JP3702127B2 - Document size detection apparatus, document detection apparatus, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a document size detecting device.Document detection deviceAnd an image forming apparatus having an automatic document size detection function such as a copying machine and a facsimile.
[0002]
[Prior art]
In an image forming apparatus such as a copier or a facsimile, a document size is detected by a document size detection device and a paper tray or the like is selected. In JP-A-2-308236, a document table is scanned with two scanning lights to detect a light reception signal from the document, and position information of the document is determined in advance from each scanning locus of the two scanning lights. A document size / position detection device that determines the size and position of a document by comparing with setting information is described.
[0003]
Japanese Patent Laid-Open No. 7-295116 describes a copying apparatus in which a density reference plate is provided on a member that supports a document, and the density reference plate is arranged at a place other than the exposure movement as compared with an output signal from a detection means. . Japanese Patent Laid-Open No. 9-163083 has at least four light receiving regions arranged at positions symmetrical with respect to the center of the light receiving means, and is provided with a lens that collects incident light at one point and a cylindrical lens or an edge. A document edge detection device is described.
[0004]
In addition, a reference signal indicating the start of scanning is generated, the position of scanning after the start of scanning is measured, and the measurement data when the reflected light from the original is first received and the measurement data when the last received light is received. There has been proposed a document detection apparatus that repeats the document detection operation when the document pressing unit is open, and updates the result each time as the data of both ends. Further, a reference signal indicating the scanning start of the document and the position of the scanning light at every predetermined interval is generated, and the position of the scanning light is measured by the pulse count value of the reference signal and the clock signal count value interpolating between the pulses. Document detection devices have been proposed.
[0005]
[Problems to be solved by the invention]
In image forming apparatuses such as copiers and facsimiles equipped with a document size detection device, if the installation position and installation environment are sensitive to ambient light, the sensitivity is too good and noise due to ambient light It becomes easy to be affected. Further, since the sensitivity is too good, there is a problem that when image formation is performed with the pressure plate open, a human body (for example, an arm) is detected, and an erroneous detection of the document size occurs.
[0006]
Also, in the document size / position detection device that determines the size and position of the document using two scanning lights, the scanning trajectories of the two scanning lights are different, so the two scanning lights scan the document. There is a difference in the amount of light when returning from. Therefore, for example, if the light receiving sensitivity of the two scanning lights is not adjusted at all, if the maximum image density that can be recognized by one scanning light is 1.0, the other scanning light is scanned by the scanning light. The maximum image density that can be recognized by the locus is 1.0 or less. As described above, when the maximum densities that can be recognized by the two scanning lights are different, there is a problem that an erroneous detection of the document size occurs.
[0007]
  Claim 1,2,5, 7The present invention relates to a document size detecting device that can reduce erroneous detection of a document size.And document detection deviceThe purpose is to provide.
  Claim34, 6, 8An object of the present invention is to provide an image forming apparatus capable of reducing erroneous detection of the document size.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1When a document on the document table is scanned with a plurality of scanning trajectories by light, a detection unit that detects a light reception signal reflected by the document and having a size of the document based on a detection value of the detection unit is provided. In the document detection apparatus for determining the position and the position, the storage means for holding the light receiving sensitivity set value of the detecting means in a readable / writable manner, and the light receiving sensitivity of the detecting means corresponding to the plurality of scanning trajectories separately. And a control for transmitting the set value of each changed light receiving sensitivity to the light receiving sensitivity adjusting means each time the light receiving sensitivity corresponding to each scanning locus of the detecting means is changed. With meansIs.
[0009]
  The invention according to claim 22. The document detection apparatus according to claim 1, wherein the light receiving sensitivity is set by extracting an arbitrary set value from a plurality of set values prepared in advance and setting the set value as the light receiving sensitivity.It is.
[0010]
  The invention according to claim 3An image forming apparatus comprising the document detection device according to claim 2.It is.
[0011]
  The invention according to claim 4An image forming apparatus comprising the document detection device according to claim 1.It is.
[0012]
  The invention according to claim 5A document size detection apparatus of an image forming apparatus having an image reading unit for reading an image of a document on a document table, wherein the device is disposed below the document table and irradiates a plurality of light beams toward the document table. The plurality of light beams are scanned in a curved line to detect the reflected light from the original on the original table, and only the original is detected based on the detection signal from the original sensor. A signal is obtained to generate a second signal indicating scanning start and scanning position of the plurality of light beams, and each scanning trajectory of the plurality of light beams is based on the second signal and the first signal. In the document size detection apparatus having means for generating document measurement data in the document and means for determining the document size based on the document measurement data from the means, the light receiving sensitivities of the plurality of light beams are adjusted separately. Equipped with meansIs.
[0013]
  The invention according to claim 66. A document size detection device according to claim 5, wherein the document size detection device detects the size of the document on the document table in the image reading unit.Is.
  According to a seventh aspect of the present invention, there is provided a document size detecting device of an image forming apparatus having an image reading unit that reads an image of a document on a document table, and a plurality of document size detectors arranged below the document table and facing the document table. An original sensor that irradiates a plurality of light beams and scans the plurality of light beams in a curved line to detect reflected light from the original on the original table, and an original based on a detection signal from the original sensor A first signal is obtained by detecting only the first signal, a second signal indicating a scanning start and a scanning position of the plurality of light beams is generated, and the plurality of the plurality of light beams are generated based on the second signal and the first signal. In a document size detection apparatus, comprising: means for generating document measurement data for each scanning locus of a light beam of a book; and means for determining a document size based on document measurement data from the means. Our specific light Those having a means for adjusting the receiving sensitivity of the beam on the basis of the difference between the light receiving sensitivity of the light beam other than the specific light beam among the plurality of light beams.
  The invention according to claim 8 is provided with the document size detection device according to claim 7, and detects the size of the document on the document table in the image reading unit by the document size detection device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 1 shows an embodiment of the present invention.The imageThe reading unit 11 reads an image of the document 13 placed on the document table 12, and the main control unit 14 as a control unit performs a predetermined process on the image signal from the image reading unit 11 and then processes the processed image. The signal is output to the image forming unit 15. The image bearing member may be a belt-like photoreceptor or a sheet-like photoreceptor.
[0015]
As is well known, the image forming unit 15 rotates a drum-shaped photoconductor as an image carrier by a photoconductor driving unit and uniformly charges it by a charger, and an image from the main control unit 14 by an exposure device. The photosensitive member is exposed with an optical signal modulated by the signal to form an electrostatic latent image, and the electrostatic latent image on the photosensitive member is developed with a developing device to form a toner image, which is fed from the paper feeding unit 16. The toner image on the photoconductor is transferred to a transfer sheet as a transfer material by a transfer unit, and the toner image on the transfer sheet is fixed by a fixing device, and then discharged to the outside.
[0016]
The paper feed unit 16 has a plurality of paper trays each accommodating various sizes of transfer paper, and feeds the transfer paper from a selected paper tray of the plurality of paper trays. The operation / display unit 17 is controlled by the main control unit 14 to perform various displays by the display unit, and the operation unit is operated by a user or the like to input various instructions. The main control unit 14 controls the image reading unit 11, the image forming unit 15, the paper feeding unit 16, and the like based on input signals from the operation / display unit 17 and the like.
[0017]
The size of the document 13 placed on the document table 12 is detected by a document size detection device having a scanning document sensor 18. As shown in FIG. 2, the scanning document sensor 18 is disposed inside the optical unit of the image reading unit 11 and disposed below the document table 12. In the document sensor 18, a light beam emitted from a light emitting diode 19 as a light source is condensed by a lens 20, reflected by a reflecting portion 21 a of a partially reflecting mirror 21, and attached to a rotating mirror 22 with different inclination angles 2. Two light beams are obtained by being reflected by the mirrors 22a and 22b. Here, the light emitting diode 19 is driven by a power signal drive unit (not shown) with a drive signal of a predetermined frequency, for example, 40 KHz, and emits a 40 KHz light beam.
[0018]
The rotary mirror 22 and the encoder 24 are driven to rotate by a rotary drive unit 25, and the mirrors 22a and 22b alternately reflect the light beam from the reflection unit 21a of the partial reflection mirror 21 every half rotation, thereby providing two light beams. 26 and 27 are generated alternately. As shown in FIG. 3, the document table 12 has a left end (left end in the left-right direction) 12 a and a rear end (rear end in the front-rear direction) 12 b as the document placement reference, and the document 13 of each size has a left end on the document table 12. The rear end of the document table 12 is placed on the left end 12a and the rear end 12b. A reference plate 28 for automatic paper selection (APS) is installed adjacent to the front end of the document table 12 different from the document placement reference. Further, as shown in FIG. 6, after the document 13 is placed on the document table 12, it is covered with a pressure plate 38 and pressed.
[0019]
The two light beams 26 and 27 from the mirrors 22a and 22b are scanned by the mirrors 22a and 22b and irradiated to the reference plate 28, the document 13 on the document table 12, and the pressure plate 38, and the reflected light is reflected on the mirrors 22a and 22b. The light is received by the light receiving element 30 through the partial reflection mirror 21 and the cylindrical lens 29 and detected. The scanning trajectories 36 and 37 of the two light beams 26 and 27 are respectively curved when the two light beams 26 and 27 are scanned by the two mirrors 22a and 22b having different angles.
[0020]
The drive circuit 30 drives the light emitting diode 19 to emit light,
It is controlled by a control signal from a signal processing circuit 31 as signal processing means. The drive circuit 32 drives the rotation drive unit 25 and is controlled by a control signal from the signal processing circuit 31. The detection circuit 33 detects the output signal of the light receiving element 30 and outputs it to the signal processing circuit 31, and the detection circuit 34 detects the output signal of the encoder 24 and outputs it to the signal processing circuit 31.
[0021]
Here, astigmatism is generated in the light beams 22 a and 22 b by the cylindrical lens 29, and the spot waveform on the light receiving element 30 changes depending on whether or not the light beams 22 a and 22 b are reflected by the document 13. The light receiving element 30 is, for example, a multi-divided light receiving element (four-divided light receiving element). It is determined whether or not only a light reception signal (for the original) by the light beam reflected by the original 13 is distinguished and detected.
[0022]
The light reception sensitivity adjustment circuit 35 adjusts the light reception sensitivity of the image sensor 18 to a set value based on the signal from the signal processing circuit 31. A control unit 39 formed of a microcontroller exchanges signals with the main control unit 14, outputs a control signal to the signal processing circuit 31, and takes in document size data from the signal processing circuit 31.
[0023]
The light beams 26 and 27 are scanned every half rotation by the mirrors 22a and 22b and are alternately generated. However, both the light beams 26 and 27 are scanned simultaneously with the output of the ST signal from the timing when the reference plate 28 is scanned. The document size measurement is started, and the document size measurement is completed when the document edge is detected. The ST signal is a signal from the encoder 24 and is output as a signal indicating the scanning start and scanning position of the light beams 26 and 27 at the timing when the light beams 26 and 27 pass through the reference plate 28 as shown in FIG. It is structured mechanically.
[0024]
When the signal processing circuit 31 receives the ST signal from the encoder 24, a series of document size detection processing is started, and the light beams 26 and 27 are scanned from the reference plate 28 toward the document position. The light receiving signal input from the light receiving element 30 that receives the two light beams 26 and 27 to the signal processing circuit 31 via the detection circuit 33 is one signal, and this light receiving signal (RCV signal) is the light beam 26. , 27 are generated for a distance sufficient to detect the document.
[0025]
The adjustment of the light receiving sensitivity of the document sensor 18 is to adjust how much the received light quantity generates the RCV signal. For example, in an environment in which originals with gloss and little dirt are mainly used, the light receiving sensitivity of the image sensor 18 is preferably low. If the light receiving sensitivity of the image sensor 18 is high, an RCV signal is generated even at a height of 20 mm to 25 mm on the document table 12 as shown in FIG. Cause.
[0026]
Further, in an environment in which originals with low gloss such as newspaper are mainly used, the light receiving sensitivity of the image sensor 18 is good. For example, as shown in FIG. 6, in the process of setting the document 13 on the document table 12, the height of 20 mm to 25 mm on the document table 12 is less glossy and the amount of reflected light is less, so that the RCV signal is hardly generated. . On the other hand, when the original 13 is set on the original table 12, the light receiving sensitivity of the image sensor 18 must be increased in order to apply a light beam to the original with less gloss and detect the reflected light.
[0027]
When the light receiving sensitivity of the document sensor 18 is adjusted in this way, the light receiving sensitivity adjustment mode of the document sensor 18 is entered, and the light receiving sensitivity of the document sensor 18 is adjusted so as to be the optimum light receiving sensitivity. In this embodiment, a plurality of stages of light reception sensitivity thresholds are provided. For example, as shown in FIG. 8, the light reception sensitivity of the document sensor 18 is adjusted to one of the five stages of light reception sensitivity of 1 to 5. It is possible. For example, when adjusting the light receiving sensitivity of the document sensor 18 to the strongest light receiving sensitivity, the strongest light receiving sensitivity data is transmitted from the light receiving sensitivity adjustment circuit 35 to the document sensor 18, and light reception of the generation of the RCV signal output from the document sensor 18 is received. The sensitivity threshold is lowered. If the light receiving sensitivity threshold is lowered, the image sensor 18 generates an RCV signal even with a small amount of received light.
[0028]
When the signal processing circuit 31 receives the ST signal from the encoder 24, the signal processing circuit 31 starts a series of document size detection processing, recognizes the presence or absence of the document from the RCV signal input from the light receiving element 30 via the detection circuit 33, and also determines the RCV. Depending on whether or not the signal has a frequency of 40 KHz, it recognizes whether it is a light reception signal by a light beam from the original 13 or a light reception signal by a light beam from other than the original 13 and performs recognition processing of disturbance light reception. .
[0029]
The signal processing circuit 31 determines the document size based on the light reception signal by the light beam from the document 13, that is, the measurement value of the scanning locus 36 and the scanning locus 37 (document) based on the light reception signal by the light beam from the document 13. The orientation of the document 13 is determined by determining the size relationship between the placement standards 12 a and 12 b) and determining the size relationship between the vertical and horizontal sizes of the document 13. The size of the document 13 is determined, and these determination results are sent to the main control unit 14 via the control unit 39.
[0030]
The main control unit 14 selects one paper tray from a plurality of paper trays in the paper supply unit 16 based on the sent determination results (original direction and original size). That is, when the magnification mode is the same magnification mode, the main control unit 14 selects a paper tray in which transfer paper having the same size as the original size (original direction and original size) of the determination result is selected, and the magnification mode Is in the scaling mode, a paper tray is selected that stores transfer paper of the same size as the size of the original (the orientation of the original and the original size) of the determination result.
[0031]
FIG. 7 shows a light receiving sensitivity setting flow of the present embodiment. When the power is turned on, the control unit 39 reads the light receiving sensitivity setting value written in the readable / writable ROM and transmits it to the sensitivity adjusting device (light receiving sensitivity adjusting circuit 35) via the signal processing circuit 31, and the light receiving sensitivity adjusting circuit. 35 sets the light receiving sensitivity of the document sensor 18 to the set value of the light receiving sensitivity.
[0032]
After the initial setting of the light receiving sensitivity, the control unit 39 changes the light receiving sensitivity setting value of the document sensor 18 every time the light receiving sensitivity setting value of the document sensor 18 is changed by the operation / display unit 17. Is transmitted to the sensitivity adjustment device (light reception sensitivity adjustment circuit 35) via the signal processing circuit 31, and the set value of the light reception sensitivity is saved in the ROM. The light reception sensitivity adjustment circuit 35 determines the light reception sensitivity of the document sensor 18 as the light reception sensitivity. Set to the set value.
[0033]
The default value of the light receiving sensitivity setting value of the document sensor 18 is written in a readable / writable ROM at the time of shipment. However, an optimal setting value may be set by a serviceman or set by the user himself / herself according to the environment used by the user. To do.
[0034]
According to the first embodiment, an image forming apparatus having an image reading unit 11 that reads an image of a document on a document table 12 is disposed below the document table 12 and faces the document table 12. A document sensor 18 that irradiates a plurality of light beams 26 and 27, scans the plurality of light beams 26 and 27 in a curved line, and detects reflected light from the document 13 on the document table 12, and Only an original is detected based on a detection signal from the original sensor 18 to obtain an RCV signal as a first signal, and a second signal indicating the start of scanning and the scanning position of the plurality of light beams 26 and 27 is obtained. An encoder 24 serving as means for generating an ST signal and generating document measurement data in each of the scanning trajectories 36 and 37 of the plurality of light beams 26 and 27 based on the second signal and the first signal, and detection Circuit 33 34 and a signal processing circuit 31, and a signal size detection device having a signal processing circuit 31 as a means for determining the document size based on the document measurement data from the means, and a light receiving area of the light beams 26 and 27. Since the light-receiving sensitivity adjustment circuit 35 is provided as a means for adjusting the software, the light-receiving sensitivity of the document sensor can be adjusted to an optimum sensitivity, and erroneous detection of the document size can be reduced.
[0035]
In the first embodiment, as shown in FIG. 3, the scanning locus 36 of the light beam 26 and the scanning locus 37 of the light beam 27 have a difference of about 10 mm depending on the angles of the mirrors 22a and 22b. Because of the difference of about 10 mm, the light beam 26 of the scanning locus 36 and the light beam 27 of the scanning locus 37 are received by the light receiving element 30 with the same light receiving sensitivity. A difference occurs in the density value of the original that can be received.
[0036]
For example, when an A4 size original 13 is placed on the original table 12 as shown in FIG. 5, the maximum density value of the A4 size original 13 that can be detected by the light beam 26 of the scanning locus 36 is 1.02, and the scanning locus The maximum density value of the A4 size original 13 that can be detected by the 37 light beams 27 may be 0.95. Such a difference in light receiving sensitivity causes an erroneous detection of the document size.
[0037]
  ThereAnd this departureIn the bright second embodiment, in the first embodiment, a light receiving sensitivity adjustment mode for separately adjusting the light receiving sensitivity with respect to the scanning trajectories 36 and 37 of the document sensor 18 is provided. In this light reception sensitivity adjustment mode, the control unit 39 operates the operation / display unit to set the light reception sensitivity setting value for the light beam 26 of the scanning locus 36 and the light reception sensitivity setting value for the light beam 27 of the scanning locus 37 in the document sensor 18. 17, the sensitivity of the set value of the light receiving sensitivity for the light beam 26 of the scanning locus 36 and the setting value of the light receiving sensitivity of the scanning locus 37 for the light beam 27 is changed. After transmitting the signal to the adjusting device (light receiving sensitivity adjusting circuit 35) via the signal processing circuit 31, the light receiving sensitivity setting value for the light beam 26 of the scanning locus 36 and the light receiving sensitivity setting of the scanning locus 37 for the light beam 27 are set in the ROM. Save the value.
[0038]
The light receiving sensitivity adjustment circuit 35 is a setting value of the light receiving sensitivity for the light beam 26 of the scanning locus 36 and the setting value of the light receiving sensitivity for the light beam 27 of the scanning locus 37 transmitted from the control unit 39 via the signal processing circuit 31. Thus, the light receiving sensitivity of the scanning locus 36 of the original sensor 18 with respect to the light beam 26 and the light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 are respectively set to the light receiving sensitivity setting value of the scanning locus 36 with respect to the light beam 26 and The set value of the light receiving sensitivity for the light beam 27 is set.
[0039]
In the present embodiment, the maximum light receiving sensitivity of the scanning locus 36 with respect to the light beam 26 and the maximum light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 in the original sensor 18 are shown in 10 steps of light receiving sensitivity of 1 to 10, as shown in FIG. It is possible to adjust to any one of the light receiving sensitivities.
[0040]
According to the second embodiment, the control unit 39 and the light receiving sensitivity adjustment circuit 35 are provided as means for separately adjusting the light receiving sensitivities of the plurality of light beams 26 and 27, so that each light beam is scanned differently. It is possible to reduce false detection of the document size due to scanning the trajectory.
[0041]
  Of the present inventionIn the third embodiment, in the light receiving sensitivity adjustment mode, in the light receiving sensitivity adjustment mode, the light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 is determined based on the light receiving sensitivity of the scanning locus 36 with respect to the light beam 26. The difference between the inspection locus 36 and the light receiving sensitivity with respect to the light beam 26 is set.
[0042]
That is, in the light reception sensitivity adjustment mode, the control unit 39 determines the difference between the light reception sensitivity setting value for the light beam 26 of the scanning locus 36 and the light reception sensitivity setting value for the light beam 27 of the scanning locus 37 in the document sensor 18. Each time the operation / display unit 17 is changed separately, the set value of the light receiving sensitivity for the light beam 26 in the scanning locus 36 and the setting of the light receiving sensitivity for the light beam 27 in the scanning locus 37 are changed. After changing the set value of the light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 by the difference from the value and transmitting it to the sensitivity adjusting device (light receiving sensitivity adjusting circuit 35) via the signal processing circuit 31, the changed scanning locus to the ROM. The set value of the light receiving sensitivity for the 37 light beams 27 is saved.
[0043]
The light reception sensitivity adjustment circuit 35 transmits the light reception sensitivity for the light beam 27 of the scanning locus 37 in the document sensor 18 transmitted from the control unit 39 via the signal processing circuit 31 from the control unit 39 via the signal processing circuit 31. The set value of the light receiving sensitivity with respect to the light beam 27 of the scanning trajectory 37 has been set.
[0044]
In this embodiment, by adjusting the difference between the maximum light receiving sensitivity of the scanning locus 36 with respect to the light beam 26 and the maximum light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 in the document sensor 18, the maximum of the inspection locus 37 with respect to the light beam 27 is adjusted. As shown in FIG. 10, the light receiving sensitivity can be adjusted to any one of 10 levels of light receiving sensitivity of 1 to 10.
[0045]
For example, when the maximum light receiving sensitivity with respect to the light beam 26 of the scanning locus 36 in the original sensor 18 is 0.95 and the maximum light receiving sensitivity with respect to the light beam 27 of the scanning locus 37 is 1.02, the difference k0.07 ( = 1.02-0.95) can be adjusted so that the maximum light receiving sensitivity of the scanning locus 37 with respect to the light beam 27 can be adjusted.
[0046]
According to the third embodiment, the light receiving sensitivity of the specific light beam 26 out of the plurality of light beams 26, 27 is set to be other than the specific light beam 26 out of the plurality of light beams 26, 27. Since the control unit 39 and the light receiving sensitivity adjustment circuit 35 as means for adjusting based on the difference between the light receiving sensitivity of the light beam 27 and the light receiving sensitivity adjusting circuit 35 are provided, the erroneous detection of the document size due to each light beam scanning a different scanning locus is reduced. Can be made.
In addition, this invention is not limited to the said embodiment, For example, three or more light beams may be sufficient.
[0047]
【The invention's effect】
  Claim 1 as described above2According to the invention according to the above configuration,It is possible to reduce erroneous detection of the size and position of the document due to each light beam scanning a different scanning locus.
  Claim3, 4According to the invention according to the above configuration,It is possible to reduce erroneous detection of the size and position of the document due to each light beam scanning a different scanning locus.
[0048]
  Claim5According to the invention related to the above, with the above-described configuration, it is possible to reduce the erroneous detection of the document size due to the scanning of each light beam with a different scanning locus.
  Claim6According to the invention related to the above, with the above-described configuration, it is possible to reduce the erroneous detection of the document size due to the scanning of each light beam with a different scanning locus.
[0049]
  Claim7According to the invention related to the above, with the above-described configuration, it is possible to reduce the erroneous detection of the document size due to the scanning of each light beam with a different scanning locus.
  Claim8According to the invention related to the above, with the above-described configuration, it is possible to reduce the erroneous detection of the document size due to the scanning of each light beam with a different scanning locus.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of the present invention.
FIG. 2 is a perspective view showing the vicinity of the image sensor of the embodiment and a cross-sectional view showing a rotating mirror of the image sensor.
FIG. 3 is a plan view for explaining document placement on a document table and reference plate / document scanning by a document sensor in the same embodiment;
FIG. 4 is a timing chart showing the operation timing of the embodiment.
FIG. 5 is a plan view for explaining the embodiment;
FIG. 6 is a front view showing the vicinity of the current platform of the embodiment.
FIG. 7 is a flowchart showing a light receiving sensitivity setting flow according to the embodiment;
FIG. 8 is a plan view showing a display portion of the operation / display unit according to the embodiment;
FIG. 9 is a plan view showing a display portion of an operation / display unit according to another embodiment of the present invention.
FIG. 10 is a plan view showing a display portion of an operation / display unit according to another embodiment of the present invention.
[Explanation of symbols]
11 Image reading unit
12 Document table
18 Document sensor
24 Encoder
33, 34 detection circuit
31 Signal processing circuit
35 Light sensitivity adjustment circuit
35 Control unit

Claims (8)

When a document on the document table is scanned with a plurality of scanning trajectories by light, a detection unit that detects a light reception signal reflected by the document and having a size of the document based on a detection value of the detection unit is provided. And an original detection device for determining the position,
Storage means for holding the light receiving sensitivity setting value of the detection means in a readable and writable manner;
A light receiving sensitivity adjusting means for saving the light receiving sensitivity of the detecting means separately in the storage means corresponding to the plurality of scanning trajectories;
A control means for transmitting a set value of each changed light receiving sensitivity to the light receiving sensitivity adjusting means each time the light receiving sensitivity corresponding to each scanning locus of the detecting means is changed;
A document detection apparatus comprising: 2. The document detection apparatus according to claim 1, wherein the light receiving sensitivity is set by extracting an arbitrary set value from a plurality of set values prepared in advance and setting the set value as the light receiving sensitivity. An image forming apparatus comprising the document detection device according to claim 2. An image forming apparatus comprising the document detection device according to claim 1. A document size detection apparatus of an image forming apparatus having an image reading unit for reading an image of a document on a document table, wherein the device is disposed below the document table and irradiates a plurality of light beams toward the document table. The plurality of light beams are scanned in a curved line to detect the reflected light from the original on the original table, and only the original is detected based on the detection signal from the original sensor. A signal is obtained, and a second signal indicating scanning start and scanning position of the plurality of light beams is generated, and the second signal and the first signal are generated.
In the document size detection apparatus, comprising: means for generating document measurement data for each scanning locus of the plurality of light beams based on the number; and means for determining the document size based on the document measurement data from the means. An original size detecting device comprising means for separately adjusting the light receiving sensitivities of a plurality of light beams . 6. An image forming apparatus comprising the document size detection device according to claim 5, wherein the document size detection device detects a size of a document on the document table in the image reading unit . A document size detection apparatus of an image forming apparatus having an image reading unit for reading an image of a document on a document table, wherein the device is disposed below the document table and irradiates a plurality of light beams toward the document table. The plurality of light beams are scanned in a curved line to detect the reflected light from the original on the original table, and only the original is detected based on the detection signal from the original sensor. A signal is obtained to generate a second signal indicating scanning start and scanning position of the plurality of light beams, and each scanning trajectory of the plurality of light beams is based on the second signal and the first signal. In the document size detection apparatus having means for generating document measurement data in the document and means for determining the document size based on the document measurement data from the means, receiving a specific light beam among the plurality of light beams The sensitivity is Specific document size detection apparatus characterized by comprising means for adjusting based on the difference between the light-receiving sensitivity of the light beams other than the light beam of the light beam. 8. An image forming apparatus comprising the document size detection device according to claim 7, wherein the document size detection device detects the size of the document on the document table in the image reading unit.

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