JP2637150B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as an electronic copier capable of detecting a document size by moving a carriage.

(Prior Art) In an image forming apparatus, for example, an electronic copying machine, a scanning unit including an exposure lamp and a carriage is moved to a predetermined position (a home position corresponding to a magnification) according to a sheet size and a copying magnification. In such a case, a copyable range (image forming range of a document) corresponding to a sheet as a material to be transferred is displayed on a document table. In this type of copying machine, for example, a scale (display means) is provided on the upper surface of the scanning means, and the display position of the scale indicates the distance from the scanning start position of the copyable range in the scanning direction of the original. It is supposed to be.

In a copying machine having such a configuration, for example, when an original detecting device (detecting unit) is provided in the scanning unit to automatically detect the size of the original placed on the original table, an instruction to start copying is issued. In response to the input, the scanning means is moved from the standby position (the display position of the copyable range by the scale) to the scanning start position, and the movement of the scanning means for document size detection by the document detection device is started therefrom. Was. Therefore, there is a problem that it takes time to detect the size of the document.

(Problems to be Solved by the Invention) According to the present invention, when the document size is detected by the document detection unit provided on the scanning unit, it is necessary to return the scanning unit to the end of the document table before scanning. To be
An object of the present invention is to provide an image forming apparatus capable of reducing the time required for detecting the size of a document, in order to solve the problem that it takes time to detect the size.

[Structure of the Invention] (Means for Solving the Problems) The image forming apparatus of the present invention moves from a start position provided on one end side of the original platen to the other end of the original platen so as to be placed on the original platen. Scanning means for scanning the placed document, detection means provided on the scanning means for detecting the presence or absence of the document placed on the document table, and the scanning means being located at a standby position When a document is detected on the platen by the detection unit, the scanning unit is moved in a direction away from the start position, and the detection unit detects the document when the scanning unit is located at the standby position. When a document is not detected on the platen, a moving means for moving the scanning means in a direction approaching the start position; and a detecting means for moving the scanning means by the moving means. Referring to stage detection results are provided with a judging means for judging the size of the document placed on the document table.

(Operation) The present invention detects whether or not a document is present on a document table by detecting means provided on the scanning means. When the scanning means is at the standby position,
By changing the moving direction of the scanning means for detecting the size of the original by the detecting means depending on whether or not the original is detected on the platen, the detecting means while the scanning means is moving. The size of the document is determined with reference to the detection result of.

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

FIGS. 6 and 7 schematically show an image forming apparatus of the present invention, for example, an electronic copying machine. That is, a document table (transparent glass) 2 for supporting a document is fixed to the upper surface of the copying machine body 1. This is the document platen 2 fixed scale 2 ₁ as the set reference of the document is provided, and further in the vicinity of the platen 2 is provided document cover 1 ₁ and the work table 1 ₂ opened and closed. The original placed on the platen ₂ is reciprocated in the directions of arrows a ₁ and a ₂ along the lower surface of the platen 2 by an optical system including an exposure lamp 4 and mirrors 5, 6 and 7. Thus, exposure scanning is performed. In this case, the mirrors 6 and 7 are moved at half the speed of the mirror 5 so as to maintain the optical path length. The reflected light from the original by the scanning of the optical system, that is, the reflected light from the original due to the irradiation of light from the exposure lamp 4 is reflected by the mirrors 5, 6, and 7 and then passes through the lens block 8 for zooming. The light is reflected by the photosensitive drum 9 and guided to the photosensitive drum 10, and an image of the document is formed on the surface of the photosensitive drum 10.

The photoreceptor drum 10 is rotated in the direction of arrow c in the figure, and the surface is first charged by a charging charger 11. After this,
When the image is subjected to slit exposure, an electrostatic latent image is formed on the surface. The electrostatic latent image is visualized by the toner attached by the developing device 12.

On the other hand, the paper (transferred material) P is fed from the selected upper paper cassette 13 or the lower paper cassette 14 to a delivery roller.
The sheet is taken out one by one by 15 or 16, and the taken out sheet is guided to a registration roller pair 19 through a sheet guide path 17 or 18, and is guided to a transfer unit by the registration roller pair 19. .

Here, the paper feed cassettes 13 and 14 are provided detachably at the lower right end of the main body 1 so that either one can be selected on an operation panel described later.
The cassette sizes of the sheet cassettes 13 and 14 are detected by cassette size detection switches 60 ₁ and 60 ₂ , respectively. This cassette size detection switch
Reference numerals 60 ₁ and 60 _{2 each} include a plurality of micro switches that are turned on and off in response to insertion of cassettes having different sizes.

The sheet P sent to the transfer section is brought into close contact with the surface of the photosensitive drum 10 at the transfer charger 20, and the toner image on the photosensitive drum 10 is transferred by the action of the charger 20.
The transferred paper P is electrostatically peeled off from the photosensitive drum 10 by the action of the peeling charger 21, and is fixed by a transport belt 22 to a fixing roller 23 provided at the end of the photosensitive drum 10.
Sent to Then, the transferred image is fixed by passing therethrough, and the sheet P after the fixing is discharged to the tray 25 outside the main body 1 by the sheet discharging roller pair 24.

After the transfer, the photoreceptor drum 10 is returned to its initial state by being charged by the charge removing charger 26, and then the residual toner on the surface is removed by the cleaner 27, and the residual image is erased by the charge removing lamp 28. It is supposed to be. Reference numeral 29 denotes a cooling fan for preventing the temperature inside the main body 1 from rising.

FIG. 8 shows an operation panel 30 provided on the main body 1. 30 ₁ copy key for commanding copy start, 30 ₂ numeric keypad also establishes the number of copies, 30 ₃ the display unit for displaying the jam of each part of the operating state or sheet, 30 ₄ upper, lower sheet cassette Cassette selection key to select 13,14, 30 ₅
Is the cassette display that shows the selected cassette, 30 ₆
Expansion of copying, magnification setting keys for setting reduction ratio in a predetermined relationship, 30 ₇ larger, the display unit zoom key 30 ₈ for displaying the set magnification for setting a reduction ratio steplessly, 30 ₉ copy A density setting unit for setting the density.

FIG. 9 shows a drive mechanism for reciprocating the optical system. That is, the mirror 5 and the exposure lamp ₁ the first carriage 41, the mirror 6 and 7 the second carriage
41 ₂ are supported respectively, these first and second carriages 41 _1, 41 ₂ guide rails 42 _1, 42 ₂ is guided by the by arrows a _1, a
It is freely movable in _two directions. The four-phase pulse motor 33 drives a pulley 43. This is between the pulley 43 and the idle pulley 44 endless belt 45 is stretched over one end of the first carriage 41 ₁ which supports the mirror 5 to the middle portion of the belt 45 is fixed.

On the other hand, the the second carriage 41 _{and second} guide portions 46, spaced apart in the axial direction of the rail 42 ₂ two pulleys 4 supporting the mirror 6
7,47 are provided rotatably, these pulleys 47,47
A wire 48 extends between them. One end of the wire 48 is fixed to the fixing portion 49, and the other end is fixed to the fixing portion 49 via a coil spring 50. Also the above wire
₁ end the first carriage 41 is fixed to the intermediate portion 48. Therefore, by the pulse motor 33 is rotated, the first carriage 41 ₁ is moved by rotating the belt 45, ₂ second carriage 41 with the also moved. In this case, the pulleys 47, 47 to serve the Gado pulley, the first carriage 41 _{1 2} second carriage 41 is 1 /
Moved in the same direction at speed 2. The direction of movement of the first and second carriages 41 ₁ and 41 ₂ is controlled by switching the rotation direction of the pulse motor 33.

Further, on the document table 2, a copyable range (image forming range of the document) corresponding to the designated sheet P is displayed.
That is, the paper size (Px, Py) designated by the cassette selection key 30 ₄ and, when the copy magnification specified by the magnification setting key 30 ₆ or zoom key 30 ₇ and K,
The copyable range (x, y) is “x = Px / K”, “y = Py / K”
Becomes In the copyable range (x, Y), the x direction is indicated by the distance between the hands 51 and 52 disposed on the back surface of the document table 2, and the y direction (the document scanning direction) is the first carriage. and it is displayed by the mutual distance between the scale (display means) 53 provided with the fixed scale 2 ₁ to the upper surface portion 41 _1.

As shown in FIG. 10, the hands 51 and 52 are provided on a wire 57 which is bridged between the pulleys 54 and 55 via a spring 56. The pulley 55 is configured to be rotated by a motor 58, and the motor 58 is driven according to the determined copyable range in the x direction, thereby changing the distance between the hands 51 and 52. It is supposed to be.

The first carriage 41 _1, when the motor 33 is driven in accordance with the paper size and copy magnification, and is moved to a predetermined position (home position corresponding to the magnification). Then, when the scanning of the original, the first carriage 41 ₁ first home position is the scanning start position direction from the position is moved to the second carriage 41 in _two directions (a ₂ direction), then the exposure lamp 4 is turned scanned It is moved in a second direction away from the carriage 41 ₂ from the start position (a ₁ direction). When the scanning of the document is completed, the exposure lamp 4 is turned off and the first carriage 41 ₁
Is returned to the home position.

Further, when scanning the document by turning on the exposure lamp 4, the size of the document is detected in advance. That is, the ninth carriage 41 ₁
As shown in the figure, document detectors 63a and 63b including a photo sensor 61 and a light emitting diode 62 are provided. The document detectors 63a, 63b, as shown in FIG. 11, the photo sensor light reflected through the platen 2 from the document (white original) G and a document cover 1 ₁ by light irradiation of the light emitting diode 62
Received at 61, where it converts into an electric signal corresponding to the original G and the document cover 1 ₁ each reflectance. This electric signal is supplied to a processor group described later,
In this processor group, the presence or absence of the document G is identified, and the size is automatically determined.

In this case, the document cover 1 _1, the back surface is colored in a color having high sensitivity to the photosensitive drum 10. For example, the case where the photosensitive drum 10 is made of a photoconductor of selenium, the rear surface portion of the document cover 1 ₁ is colored pale blue.
This is because a blue image is unlikely to appear on the photosensitive drum 10 made of a selenium-based photoconductor, that is, the highly sensitive blue is hardly exposed on the selenium-based photosensitive drum 10. Absent. Therefore, in the case of using a fluorescent lamp as an exposure lamp 4, light blue will be treated the same as almost white, the color of the document cover 1 ₁ is such that no such affect the copied image I have.

On the other hand, the light emitting diode 62 is
The difference between the white of the original G is adapted to generate light having a waveband remarkable in the spectral characteristics of the reflected light to 1 ₁ color. That is, light blue has a reflectance spectral characteristic as shown by a dotted line in FIG. As is clear from this figure, the reflectance of light blue is about 600.0μ in wavelength.
In the band from m to 700.0 μm, that is, in the range from red to orange, it is about 1/2 of the white shown by the solid line in the drawing. However, for example, when the photosensitive drum 10 is made of a light conductor selenium may color the back surface of the document cover 1 ₁ light blue spectral wavelengths of light from the light emitting diode 62 of the reflectivity for light blue by setting the red or orange color, which is the absorption band of the characteristic, without affecting the copied image, easily identified by the photosensors for visible light them with the original G and the document cover 1 ₁ from the difference in reflectance It is possible to do. Therefore, an inexpensive photosensor 61 can be used, and the original size can be automatically detected at low cost.

Incidentally, the first carriage 41 ₁ of the document detectors 63a, 63b
As shown in FIG. 13, are arranged at positions such that they move (scan) along the illustrated straight lines AA and BB with respect to the document 2 respectively. Then, on the platen 2,
For example, originals ranging in size from “A5” to “A3” can be placed, and all the originals are placed with reference to the center of the platen 2 (indicated by a dashed line in the drawing). .

Further, illustration T, U, V, X, Y, a first position of the carriage ₄₁₁ during each sensing location size detection of Z, these detection position
T, ~, at the timing when the first carriage 41 ₁ is positioned in the Z,
The output level of each photo sensor 61 of the document detectors 63a and 63b is checked, and the presence or absence of the document G is determined based on the result of the check.

FIG. 1 shows a main part of the control circuit. The processor group 71 includes an operation panel 30, various switches and sensors,
For example, a high-voltage transformer that detects input from input devices such as the cassette size detection switches 60 ₁ and 60 ₂ and drives the various chargers, the static elimination lamp 28, and the cleaner 27
A blade solenoid, a heater for the fixing roller pair 23,
The above-described copying operation is performed by controlling the exposure lamp 4 and the like, and before the scanning of the document related to this copying operation is started, the _first operation is performed according to the operation of the copy key 301 of the operation panel 30.
Carriage 41 ₁ position checks for the original G on the platen 2 to (home position), the first and controls the pulse motor 33 according to the result of this check
And moving the carriage _411, performs a discrimination operation for detecting the document size based on the input from the document detectors 63a, 63b for each detecting position during the movement.

The document detector 63a, the light emitting diode 62 63 b, for example for illuminating the red or orange light to the document (white original) G and a document cover 1 ₁ colored in pale blue,
Photosensor 61 for receiving reflected light from the original G and the document cover 1 ₁ by light irradiation of the light-emitting diode 62, an amplifier 66 for converting the output of the photo sensor 61 into a voltage signal,
A comparison circuit 68 for comparing the output of the sensor 61 supplied via the amplifier 66 with a reference voltage (Vref) for correcting a variation in the output level of the sensor due to a variation in sensor sensitivity or a temperature change. It is configured.

The pulse motor 33, the pulse motor driver 72 is adapted to be controlled by the processor unit 71 via, during determination operation for detecting the document size, the document detector 63a in the first carriage 41 _first home position , 63b, the rotation direction is controlled according to the detection result of the original G. That is, when the document G is detected in the first position of the carriage ₄₁₁ at the time the copy key 30 ₁ of the operation panel 30 is operated, the pulse motor 33 is first
The carriage 41 ₁ scan start position from the position rotated in the direction of movement in a direction (a ₁ direction) away from the second carriage 41 _{and second} opposite, first time the copying key 30 ₁ is operated
When the document G at the position of the carriage ₄₁₁ is not detected, the pulse motor 33 is rotated in a direction to move _a first carriage 41 and the second carriage direction 41 _second direction from its position, that is, the scanning start position direction (a ₂ direction) It is supposed to be.

The processor group 71 includes a pulse motor driver 72.
Pulse counter 7 that counts the number of pulses supplied to
3, and a memory 74 storing various data used for determining the size of the document. This memory 74
Includes a position data indicating a first position of the carriage ₄₁₁ in accordance with the number of pulses the RAM (detection position) is stored (random access memory), the position data and the sensor 61
And a ROM (read only memory) in which determination data for determining a document size in accordance with a combination with the output level is stored.

FIG. 2 logically shows the discrimination data stored in the memory 74. The determination data are those referred to by the processors 71, the first carriage 41 ₁ detection position (position data), various document by the output level of the original detectors 63a, each sensor 61 in 63b at that time The size is determined. In this figure, the output level at each detection position of the sensor 61 of the document detector 63a which moves the position of the document table 2 indicated by a straight line AA in FIG. The output levels at the respective detection positions of the sensor 61 of the document detector 63b moving at the position of the document table 2 indicated by BB are indicated by ○ and ×. Here, the level output corresponding to the reflected light from the original G by ○, that is, the case where the document G is detected and the level output corresponding to the reflected light from the document cover 1 ₁ by ×, i.e. the document cover 1 ₁ Shows a case where is detected.

Here, a determination operation when automatically detecting the size of a document will be described. In the processor group 71,
With pulse counter (pulse number) count data supplied from 73 and from the position data in the memory 74 of the first carriage 41 ₁ position is determined, the detection position T, U,
The output levels of the respective sensors 61 of the document detectors 63a and 63b in V, W, X, Y and Z are determined, and the document size is determined from these determination results and the determination data in the memory 74. That is, by light irradiation red to the orange from the light emitting diode 62, from the original G reflected light corresponding to white, also from the original cover 1 ₁ is incident on the reflected light photosensor 61 corresponding to light blue. In this case, as described above, the document cover 1 ₁ colored in light blue is as red to orange reflectance to light irradiation is low. Therefore, the output from the photo sensor 61 is lower than the light reflected by the document G. Therefore, the output level of the sensor 61, the document G and the document cover 1 ₁ and can be easily identified, the detection position T the presence of the original G by the identification, ~ the size of the original G by determining the Z discriminated It is supposed to be.

For example, as shown in FIG. 3 (a), if on the document table 2 "A3" size of the original G is placed, a first carriage 41 of ₁ any detection position T to move, ~, the Z Also in the case where the original is positioned, the original G is detected (○) by the original detectors 63a and 63b. Such a detection state is caused by the second
As shown in the figure, only when the original G is "A3" size,
In such a case, the original G is “A3” in the processor group 712.
The size is determined.

Further, as shown in FIG. 3 (e), if on the document table 2 "A4 Tate置" size of the original G is placed, the first carriage 41 ₁ detection position T to move, ~, the V The original G is detected (○) by the original detectors 63a and 63b when the original is detected, and the original detector is detected when the original is detected at the detection positions W, Z.
63a, the document cover 1 ₁ is detected (×) by 63 b. Such a detection state occurs as shown in FIG.
Is the size of “A4 length”, and in such a case, the processor group 71 determines that the document G is of the “A4 length” size.

Further, as shown in FIG. 3 (h), "A5
If Tate置"size of the original G is placed, the document G is detected (○) only by the document detector 63b when the first carriage 41 ₁ moves is located at the detection position T, the detection position T The document cover ₁₁ is detected (×) by the document detector 63a when it is located and the document detectors 63a and 63b when it is located at the detection positions U, Z. Such a detection state occurs only when the document G is the “A5 vertical” size, as shown in FIG.
In the processor group 71, the document G is determined to be the “A5 vertical” size.

3 (b), (c), (d), (f),
(G) shows a case where a document G of “B4” size, “A4 landscape” size, “B5 landscape” size, “B5 length” size, and “A5 landscape” size is placed, respectively. In either case, as shown in FIG.
41 ₁ of the position data and the information indicating the presence or absence of the original G, that is, each detection position T, ~, 2 one sensor 61 in the Z (document detectors 63
The size of the document G is accurately determined by the combination of the outputs (a, 63b).

Next, the operation of the above configuration will be described. For example now, the first carriage 41 ₁ is a predetermined position according to a predetermined paper size and magnification (home position corresponding to the magnification)
Is placed on the document table 2 and the document cover ₁₁ is closed. Then, the multi-key 30 ₁ of the operation panel 30 is operated. Then, the document detectors 63a, 63b is operated, the presence of the original G in the first carriage 41 _first home position (display position of the copy range by the scale 53) is checked.
That is, the reflected light from the original G or the document cover 1 ₁ by lighting of the light emitting diode 62 is received by the photo sensor 61. The reflected light from the original G and the document cover 1 ₁ is photoelectrically converted by the photo sensor 61 is a voltage signal by the amplifier 66. This signal is supplied to a comparison circuit 68 where it is compared with a reference voltage. Then, the comparison result, that is, the output of the sensor 61 corrected by the reference voltage is supplied to the processor group 71. In the processors 71, by checking the output level of the original detectors 63a, 63b each sensor 61, whether the document G on the original table 2 corresponding to the first carriage 41 _first home position there is Is determined.

This check the case where the original G is determined that there on the document table 2 corresponding to the first carriage 41 _first home position, the first carriage 41 ₁ through the pulse motor driver 72 by the processor unit 71 according to the control of the pulse motor 33, is moved away from the second carriage 41 ₂ opposite to the scanning start position than the home position (the direction indicated by a ₁ in FIG. 7). That is, when the document G is detected (○) in a first position of the carriage ₄₁₁ at the time the copy key 30 ₁ is operated, the document G is the first
It is determined to be greater than the copying range displayed by such scale 53 on the carriage 41 _1. This allows
The first carriage 41 _1, its position (home position)
It is moved to the scanning end away from the from the second carriage 41 _2. At this time, the light emitting diodes 6 of the original detectors 63a and 63b
2 is turned on, the reflected light from the original G and the document cover 1 ₁ by lighting of the light emitting diode 62 is received by the photo sensor 61. The reflected light from the original G and the document cover 1 ₁ is photoelectrically converted by the photo sensor 61, amplifier
After being converted into a voltage signal by 66, it is compared with a reference voltage by a comparison circuit 68. Then, the output of the sensor 61 corrected by the reference voltage is supplied to the processor group 71.

The processor group 71 is supplied with count data obtained by counting the number of pulses supplied from the pulse counter 73 to the pulse motor driver 72. Then, the processors 71, the count data (number of pulses) supplied from the pulse counter 73 from the position data in the memory 74 together with the first carriage 41 ₁ position is determined, ₁ is a first carriage 41 passes The output level of each sensor 61 of the document detectors 63a and 63b at each detection position is determined, and the document size is determined based on the determination results and the determination data in the memory 74.

For example, as shown in FIG. 4, on the original table 2 "A3" size original (shown hatched portion) G is placed, when the first carriage 41 ₁ can copy the scope of "A4 Tate置" document When the document has been moved to the home position (detection position V) within the range, the document G is detected (（) by the document detectors 63a and 63b. Then, the first carriage 41 ₁ is shown as a ₁
Then, scanning is performed for document size detection by the document detectors 63a and 63b. In this case, the first carriage 41 ₁ detection position V, ~, the document G is detected (○) by the document detector 63a, 63b in the case of located Z. Such a detection state (assuming that the document G is also detected at the detection positions T and U) occurs only when the document G is the “A3” size as shown in FIG. In this case, the processor group 71 determines that the document G is the “A3” size.

Incidentally, when the above-mentioned first carriage 41 ₁ reaches the end of the document table 2 (scanning end position) is determined by the data from the pulse counter 73, the first carriage 41 ₁ pulse motor driver 72 by the processor unit 71 the second carriage 41 _{and second} directions according to control of the pulse motor 33 through (a ₂
Direction) and is stopped at the scanning start position.

On the other hand, the above check indicates that the first carriage 41 ₁
The original G on the platen 2 corresponding to the home position of
If it is determined that there is no, the first carriage 41 _1, the scan start position direction (Fig. 7 in response to the control of the pulse motor 33 through a pulse motor driver 72 by the processor unit 71
a ₂ ). That is, copy key 30 ₁
Display but when the document G at the first position of the carriage ₄₁₁ at the time of the operation is not detected, that is, when the document cover 1 ₁ is detected (×), the document G such as by the scale 53 of the first carriage 41 on ₁ Is determined to be smaller than the permitted copy range. Thereby, the first carriage 41
_1, the second carriage 41 a _second direction from its position, is moved that is the scanning start direction. At this time, the original detectors 63a and 63b
The light emitting diode 62 is turned on, and the light emitting diode 62
Reflected light from the original G and the document cover 1 ₁ due to the lighting of the is received by the photo sensor 61. The reflected light from the original G and the document cover 1 ₁ is photoelectrically converted by the photo sensor 61 is converted into a voltage signal by the amplifier 66,
The comparison circuit 68 compares the reference voltage. Then, the output of the sensor 61 corrected by the reference voltage is supplied to the processor group 71.

The processor group 71 is supplied with count data obtained by counting the number of pulses supplied from the pulse counter 73 to the pulse motor driver 72. Then, the processors 71, the count data (number of pulses) supplied from the pulse counter 73 from the position data in the memory 74 together with the first carriage 41 ₁ position is determined, ₁ is a first carriage 41 passes The output level of each sensor 61 of the document detectors 63a and 63b at each detection position is determined, and the document size is determined based on the determination results and the determination data in the memory 74.

For example, as shown in Figure 5, document "A4 Tate置" size on the document table 2 (shown hatched portion) G is placed, the scope first carriage 41 ₁ is "A4 Yoko置" document at this time Home position position (detection position X) within which copying is possible
In this case, the original cover ₁₁ is detected (×) by the original detectors 63a and 63b. Then, the first carriage
41 ₁ is moved to the illustrated a ₂ direction, the document detector 63a, the scanning for the document size detection by 63b is performed. In this case, the first carriage 41 ₁ detection position V, ~, document detector 63a when located in T, the original G is detected (○) by 63 b. Such a detection state (at the detection positions W, to Z, assuming that the document cover ₁₁ is detected) is the second state.
As shown in the figure, this is only when the original G is in the “A4 vertical” size. In such a case, the processor group 71 determines that the original G is in the “A4 vertical” size.

Incidentally, the first carriage 41 ₁ is stopped when it reaches the scan start position.

As described above, the first point in time when the support for starting copying is input.
Position of the carriage ₄₁₁ to detect the presence or absence of the document G in (a display position of the copy range of scale 53), the scanning direction (first carriage 41 ₁ in the moving direction) for the document size detection in accordance with the detection result by varying, because they allow to start the operation for document size detection from the first carriage 41 ₁ position, it reduces the time it takes to detect.

When the automatic detection of the document size is terminated, the first carriage 41 _1, the pulse motor driver 7 by a processor group 71
It is moved to the control of the pulse motor 33 through a 2 second direction away from the carriage 41 ₂ (a ₁ direction). Also,
The exposure lamp 4 is turned on by the processor group 71, and the first
By the movement of the scanning end position from the scanning start position of the carriage _411, the image scanning of the document G is started. At this time,
For example, regardless of the copyable range displayed corresponding to the specified paper P, the paper size is automatically selected (at the same-size copying) according to the detected original size, or the original size and the magnification are determined. Automatically select the paper size according to the determined copy size, or automatically set the copy magnification based on the original size and paper size (at the time of variable-size copying)
This enables an efficient image forming operation.

As described above, at the display position of the image forming range of the document on the platen by the display unit provided in the scanning unit,
The detection means detects whether or not there is a document on the platen. The scanning for detecting the size of the document is performed by the detection means depending on whether the detection means detects the document from the display position or not. By changing the direction of the movement of the means, the detection of the size of the document can be started by the movement of the scanning means from the display position of the image forming range by the display means.

That is, the presence or absence of a document at the position of the first carriage at the time when the copy key is operated is detected, and the scanning direction for document size detection is changed according to the detection result. Thus, in a copying machine in which the scale for displaying the copyable range is provided on the first carriage, the first carriage is located in the middle of the scanning area. Scanning can be started. Therefore, since it is not necessary to move the first carriage to the scanning start position each time, it is possible to reduce the time required for detecting the size of the document.

Further, by shortening the detection time, the operation time from the input of the copy key to the end of the copy can be reduced, and the efficiency of the copy is improved.

In the above embodiment, the original cover is colored,
The original cover and the original are irradiated with light in a wavelength band where the reflectance from the original cover is low, and the reflected light from the original and the original cover is received using a visible light photosensor. However, the present invention is not limited to this. For example, the original and a colored original cover may be irradiated with light from an exposure lamp, and the reflected light from the original and the original cover may be received by a color sensor. The reflected light from the document cover may be received by the photo sensor via a filter in a wavelength band where the difference in the reflectance of the reflected light is conspicuous.

Also, the copier in which the photosensitive drum is made of a selenium-based photoconductor has been described as an example. It can be easily applied by changing the parameters.

Further, the reference voltage is read from the reference reflector at the time of the document size detection operation, and the fluctuation of the output level of the photosensor is constantly corrected with a constant reflectance by the reference voltage read from the reference reflector, thereby providing a sensor sensitivity. It is also possible to prevent erroneous detection due to variations in temperature, temperature change, and the like.

The above-described document size detection operation may be executed in accordance with the mode designation, or may be stopped when a copy magnification (other than the same magnification) and a paper size are input. In this case, it is possible to easily select and execute copying according to an arbitrary designation and copying automated according to the detected document size.

Of course, various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an image forming apparatus capable of reducing the time required for detecting the size of a document.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing a main part of a control circuit, FIG. 2 is a diagram logically showing discrimination data used for discriminating the size of a document, and FIG. FIGS. 4A and 4B are diagrams for explaining a document size determination operation, and FIGS. 4 and 5 are diagrams for explaining a detection operation, respectively.
6 is an external perspective view of the electronic copying machine, FIG. 7 is a side sectional view of the electronic copying machine, FIG. 8 is a plan view showing a configuration of the operation panel,
FIG. 9 is a perspective view schematically showing a driving mechanism of the optical system, and FIG.
FIG. 11 is a perspective view schematically showing a driving mechanism of a pointer, FIG. 11 is a cross-sectional view for explaining a document detector, FIG. 12 is a diagram showing reflection spectral characteristics of white and light blue, and FIG. FIG. 9 is a diagram illustrating an operation of the document detector. 1 ... copy machine body, 1 ₁ ... original cover, 2 ... original plate,
4 Exposure lamp, 10 Photoconductor drum, 33 Pulse motor, 41 ₁ First carriage, 53 Scale (display means), 61 Photosensor, 62 Light emitting diode, 63a, 63b: Document detector (detection means), 71: Processor group, 73: Pulse counter, 74: Memory, G:
… Manuscript.

Claims (1)

(57) [Claims] A scanning means for scanning an original placed on the original table by moving from a start position provided on one end side of the original table toward the other end of the original table; Detecting means for detecting the presence or absence of a document placed on the document table; and detecting a document on the document table by the detecting means when the scanning means is located at a standby position. ,
When the scanning means is moved in a direction away from the start position, and when the scanning means is located at the standby position, and the detection means does not detect a document on the platen, the scanning means is moved to the start position. A moving means for moving in a direction approaching the scanner, and determining a size of a document placed on the document table with reference to a detection location result of the detecting means while the scanning means is moved by the moving means. An image forming apparatus, comprising: