JP4744898B2 - Document size detection device, document reading device, and image forming device - Google Patents

Description

  The present invention relates to a document size detection device, a document reading device, and an image forming apparatus.

  A conventional document size detection device includes a plurality of reflection type photosensors arranged below a glass platen on which a document is placed, and each reflection type photosensor is directed toward a predetermined detection area of the document table. A light emitting element that emits light and a light receiving element that receives light reflected from the original when the original is present, and the size of the original can be detected by a combination of the presence or absence of reflected light (For example, refer to Patent Document 1).

  Specifically, as shown in FIG. 8, for example, detection areas 1 to 4 are set on the document table, the detection area 1 has reflected light from the original, and the detection areas 2, 3 and 4 from the original If there is no reflected light, the document placed on the document table is detected as a vertical B5 size.

Japanese Patent Laid-Open No. 10-10651 (page 3, FIG. 1, FIG. 5)

  However, in the conventional document size detection device, when the document is placed on the document table, if the operator's hand attached to the document is within the range including the document detection area, the document size is erroneously detected. There was a problem.

  For example, in FIG. 8, when a B5 size document is placed vertically, and the operator's hand attached to the document is in the detection area 2, the reflection type light that detects the presence or absence of the document in the detection area 2. There is a problem that the sensor receives reflected light from the operator's hand, and the B5 size is erroneously detected as the A4 size.

  The present invention has been made to solve such a problem, and provides a document size detection device, a document reading device, and an image forming device that can prevent erroneous detection of a document size.

The document size detection apparatus of the present invention includes a document presence / absence detection unit that detects the presence / absence of a document in a predetermined detection area of a document table, and a document that detects the size of the document based on a detection result of the document presence / absence detection unit. Size detection means, and the document presence / absence detection means includes light irradiation means for irradiating light on the document placed on the document table, and light receiving means for receiving reflected light from the document, The light irradiating means adjusts the amount of light applied to the original so that the original presence / absence detecting means can detect the original in the detection area but cannot be detected by an operator's hand attached to the original. The light amount adjusting unit includes an adjustment hole for adjusting the amount of light emitted from the light irradiation unit between the light irradiation unit and the document table .

With this configuration, the document size detection apparatus of the present invention can detect the document in the document detection area, but adjusts the amount of light applied to the document so that the operator's hand attached to the document cannot detect it. And erroneous detection of the document size can be prevented.
Also, with this configuration, the document size detection apparatus of the present invention can detect the document in the document detection area, but the amount of light applied to the document is such that the operator's hand attached to the document cannot be detected. Alternatively, the amount of reflected light from the original can be adjusted by the adjustment hole, and erroneous detection of the original size can be prevented.

The document size detection apparatus of the present invention also detects a document presence / absence detection unit for detecting the presence / absence of a document in a predetermined detection area of the document table, and detects the size of the document based on a detection result of the document presence / absence detection unit. A document size detecting unit, and the document presence / absence detecting unit includes a light irradiating unit for irradiating light on the document placed on the document table, and a light receiving unit for receiving reflected light from the document. The light receiving means adjusts the amount of light reflected from the document so that the document presence / absence detecting unit can detect the document in the detection area but cannot be detected by the operator's hand attached to the document. The light amount adjusting unit includes an adjustment hole for adjusting the amount of reflected light from the document between the document table and the light receiving means .

  With this configuration, the document size detection apparatus of the present invention can detect the document in the document detection area, but adjusts the amount of reflected light from the document so that the operator's hand attached to the document cannot detect it. And erroneous detection of the document size can be prevented.

Also, with this configuration, the document size detection apparatus of the present invention can detect the document in the document detection area, but the amount of light applied to the document is such that the operator's hand attached to the document cannot be detected. Alternatively, the amount of reflected light from the original can be adjusted by the adjustment hole, and erroneous detection of the original size can be prevented.

  Furthermore, the document size detection apparatus of the present invention includes temperature detection means for detecting temperature, and the light amount adjustment unit has a configuration for adjusting the light amount based on the temperature.

  With this configuration, when the temperature detection unit detects the operator's hand attached to the document, the light amount adjusting unit detects the light amount that cannot be detected by the operator's hand attached to the document. As described above, the amount of light applied to the document or the amount of reflected light from the document can be adjusted, and erroneous detection of the document size can be prevented.

  The document reading apparatus according to the present invention includes a document size detection device, a document table on which the document is placed, and an image reading unit that reads an image of the document.

  With this configuration, the document reading apparatus of the present invention includes a document size detection device that detects the document in the document detection area but does not detect the hand of the operator attached to the document, thereby preventing erroneous detection of the document size. can do.

  The image forming apparatus of the present invention includes a document reading device and an image forming unit that forms an image based on the image of the document.

  With this configuration, the image forming apparatus of the present invention includes a document reading device that detects a document in the document detection area but does not detect the hand of the operator attached to the document, thereby preventing erroneous detection of the document size. be able to.

  The present invention can provide a document size detecting device, a document reading device, and an image forming device having an effect of preventing erroneous detection of a document size.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, the configuration of the image forming apparatus according to the first embodiment of the present invention will be described.

  As shown in FIG. 1, an image forming apparatus 10 according to the present embodiment includes a document size detection unit 14 that detects the size of a document, a main control unit 19 that controls the entire apparatus, and an image reading that reads an image of a document. The image forming unit 21 includes an image forming unit 21 that forms an image, a paper feeding unit 22 that feeds paper, and an operation / display unit 23 that displays an operation command and a predetermined comment selected by an operator. The document size detection unit 14 constitutes the document size detection device of the present invention.

  As shown in FIG. 2, the image forming apparatus 10 according to the present exemplary embodiment includes a document table 11 made of, for example, glass, a document guide 12 in the vertical direction, and a document guide 13 in the horizontal direction. . The document 5 is set on the document table 11 with the document guide 12 and the document guide 13 as a reference. The document table 11, the document size detection unit 14, and the image reading unit 20 (see FIG. 1) constitute the document reading apparatus of the present invention.

  The document size detection unit 14 includes a reflection type optical sensor 14 a to 14 d as shown in FIG. 2 and a CPU 5, a memory, a sensor signal processing circuit, etc. (not shown), and a document 5 placed on the document table 11. The original size is detected. That is, the reflection type optical sensors 14a to 14d detect the presence or absence of a document by reflection of light in the detection areas 1 to 4, respectively, and the document size detection unit 14 detects the size of the document based on the combination of the presence or absence of the document. It has become. The reflection type optical sensors 14a to 14d constitute the document presence / absence detection means of the present invention. The document size detection unit 14 constitutes a document size detection unit of the present invention.

  Next, the configuration of the reflective optical sensor 14a will be described with reference to FIG. FIG. 3A shows an example of detecting the presence or absence of the document 5 in the detection area 1 with the first light quantity, which can also detect a document with a low brightness (hereinafter referred to as “high sensitivity”). These show an example in which the presence or absence of the document 5 in the detection area 1 is detected with a second light amount smaller than the first light amount. Examples of the surface document with low brightness include a document in which white characters are written on a black background, a photo document, and the like.

  As shown in FIGS. 3A and 3B, the reflection type optical sensor 14 a has a light source 31 that emits light to irradiate the detection area 1 of the document table 11 and an output 32 that passes the emitted light 32 from the light source 31. A light emitting hole 33, a light quantity limiting unit 34 that limits the light quantity of the outgoing light 32, a reflected light hole 35 that allows the reflected light reflected by the document 5 in the detection region 1 to pass, and a transmitted light 36 that has passed through the reflected light hole 35. And a light receiving element 37 for receiving light. The light source 31 is composed of, for example, a light emitting diode, and the light receiving element 37 is composed of, for example, a photodiode.

  The light quantity limiting unit 34 includes a light quantity limiting hole 34 a having a diameter smaller than the diameter of the outgoing light hole 33. The diameter of the light quantity limiting hole 34 a can detect the document 5 in the detection area 1, but is attached to the document 5. The operator's hand is not detected (hereinafter referred to as “low sensitivity”). The light source 31 and the light receiving element 37 constitute the light irradiation means and the light receiving means of the present invention, respectively. Further, the light amount limiting unit 34 constitutes a light amount adjusting unit of the present invention. The light quantity limiting hole 34a constitutes the adjustment hole portion of the present invention.

  Further, the light quantity limiting unit 34 is configured to be slidable as shown in FIGS. 3A and 3B, and the high sensitivity side shown in FIG. 3A and the configuration shown in FIG. The low sensitivity side can be switched. Therefore, the reflection type optical sensor 14a operates such that the manuscript 5 attached to the manuscript 5 is not sensed by detecting the manuscript 5 in the detection region 1 by setting the light amount limiting unit 34 to the low sensitivity side. To do.

  Note that the means for switching the light amount limiting unit 34 to the high sensitivity side or the low sensitivity side may be configured to be electrically switched using a solenoid, for example, or may be configured to be performed manually.

  Further, only the configuration of the reflective optical sensor 14a has been described, but the reflective optical sensors 14b to 14d are configured in the same manner as the reflective optical sensor 14a, and are respectively in the detection regions 2 to 4 shown in FIG. The presence or absence of the document 5 is detected.

  Next, the operation of the image forming apparatus 10 of the present embodiment will be described. It is assumed that the light amount limiting units 34 of the reflection type optical sensors 14a to 14d are set on the low sensitivity side.

  First, the operation / display unit 23 is operated by the operator, the power is turned on, and a predetermined menu is displayed. Next, the document size detector 14 detects the document size. For example, as shown in FIG. 2, when the document 5 is placed on the document table 11, the presence or absence of the document 5 is detected by the reflective optical sensors 14a to 14d.

  In FIG. 2, the detection areas 1 and 3 of the reflective optical sensors 14a and 14c are within the range where the document 5 is placed. Therefore, for example, the light emitted from the light source 31 of the reflection type optical sensor 14 a passes through the light amount restriction hole 34 a of the light amount restriction unit 34, is reflected by the detection region 1, and reaches the light receiving element 37 through the reflection light hole 35. Therefore, the reflective optical sensor 14a detects the document 5. Similarly, the reflective optical sensor 14 c also detects the document 5.

  On the other hand, the detection areas 2 and 4 of the reflection type optical sensors 14b and 14d are outside the range where the document 5 is placed and no reflected light is generated. Therefore, the reflection type optical sensors 14b and 14d do not detect the document 5.

As described above, based on the combination of the presence or absence of the document 5 detected by the reflective optical sensors 14a to 14d, the document size detection unit 14 detects the size of the document 5 as shown in the following table, for example. For example, as shown in FIG. 2, when the reflection type optical sensors 14a to 14d are arranged and the document 5 is detected only in the detection area 1, the document size detection unit 14 detects the size of the document 5 as B5 vertical size. To do.

  Here, since the light amount limiting units 34 of the reflection type optical sensors 14a to 14d are respectively set on the low sensitivity side, even when the operator's hand attached to the document 5 is in the detection area 2 or 4, the reflection type optical sensors 14a to 14d are reflected. Both the mold optical sensors 14b and 14d do not detect the operator's hand, and can prevent erroneous detection of the document size.

  Next, the document size detection unit 14 transmits a signal indicating the detected document size to the main control unit 19. Further, the image reading unit 20 reads an image of the document 5, and the image data is transmitted to the image forming unit 21 via the main control unit 19.

  Next, the image forming unit 21 forms an image to be copied by processing such as charging, optical writing, and development based on the image data read by the image reading unit 20. Then, a paper feeding operation is performed by the paper feeding unit 22, and image transfer, fixing, paper ejection, and the like are performed by the main control unit 19.

  As described above, according to the image forming apparatus 10 of the present embodiment, the reflection type optical sensors 14 a to 14 d can detect the document 5 in the detection areas 1 to 4, respectively, but an operator attached to the document 5. The hand is provided with a light amount limiting unit 34 for setting a light amount that cannot be detected, and the document size detecting unit 14 detects the size of the document based on the combination of the presence or absence of the document 5 detected by the reflective optical sensors 14a to 14d. Since the configuration is adopted, erroneous detection of the document size can be prevented.

  Further, according to the image forming apparatus 10 of the present embodiment, the reflection type optical sensors 14 a to 14 d have a simple configuration including the light amount limiting unit 34, and therefore, dedicated for detecting the operator's hand attached to the document 5. The cost can be reduced as compared with the sensor using this sensor.

  Further, according to the image forming apparatus 10 of the present embodiment, the detection sensitivity of the reflective photosensors 14a to 14d is set to a desired sensitivity by changing the diameter of the light amount restriction hole 34a of the light amount restriction unit 34. be able to.

  In the above-described embodiment, the configuration in which the light quantity limiting unit 34 is provided on the light source 31 side has been described as an example. However, the present invention is not limited to this, and the light quantity limiting unit 34 is provided on the light receiving element 37 side. The same effect can also be obtained by providing a configuration in which the amount of reflected light from the document 5 is adjusted.

  Further, in the above-described embodiment, the light quantity limiting unit 34 has been described by taking the configuration having one light quantity limiting hole 34a as an example. However, the present invention is not limited to this, and a plurality of different diameters are provided. The same effect can be obtained with a configuration having a hole.

  In the above-described embodiment, the configuration in which the light amount limiting unit 34 can slide is described as an example. However, the present invention is not limited to this, and for example, the light amount limiting unit 34 can be attached and detached. The same effect can be obtained when the light quantity is set by rotating a disk-shaped plate having a plurality of holes having different diameters.

(Second Embodiment)
First, the configuration of the image forming apparatus according to the second embodiment of the present invention will be described. The image forming apparatus according to the present embodiment is obtained by changing a part of the reflection type photosensors 14a to 14d according to the image forming apparatus 10 according to the first embodiment of the present invention. The same reference numerals are assigned to the same components as those in FIG.

  As shown in FIG. 4, the reflective optical sensor 14 a according to the image forming apparatus of the present embodiment is configured to emit a light source 31 that emits light to irradiate the detection area 1 of the document table 11 and emitted light 32 from the light source 31. An outgoing light hole 33 that passes through, a reflected light hole 35 that passes reflected light reflected by the document 5 in the detection region 1, a light receiving element 37 that receives the passed light 36 that has passed through the reflected light hole 35, and a light source 31. And a jumper switch 41 for setting the amount of emitted light. Although only the configuration of the reflective optical sensor 14a has been described, the reflective optical sensors 14b to 14d are also configured in the same manner as the reflective optical sensor 14a. For example, the detection regions 2 to 4 illustrated in FIG. The presence / absence of the document 5 is detected in FIG.

  As shown in FIG. 5, the jumper switch 41 selects one of two current limiting resistors R1 and R2 that limit the current flowing through the light source 31. The jumper switch 41 constitutes the switch of the present invention. Further, the jumper switch 41 and the current limiting resistors R1 and R2 constitute a current control unit of the present invention.

  When the current limiting resistor R1 is selected by the jumper switch 41, the light source 31 irradiates the detection area 1 with a first light amount that can detect a document with a low brightness surface, and the reflective photosensor 14a is on the high sensitivity side. Is set. On the other hand, when the current limiting resistor R2 is selected by the jumper switch 41, the light source 31 irradiates the detection region 1 with a second light amount smaller than the first light amount, and the reflective optical sensor 14a is in the detection region 1. Although the document 5 can be detected, the operator's hand attached to the document 5 is set to the low sensitivity side where it cannot be detected.

  Similarly to the reflection type optical sensor 14a, the reflection type optical sensors 14b to 14d also select either the current limiting resistor R1 or R2 by the jumper switch 41 and set it to the high sensitivity side or the low sensitivity side.

  As described above, according to the image forming apparatus of the present embodiment, the light amount of the light source 31 is set by the jumper switch 41, and the reflective photosensors 14a to 14d are set to the high sensitivity side or the low sensitivity side. Therefore, although the document 5 can be detected in the detection areas 1 to 4, it can be set so that the amount of light that cannot be detected by the operator's hand attached to the document 5 can prevent erroneous detection of the document size.

  Further, according to the image forming apparatus of the present embodiment, since the light quantity of the light source 31 is set by the jumper switch 41, the operator can easily set the detection sensitivity set in the reflection type photosensors 14a to 14d. It can be visually recognized.

  In the above-described embodiment, the configuration in which the light amount of the light source 31 is set by the jumper switch 41 has been described as an example. However, the present invention is not limited to this, and the jumper switch 41 can A similar effect can be obtained by adjusting the light receiving sensitivity with the current limiting resistor R1 or R2.

  In the above-described embodiment, the configuration in which the jumper switch 41 selects one of the two current limiting resistors has been described as an example. However, the present invention is not limited to this, and the jumper switch 41 is not limited to this. A similar effect can be obtained by selecting any of the three or more current limiting resistors.

(Third embodiment)
First, the configuration of the image forming apparatus according to the third embodiment of the present invention will be described. The image forming apparatus according to the present embodiment is obtained by changing the reflection type photosensors 14a to 14d according to the image forming apparatus according to the second embodiment of the present invention, and thus has the same configuration as the image forming apparatus. Are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 6, the reflective optical sensor 14a according to the image forming apparatus of the present embodiment includes an analog switch 42 instead of the jumper switch 41 according to the image forming apparatus of the second embodiment of the present invention. ing. The analog switch 42 includes a high sensitivity setting switch 42a and a low sensitivity setting switch 42b, and is operated by an analog switch switching control signal from a switch switching control circuit (not shown). The reflection type optical sensors 14b to 14d are also configured in the same manner as the reflection type optical sensor 14a, and each detects the presence or absence of the document 5 in the detection areas 2 to 4 shown in FIG. 2, for example. .

  The analog switch 42 selects one of the two current limiting resistors R1 and R2 that limit the current flowing through the light source 31. Here, when the current limiting resistor R1 is selected by the analog switch switching control signal, the high sensitivity setting switch 42a is turned on, the low sensitivity setting switch 42b is turned off, and when the current limiting resistor R2 is selected, the current limiting resistor R2 is high. The sensitivity setting switch 42a is turned off and the low sensitivity setting switch 42b is turned on. In addition, it is good also as a structure which displays whether the analog switch 42 is set to the high sensitivity side or the low sensitivity side by LED, for example. The analog switch 42 constitutes the electronic switch element of the present invention. The analog switch 42 and the current limiting resistors R1 and R2 constitute a current control unit of the present invention.

  When the current limiting resistor R1 is selected by the analog switch 42, the light source 31 irradiates the detection region 1 with a first light amount that can also detect a surface document with low brightness, and the reflective photosensor 14a is on the high sensitivity side. Is set. On the other hand, when the current limiting resistor R2 is selected by the analog switch 42, the light source 31 irradiates the detection region 1 with a second light amount smaller than the first light amount, and the reflective photosensor 14a is in the detection region 1. Although the document 5 can be detected, the operator's hand attached to the document 5 is set to the low sensitivity side where it cannot be detected.

  Similarly to the reflection type photosensor 14a, the reflection type photosensors 14b to 14d also select either the current limiting resistor R1 or R2 by the analog switch 42 and set it to the high sensitivity side or the low sensitivity side.

  As described above, according to the image forming apparatus of the present embodiment, the light amount of the light source 31 is set by the analog switch 42, and the reflective photosensors 14a to 14d are set to the high sensitivity side or the low sensitivity side. Therefore, although the document 5 can be detected in the detection areas 1 to 4, it can be set so that the amount of light that cannot be detected by the operator's hand attached to the document 5 can prevent erroneous detection of the document size.

  In the above-described embodiment, the configuration in which the analog switch 42 is provided on the light source 31 side has been described as an example. However, the present invention is not limited to this, and the analog switch 42 is provided on the light receiving element 37 side. The same effect can be obtained by adjusting the light receiving sensitivity of the light receiving element 37 with the current limiting resistor R1 or R2.

  In the above-described embodiment, the configuration in which the analog switch 42 selects one of the two current limiting resistors has been described as an example. However, the present invention is not limited to this, and the analog switch 42 A similar effect can be obtained by selecting any of the three or more current limiting resistors.

(Fourth embodiment)
First, the configuration of the image forming apparatus according to the fourth embodiment of the present invention will be described. Note that the image forming apparatus according to the present embodiment is obtained by changing a part of the configuration of the image forming apparatus according to the third embodiment of the present invention. The detailed explanation is omitted.

  As shown in FIG. 7, the image forming apparatus 50 according to the present embodiment includes a reflection type optical sensor 14a to 14d, an infrared sensor 15 that detects temperature, a sensor control unit 16 that controls the operation of each sensor, and an apparatus. A main control unit 19 that performs overall control, an image reading unit 20 that reads an image of a document, an image forming unit 21 that forms an image, a paper feeding unit 22 that feeds paper, an operation command selected by an operator, and And an operation / display unit 23 for displaying a predetermined comment. The reflection type optical sensors 14a to 14d, the infrared sensor 15, and the sensor control unit 16 constitute the document size detection device of the present invention.

  The infrared sensor 15 converts infrared energy into an electrical signal and detects the surface temperature of the object to be detected in a non-contact manner. For example, the infrared sensor 15 is installed in the vicinity of the reflective optical sensor 14b shown in FIG. The presence or absence of the operator's hand attached to the document 5 is detected. The infrared sensor 15 constitutes the temperature detecting means of the present invention.

  The sensor control unit 16 includes a CPU, a memory, a sensor signal processing circuit, and the like, and controls operations of the reflective photosensors 14a to 14d and the infrared sensor 15. In addition, when the operator's hand is detected by the infrared sensor 15, the sensor control unit 16 sets the detection sensitivity of the reflection type optical sensors 14 a to 14 d to the low sensitivity side.

  Next, the operation of the image forming apparatus 50 of the present embodiment will be described. However, only operations relating to document size detection will be described, and descriptions of operations similar to those of the image forming apparatus according to the third embodiment of the present invention will be omitted. It is assumed that each of the reflection type optical sensors 14a to 14d is set on the high sensitivity side as an initial state. The infrared sensor 15 is assumed to be installed in the vicinity of the reflective optical sensor 14b in FIG.

  First, the sensor control unit 16 sets the reflective optical sensors 14a to 14d and the infrared sensor 15 to the operating state, and starts detecting the document size. Here, when the operator's hand is detected by the infrared sensor 15, the sensor switch 16 changes the analog switch 42 of the reflective optical sensors 14 a to 14 d from the high sensitivity side to the low sensitivity side. That is, the analog switch 42 is set in a state in which the high sensitivity setting switch 42a is off and the low sensitivity setting switch 42b is on.

  Next, the presence or absence of the document 5 is detected by the reflective optical sensors 14a to 14d, and the document size of the document 5 is detected by the sensor control unit 16 based on the combination of the detection results of the presence or absence of the document 5.

  As described above, according to the image forming apparatus of the present embodiment, when the operator's hand is detected by the infrared sensor 15, the sensor control unit 16 reduces the detection sensitivity of the reflective optical sensors 14 a to 14 d. Since the configuration is set on the side, it is possible to prevent erroneous detection of the document size.

  In the above-described embodiment, when the operator's hand is detected by the infrared sensor 15 installed in the vicinity of the reflective optical sensor 14a, the analog switches 42 of the reflective optical sensors 14a to 14d are moved from the high sensitivity side. Although the configuration changed to the low sensitivity side has been described as an example, the present invention is not limited to this. For example, when an operator's hand is detected by the infrared sensor 15 installed in the vicinity of the reflective optical sensor 14a, only the analog switch 42 of the reflective optical sensor 14a is changed from the high sensitivity side to the low sensitivity side. The same effect can be obtained.

  As described above, the document size detection device, the document reading device, and the image forming apparatus according to the present invention have an effect of preventing erroneous detection of the document size, and can be used as a copying machine, a facsimile device, a scanner device, or the like. Useful.

1 is a block diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating an arrangement example of a reflective photosensor according to the image forming apparatus of the first embodiment of the present invention. (A) An example in which the reflective optical sensor according to the image forming apparatus of the first embodiment of the present invention detects the presence or absence of a document in a detection area with a first light amount that can also detect a document with a low brightness surface. FIG. 5B is a diagram showing an example in which the reflective optical sensor according to the image forming apparatus of the first embodiment of the present invention detects the presence or absence of a document in the detection area with a second light amount smaller than the first light amount. The figure which shows the structural example of the reflection type optical sensor which concerns on the image forming apparatus of the 2nd Embodiment of this invention. FIG. 10 is a diagram illustrating a selection example of a current limiting resistor by a jumper switch according to the image forming apparatus of the second embodiment of the present invention. FIG. 10 is a diagram illustrating a selection example of a current limiting resistor by an analog switch according to the image forming apparatus of the third embodiment of the present invention. Block diagram of an image forming apparatus according to a fourth embodiment of the present invention The figure which shows the example of arrangement | positioning of the reflection type optical switch in an image forming apparatus

Explanation of symbols

1-4 Detection area 5 Document 10, 50 Image forming apparatus 11 Document table 12, 13 Document guide 14 Document size detection unit (document size detection means)
14a to 14d Reflective optical sensor (document presence / absence detection means)
15 Infrared sensor (temperature detection means)
Reference Signs List 16 sensor control unit 19 main control unit 20 image reading unit 21 image forming unit 22 paper feeding unit 23 operation / display unit 31 light source (light irradiation means)
32 Outgoing light 33 Outgoing light hole 34 Light quantity limiting portion 34a Light quantity limiting hole 35 Reflected light hole 36 Passing light 37 Light receiving element (light receiving means)
41 Jumper switch 42 Analog switch (electronic switch element)
42a High sensitivity setting switch 42b Low sensitivity setting switch

Claims (5)

A document presence / absence detection means for detecting presence / absence of a document in a predetermined detection area of the document table; and a document size detection means for detecting the size of the document based on a detection result of the document presence / absence detection means. Presence / absence detecting means includes light irradiating means for irradiating light on the original placed on the original table and light receiving means for receiving reflected light from the original, and the light irradiating means detects the presence / absence of the original. The means includes a light amount adjustment unit that adjusts the amount of light applied to the document so that the amount of light that can be detected by the operator attached to the document but cannot be detected by an operator attached to the document, and the light amount adjustment unit includes: An original size detection apparatus comprising an adjustment hole for adjusting an amount of light emitted by the light irradiation means between the light irradiation means and the document table . A document presence / absence detection means for detecting presence / absence of a document in a predetermined detection area of the document table; and a document size detection means for detecting the size of the document based on a detection result of the document presence / absence detection means. Presence / absence detecting means includes light irradiating means for irradiating light on the original placed on the original table and light receiving means for receiving reflected light from the original, and the light receiving means includes the original presence / absence detecting means. There comprises a light quantity adjustment section wherein at the detection region document can be detected to adjust the amount of light reflected from the document to be a quantity that can not be detected the operator's hand that is appended to the document, the light amount adjustment unit, the An original size detecting apparatus comprising an adjustment hole for adjusting an amount of reflected light from the original between the original table and the light receiving means . The document size detection apparatus according to claim 1 , further comprising a temperature detection unit configured to detect temperature, wherein the light amount adjustment unit adjusts the light amount based on the temperature . An original document comprising: the original size detecting device according to any one of claims 1 to 3, an original document table on which the original document is placed, and an image reading unit that reads an image of the original document. Reader. An image forming apparatus comprising: the document reading device according to claim 4; and an image forming unit that forms an image based on an image of the document.

Images