JPH0713397A - Image processing device - Google Patents

Abstract

PURPOSE:To save a labor of pre-scanning and to improve the through put of image processing by providing a document density detecting means in a conveying path in a document feeding means and detecting the density while conveying the document. CONSTITUTION:A document is conveyed on an exposure face by a document feeder 200, and the density of the conveyed document is detected by an AE sensor 25 when the document is in a conveying path. Before a start of an exposure process, quantity of light of an exposure lamp 103 is corrected on the basis of the detected density. In other words, the AE sensor 25 is turned on synchronously when conveying of the document is started, and sensor data corresponding to the document density of the AE sensor 25 at this time is stored in a RAM 302, and on the basis of this data, quantity of light of the exposure lamp 103 is computed by a CPU 301 so that a correction is made. Therefore, computing for a correction on the quantity of light is started before the rear end of the document passed a paper feeding resist sensor 14, so that the quantity of light of the exposure lamp 103 can be restricted before a start of image reading.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus which conveys a document on an exposed surface to read the document image and performs a predetermined process.

[0002]

2. Description of the Related Art Among known image processing apparatuses, in particular, a function of conveying an original on a platen glass,
The one having a so-called AE function of automatically detecting the density of an image of an original or the like and changing the light amount of the exposure lamp of the scanning optical system to adjust to an appropriate density is used after the original is stopped on the platen glass. , The scanning optical system is pre-scanned to sample the AE data, the light amount of the exposure lamp is changed based on the sampled AE data, and then,
It was supposed to scan again for image reading.

[0003]

As described above, in the conventional image processing apparatus, after the original is stopped on the platen glass, the pre-scan for sampling the AE data is first performed, and then the scanning for image reading is performed. Therefore, there is a problem that the throughput cannot be improved because the throughput is limited.

Further, when trying to shorten the sampling time of the AE data, the prescan of the image has to stay within a limited range, and it is impossible to obtain the averaged AE data of the entire document. There was a problem.

Therefore, in view of the above points, the object of the present invention is to
An object of the present invention is to provide an image processing apparatus capable of further improving the throughput of image processing while obtaining density data equivalent to that of prescan which has been conventionally performed.

[0006]

SUMMARY OF THE INVENTION An image processing apparatus according to the present invention relates to an original document conveying means for conveying an original document on an exposure surface, and a density of the original document conveyed by the original document conveying means, in the conveying path of the original document. And a light amount correction unit for correcting the exposure lamp light amount based on the detected density before starting the exposure process.

[0007]

According to the present invention, since the original density detecting means is provided in the conveying path of the original feeding means and the density is detected while the original is being conveyed, the original density can be detected without pre-scanning. can do.

[0008]

EXAMPLES Examples of the present invention will be described in detail below.

Embodiment 1 FIGS. 1 to 5 are configuration diagrams showing an image recording apparatus which is an embodiment of the present invention. The present embodiment is an example in which the present invention is applied to an image recording apparatus having a circulation type document feeding apparatus (hereinafter referred to as RDF).

Here, FIG. 1 is a block diagram showing a control device of the present embodiment, FIG. 2 is a sectional configuration diagram of the present embodiment, and FIG. 3 is an RD.
FIG. 4 is a cross-sectional configuration diagram of F, FIG. 4 is a detailed cross-sectional configuration diagram of the driving unit of the RDF, and FIG. 5 is a circuit configuration diagram of the AE sensor 25 illustrated in FIG.

Copier main body 100 The copier main body 100 has an image reading function and an image recording function.

In FIG. 2, 101 is an original table glass on which an original is placed, 103 is an exposure lamp for illuminating the original, and 10 is an exposure lamp.
Reference numerals 5, 107, and 109 denote scanning reflection mirrors (scanning mirrors) that change the optical path of the reflected light of the document, 111 denotes a lens having a focusing and zooming function, and 113 denotes a fourth reflection mirror (scanning) that changes the optical path. Mirror). 115 is an optical system motor for driving the optical system, 117 is an image sensor, 1
Reference numeral 19 is a home position sensor.

Reference numeral 131 is a photosensitive drum, 133 is a main motor for driving the photosensitive drum 131, 135 is a high voltage unit, 137 is a blank exposure unit, 139 is a developing device,
Reference numeral 141 is a transfer charging device, 143 is a separating electric device, and 145 is a cleaning device.

Reference numeral 151 is an upper cassette, 153 is a lower cassette, 155 and 157 are paper feed rollers, and 159 is a registration roller. Reference numeral 161 is a conveyor belt that conveys the image-recorded sheet to the fixing side, and 163 is a fixing device that fixes the conveyed sheet by thermocompression bonding.

The surface of the above-mentioned photosensitive drum 131 is composed of a photoconductor and a seamless photosensitive member using a conductor. The photosensitive drum 131 is rotatably supported and responds to the pressing of a copy start key described later. The main motor 133, which operates in this manner, starts rotating in the direction of the arrow in FIG.

Next, when the predetermined rotation control of the photosensitive drum 131 and the potential control processing (preprocessing) are completed, the original placed on the original table glass 101 is scanned by the first scanning mirror 105.
Is illuminated by an exposure lamp 103 integrally configured with
The reflected light of the original document forms an image on the photosensitive drum 131 via the first scanning mirror 105, the second scanning mirror 107, the third scanning mirror 109, the lens 111 and the fourth scanning mirror 113.

The photosensitive drum 131 is corona charged by the high voltage unit 135. After that, the image (original image) irradiated by the exposure lamp 103 is slit-exposed, and an electrostatic latent image is formed on the photosensitive drum 131 by a known NP method.

Next, the electrostatic latent image on the photosensitive drum 131 is
It is developed by the developing roller 140 of the developing device 139 and visualized as a toner image, and the toner image is transferred to the transfer charger 14.
1 is transferred onto the sheet as described later.

That is, the sheets in the upper cassette 151 or the lower cassette 153 are sent to the inside of the main body apparatus by the sheet feeding roller 155 or the sheet feeding roller 157, and are sent to the photosensitive drum 131 at the correct timing by the registration roller 159. , The leading edge of the latent image and the leading edge of the sheet are aligned.

After that, the transfer charger 141 and the photosensitive drum 1
By passing the sheet between the sheet 31 and 31, the toner image on the photosensitive drum 131 is transferred onto the sheet.

After completion of this transfer, the sheet is the photosensitive drum 13.
1 is separated by the separation charger 143, and the conveyor belt 1
It is guided to the fixing device 163 by 61 and is fixed by pressure and heating, and then the main body 10 is discharged by the discharge roller 165.
It is discharged outside 0.

After the transfer, the photosensitive drum 131 continues to rotate and its surface is cleaned by a cleaning device 145 composed of a cleaning roller and an elastic blade.

Regarding RDF 200 FIG. 3 shows a sectional structure of the RDF 200 shown in FIG.

In FIG. 3, 1 is a document placing table, 2 is a feeding belt driving shaft, 2a is a paper feeding belt driven shaft, between which the paper feeding belt 3 is hung, and in the direction of arrow C in the drawing. Rotate. Reference numeral 4 denotes a separation belt drive shaft, and 4a denotes a separation belt driven shaft, on which a separation belt 5 is attached, which rotates in the direction of arrow D in the figure. A half-moon roller 2b rotates in the direction of arrow E in the figure.

A plurality of sheet-shaped stacked originals placed on the original placing table 1 are separated one by one from the lowermost portion by the paper feed belt 3, the separation belt 5 and the half-moon roller 2b.

Reference numeral 6 is a conveying roller, and 6a and 6b are rollers which are in pressure contact with the conveying roller 6, respectively. Reference numerals 9, 10, and 11 denote transport rollers, and reference numerals 9a, 10a, and 11a denote rollers that are in pressure contact with the transport rollers 9, 10, and 11, respectively.

Reference numeral 7 denotes a conveyor belt driving roller located near the left side of the platen glass 12 arranged on the upper plate of the copying machine main body, and 7a denotes a platen glass (exposure surface) 12 (1 in FIG. 2).
(Corresponding to 01), the conveyor belt driven roller is located on the right side of (between 01 and
A conveyor belt 8 that rotates in the direction is hung.

The lower surface of the conveyor belt 8 is in close proximity to or in contact with the upper surface of the platen glass 12.

Numerals 13 to 17 are a reflection type optical sensor and a transmission type optical sensor which detect the leading edge or the trailing edge of the document, which are arranged at required places in the document circulation path (paper path).
That is, the sensors 13 and 14 are a paper feed sensor and a paper feed registration sensor, respectively, 53 is a document width regulating plate, and 54 is a sensor for detecting the size in the width direction of a document placed on the tray.

Reference numeral 20 is a reflection type optical sensor (ES) for detecting the original placed on the original placing table 1, 19 is a recycle sensor (RS) for detecting one circulation of the original bundle, and the partition arm 22 is a recycle motor. When the document is stopped on the bundle of documents by 21 and the recycle sensor (RS) 19 is turned on at that time, the document is fed separately from the bottom document, and when the trailing edge of the final document passes through the partition arm 22, The partition arm 22 has a mechanism to pass through the position of the recycle sensor (RS) 19 by its own weight and to be turned off.

Reference numeral 51 is an auxiliary tray used when setting a large size original document, and 52 is an auxiliary tray opening / closing switch.

FIG. 4 shows the driving section of the RDF. In FIG. 4, reference numeral 80 is a motor (M2), and 81 is a motor gear that transmits the driving force to the paper feed belt drive shaft 2, the separation belt drive shaft 4 and the half-moon roller 2b through a gear 96. Reference numeral 82 is a belt drive motor (M1), 83 is a motor pulley, and 86 is a two-stage pulley, which transmits drive from the belt 87 to the belt 88. 89 is also integrated with a two-stage pulley, and the belt 8
The driving force is transmitted from 8 to the belt 90, so that the driving force is always transmitted to the driving roller 7 of the conveyor belt 8 through the pulley 91.

Reference numeral 93 is a disk having a notch groove 94 that is integrally rotated with the two-stage pulley 89, and the amount of movement of the belt 88 can be detected by the photoelectric sensor 95. Reference numeral 92 is an electromagnetic brake (BK), which is capable of instantaneously stopping the belt 88 when turned on.

Reference numeral 97 is a conveyance motor (M3), 98 is a gear,
Reference numeral 99 is a pulley, and reference numerals 6, 9, 10, and 11 are belt conveying rollers.

Reference numeral 203 denotes a disc having a notch groove 204 which is integrally rotated with the pulley 99, and the photoelectric sensor 205 detects the rotation amount of the conveying rollers 6, 9, 10, 11; be able to.

Reference numeral 23 is a switching claw, and a tension spring 24 is used to switch whether the original on the platen glass 12 is conveyed by the fulcrum 206 toward the conveying roller 6 or from the conveying roller 9 toward the platen glass 12. Solenoid (S
L) 207.

Next, the document feeding operation by the RDF 200 at the time of one-sided document copying will be described.

First, in FIG. 3, a plurality of sheet-shaped single-sided originals arranged in page order are placed on the original placing table 1 with the first page facing upward.

The placed originals are separated and fed one by one from the bottom by the paper feed belt 3 and the separation belt 5, and the fed originals pass through the paper path Ia and are conveyed onto the platen glass 12 by the conveyor belt 8. The document is sent with the image side facing down.

When the rear end of the original is detected by the sensor (S2) 14, the counting of the number of the cutout grooves 94 of the disk 93 (FIG. 4) is started from that point, and after the predetermined count is counted, the motor ( M1) 82 is turned off and the electromagnetic brake (B
K) 92 is turned on, and the rotational drive of the conveyor belt 88 is instantaneously stopped. As a result, the original is automatically placed in a predetermined position on the surface of the platen glass 12 in a set position.

In this way, the original is placed on the platen glass 12
When positioned above, the copying operation is started, one exposure scan is performed, and the copied copy paper is stored in the paper discharge tray. After the exposure of the original document, the solenoid (SL) 207 is turned on, the switching claw is in the state of the broken line, and the exposed original document is discharged through the paper paths IIIa and IVa. At the same time, the next original is fed in parallel by the above-described operation and positioned and set on the platen glass 12.

This parallel operation is simply an operation of circulating the original document, and since the original document is not inverted during the original document or the next original document, it is referred to as a normal discharge normal feeding operation. Then, the normal feeding and normal feeding operation is sequentially performed, one circulation of the set originals is detected by the recycle sensor (RS) 19, the end of the circulation is sent to the copying machine main body 100, and the number of copies is counted. The above operation is repeated until the set number of copies is reached, and the required number of copies are stored in the discharge tray of the copying machine.

The RDF 200 has a circulation function for double-sided originals, but the description of this function is omitted because it is not directly related to the purpose of the present invention.

In FIG. 5, 24 is a standard white plate,
It is opposed to the AE sensor 25. Then, it is used to correct the white level of the AE sensor 25.

In FIG. 1, 301 is a central processing unit (C
PU), for example, a microcomputer μCOM87AD manufactured by NEC (NEC Corporation), which calculates an appropriate exposure amount based on the detected document density as an exposure amount calculation means. Further, the CPU 301 serves as a document density sensor level correcting means for correcting the AE sensor level when the document is not in the conveyance path.

Reference numeral 302-1 is a read-only memory (ROM) in which a control procedure (control program) as shown in FIG.
Controls each constituent device connected via the bus according to the control procedure stored in the ROM. A random access memory (RAM) 302-2 is a main storage device used as a storage area for input data, a work storage area, or the like.
Is.

303 is an interface (I / O),
The control signal of the CPU 301 is output to the load of the optical system motor 115 or the like. 304 is an interface,
The input signal of the image sensor 117 or the like is input to the CPU 301.
To send to.

Reference numeral 305 is an interface connected to a load such as the conveyance motor 97 of the RDF 200, 306 is an interface connected to the paper feed sensor 14 and the like, and 307 is A / D conversion of analog data from the AE sensor 25 and a CPU
It is an A / D converter to be sent to 301. Reference numeral 308 denotes a CVR (control voltage regulator), which constitutes a light amount correction means together with the CPU 301, and corrects the exposure lamp light amount based on the appropriate exposure amount calculated by the CPU 301 until the original is aligned on the platen glass. It is a thing.

Reference numeral 309 is an A / D output of the paper feed sensor 13.
It is an A / D converter for conversion. 310 is the AE sensor 2
5 is a D / A converter for correcting the lamp light amount and the shift voltage of No. 5 of FIG.

Next, the structure of the AE sensor 25 will be described with reference to FIG. In the figure, 321 is a lamp which is a light source of the AE sensor. Reference numeral 322 is a photosensor that converts the reflected light from the document into an electric current (the light source of the reflected light is the lamp 321).

Reference numeral 323 is an AE amplifier which converts the photoelectric current of the photo sensor 322 into a voltage and further amplifies the voltage.
Reference numeral 324 is an offset amplifier for correcting the offset and drift of the AE amplifier 323. 325 is
It is a diode whose reverse impedance is selected to be substantially equal to that of the photo sensor 322.

326 is an output v from the AE amplifier 323
_{It is a} reference power source for level shifting a. 32
A buffer amplifier 7 is an output of the D / A converter 310 (a). Reference numeral 328 is a transistor that amplifies the current output of the buffer amplifier 327. Reference numeral 329 is an optical filter for selecting a desired wavelength from the light source of the lamp 321. 330 is a lamp 3 reflected by the original
It is a lens for collecting the light input from 21, and also serves as an optical filter.

Further, in FIG. 5, 400 is the AE amplifier 3
23 Output v _a, 401 output v _h, 4 output v _s, 403 are offset amplifier 324 of the output current i _d, 402 of the photosensor 322 D / A converter 310 (b) of
04 is the voltage v _ref of the reference power supply 326, 405 is the output v _o of the inverting amplifier 312, and 406 is the D / A converter 310.
The output voltages v ₁ and 407 of (a) are the lamp voltages v _L and 41
0 to 415 are resistors that determine the gain of each amplifier.

In the above structure, the output v _a of the AE amplifier 323 is given by the following equation.

[0055]

[Formula 1] v _a = v _s + (R2 / R3) (v _s −v _h ) + R1 _{i d} (1 + R2 / R3 + R2 / R1) (1) Here, since the photoelectric current i _d is very small, R1 , R2
>> If R3 and R1≈R2, then the equation (1) can be approximated as follows.

[0056]

[Formula 2] v _a ≈v _s + (R2 / R3) (v _s −v _h ) + (R1 · R2 / R3) i _d (2) Equation (2) is the output conversion offset of the AE amplifier 323. The voltage v _of1 , the offset current i _of1, and the output-converted offset voltage v _{of2 of} the offset amplifier 324 and the offset current i _of2 are not included. Considering these, v _s → v _s + v _of1 v _h → v _{s + v of2 + R4i of2 i d} → i d + i of1 next, second (2) is as follows.

[0057]

[ _Formula 3] v _a ≈ (v _s + v _of1 ) + (R2 / R3) (v _of1 −v _of2 ＋ R1if1 −R4if2) ＋ (R1R2 / R3) i _d (3) In the formula (3)

[0058]

[ _Equation 4] If v _of1 << v _s , (R2 / R3) (v _of1 −v _of2 + R1if1 −R4if2), (R1R2 / R3) i _d (4)

[0059]

[Number 5] _{v a = v s + (R2} / R3) (v of1 -v of2 + R1if1 -R4if2) + (R1R2 / R3) i d ... (5) Now, AE amplifier 323 and the offset amplifier 324 of the same process If anything,

[0060]

[ _Equation 6] v _of1 ≈ v _of2 , if1 ≈ if2 (6), and in the second term of the equation (5)

[0061]

(7) (v _ofl −v _of2 + R1if1 −R4if2) (7) can be made very small. However, when the photoelectric current i _d is very small, R2 / R3 has a large value, and the second term of the formula (5) cannot be ignored.

FIG. 6 shows an example of the control procedure stored in the ROM 302-1 of FIG.

In FIG. 6, first, in step S1,
It is determined whether or not the condition for the sensor correction of the AE sensor 25 is possible. The correction of the AE sensor is performed immediately after the power is turned on or immediately after the copying is completed and it is confirmed that there is no document in the conveyance path where the AE sensor is located. If no correction is made, leave lamp preheated.

In step S2, offset adjustment of the AE amplifier 323 output v _a is performed. This is because the output v _d (406) of the D / A converter 310 (a) is set to 0 volt and the applied voltage v _L (407) to the lamp 321 is set.
To 0 volts. In this state, the photo sensor 322
The photoelectric current does not flow through, the output v _a of AE amplifier 323, and the dark current of the photo sensor 322, AE amplifiers 323
And the total offset voltage due to the offset of the offset amplifier 324 itself, and the D / A converter 310.
An output obtained by adding the output v _s of (b) appears.

To obtain an accurate document reflection density, the output voltage v _a of the AE amplifier 323 when the lamp 321 is off must be equal to the voltage v _ref (404) of the reference power supply 326. _Yes , D so that v _a = v _ref
The output v _{s of the} A / A converter 310 (b) is adjusted.

The problem due to the offset voltage of the AE amplifier 323 is particularly important when the photoelectric current i _d (401) is extremely small as in this embodiment, because the amplifier gain is very large. In some cases, the output of the AE amplifier 323 may be saturated due to the offset voltage.

In step S3, the lamp light amount of the AE sensor is corrected. In general, the light source of the AE sensor, which is housed in the transport path of the document transport device, must use a light source whose output greatly changes due to power supply fluctuation.

Further, the optical filter 329 and the condenser lens 3
The amount of light incident on the photo sensor 401 changes greatly even by mounting 30 or the like, and if the power supply voltage of the lamp 321 is kept constant, the AE output due to the photoelectric current i _d exceeds the dynamic range of the AE amplifier 323. There is also. Therefore, when there is no document, the D / A converter 310 is configured so that the reflection input from the reflection plate 24 is always constant.
The output vl of (a) is set.

In step S4, the value of the lamp voltage v _L for changing the setting of the D / A converter 310 (a) so that the lamp voltage v _L is such that the lamp 321 does not generate heat. It is set so as to prevent a sudden change in the light emission output when a specified voltage is applied to.

In step S5, it is determined whether or not the original is set on the original tray and the copy key of the copying machine is turned on.

In step S6, the document size is determined. This determination is made by the document detection sensor 53 and the auxiliary tray switch 52. FIG. 7 shows a document detection table, and the document size is estimated based on this table.

FIG. 8 shows the conveyance direction of the document size shown in FIG. 7, and the document is conveyed in the direction of the arrow in the figure.

Here, the original detection sensor 53 is composed of a sliding resistance as shown in FIG.
It works together with 4. Therefore, the voltage corresponding to the moving distance of the document guide is A / D converter 309.
The CPU 301 detects the document width from the output of the A / D converter 309. For example, A4 on the document tray
A / D converter 309 when the size is placed horizontally
Input voltage becomes 0 volt, and it becomes 00H to CPU301.
Is output. When placed vertically on the document tray,
The input voltage of the A / D converter 309 is 2.5 V, and 80H is output to the CPU 301.

In step S6, the point at which the density of the original is measured is also determined according to the size and orientation of the original to be conveyed. The measurement point can be designated by a measurement start point A and a measurement pitch B as shown in FIG.
It can be different for each size as shown in FIG. In addition, N shown in FIG. 11 is the number of measurement points.

Then, in step S7 of FIG. 6, the copy key is turned on in the copying machine to start separation, separate the originals one by one from the bottom, and determine whether the leading edge of the original has arrived at the paper feed sensor 13. . At the same time when the conveyance is started in step S8, the AE lamp 25 is turned on, and
At 9, the data of the AE sensor 25 at that time, that is, the AE sensor data corresponding to the document density is stored in the RAM 302-2.

FIG. 12 is a flow chart showing in detail the contents of step S9 shown in FIG.

In FIG. 12, in step S5, AE
Initialize variables for sensor output calculation. The variables to be initialized are the number of measurements x and y, which is the sum of the sensor levels, and are set to x = 1 and y = 0.

In step S51, a counter for counting the output of the photoelectric sensor 95 (hereinafter referred to as a belt clock sensor) is cleared.

In step S52, the number of clocks from the belt clock sensor 95 is counted. The number of clocks is proportional to the moving distance of the original, and for example, the original advances 0.5 mm in one clock.

In step S53, it is determined whether or not the number of clocks counted in step S52 has reached a predetermined number of clocks K. The predetermined number of clocks K is obtained from the table of FIG. 11. For example, when the document size is A4 portrait, A = B = 35 mm, and the distance the document advances in one clock is 1.5 mm, so K = 70. Become.

In step S54, the AE sensor level is measured when the document reaches the reflected light amount measurement point. This is performed by A / D converting the input of the A / D converter 307 (a). At this time, the document is moving by the drive of the belt motor 82, and the inverting amplifier 312 is also driven by the resistor 415 and the capacitor 416. Since the low-pass filter is configured, the measured reflected light amount is observed as an average value per unit time, and the level close to the background color of the original can be measured. The sensor level thus measured is Z.

In step S55, in order to obtain the arithmetic mean, the measurement levels of the AE sensors each time are added.

In step S56, the number of measurements is incremented.

In step S57, it is determined whether or not the number of measurements has reached a prescribed number. The prescribed number N is shown in FIG.
As shown in.

In step S57, even when the specified number of times has not been reached, it is determined that the specified number of times has been reached when the trailing edge of the document passes the registration sensor 14. This is to prevent the final output from becoming improper when the sensor level measurement is performed a prescribed number of times when a document shorter than the document size shown in FIG. 7 is conveyed.

In step S58, the counter value of the belt clock counter is cleared and B in FIG.
The count value K corresponding to is set.

In step S59, the arithmetic mean of the measurements is calculated.

In step S10 of FIG. 6, the lamp 321
To the preheating mode again to suppress the temperature rise of the lamp 321.

In step S11, the light quantity of the exposure lamp 103 is corrected based on the data obtained in step S9. The calculation of the light amount correction is started before the trailing edge of the original passes through the paper feed registration sensor 14, so that the light amount of the exposure lamp can be controlled before the image reading is started.

Then, in step S12, after the trailing edge of the original has passed through the paper feed registration sensor 14, the registration count of a predetermined value is started in step S13, and the count up by the belt clock is waited in step S14.

Then, in step S15, the conveyance of the original is stopped, and the original is stopped at a predetermined position on the platen glass.
In step S16, the optical system is started and image reading is started.

FIG. 13 shows the AE sensor output (v
₀ ) Shows the waveform of 405 and its sampling timing.

Embodiment 2 In Embodiment 1 described above, in step S9 of FIG.
The belt clock sensor 9 is used to read the document density reading timing.
Although it was performed based on the number of clocks of 5, it is also possible to perform it by a timer interrupt as shown in the flowchart of FIG.

That is, in step S60, the variables are initialized in the same manner as in step S50 of FIG.

In step S61, the distance A shown in FIG. 11 is set for the time T1 during which the document advances.

In step S62, a timer is activated.

In step S63, it is determined whether or not the timer has timed up within the time set in step S61.

From step S64 to step S67,
This is exactly the same as steps S54 to S57 shown in FIG.

In step S68, the time T2 corresponding to the reading pitch B in FIG. 11 is set.

In step S69, step S in FIG.
The same processing as 59 is performed.

Embodiment 3 In the above embodiment, the image density smoothing means is provided in the inverting amplifier 312 as shown in FIG. 5, but as shown in FIG.
The capacitor C1 may be placed in parallel with the current-voltage conversion resistor R1 of the amplifier 323, or the feedback resistor R2 and the parallel capacitor C2 of the AE amplifier 323 may be placed.

[0102]

As described above, according to the present invention, since the document density can be detected in the document transport path, it is possible to eliminate the prescan for reading the image density and improve the throughput. While you can
It is possible to detect the density over a wide area on the document.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control device included in an embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing an entire embodiment of the present invention.

FIG. 3 is a cross-sectional configuration diagram of the circulation type document feeder (RDF) shown in FIG.

4 is a cross-sectional configuration diagram showing a driving unit of the RDF shown in FIG.

FIG. 5 is a circuit configuration diagram of an AE sensor 25 according to an embodiment of the present invention.

FIG. 6 is a flowchart showing an entire control procedure in one embodiment of the present invention.

FIG. 7 is a diagram showing an example of a document size detection table.

FIG. 8 is a diagram illustrating an example of a document feeding direction.

FIG. 9 is a schematic diagram of a document width detection mechanism.

FIG. 10 is a diagram showing reading points of the AE sensor.

FIG. 11 is an explanatory diagram of the number of reading points and the pitch of the AE sensor.

FIG. 12 is a flowchart showing a reading control procedure of the AE sensor.

FIG. 13 is a diagram showing an example of AE sensor output.

FIG. 14 is a flowchart showing an AE sensor reading control procedure according to the second embodiment of the present invention.

FIG. 15 is a diagram showing a circuit configuration of an AE sensor according to a third embodiment of the present invention.

[Explanation of symbols]

 25 AE sensor 200 Circulation type document feeder 301 Central processing unit 308 CVR (control voltage regulator)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shunji Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. An original document carrying unit for carrying an original document onto an exposure surface, an original document density detecting unit for detecting the density of the original document carried by the original document carrying unit when the original document is in a carrying path, and an exposure process. An image processing apparatus comprising: a light amount correction unit that corrects the exposure lamp light amount based on the detected density before starting. 2. The image processing apparatus according to claim 1, wherein the document density detecting unit includes a document density smoothing unit. 3. The image processing apparatus according to claim 1, wherein the document density detecting means performs density detection for one document a plurality of times. 4. The image processing apparatus according to claim 1, wherein the original density detecting means has a calculating means for calculating an average density of a plurality of original density detection data.