JPS6319848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device that places a document on a contact glass plate and reads its image information using a solid-state imaging device such as a CCD element, and particularly to a document starting edge detection method in this type of image reading device. Regarding.

FIG. 1 shows an example configuration of a copying machine using this type of image reading device. In this copying machine,
The light reflected from the document IP by the light emitted from the illumination lamp HLA is guided to the surface of the photoreceptor on the drum 1 by the first mirror FMI, the second mirror SMI, the in-mirror lens IMI, and the third mirror TMI. On the other hand, the photoreceptor is uniformly charged by the main charger 2, and is exposed to the guided light to form an electrostatic latent image. This electrostatic latent image is made visible by depositing charged toner supplied by the developing device 4. On the other hand, the copy paper is taken out from the cassette CAS1 or CAS2 by the paper feed roller PSR1 or PSR2. The taken-out copy paper is sent to the transfer section by rotating the registration rollers 6 in synchronization with the position of the latent image (the edge of the document). In the transfer section, the toner attached to the latent image area is transferred onto the copy paper by the transfer charger 7.
The copy paper is separated from the drum 1 by the separation roller 8, the toner is adhered (fixed) onto the copy paper by the fixing heater HEP, and the copy paper is sent to the paper output tray COT. On the other hand, the toner remaining on the drum 1 is neutralized by the static eliminating charger 5 and collected by the cleaning roller 10. 11 is a cleaning blade.

The document reading scanning system includes illumination light HLA, mirror FMI,
It consists of an SMI and a carriage that moves them in the direction of the solid arrow AR without changing the optical path length.

FIG. 2 shows the operation timing of each part shown in FIG. 1. The copying machine shown in Figure 1 is not a type that copies the entire surface at once, but a slit exposure type, and the positions of charging, exposure, development, and transfer are shifted, as shown in Figure 2. Each part must be energized in sequence. That is,
The actual copying operation is started by the copy start signal A obtained by pressing the copy button, etc., and the main charger 2 is energized. It takes a time of t ₀ - t ₁ for the charging position to reach the exposure position. be.
However, in an actual machine, a certain amount of time is required from when the carriage equipped with the scanning optical system starts operating until it actually reaches the reading start position (starting edge of the original) of the original, and this time varies. ing. Therefore, after considering the variation, t ₀ −t ₁ is determined from the bias of the main charger 2.
After the time has elapsed, the carriage will start moving forward. After detecting the document end signal E, exposure F, developing bias G, registration roller drive H, transfer charge biasing I, carriage backward movement J, etc. are performed.
The backward movement of the carriage J continues after the period of time for the carriage to move forward until a home position signal (Home signal) K indicating that the carriage has reached its initial position is output. Further, the paper feed roller C is driven and energized by the copy start A, thereby feeding the edge of the copy paper to the registration roller 6.

Conventionally, in order to control the start and end of each of these operations, many detection switches were installed adjacent to the machine operation part, and control timing signals were obtained from these switches, but their installation and adjustment were complicated and However, there was a problem that fine synchronization was difficult.

The copying apparatus shown in FIG. 1 includes an OFT (optical fiber tube) 3 other than the original image projection optical system described above, a half mirror 14, a lens 15,
The CCD element 16 converts the optical signal of the original image into an electrical signal, and the image signal is added to the OFT 3.
Photoconductor drum 1 from the face plate of OFT3
It is possible to operate as a facsimile image reading and recording device by projecting optical information of
It may be recorded over and over again. In such a copying device,
When reading an original image and obtaining an image signal from the CCD element 16, only the optical system consisting of the light source HLA and the first and second mirrors FMI and SMI needs to be scan-driven by the carriage. Also, when copying
To prevent the face plate of OFT3 from getting dirty, slide the OFT holder 12 on the board 13.
Place OFT3 in the retreat position. In the case of recording only by energizing OFT3, the carriage is kept stationary and the main charger 2 and below are operated in the same way as when copying, but the exposure position of OFT3 is different from the exposure position by mirror TMI, and moreover, the recording operation speed is It may be preferable to change it from when copying. Copy operation and
When combining exposure by the OFT 3, a sequence control signal is required to match the exposure position by the mirror with the exposure position by the OFT 3.

In such a copying apparatus, whether it is operated in copying (mirror exposure/recording) mode, facsimile transmission (image reading/sending) mode, or facsimile receiving (image information receiving/recording) mode, each In the sequential operation of the mode, the timing of document edge detection E is extremely important. However, in the past, a magnet was connected to an optical scanning system, a reed switch or a Hall element was fixed to a base part, and the setting position of the magnet, reed switch, or Hall element was adjustable by a fixing tool. The element is activated by the arrival of the magnet to emit an electric signal, that is, document edge detection E, and the operation of each part is controlled based on this electric signal, so the document edge detection timing is inaccurate and timing adjustment is troublesome. , or there were problems such as limited placement locations.

Japanese Unexamined Patent Publication No. 48-54592 discloses a copying machine equipped with a document end detector for cutting out recording sheets corresponding to the document size from roll paper. The document end detector is located below the contact glass plate.
It mainly consists of a light emitter and receiver installed outside the field of view of the exposure optical system, and is driven to scan along one side of the contact glass plate. The light projector/receiver detects the reflected light from the document, and when the electric circuit no longer detects the reflected light from the document, it issues a document end detection signal and energizes the roll paper cutter. Since manuscript sizes vary,
A low reflection band corresponding to the scanning area of the light projector/receiver is formed on the holding plate that presses the original against the contact glass plate. When the scanning of the light emitting and receiving device deviates from the end of the document, the light projecting and receiving device detects the low reflection band, and based on this, it is determined that the end of the document has been reached.

In this copying machine, the light emitting/receiving device and its scanning mechanism are added to detect the end of the document, so it may be possible to design it to detect the end of the document with a fairly high degree of accuracy. Since the distance between the contact glass plate and the contact glass plate surface changes depending on the thickness of the document, the depth of focus of the light emitter and receiver must be increased. However, in the case of a book original, the holding surface of the original holding plate is too far away from the contact glass plate, or the holding plate remains open, making it impossible to detect the end of the original. In addition, the document contacting surface of the presser plate is easily soiled and worn out, and the black surface may fade. This results in false positives. Therefore, there is a great disadvantage in using such a trailing edge detection method for detecting the beginning edge of a document.

Japanese Patent Application Laid-Open No. 52-23688 discloses that when writing image information to a memory, in order to prevent information from being written outside the original document, that is, to increase the writing efficiency of the memory, an image reading drum is wound around the image reading drum. Although it has been disclosed to add colored lines to the beginning and end of a document, in general image reading devices, adding color lines to the document requires too much labor and damages the original form of the document. Further, it can only be used for originals with printing colors other than color lines, and the hardware configuration required to specifically detect only color lines is difficult. Therefore, it is disadvantageous to use such a starting edge/ending edge detection method for detecting the starting edge of a document.

As described above, the present invention provides a contact glass plate on which a document is placed, and an imaging means installed on the back side of the contact glass plate, which generates an image signal corresponding to an image in the main scanning direction along one side of the contact glass plate. , an optical means for projecting an image of the surface of the contact glass plate onto the imaging means, and a sub-scanning means for driving at least one of the optical means and the contact glass plate in a sub-scanning direction along the other side of the contact glass plate; The purpose of this invention is to accurately detect the starting edge of a document placed at a predetermined position on the surface of a contact glass plate in an image reading device having a do.

In order to achieve this object, the present invention provides the image reading device with an edge on the surface of the edge of the contact glass plate on the starting end side in the sub-scanning direction. an indicator member on which at least a part of the surface in contact with the contact glass plate has a low reflectance; and detecting disappearance of a signal corresponding to the surface of the indicator member in the image signal of the imaging means. A document edge detecting means for generating a detection signal representing this is provided.

According to this, when the image reading by the imaging means is transferred from the index member to the original, the original edge output means generates a detection signal. This can be used as the document edge detection E described above. Generally, the focus of the imaging means is a narrow range that matches the surface of the contact glass plate, but when reading an image of an original of any thickness, the index member is always in contact with the surface of the contact glass plate, just like the original, so the index member is in constant contact with the surface of the contact glass plate. The member is located in the focus of the imaging means and the imaging means does not produce errors in reading the indicator member. That is, the detection of the starting edge of the document is accurate. In addition, since the surface of the indicator member is always in contact with the contact glass plate, it does not get dirty or wear out.
No reading errors occur over time. Furthermore, since the imaging means for reading the original image is also used for reading the index member, there is no need to add any special mechanical elements. As will be specifically exemplified in the embodiments to be described later, the document edge detection means can be constituted by a relatively simple electric signal processing means.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

FIG. 3 shows an indicator member installed in the copying machine shown in FIG. 1 based on the present invention. Note that FIG. 3 is an enlarged sectional view of the sub-scanning start end of the contact glass plate located above the FMI in FIG. 1. In this example, a black film 18 as an index member is placed between the contact glass plate 17 and a fixed frame 19 that holds down the contact glass plate 17 mounted on the upper wall 20 of the outer case of the copying machine, in a shape along the reading start edge of the document IP. It is inserted in In addition to this, there is also a fourth indicator member.
As shown in the figure, it may be a black paint film 21 applied to the inside of the fixed frame 19 or a plating layer. Alternatively, it may be applied to the contact glass plate 17 side. Note that the CCD element 16 simultaneously converts one line's worth of optical image into electrical information, and the optical system that projects one line's worth of optical image onto it is the third one.
The sub-scanning drive is performed in the direction of the arrow AR shown in the figure and FIG. When looking through the fixed frame 19 from above the contact glass plate 17, the black film 18 is visible.
Alternatively, as shown in FIG. 5, the black coating film 21 is a single black band extending over the entire width of the contact glass plate 17 along the document IP. In addition, the 6th
As shown in the figure, a predetermined pattern may be defined by the black portions 22 ₁ to 22 ₃ and the transparent or white portions 23 ₁ and 23 ₂ .

FIG. 7 shows an image reading signal when a member having the pattern shown in FIG. 5 or 6 is used. In FIG. 7, a indicates a sub-scanning timing pulse that is emitted every time the original is sub-scanned (movement in the AR direction) by one line width, and b indicates an image signal for one line read by the CCD element 16, which is output from the CCD element. sometimes,
This is a main scanning synchronization pulse for indicating the division corresponding to each pixel of the image signal for one line.

When the index member 18 or 19 has a pattern as shown in _FIG .
After FIG. 7), an image signal of a white level begins to appear in the original reading signal c. When the index member has a pattern as shown in FIG. 6, an image signal corresponding to the pattern of the index member appears until sub-scanning reaches the starting edge of the document (up to P _A ), as shown in d of FIG. However, when sub-scanning reaches the starting edge of the document (after P _A ), the image signal distribution becomes unique to document scanning, with a high white level due to reflection from the white background of the document. Therefore, the starting edge of the document can be detected by capturing such changes in the image signal.

In FIG. 8a, a document edge detection signal is emitted when an index member having the pattern shown in FIG. 5 is used.
The configuration of one document edge detection circuit is shown. The main scanning synchronizing pulse b shown in FIG. 7 and a signal obtained by inverting the read signal c by the inverter INV1 (black level: "0") are input to the AND gate AND1. Flip-flop FF1 is set at the rising edge of the output of AND gate AND1 (high level "1"), and is reset at the rising edge of copy start A (FIG. 2). According to this document edge detection circuit, when a white signal (low level "0") appears in the read signal, the AND gate AND1 produces an output of high level "1",
As a result, flip-flop FF1 is set and its Q output becomes high level "1". This Q
The output represents document edge detection.

FIG. 8b shows another document edge detection circuit.
This circuit is configured to generate a document edge detection signal when a white signal "0" exists for a predetermined length in one line of reading signals, and while the reading signal is a white signal, an AND gate AND1 is output. Then, the main scanning synchronization pulse b is applied to the count input terminal CK of the counter COU1, and the counter COU1 is cleared by the sub-scanning timing pulse a. counter COU
When the count value of 1 reaches the set value, the decoder DEC
A 1 produces a pulse output, which sets flip-flop FF2, with a high level ``1'' signal at its Q output representing document edge detection. When using this document edge detection circuit, if the reading signal c of one line is equal to or greater than the set number of pixels, the white signal is "0".
Since it is determined that the edge of the document has reached the end of the document, the edge of the document can be detected accurately even if there are a certain number of abnormal bits (less than the set number) or noise in the read signal c. Note that this document edge detection circuit can be similarly used when using an index member having the pattern shown in FIG. In this case, the count setting value at which the output of the decoder DEC1 becomes "1" is set to the white part 23 ₁
and ₂₃₂ is set to be larger than the sum of the number of main scanning synchronizing pulses (number of pixels) assigned to 2.

FIG. 8c shows yet another document edge detection circuit. This circuit detects the edge of a document when an index member having a pattern shown in FIG. 6 is used. Counter COU2 counts main scanning synchronizing pulses b and is cleared by sub-scanning synchronizing pulses a. The decoder DEC2 determines that the count value of the counter COU2 is the first one corresponding to time _t1 shown in FIG.
When the set value is reached, a high level "1" is output at the output terminal OUT1, and when the count value reaches the second set value corresponding to time _t2 , a low level "0" is output at the output terminal OUT1. A high level "1" is output to OUT2, and when the count value reaches the third set value corresponding to time _t3 , the output terminal OUT2
This produces a low level "0" output. In other words, a high level "1" output appears at the output end OUT1 of the decoder DEC1 when the image is read in the white part ₂₃₁ , and at the output end OUT2, when the image is read in the black part ₂₂₂ . High level "1"
The output will appear.

Each of these outputs is an AND gate AND2
and given to AND3. and gate AND
2 further includes a main scanning synchronizing pulse b and a read signal d.
The AND gate AND3 is further supplied with a main scanning synchronizing pulse b and an inverted signal (white: high level "1") of the read signal d passed through the inverter INV2. This makes the andgate
AND2 outputs the main scanning synchronizing pulse b while the reading is from _t1 to _t2 and the read signal d has a black signal "1", and the AND gate AND3 outputs the main scanning synchronizing pulse b.
During reading from t ₂ to _{t 3} and while the read signal d has a white signal "0", the main scanning synchronizing pulse b is output.
The output pulses of these AND gates AND2 and AND3 are sent to the counter COU3 through the OR gate OR1.
is applied to the count input of counter COU
3 is cleared by the sub-scanning synchronization pulse a. When the sub-scan (AR) is in the region of the index member, when the main scan is at 23 ₁ of the pattern of the index member, COT1 of the counter COU2 is "1", but the read signal d is white "0". So, and gate AND
The output of 2 is "0", and the counter COU3 does not count up. Main scanning is pattern 22 ₂
, CUT2 of counter COU2 is "1", but the inverter of black "1" of read signal d
Since the inverted signal by INV2 is "0", the counter COU3 does not count up.

When the sub-scanning (AR) is removed from the index member and moved to the original, the reading signal d is white "0" or black "1" is scattered over almost the entire length of one line at the beginning of the original, so the main scanning is the index member pattern 2
3 When it is ₁ , OUT1 of counter COU2 is “1”
When the read signal d is white "0", the counter
COU3 does not count up, but when black is "1", counter COU3 counts up. When main scanning is at 22 ₂ of the index member pattern, when OUT2 of counter COU2 is "1" and reading signal d is white "0", counter COU3 counts up (this count up amount is large), and the reading When the signal d is black "1", the counter COU3 does not count up. As a result, when the sub-scanning advances to the starting edge of the document, the count up amount of the counter COU3 becomes much larger than when the sub-scanning reaches the index member, and when the count value of the counter COU3 reaches the set value, Decoder DEC3 generates an output pulse, flip-flop FF3 is set, and a high level "1" output representing document edge detection appears at its Q output.

As explained above, according to the present invention, the image reading signal of the imaging means 16 for reading the original image is used to read the original image.
Since the IP reading start edge is detected, the detection accuracy can of course be extremely high, and no mechanical adjustments or settings are required.

Generally, the focus of the imaging means 16 is a narrow range that matches the surface of the contact glass plate 17, but when reading an image of a document of any thickness, the index member 18,
21 is the contact glass plate 17 like the original IP
Since the index member 18 is in constant contact with the surface of
21 is located at the focal point of the imaging means, and the imaging means 16 does not cause reading errors of the index members 18 and 21. That is, the detection of the starting edge of the document is accurate. In addition, the surfaces of the indicator members 18 and 21 are always in contact with the glass plate 17.
Since the sensor is in contact with the sensor, it does not get dirty or wear out, so reading errors do not occur over time.
Furthermore, an imaging means 16 for reading the original image is attached to the index member 1.
Since it is commonly used for reading 8 and 21, there is no need to add any special elements mechanically. The document edge detection means (FIGS. 8a, 8b, and 8c) can be constructed from relatively simple logical processing means.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an outline of the configuration of a copying machine embodying one embodiment of the present invention. FIG. 2 is a time chart showing the operation timing of each element of the copying machine shown in FIG. FIG. 3 is an enlarged sectional view of the starting end of the original document placement on the contact glass plate of the copying machine shown in FIG. 1, and shows one manner in which the indicator member is installed. FIG. 4 is an enlarged sectional view showing another installation mode of the indicator member. FIG. 5 is a plan view showing one aspect of the distribution pattern of the low reflectance surface of the index member, and FIG. 6 is a plan view showing another aspect of the pattern.
FIG. 7 is a time chart showing the timing of generation of the sub-scanning synchronizing pulse a of the copying machine, the main-scanning synchronizing pulse b of the CCD element 16, the read signals c and d, etc. shown in FIG. FIG. 8a is a block diagram showing one embodiment of the document edge detection circuit used in the copying machine shown in FIG. 1, FIG. 8b is a block diagram showing another embodiment, and FIG. 8c is a block diagram showing still another embodiment. It is. 1: Photosensitive drum, 2: Main charger,
3: OFT, 4: Developing device, 5: Static elimination charger,
6: Registration roller, 7: Transfer charger, 8:
Separation roller, 9: Transfer paper transfer line, 10: Cleaning roller, 11: Cleaning blade,
12: OFT holder, 13: Substrate, 14: Half mirror, 15: Lens, 16: CCD element (imaging means), 17: Contact glass plate (contact glass plate), 18: Film (index member), 19:
Holding frame (second support member), 20: Upper wall (first support member), 21: Paint film (index member), IP: Original (original), HLA: Lighting light, FMI: First mirror,
SMI: 2nd mirror, IMI: In-mirror lens,
TMI: third mirror, FMI, SMI: (optical means),
FF1: Flip-flop (memory means), AND
1: AND gate (logic means), INV1: inverter (logic means), COU1: counter (counting means), DEC1: decoder (logic means), COU
2: Counter (first counting means), DEC2: Decoder (means for generating a signal indicating whether the main scanning is on a low reflection surface or a high reflection surface of a predetermined pattern), COU2: Counter (second counting means) ,
DEC3: Decoder (logical means).

Claims (1)

[Scope of Claims] 1. A contact glass plate on which a document is placed, a first support member that supports the edge of the contact glass plate on the back side of the contact glass plate, and the contact glass installed on the back side of the contact glass plate. an imaging means for generating an image signal corresponding to an image in the main scanning direction along one side of the plate; an optical means for projecting an image of the surface of the contact glass plate onto the imaging means; and at least the optical means and the first support member. In an image reading device having a sub-scanning means for driving one side of the contact glass plate in the sub-scanning direction along the other side of the contact glass plate, on the surface of the edge of the contact glass plate on the starting end side in the sub-scanning direction, the contact glass plate an index member whose end portion is located at the starting end of document placement in the sub-scanning direction, and at least a portion of the surface in contact with the contact glass plate has a low reflectance; and the index member in the image signal of the imaging means. An image reading device comprising: document edge detection means for detecting disappearance of a signal corresponding to a surface of a member and generating a detection signal representing the disappearance. 2. The index member is a film inserted between the contact glass plate and the second support member that supports the sub-scanning start end side edge of the contact glass plate on the front side of the contact glass plate. Image reading device. 3. The indicator member is a low reflection surface facing the contact glass plate of the second support member that supports the sub-scanning start end side edge of the contact glass plate on the front side of the contact glass plate. image reading device. 4. The surface of the index member that is in contact with the contact glass plate has a low reflectance over the entire length in the main scanning direction; logic means for generating a signal instructing the memory means to hold the detection signal in synchronization with a main scanning synchronization pulse indicating a pixel division in the main scanning direction of the imaging means when a signal indicating a high reflectance appears; An image reading device according to claim 1. 5. The index member has a low reflection surface and a high reflection surface distributed in a predetermined pattern in the main scanning direction; a counting means that counts the signal indicating reflectance in units of main scanning synchronizing pulses and is initialized in response to sub-scanning synchronizing pulses; 2. The image reading apparatus according to claim 1, further comprising logic means for generating a signal instructing the memory means to hold the detection signal when the direction length corresponding value is exceeded. 6. The index member has a low reflection surface and a high reflection surface distributed in a predetermined pattern in the main scanning direction; the document edge detection means includes a memory means for holding the detection signal and counts main scanning synchronization pulses. a first counting means; a means for decoding the count value of the first counting means to generate a signal indicating whether the main scanning is on a low reflection surface or a high reflection surface of the predetermined pattern; and a means responsive to the signal. When a signal indicating a high reflectance appears in the image signal of the imaging means when the main scanning is in an area corresponding to a low reflection surface of the pattern, this is counted in units of main scanning synchronization pulses and initialized in response to sub-scanning synchronization pulses. a second counting means;
2. The image reading device according to claim 1, further comprising logic means for generating a signal instructing the memory means to hold the detection signal when the count value of the counting means exceeds a predetermined value. 7. The index member has a low reflection surface and a high reflection surface distributed in a predetermined pattern in the main scanning direction; the document edge detection means includes a memory means for holding the detection signal and counts main scanning synchronization pulses. a first counting means; a means for decoding the count value of the first counting means to generate a signal indicating whether the main scanning is on a low reflection surface or a high reflection surface of the predetermined pattern; and a means responsive to the signal. When a signal indicating a low reflectance appears in the image signal of the imaging means when the main scanning is in a region corresponding to a high reflective surface of the pattern, this is counted in units of main scanning synchronizing pulses and initialized in response to sub-scanning synchronizing pulses. a second counting means;
2. The image reading device according to claim 1, further comprising logic means for generating a signal instructing the memory means to hold the detection signal when the count value of the counting means exceeds a predetermined value. 8. The index member has a low reflection surface and a high reflection surface distributed in a predetermined pattern in the main scanning direction; the document edge detection means includes a memory means for holding the detection signal and counts main scanning synchronization pulses. a first counting means; a means for decoding the count value of the first counting means to generate a signal indicating whether the main scanning is on a low reflection surface or a high reflection surface of the predetermined pattern; and a means responsive to the signal. If a signal indicating high reflectance appears in the image signal of the imaging means when the main scanning is in the area corresponding to the low reflection surface of the pattern, this is counted in units of main scanning synchronization pulses, and the main scanning is in the area corresponding to the high reflection surface of the pattern. a second counting means which, when a signal indicating a low reflectance appears in the image signal of the imaging means in the region, counts this in units of main scanning synchronization pulses and is initialized in response to the sub-scanning synchronization pulses;
2. The image reading device according to claim 1, further comprising logic means for generating a signal instructing the memory means to hold the detection signal when the count value of the second counting means exceeds a predetermined value.