based on the detection result, so that the paper 14 is placed in a normal posture. It can be transported while returning to.

As described above, in the paper detection apparatus of this embodiment, the semiconductor laser 1 which is the light source of the laser printer is used as the light source of the illumination light 13b for detecting the paper size. There is no need to provide a separate light source for paper detection. As a result, it is possible to configure the paper detection device at a lower cost than the conventional one.

Further, in the conventional apparatus, in order to detect the paper 14 accurately, it is necessary to provide the reference position of the paper 14 in the paper feed tray or the like, and the paper 14 can be detected only at the position where the detecting means is provided.
However, in the present device, the rotating mirror 3 scans the light guide plate 8 on the light guide plate 8 in the width direction of the paper, so that continuous position information in the width direction of the paper 14 can be obtained. . As a result, the paper size can be detected without providing a fixed reference position as in the prior art, and a nonstandard size such as a size between A4 and B5 can be detected.

Further, since the size of the middle paper 14 is detected while the paper 14 is passing over the light guide plate 8, the paper 14 is also scanned in the paper conveyance direction.
The properness of the posture of the paper 14 can be accurately detected, and the information is fed back to the conveyance system or the image forming processing system to correct the posture 14 of the paper to control the conveyance of the paper 14 or to convey the paper 14. It is possible to perform a process of writing print information on the photosensitive drum 5 according to the inclination of the paper 14.

The incident surface 8a on which the illumination light 13b is incident
By providing the blaze 8b on the surface facing the blaze 8b, the illuminating light 13b incident on the light guide plate 8 can be directly applied to the blaze 8b, so that the light can be efficiently received.
It can be deflected in 9 directions. Further, the light receiving element 9
The light from the light guide plate 8 can be introduced more efficiently by bringing 9 into close contact with the light guide plate 8. Further, by adding a reflective film to the blaze 8b, the effect of reflecting the illuminating light 13b by the blaze 8b is enhanced, and the escape of the illuminating light 13b from the light guide plate 8 is prevented. On the other hand, a reflection film is not added to the surface of the light guide plate 8 other than the blaze 8b surface, so that the light reflected by the blaze 8b is totally reflected and guided to the light receiving elements 9 and 9 to reduce light loss. Further, the blaze width W ₂ is formed only in a region narrower than the width of the surface of the light guide plate 8 so as not to prevent the propagation of the totally reflected light.

Further, since the light guide plate 8 is made of a transparent resin such as a translucent material such as acrylic or polycarbonate, the light guide plate 8 and the blazes 8b can be integrally formed.
Thereby, the light guide plate 8 including the blaze 8b can be mass-produced easily and inexpensively.

Further, in the conventional device, the detecting means is required for the number of sizes to be detected, but in the present device, the light guide plate 8 is used to illuminate the illumination light 13b at a certain place, that is, the light guide plate 8.
Since it can be guided to both ends of the
Individuals are all right.

Although the blaze 8b is used as the deflecting surface in this embodiment, even if the reflecting / scattering surface 28b in which fine irregularities are randomly formed on the surface as shown in FIG. By scattering the light 13b, the same effect as when using the blaze 8b is obtained.

Further, in the present embodiment, two light receiving elements 9 are provided, but the illuminating light 1 on the blaze forming surface of the light guide plate 8
By adjusting the inclination angle with respect to 3b and the angles α and β formed by the slopes of the blaze 8b and the plane P in contact with the respective vertices of the blaze 8b, it is possible to use only one light receiving element 9/9. For example, as shown in FIG. 11A, the blaze forming surface of the light guide plate 38 is tilted, and the light receiving element 39 is arranged on the left side of the light guide plate 38 and the reflecting surface 37 is arranged on the right side of the light guide plate 38 in the figure. Further, as shown in FIG.
By setting the angle of b to α> β, it is possible to reflect the illumination light 13b toward the light receiving element 39 side as much as possible. The light scattered in the direction of the reflecting surface 37 is reflected by the reflecting surface 37, and finally the light enters the light receiving element 39.
In this case, the light receiving element 39 and the reflecting surface 37 may be reversed left and right, and the angle of the blaze 38b may be α <β. As a result, the same effect as in the case of two light receiving elements can be obtained by installing only one light receiving element 39 on either the left or right side of the light guide plate 38.

Further, for example, as shown in FIG.
The light receiving element 49 is arranged on the left side of the light guide plate 48, and the reflecting surface 47 is arranged on the right side of the light guide plate 48 without tilting the blaze forming surface. Further, as shown in FIG. 11B, the angle of the blaze 48b is set to α = 90 ° and β is set to 45 ° to 65 ° so that one light receiving element 49 is provided as in the case of FIG. You can Also in this case, the light receiving element 49 and the reflecting surface 47 may be reversed left and right and the values of α and β may be exchanged. As a result, the same effect as in the case of two light receiving elements can be obtained by installing only one light receiving element 49 on either the left or right side of the light guide plate 48.

In this embodiment, the illumination light 13b is guided along the path for conveying the copy sheet to the photosensitive drum 5,
Although the case of detecting a copy sheet is shown, the present invention is not limited to this. For example, the paper detection device may be configured to detect the document by guiding the illumination light 13b to the document reading part on the way of conveying the document to the document reading part.

[Embodiment 2] Another embodiment of the present invention will be described below with reference to FIGS. 13 to 18. For the sake of convenience of explanation, the same members as those shown in the drawings of the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The sheet detecting apparatus of this embodiment is provided with a light guide plate 58 and light receiving elements 59, 59 instead of the light guide plate 8 and light receiving element 9 of the first embodiment. Is the same.

The illuminating light 13b is adapted to scan on the straight line X along the width direction of the sheet feeding section by the rotating mirror 3, and also as a sheet of paper and a transparent sheet such as an OHP film (hereinafter referred to as these). Are collectively referred to as paper 54) and are obliquely irradiated to the surface.

The light guide plate 58 (light guide means) is provided with a light collecting function for the light guide plate 58 itself in order to efficiently take in the light scattered by the paper 54. That is, as shown in FIG. 15, a lens 58a having a curved surface (first surface) for taking in light is formed. A blaze 58b similar to that in the first embodiment is formed on the surface (second surface) facing the surface of the lens 58a.

Further, the light guide plate 58 is located above the surface through which the conveyed paper 54 passes and is extended in the width direction of the paper feeding section, and is reflected by the specular reflection light component scattered by the paper 54. In order to efficiently collect the light 13c, the light guide plate 58 is installed so that the specular reflection light is directly emitted to the blaze 58b via the surface of the lens 58a.

The light receiving elements 59, 59 arranged at both ends of the light guide plate 58 have the same structure as in the first embodiment.

In the above structure, the laser light 13 emitted from the semiconductor laser 1 is the writing light 1 as in the first embodiment.
3a and illumination light 13b are alternately deflected. The writing light 13a is applied to the photosensitive drum 5, while the illumination light 13b is applied.
Is obliquely irradiated by the reflector to the surface of the sheet 54 and scattered. The reflected light 13c is focused on the lens 58a and applied to the blaze 58b, and is received by the light receiving elements 59, 59 arranged at both ends of the light guide plate 58. At this time, it is preferable that the specularly reflected light of the reflected light 13c is guided to the center of the width of the blaze 58b.

The paper detection method in this configuration is as follows.

When the paper 54 is not present on the straight line X, the reflected light 13c from the paper 54 cannot be obtained, and therefore the light receiving element 59 is used.
・ No output from 59. On the other hand, when the sheet 54 is conveyed on the straight line X, the illumination light 13b is scattered only at a portion (scanning position) on the straight line X where the sheet 54 is present, and the reflected light 13c enters the light guide plate 58. Element 59/5
9, a detection signal D ₂ having a waveform that rises at one end and falls at the other end as shown in FIG. 17 is obtained. That is, the output width L is the paper size, and
The rising and falling edges of the detection signal D ₂ are determined by the paper 54.
The position of is shown. Therefore, the sheet can be detected as in the case of the first embodiment. In this case, as in the case of the first embodiment, it is necessary to perform a process of making a difference between the output signal in the initial state in which the paper is not on the light guide plate and the output signal in the state in which the paper is passing on the light guide plate. There is no.

As described above, the present paper detection device can detect a transparent sheet such as an OHP film which cannot be detected by the transmissive paper detection device as in the first embodiment. The reason for this is that almost all the light that is illuminated perpendicularly to the transparent sheet passes through the sheet, but the light that is illuminated obliquely to the sheet provides several percent of the regular reflection light relative to the amount of illumination light. Is. For example, when the OHP film is irradiated with an inclination of about 60 °, a specular reflection light amount of about 5 to 6% is obtained. FIG. 17 shows the results of examining the distribution of the amount of reflected light when the illumination light 13b is incident on the surface of the paper 54 at an incident angle of 50 ° for the OHP film and the blank paper. As can be seen from FIG. 17, by detecting the specular reflection light amount (light amount at a reflection angle of 50 °), this light amount is larger in a glossy paper sheet such as an OHP film than in a white paper sheet, and thus it is easy to detect. Recognize. However, as compared with the case of the first embodiment, since the output level of the light receiving elements 59, 59 is very low, the light receiving elements 59, 5
It is necessary to provide an amplifier circuit or the like after 9.

As in the case of the first embodiment, the blaze 58b may be the reflection / scattering surface 28b, and the light receiving element is set by setting the inclination angle of the blaze forming surface of the light guide plate 58 and the angle of the blaze 58b. The same effect can be obtained by disposing 59 and 59 at one of the ends of the light guide plate 58.

In each of the above-described embodiments, the semiconductor laser is used as the light source, the rotating mirror is used as the light separating means, and the paper feeding unit is scanned in the width direction by the laser light. It is also applicable to an electrophotographic apparatus configured to irradiate light and guide reflected light from a document to a photoconductor.
That is, the light of the copy lamp may be guided to the paper feeding unit so that the paper feeding unit for the copy paper is irradiated in the width direction. Also in this case, it is possible to detect an arbitrary paper size, paper position and posture.

[0058]

As described above, the sheet detecting device of the electrophotographic apparatus according to the first aspect of the present invention is configured so that the same light source irradiates the photosensitive member with the optical path and the sheet in the sheet feeding section. A light separating unit that separates an optical path for irradiating the width direction, and a change in the amount of light that is provided in the vicinity of the paper feeding unit is detected in the width direction, and position information continuous in the width direction is detected. It is the structure provided with the photon detection means to output.

Since the light source for writing on the photoconductor is used as the light source for detecting the paper in the paper feeding section, the paper detecting device can be constructed at a lower cost than the conventional one.

Further, the paper size can be detected without providing a reference position for setting the paper in the paper feed tray or the like provided in the conventional paper detection device, and the paper of the nonstandard size can be detected. Detection is also possible.

Further, by detecting the change in the amount of light at the position of the conveyed sheet in the width direction, it is possible to easily detect whether or not the posture of the conveyed sheet is proper.

In the paper detecting device of the electrophotographic apparatus according to the second aspect, the light source is a light source which emits a light beam, and the light separating means directs the light beam from one end to the other end in the width direction of the paper feed section. An optical path changing unit that changes the optical path of the light beam so as to scan is provided, and the light detecting unit includes a light guiding unit that collects the light beam that scans the paper feeding unit in the width direction at an end in the width direction, and It is a structure provided with an optical detection signal output means which is arranged at an end portion and outputs a signal according to a change in the amount of light applied to the paper feeding portion.

As a result, unlike the conventional case, it is not necessary to provide as many light detecting means as the number of paper sizes to be detected, and at least one light detecting signal output means is provided at the end portion in the width direction of the paper feeding section. Then, since the effect of the configuration of claim 1 is obtained,
The effect that it contributes to simplification of the structure of the photon detection means in Claim 1 is produced.

According to a third aspect of the present invention, there is provided a paper detecting device for an electrophotographic apparatus, wherein the light guide means has a first surface which is an incident surface of the light beam and a second surface which opposes the first surface. The second surface has a deflecting surface for guiding a light beam to the photodetection signal output means arranged at the end of the light guide means.

As a result, the light beam can be efficiently guided to the light detection signal output means. Further, since the deflecting surface can be formed at the same time when the light guide means is formed, the light guide means having the deflecting surface can be mass-produced easily and inexpensively.

According to a fourth aspect of the present invention, there is provided a paper detection device for an electrophotographic apparatus, wherein the light detection means is arranged so as to receive reflected light obtained by irradiating the surface of the paper with light from a light source obliquely. This is the configuration.

As a result, in addition to the effect of the first or second aspect, O which cannot be detected by the conventional transmissive paper detection device is obtained.
It is possible to detect a transparent sheet such as an HP film.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an outline of a sheet detection device of a laser printer according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an outline of a sheet detection device of a laser printer according to an embodiment of the present invention, similar to FIG.

3A and 3B are a side view, a plan view, and a bottom view of a light guide plate of the paper detection device.

FIG. 4 is a perspective view of a light guide plate and a light receiving element of the paper detection device.

FIG. 5 is a cross-sectional view of a light guide plate showing reflection of illumination light due to a blaze formed on the lower surface of the light guide plate.

FIG. 6 is a cross-sectional view of a light guide plate showing reflection of illumination light by a reflection / scattering surface formed on a lower surface of the light guide plate according to another embodiment of the present invention.

FIG. 7A is a graph showing an output signal waveform of the light receiving element when there is no paper on the light guide plate in the embodiment of the present invention. (B) is a graph showing an output signal waveform of the light receiving element when there is a sheet on the light guide plate.
(C) is a graph showing an output signal waveform obtained by subtracting the output of (b) from the output of (a).

FIG. 8 is an explanatory diagram showing reflection of illumination light when there is a sheet on the light guide plate.

FIG. 9 is a plan view showing a case where a sheet is conveyed obliquely on the light guide plate.

FIG. 10 is a graph showing a change in output signal when a sheet is obliquely conveyed on the light guide plate.

FIG. 11A is a cross-sectional view showing another configuration example of the light guide plate according to the present invention. (B) is a cross-sectional view showing the shape of the blazes formed on the lower surface of the light guide plate of (a).

FIG. 12A is a cross-sectional view showing still another configuration example of the light guide plate. (B) is a cross-sectional view of the blaze formed on the lower surface of the light guide plate of (a).

FIG. 13 is a perspective view showing an arrangement example of a light guide plate of a paper detection device according to another embodiment of the present invention.

FIG. 14 is an explanatory diagram showing reflected light of illumination light applied to a sheet of the sheet detection apparatus.

15 is a perspective view of the light guide plate shown in FIG.

16 is an explanatory diagram showing a condensed state of reflected light on the light guide plate shown in FIG.

FIG. 17 is a diagram illustrating a blank sheet and an OHP in the above-described sheet detection device.
The incident angle of the illumination light radiated on each film is 50 °
7 is a graph showing the distribution of the amount of reflected light in the case of.

18 is a graph showing an output signal waveform of the light receiving element when reflected light is incident on the light guide plate shown in FIG.

FIG. 19 is a cross-sectional view showing a configuration of a transmissive photointerrupter used as a detection unit in a conventional paper detection device.

FIG. 20 is a cross-sectional view showing a configuration of a reflective photointerrupter used as a detection unit in a conventional paper detection device.

FIG. 21 is a cross-sectional view showing an outline of a document detection device which is an example of a conventional paper detection device.

FIG. 22 is a plan view showing the outline of a paper feed tray of the document detection apparatus.

[Explanation of symbols]

 1 Semiconductor Laser (Light Source) 3 Rotating Mirror (Light Separating Means / Optical Path Changing Means) 5 Photosensitive Drum (Photosensitive Body) 8 Light Guide Plate (Light Detecting Means / Light Guide Means) 8a Incident Surface (First Surface) 8b Blazing (Deflection) Surface 9 Light receiving element (light detection means / light detection signal output means) 13b Illumination light (light / light beam) 13c Reflected light 14 Paper (paper) 54 Paper and transparent sheet (paper) 58 Light guide plate (light guide) 59 Light receiving element (light detection means / light detection signal output means)

Claims (4)

[Claims] 1. A sheet detection device for an electrophotographic apparatus, which is provided in an electrophotographic apparatus for writing information by irradiating light on a photoconductor and detects a sheet conveyed in a sheet feeding section of the electrophotographic apparatus. , A light separating unit that separates an optical path for irradiating the photosensitive member and an optical path for irradiating the width direction of the paper in the paper feeding unit with respect to the same light source; A sheet detection device for an electrophotographic apparatus, comprising: a light detection unit that detects a change in the amount of light applied to the paper portion in the width direction and outputs continuous position information in the width direction. 2. The light source is a light source that emits a light beam, and the light separating means sets an optical path of the light beam so that the light beam scans the paper feed section from one end to the other end in the width direction. An optical path changing means for changing the optical path is provided, and the light detecting means is provided with a light guiding means for collecting a light beam obtained by scanning the paper feeding section in the width direction at an end portion in the width direction and a light feeding means arranged at the end portion in the width direction. 2. The sheet detecting apparatus for an electrophotographic apparatus according to claim 1, further comprising: a photodetection signal output unit that outputs a signal according to a change in the amount of light applied to the sheet. 3. The light guide means has a first surface, which is an incident surface of the light beam, and a second surface facing the first surface, and extends in the width direction. 3. A deflecting surface for guiding a light beam to the light detection signal output means arranged at the end of the light guide means is formed on the two surfaces.
A paper detection device for the electrophotographic device described. 4. The light detecting means is arranged so as to receive reflected light obtained by obliquely irradiating the surface of the paper with the light from the light source. The sheet detection device of the electrophotographic apparatus according to 1, 2, or 3.