JP2006306609A - Paper sheet detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper sheet detecting device for a document or transfer paper conveying device capable of preventing intrusion of a foreign material by forming a bag-shape (a recess-shaped part) in place of an opening part, and capable of preventing wrong detection by eliminating the reflected light from a reflection type optical sensor even if the recess-shaped part is small by using direct reflection of a material, namely a paper sheet (a document and a transfer paper), not shielding the reflected light. <P>SOLUTION: This paper sheet detecting device passes the document or the transfer paper in a conveying passage maintained by two of an upper and a lower guide plates 1 and 2, and has the reflection type optical sensor 4 for detecting a tip position or a rear end position of the document or the transfer paper on an upper guide plate side thereof, and has the recess-shaped part 5 as a part, in which the light from the reflection light type sensor 4 enters for relief, in the lower guide plate. This paper sheet detecting device is provided with a light reflection preventing means 6 for preventing reflection of the light from the reflection type optical sensor 4 over the whole area of the recess-shaped part 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reading apparatus, a sheet feeding apparatus, or an image forming apparatus including these, which is configured to detect a leading edge position and a trailing edge position of a document to be conveyed and a transfer sheet with a reflective optical sensor.

In a document feeding (conveying) device and a transfer paper feeding (conveying) device installed in a document image reading device or an image forming device, a predetermined conveying space is provided between guide plates arranged opposite to each other. In addition to having a configuration for conveying a sheet, a reflection type optical sensor for detecting the passage of the sheet is provided at a required portion of the conveyance path to obtain information for various controls.
In response to demands for miniaturization of various devices, it is not possible to ensure a wide conveyance path for an original or transfer paper (hereinafter referred to as paper) formed between two guide plates. On the other hand, the reflection type optical sensor that detects the passage of the paper is turned on when the light receiving element receives the reflected light from the paper because the paper blocks the sensor light from the light emitting element, and the light receiving element is released when the light shielding is released. Turns off when no reflected light is received, but in order to ensure that the reflective photosensor is off, the sensor light emitted from the light emitting element reaches the other guide plate surface at the nearest position and reflects it. Thus, it is known that an opening must be provided in the mating guide plate so that it is not received by the light receiving element (see, for example, Patent Documents 1 to 4).
FIG. 14 is a schematic diagram showing a conventional detection device for detecting the passage of paper. When detecting the paper feed position, it is generally detected by a photo interrupter with a filler or by a reflective optical sensor 4.
In the case of a photo interrupter with a filler, it is necessary to design the movable range of the filler carefully, and signal chattering due to filler operation must also be taken into consideration.
In the case of a system with a high feed rate, the reflective optical sensor is more advantageous. In the case of using a reflection type optical sensor, the apparatus is designed so that the sensor is turned on when the leading edge of the sheet is detected and turned off when the trailing edge of the sheet is removed. If the product layout is permitted, a hole is made in the conveyance guide plate facing the optical sensor to prevent reflection of the sensor light when the paper comes out.
In FIG. 14, a document or transfer paper (paper) P passes through a transport path maintained by upper and lower guide plates 1 and 2, and proceeds to the next process through the document or transfer paper transport roller 3. A reflective photosensor 4 is disposed on the upper guide plate 1. An opening 2a is opened in the lower guide plate 2 facing the reflection type optical sensor 4 to prevent reflection of the sensor light when the paper P is removed.
In this case, the opening 2a of the lower guide plate 2 is secured as large as possible to avoid erroneous detection. Here, in the case of a sheet-through document conveyance device (DF) arranged on a book scanner, the reading optical system mirror moves under the conveyance path, and therefore, it does not like the inflow of dust from the opening of the lower guide plate 2. For this reason, if a hole is made in the lower guide plate 2, dust such as paper dust enters the scanner and affects the read image.
FIG. 15 is a schematic view showing another detection device, in which a base 7 and the like are arranged under the lower guide plate 2 of FIG. In this conventional example, the optical sensor 4 cannot be turned off unless the distance from the optical sensor 4 to the base 7 is considerably increased. For example, the base 7 may be provided at a position exceeding 20 mm from the emission part of the optical sensor 4, but in this case, the apparatus configuration including the guide plates 1 and 2 for transporting the paper becomes large.

Patent Document 1 aims to provide a reflection type optical sensor. However, a reflection plate reflects light from the sensor and detects a change in the amount of received light when an object blocks the reflected light.
Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique that can properly identify the boundary between a label and a mount.
In Patent Document 3, a retroreflector that reflects the irradiated light is used, sensor light is red and infrared light, and the object is detected by blocking the reflected light path. The method to do is disclosed.
Patent Document 4 discloses that the position detection sensors on both sides are constituted by a single sensor.
JP 07-280951 A JP 09-257568 A No. 06-002348 JP 2002-274747 A

However, in the conventional technology as described above, when a book-type reading device is located below the guide plate facing the reflective optical sensor, such as a document position sensor in a sheet-through document conveying device (DF), If the opening for normalizing the operation of the reflective optical sensor is provided in the guide plate, the book type reading system is affected by minute dust, paper dust, etc. from the opening.
Therefore, the present invention passes sensor light from the light emitting element of the reflective photosensor when a reflective photosensor is arranged on one guide plate (wall) of the transport path in order to detect the conveyed paper. Instead of providing an opening in the opposing guide plate (wall), a bag-like part (concave part) is provided at that part to prevent the ingress of dust and not to block reflected light. = Providing a paper detection device that uses direct reflection of paper (original, transfer paper) to eliminate erroneous detection by eliminating reflected light from the reflective optical sensor even if the concave portion is small. .

In order to solve the above-described problem, the invention according to claim 1 detects the leading edge position or trailing edge position of the sheet conveyed in the conveyance path formed between the upper guide plate and the lower guide plate. In the paper detection apparatus, the concave-shaped portion is provided with a reflective-type optical sensor for the upper guide plate side, and a concave-shaped portion that receives sensor light from the reflective-type photosensor on the plate surface of the lower guide plate. A light reflection preventing means for preventing reflection of the sensor light from the reflection type photosensor is provided in the entire inner area.
The invention of claim 2 is characterized in that, in claim 1, the light reflection preventing means is made of a black sheet having low light reflectivity.
A third aspect of the present invention is characterized in that, in the first aspect, the light reflection preventing means is a flocking treatment portion formed in the entire concave portion of the lower guide plate.
According to a fourth aspect of the present invention, in the first aspect, the light reflection preventing means is a paint mixed with a dye or an absorbent that absorbs the wavelength of the reflection type photosensor light formed over the entire concave portion. Features.
According to a fifth aspect of the present invention, in the first aspect of the present invention, the lower guide plate having the concave-shaped portion is a dye that absorbs the wavelength of the reflective photosensor light for detecting the front end position or the rear end position of the paper. It is a molded product using a material mixed with an absorbent.
The invention of claim 6 is characterized in that, in claim 5, the color of the lower guide plate is black.
In a seventh aspect of the present invention, in any one of the second to sixth aspects, the concave portion comprises a separate light blocking member attached to the back side of the hole formed in the lower guide plate, The light blocking member is sandwiched between a lower guide plate fixing member for fixing the lower guide plate and the lower guide plate.
The invention of claim 8 is characterized in that, in claim 7, a fixing means for fixing the light blocking member to the lower guide plate is provided.

  According to the present invention, the light reflection preventing means for preventing the reflection of the reflection type photosensor light is provided over the entire concave portion arranged on the optical path of the outgoing light from the reflection type photosensor that detects the conveyed paper. As a result, it is possible to obtain a paper detection device that does not affect disturbance light, can eliminate the reflected light when there is no object to be detected, and can eliminate the occurrence of malfunction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a detection apparatus according to the present invention. In FIG. 1, a document or transfer paper (hereinafter referred to as “paper”) P to be transported passes from the left to the right through a transport path formed between the upper and lower guide plates 1 and 2, and then passes through the transport roller 3. Proceed to the process.
A reflection type photosensor 4 (light emitting element 4a, light receiving element 4b) is disposed on the upper guide plate 1. A concave portion 5, which is a relief shape portion, is provided at a position of the lower guide plate 2 facing the reflective optical sensor 4. An antireflection sheet 6 is attached to the bottom surface of the concave portion 5 so as to prevent reflection of the sensor light when the paper P passes through the sensor light irradiation position from the light emitting element 4a.
FIG. 2 is a schematic perspective view showing the configuration of the lower guide plate provided with the concave portion of FIG. The paper passing direction is a direction indicated by an arrow. The lower guide plate 2 includes a plurality of guide ribs 2a, and the concave portion 5 is provided integrally between the adjacent guide ribs 2a.
The concave portion 5 has a bag shape, and no hole is formed on the bottom surface thereof. In this way, the concave portion 5 is provided on the lower guide plate 2 so as to increase the distance from the optical sensor 4, and an antireflection sheet (not shown) is attached to the bottom surface in order to suppress the reflected light.
FIG. 3 is a schematic view showing a case where the opening diameter of the concave portion of FIG. 1 is small. In FIG. 3, since the configuration is the same as that in FIG. 1, the same reference numerals are given to the same portions, and descriptions other than those necessary are omitted.
Even if configured as shown in FIG. 1, if the opening diameter of the concave portion 5 is not sufficiently large, a part of the sensor light (generally infrared light) of the optical sensor 4 is formed on the inner wall of the concave portion 5. The light is reflected and enters the light receiving element 4b of the optical sensor 4. That is, the sensor light from the light emitting element 4a of the reflective optical sensor 4 strikes a portion of the lower guide plate (inner wall of the concave portion 5), and a small amount of light enters the light receiving portion (arrow in FIG. 3).

FIG. 4 is a graph showing the relationship between the document distance from the reflective optical sensor and the light quantity of the light receiving unit (light receiving element). FIG. 4 shows the paper of the material corresponding to the document or transfer paper, the distance between the reflective sensors, and the amount of light that is reflected from the paper into the light receiving unit. This is a pseudo-measurement of the output of the optical sensor with an analog current value.
As shown in FIG. 4, the paper transported in the transport path is close to the light emitting element of the optical sensor 4, and after the paper passes through the sensor, the light sensor 4 has a light receiving unit light amount that is a threshold value. It can be turned off by:
Therefore, if the amount of light received by the optical sensor 4 that hits the inner wall of the concave portion 5 of the lower guide plate 2 in FIG. 3 is in the region surrounded by the ellipse in FIG. become. That is, when the sensor light from the reflective optical sensor 4 hits a portion of the lower guide plate 2 and a small amount of light enters (returns) the light receiving portion, the light receiving portion current is turned off by the amount of light entering the light receiving portion. If the value is greater than (value), the optical sensor 4 cannot be turned off after the paper passes.
FIG. 5 is a graph showing the hysteresis of the reflective optical sensor. As shown in FIG. 5, the variation in the hysteresis of the reflection type photosensor is the position of the upper and lower guide plates 1 and 2 (FIGS. 1 and 3), the mounting position of the photosensor 4 (FIGS. 1 and 3), or the photosensor. 4 is caused by the characteristic variation of itself (FIG. 5).
Due to such variations in the hysteresis characteristics and sensitivity of the reflective optical sensor 4, a state occurs in which the optical sensor 4 cannot be turned off after passing through the paper. In order to avoid such inconveniences, a concave portion 5 is formed on the lower guide plate 2 (FIGS. 1 and 3), and the reflection type photosensor 4 is formed on the entire inner surface (bottom surface and inner wall) of the concave portion 5. The anti-reflection means 6 that does not reflect the light from is inserted.
FIG. 6 is a schematic perspective view showing only a concave portion of the lower guide plate. FIG. 7 is a schematic view showing a light reflection preventing material. FIG. 8 is a schematic view showing the light reflection preventing material of FIG. 7 divided into two sheets.
As one configuration example of the sensor light reflection preventing means described above, in FIGS. 6 to 8, not only the antireflection sheet 6 is pasted on the bottom surface of the concave portion 5 of the lower guide plate 2 (FIGS. 1 and 3), A black sheet 6a having a low light reflectance is fixed to the inner wall with an adhesive 6b or an adhesive.
The sheet having a low light reflectance is, for example, a black sheet subjected to flocking treatment, and a material that is lower than the sensor cutoff threshold is selected. Since a sheet having a low reflectance is used as an antireflection means, reflected light can be easily suppressed.

FIG. 9 is a schematic view showing the configuration of the lower guide plate provided with the concave portion of FIG. 1 similar to FIG. The lower guide plate 2 includes a plurality of guide ribs 2a, and the concave portion 5 is provided integrally between the adjacent guide ribs 2a.
Further, as another configuration example of the sensor light reflection preventing means 6 described above, a flocking process is directly performed on the inner wall of the concave portion 5 of the lower guide plate 2. In selecting the material and color, this may be performed so that the sensor cutoff threshold is lowered when the sensor light is applied. Since the antireflection means is processed directly on the component (concave portion 5), there is no need to perform an operation of attaching, and it is not necessary to check the attachment quality.
As another means, the reflection type optical sensor 4 (FIGS. 1 and 3) is coated on the entire inner surface of the concave portion 5 of the lower guide plate 2 with a paint mixed with a dye or an absorbent that absorbs the wavelength of light. You can also
In general, a reflection type photosensor uses a light emitting element in the wavelength region of infrared light. Therefore, it is effective to apply a paint mixed with a dye or an absorbent that absorbs infrared light.
In the antireflection means described above, secondary processing (attachment, flocking treatment, coating with paint) occurs on the lower guide plate 2. In order to avoid this, at the time of manufacturing the lower guide plate having the concave portion, a dye or an absorbent that absorbs the sensor light wavelength of the reflective optical sensor is mixed and molded.
In the above-described pasting, flocking treatment, pigment or absorbent mixture, the material of the lower guide plate (FIGS. 1 and 3) may be either Mo (molybdenum) or Pr (praseodymium). Limited to Mo parts. In this way, it is not necessary to perform secondary processing on the component by mixing the material that suppresses reflection when the lower guide plate is molded.
In addition, although the reflection of infrared light can be reduced by molding the above dye or absorbent mixed material, disturbance light may enter depending on the usage conditions (the light source for reading, illumination outside the device, etc., due to the layout of the device) May enter). Therefore, in order to prevent reflection of infrared light and visible light, the material color of the lower guide plate described above is black. By setting the color of the lower guide plate to black, it is possible to provide a paper detection device that does not affect disturbance light.

FIG. 10 is a schematic diagram (disassembled perspective view) showing an embodiment in which the concave portion of the lower guide plate is formed of a member separate from the lower guide plate. If the material color of the lower guide plate described above is black, a design failure may occur in the case of the lower guide plate corresponding to the appearance or the interior (a place that can be opened for maintenance by the user).
Therefore, the guide portion 2b of the lower guide plate 2 and the relief (recessed portion) 8 of the reflection type optical sensor (not shown) are used as separate members, and the recessed portion 8 is used as a light blocking member. The concave portion 8 of the separate member is configured so as to be positioned in the hole 2 c provided in the lower guide plate 2. The concave portion 8 may be composed of a cylindrical portion 8a and a flange portion 8b. Further, the light blocking member 8 is held so as to be held between the lower guide plate 2 and the lower guide plate fixing member (base) 7 for fixing the lower guide plate 2.
In this way, the material of the lower guide plate 2 may be the same as before, and the light blocking member 8 may be manufactured by mixing a dye or an absorbent that absorbs the emission wavelength of the reflective photosensor and molding the color in black. Unnecessary reflected light to the light receiving part of the optical sensor can be prevented.
If the light reflection preventing means is configured separately from the lower guide plate 2 by using two members, the light blocking member 8 is molded with a black sheet, flocking treatment, coating with a paint, and a wavelength-absorbing agent mixed material. You can also. Further, by making the light reflection preventing means a member different from the lower guide plate, reflected light can be suppressed without being caught by the design color of the lower guide plate.

FIG. 11 is a plan view for explaining a fixing means for fixing the light blocking member to the lower guide plate. FIG. 12 is a side view showing the fixing means of FIG. FIG. 13 is a side view showing a concave portion and a bottom view of the concave portion.
In order to hold the light blocking member 8 of FIG. 10, a member for fixing the lower guide plate (base / stay metal plate or the like) is required. When there is no member to be fixed, the molded light blocking member 8 is fastened to the lower guide plate 2.
As shown in FIGS. 11 to 13, the claw 2 c is provided at two locations on the lower guide plate 2 side, and the notch portion 8 c for passing the claw 2 c is provided on the light blocking member 8 side. If it carries out like this, if the nail | claw 2c is match | combined and pushed into the notch part 8c of the light shielding member 8, two members can be fastened easily.
As described above, when the lower guide plate itself has rigidity and the base member for fixing the lower guide plate can be eliminated, the sensor light reflection preventing means is fixed to the lower guide plate. By fastening between the two light reflection preventing means, the layout of the lower guide plate can be made without requiring holding by other members.

It is the schematic which shows the detection apparatus by this invention. It is the schematic which shows the structure of the downward guide plate which provided the concave shape part of FIG. It is the schematic which shows the case where the concave shape part of FIG. 1 is small. It is a figure which shows the relationship between the original document distance from a reflection type optical sensor, and the light quantity of a light-receiving part with a graph. It is a figure which shows the hysteresis of a reflection type optical sensor with a graph. It is a schematic perspective view which shows only the concave-shaped part of a lower guide plate. It is the schematic which shows a light reflection preventing material. It is the schematic which divides | segments into 2 sheets and shows the light reflection preventing material of FIG. It is the schematic which shows the structure of the downward guide plate which provided the concave shape part of FIG. 1 similar to FIG. It is the schematic which shows embodiment which comprises the concave shape part of a lower guide plate with a lower guide plate and another member. It is a top view explaining the fixing means which fixes a light shielding member to a lower guide plate. It is a side view which shows the fixing means of FIG. It is the side view and bottom view which show a concave shape part. It is the schematic which shows the detection apparatus which detects the passage of the conventional original or transfer paper. FIG. 15 is a schematic diagram showing a detection device that detects the passage of a conventional document or transfer paper similar to FIG. 14 when there is a structural limitation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Conveyance path | route (upper guide plate), 2 Conveyance path | route (lower guide plate), 2b Guide part, 2c Nail | claw (fixing means), 4 Reflection type optical sensor, 5 Concave-shaped part (light blocking member), 5a Antireflection material , 6 Light reflection preventing sheet, 7 Lower guide plate fixing member, 8 Light blocking member, 8c Notch

Claims (8)

  The lower guide plate is provided with a reflective optical sensor on the upper guide plate side for detecting the leading edge position or the trailing edge position of the sheet conveyed in the conveyance path formed between the upper guide plate and the lower guide plate. In the sheet detecting device having a concave portion that receives sensor light from the reflective optical sensor on a plate surface of the plate, light that prevents reflection of the sensor light from the reflective optical sensor throughout the concave portion. A paper detection apparatus comprising an antireflection means.   The paper detection apparatus according to claim 1, wherein the light reflection preventing unit is made of a black sheet having a low light reflectance.   The paper detection device according to claim 1, wherein the light reflection preventing means is a flocking treatment portion formed in the entire concave portion of the lower guide plate.   The said light reflection prevention means is the coating material which mixed the pigment | dye or absorber which absorbs the wavelength of the said reflection type optical sensor light formed in the said concave shape whole region, The claim 1 characterized by the above-mentioned. Paper detection device.   The lower guide plate having the concave portion is a molded product using a material mixed with a dye or an absorbent that absorbs the wavelength of the reflective photosensor light for detecting the leading edge position or the trailing edge position of the paper, and The paper detection device according to claim 1, wherein   6. The paper detection device according to claim 5, wherein the color of the lower guide plate is black.   The concave-shaped portion is composed of a separate light blocking member attached to the back side of the hole formed in the lower guide plate, and the lower guide plate fixing member for fixing the lower guide plate to the lower guide plate and the lower portion The paper detection device according to claim 2, wherein the paper detection device is sandwiched between the guide plate and the guide plate.   The paper detection device according to claim 7, further comprising a fixing unit that fixes the light blocking member to the lower guide plate.

Images