JPH06237340A - Picture input device - Google Patents

Abstract

PURPOSE:To allow the device to read picture information with excellent picture quality at a high speed while suppressing a motion blurring. CONSTITUTION:A read section (line sensor) 2 in which photoelectric conversion elements are arranged in the main scanning direction is relatively carried in the subscanning direction orthogonal to the main scanning direction by a carrier system 3 with respect to an original (film) F, and a light reflected in the film F or transmitted through the film F to be read by the line sensor 2 is formed by a flash light of a flash means (strobo device) 4 and the strobo device 4 is flashed intermittently and the signal is read synchronously with the flash.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for reading image information from a two-dimensional image recorded matter such as an original document or a photograph, for example, an image scanner or the like, a line sensor is arranged in the main scanning direction and the line sensor is placed on the original document. A mechanism is used in which image information is read by moving it relatively in the sub-scanning direction.

This mechanism employs a method in which a line sensor is moved in the sub-scanning direction with respect to an original or the like, and the main scanning is intermittently performed at a predetermined time to read the original. But,
In this method, although the reading time is short, since the line sensor reads the image information while moving, there is a problem that clear image information cannot be obtained, such as blurring of the read image due to motion blur. Therefore, a method has been developed in which movement of the line sensor in the sub-scanning direction is stopped each time main scanning is performed, and charges are accumulated in the sensor and read. However, this method has an advantage that a high-definition image can be obtained, but since the driving and stopping are repeated, mechanical load is likely to occur. In particular, when a stepping motor is used, a ringing phenomenon occurs and an image is blurred,
There are drawbacks such as a step out phenomenon, and there is a problem that it takes a long time to read.

Further, the light source used in the conventional image input device has a problem that the color temperature is not sufficiently high and the color reproducibility is poor, and that it takes time until the light amount of the light source stabilizes after the switch is turned on. However, this is inconvenient in that the reading operation cannot be started immediately. Further, since heat is generated with the emission of light, the temperature of the entire device is increased, and the dark current in each photodiode of the line sensor is increased, which adversely affects the electric circuit system.

On the other hand, with the development of a multimedia creating device such as an image database, it is used in a silver halide camera.
5 mm size film (for example, 24.0 mm long x 36.
There is an increasing need for an apparatus capable of inputting a high-definition image of a small-sized document (size of about 0 mm). In such an apparatus, since the screen of the original is small, it is necessary to perform the sub-scanning with a particularly high precision, and there is a problem that the image quality is greatly affected even if some motion blur occurs.

Further, in the past, even if high-definition image information was read in a short time, there was a limit to the data transmission speed, so a mechanism for reading a high-definition image at high speed had low utility value. However, due to recent improvements in the interface, it has become possible to transmit data at high speed, and it has been desired to develop an image input device capable of reading high-definition images at high speed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus capable of inputting high-definition image information at high speed without causing motion blur.

[0008]

Such an object is achieved by the present invention described below. That is,

(1) A flashing means for intermittently emitting flashing light, and a reading section which is provided so as to face the original and which has photoelectric conversion elements for reading reflected light or transmitted light from the original due to the flashing, which are arranged in the main scanning direction. And a conveying system for moving the reading unit relative to the document in a sub-scanning direction orthogonal to the main scanning direction, and the flashing means while performing relative movement between the reading unit and the document. The image input device is characterized in that a flash light is intermittently emitted by the light source and the reading unit reads the light in synchronization with the flash light.

(2) The image input device according to (1), wherein the document is stationary and the reading unit moves in the sub-scanning direction with respect to the document.

(3) The image input device according to (1) or (2), wherein the flashing means moves in the same direction as the reading section moves in the sub-scanning direction.

(4) The image input device according to any one of the above (1) to (3), wherein the unnecessary charges accumulated in the photoelectric conversion element are swept out immediately before the flash of the flash means.

(5) The image input device according to any one of the above (1) to (4), wherein the flash means is a strobe device.

(6) The image input device according to any one of the above (1) to (5), which is capable of adjusting the average amount of received light in the reading section according to the type or characteristics of the original.

(7) The adjustment is carried out by adjusting the amount of light emitted from the flashing means (1) to (6).
The image input device according to any one of 1.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an overall perspective view of a sub-scanning mechanism of the image input apparatus 1 of this embodiment. As shown in the figure, the image input device 1 of the present embodiment includes a line sensor 2 composed of a CCD (Charge Coupled Device) as a reading unit, a transport system 3 for moving the line sensor 2, Flashing means provided in the transport system 3,
Film holder 50 for holding the film F which is the original
And an optical system 53 that guides the light from the flash unit that has passed through the film F to the line sensor 2.

Examples of the film F include a developed color or black and white negative film, a color or black and white positive film, a micro film, and the like. Besides films, there are OHP sheets and the like.

In the line sensor 2, the photoelectric conversion elements are arranged in an array, and the light transmitted from the film F enters the photoelectric conversion elements through the slits 21 to accumulate charges. The line sensor 2 is electrically connected to the drive circuit 22 provided separately. The line sensor 2 can correspond to either a black and white image or a color image.

An example of the configuration of the image input device will be described below by taking the case of reading a color image as an example. The CC
D is provided with each line of a photoelectric conversion element for sensing each color of red, green, and blue for each color, and each line is covered with a filter of red, green, and blue, respectively. When sub-scanning is performed by the line sensor 2 as described above, the red, green, and blue sensing lines are sequentially moved to the same sub-scanning position, and the reading method is performed, and the sub-scanning is performed three times, and each time the sub-scanning is performed. There is a method to read each color one by one. In addition,
A plurality of sensing lines may be provided for each color. Here, the main scan means a scan that the line sensor 2 reads for each line.

FIG. 2 is a diagram showing the arrangement of each pixel of the CCD 20, and FIG. 3 is an enlarged sectional view showing a part of the CCD 20. Pixels including photoelectric conversion elements (photodiodes) 24 are arranged in the main scanning direction for each color of red, green, and blue, and charge transfer shift registers 25R and 2R, respectively.
5G and 25B are arranged in parallel for each array of each color. As shown in FIG. 3, charges corresponding to the amount of received light are accumulated in the photodiode 24, and the charges are transferred in the direction perpendicular to the paper surface via the charge transfer shift registers 25R, 25G, and 25B. To be done. The charge transfer shift registers 25R, 25G and 25B are two-phase driven, that is, driven by the drive pulse signals φV1 and φV2, respectively. Further, the charge transfer shift registers 25R, 2
The 5G and 25B driving may be four-phase driving.

A substrate voltage φV _SUB is applied to the substrate 27 via a substrate voltage control circuit 23 described later, and the P layer 2
8 is grounded. Therefore, a reverse bias voltage is applied to the substrate 27 and the P layer 28, and a depletion layer 29 is formed between the photodiode 24 and the substrate 27. Then, by increasing the substrate voltage φV _SUB , the depletion layer 29 becomes large and the photodiode 24
The unnecessary charges generated therein are absorbed in the depletion layer 29 and swept out from the photodiode 24. Examples of the unnecessary charges include dark current generated by heat radiated from the CCD and other circuits, charges accumulated by scattered light which is not transmitted light from the film F, and the like.

The line sensor 2 of this embodiment has a relatively large number of photodiodes (pixels) in one line, and its density is also high. For example, 36.
5143 pixels are arranged in the range of 0 mm (7μ
m pitch). Further, in the apparatus of this embodiment, the number of main scans is relatively large. For example, there are sub-scanning positions corresponding to 3429 pixels in the range of 24.0 mm in the sub-scanning direction.
With such a number of pixels, a high-definition image can be obtained. Note that the pixel density used for obtaining a high-definition image by the device of the present invention is 19000 to 2100.
The number can be about 0 / mm ² or more. The effect of the present invention is more effectively exhibited at a pixel density of this level.

On the other hand, the line sensor 2 is moved in the sub-scanning direction by the transport system 3. The transport system 3 includes a carriage 31 that fixes the line sensor 2 and a rod-shaped guide member 32 that guides the carriage 31 in the sub-scanning direction.
a, 32b, a nut 33 provided at a substantially central portion of the carriage 31, a lead screw 34 screwed to the nut 33, and a direct current (DC) motor 38 for driving the lead screw 34. have. In addition, as the nut 33, a ball screw having a steel ball in a thread valley portion inside can be used.

The carriage 31 has a plate-shaped base 310.
And a reading sensor mounting portion 311 provided with the line sensor 2, and insertion portions 312a and 312b through which the guide members 32a and 32b are inserted. The base 31
Each part provided at 0 is configured by bending an end portion of the base 310, and has a structure integrated with the base 310. The reading sensor mounting portion 311 is provided on the base 310.
1 is bent upward in the drawing, and the line sensor 2 is attached to the reading sensor mounting portion 311 so that the main scanning line is in the vertical direction.

A pair of insertion portions 312a and 312b are provided below the base 310, and the insertion portions 312 are
Guide members 32a and 32b are slidably inserted into a and 312b. The carriage 31 is the guide member 3
It continuously moves in the sub-scanning direction while slidingly contacting with 2a and 32b.

On the base 310, the strobe device 4 as a flash means is provided. This strobe device 4 is
Facing the position where the line sensor 2 is arranged,
They are arranged in parallel. In other words, the strobe device 4 is arranged so that the line connecting the line sensor 2 and the strobe device 4 is orthogonal to the sub-scanning direction.

The strobe device 4 includes a light emitting section 41 and a reflecting section 4.
2 and. In the present embodiment, the light emitting section 41 is constituted by vertically arranging a discharge tube filled with xenon (Xe) gas so as to be parallel to the line sensor 2.
A discharge tube having a length comparable to that of the line sensor 2 or longer than that is used.

The color temperature of the light emitting section 41 used in the present invention is not particularly limited, but is preferably 5000 to 7000K. For example, in the case of the xenon discharge tube, its color temperature is about 5500 to 6500K. The enclosed gas in the discharge tube constituting the light emitting section 41 is not limited to xenon (Xe), but may be argon (Ar) or neon (Ne).
And various inert gases such as

The reflecting portion 42 is a cylinder containing the light emitting portion 41 inside, and the entire inner surface facing the light emitting portion 41 is a reflecting surface and covers the light emitting portion 41 over the entire length. There is. The reflection part 42 has an opening 421 formed in a slit shape. The opening 421 is formed on the side surface facing the line sensor 2 in the vertical direction, that is, parallel to the line sensor 2. With such a configuration, the strobe light (flash light) radially emitted from the light emitting portion 41 is reflected on the inner surface of the reflecting portion 42, and the opening 42 is formed.
It is effectively irradiated from 1 toward the film F.

By the action of the reflecting portion 42, the strobe light is emitted as a flat light beam along the arrangement direction of the line sensor 2 (main scanning direction). Therefore, the amount of light emitted from the light emitting section 41 itself can be saved, and power can be saved. Further, since the light is concentrated on the line sensor 2 and is not scattered to other portions, it is possible to suppress the trouble that the reflected light from the other portions enters the line sensor 2 and causes noise. In order to exert such an effect more effectively, a lid may be provided at the upper end open portion of the reflecting portion 42. As described above, since a sufficient amount of light is obtained by the strobe device 4, the electric charge is accumulated in the line sensor 2 instantaneously.

A film holder 50 and an optical system 53 are provided between the strobe device 4 and the line sensor 2 independently of the transport system 3. The film holder 50 has a holder 51 and a mount 52 that holds and holds the film F in the holder 51. Holder 5
The reference numeral 1 designates a housing portion 5 which is formed in a U-shape with the upper side opened, and into which the mount 52 is housed by inserting it from above.
Have 11.

The accommodating portion 511 is formed in a groove shape, and the groove portion holds the peripheral edge of the mount 52. The mount 52 has a rectangular shape that fits the accommodation portion 511, and has a rectangular window 521 formed in the center. The film F is held so that the scanned portion is located in the window 521. The film F to be read is mount 5
By removing it from the holder 51 as a unit with 2,
Can be exchanged.

Line sensor 2 of the film holder 50
The optical system 53 is arranged on the side. This optical system 53
For guiding the transmitted light from the film F to the line sensor 2 at a predetermined magnification, for example, equal magnification, and has a lens group and an iris (aperture) 531 as a light quantity adjusting means. The iris 531 is an iris motor 5
Driven by 32, the amount of light is adjusted.

The nut 33 is provided on the lower side of the carriage 31, and a lead screw 34 is screwed into the nut 33. The lead screw 34 is supported in parallel with the guide members 32a and 32b. At the base end of the lead screw 34, by the coupling member 35,
The drive shaft of the DC motor 38 is connected, and the lead screw 34 is driven by the drive of the DC motor 38. The rotation of the lead screw 34 moves the nut 33 in the axial direction, and the carriage 31 moves in the sub-scanning direction along the guide members 32a and 32b.

Since the film holder 50 and the optical system 53 are fixed relative to the movement of the carriage 31, the line sensor 2 moves in the sub-scanning direction relative to the film F. At this time, the strobe device 4 is also the line sensor 2
Since it moves with this, shading correction of each image element signal in the sub-scanning direction described later is unnecessary.

An encoder (not shown) is built in the DC motor 38. The encoder is D
It is composed of a disc fixed to the drive shaft of the C motor 38 and having concentric circles with the drive shaft and having perforated holes at equal intervals in the circumferential direction, and a transmissive photointerrupter.

Then, the disk rotates with the rotation of the DC motor 38, and each time the transmitted light of the photo interrupter passes through the transmission hole, the light reception and the light shielding are repeated in a cycle proportional to the rotation speed. Then, an output pulse having this cycle is transmitted from the encoder. The rotation speed is controlled by the transmission pulse from the encoder so that the rotation speed of the DC motor 38 does not vary.

Next, the structure of the control system of the image input apparatus will be briefly described. FIG. 4 is a simplified block diagram of electric circuits of a drive system and a data transmission system of the image input apparatus 1 of this embodiment. Each drive circuit constituting the device of the present embodiment,
It is controlled by the system control 10. In the device of this embodiment, as shown in the figure, a CCD drive circuit 22 for driving the line sensor 2, a substrate voltage control circuit 23 for controlling the substrate voltage of the CCD, and the strobe device 4 are provided.
Strobe drive circuit 14 for driving the
A signal processing circuit 9 for processing the image signal output from
It has a system control 10 for controlling these.

The moving speed of the carriage 31 is maintained substantially constant by controlling the DC motor 38 at a constant speed by the system control 10. The system control 10 uses the pulse interval from the encoder 381 to set the DC
The rotation speed of the motor 38 is detected, and the DC motor 38 is controlled at a constant speed at a predetermined rotation speed.

Further, by counting the pulses transmitted from the encoder 381, the line sensor 2
It is possible to specify the movement amount (position) of the. The CCD drive circuit 22 sends a CCD shift pulse to the line sensor 2 and also sends a CCD drive pulse. Further, the substrate voltage control circuit 23 controls the substrate voltage of the CCD, and CC
It exerts the function of appropriately sweeping out unnecessary charges accumulated in D.

The strobe drive circuit 14 drives the strobe device 4 by a trigger signal input from the system control 10. Accordingly, the light emitting unit 41
Is flash driven. The flash time of the light emitting section 41 is, for example, about 1 to 1000 μsec, and preferably about 1 to 100 μsec. This is because within this range, motion blur does not occur and a high-definition image can be obtained. Therefore, the number of flashes may be plural within the above time. Further, by adjusting the flash time within this time range, the line sensor 2 can be operated without motion blurring.
It is also possible to adjust the integrated value of the amount of light applied to the photoelectric conversion element.

The light emitted from the strobe device 4 passes through the film F, is imaged by the optical system 53, and is emitted to the line sensor 2. This irradiation light accumulates electric charges in each pixel, and the electric charges are further accumulated in the CCD drive circuit 22.
Is output to the signal processing circuit 9 as an image signal.

The operation of the device of the present invention in the above circuit will be described with reference to the flow chart shown in FIG. 5 and the timing chart shown in FIG. The first operation at the start of reading initializes the electric circuit system. That is, memory initialization and register setting are performed (step 101).

Next, the mechanical system is initialized. That is, the DC motor 38 is rotated in the reverse direction to move the carriage 31 on which the line sensor 2 is mounted in the direction opposite to the sub-scanning direction and return to the initial position where the movement is started (step 102). The initial position at which this movement is started is provided at a position retracted by the approach distance from the reading start position at which reading is started.

The DC motor 38 is normally rotated to move the line sensor 2 in the sub-scanning direction (step 103). The moving speed of the line sensor 2 is stabilized at a constant speed by the system control 10 while moving in the approach section (between the initial position and the reading start position). This constant speed control is performed by the transmission pulse output from the encoder (see FIG. 6).
(A)).

When the line sensor 2 reaches the reading start position, the system control 1 is sent to the substrate voltage control circuit 23.
By sending a signal from 0 and raising the substrate voltage,
Sweep out unnecessary charges remaining in the CCD (Step 1
04) (Fig. 6 (e)). Then, the flash drive circuit 14
A trigger signal is transmitted from the system control 10 to flash the strobe device 4 once (step 10).
5) (Fig. 6 (b)).

Electric charges are instantly accumulated in each photodiode of the line sensor 2 by one flash (FIG. 6).
(C)). Since the charge storage time is extremely short, it is possible to read the image clearly without causing motion blur. Immediately after the strobe device 4 flashes, a shift pulse is transmitted from the CCD drive circuit 22 (FIG. 6 (d)).
The charges are transferred to the shift register (step 106).
By operating in this way, it is possible to minimize the influence on the image signal due to the dark current generated by the influence of heat or the like.

Further, a CCD drive pulse is transmitted from the CCD drive circuit 22 to read out the charge accumulated for each photodiode (step 107). The output signal of the CCD (FIG. 6 (f)) by one main scan is constituted by the information constituted by the read charges. This reading is completed by the next strobe emission.

The output signal from the CCD is input to the signal processing circuit 9 and processed. Next, it is judged whether or not a predetermined number of main scanning lines have been read (step 10).
8). If the number of lines has not reached the predetermined number, the process returns to step 104. If the number of lines has reached the predetermined number, the reading operation is stopped. Every time one main scan is performed, the operations from step 104 to step 108 are repeated to read one screen.

Here, after completion of reading, the line sensor 2 may be set to return to the initial position and stand by.
As described above, the cycle of the flash light by the strobe device 4 and the driving cycle of the CCD of the line sensor 2 are synchronized (FIG. 6).
(C), FIG.6 (d)). That is, the mutual drive timing is constant.

The reading by the line sensor 2 is performed from the transmission of a shift pulse to the transmission of the next shift pulse (see FIG. 6D). In the apparatus of this embodiment, however, It is performed after the unnecessary charges are swept out (see FIG. 6E) and thereafter until the shift pulse is transmitted (see FIG. 6D). Therefore,
During this period, t ₀ is the reading time, and flash light is emitted from the strobe device 4 within this time (see FIG. 6C). Since most of the electric charge is accumulated by the flash light, the flash time is substantially the read time.

By using the flashing means as described above, the charge accumulation time for accumulating charges in the line sensor 2 becomes extremely short. Therefore, the timing of transmitting the shift pulse is not limited to the charge accumulation time, but is limited to the time for reading from the shift register, and the time interval for performing the main scanning is shortened as compared with the case of using the conventional light source. Therefore, it becomes possible to read at a higher speed than before.

On the other hand, in the prior art, since the charge storage time was long, it was easily affected by unnecessary charges such as dark current generated during the storage time, and the charge could not be swept out. However, as described above, since it became possible to instantly accumulate charges by flashing, the time to sweep out unnecessary charges from the completion of reading from the shift register to the transmission of the shift pulse. Therefore, it is possible to effectively suppress the adverse effect of unnecessary charges.

The signal processing circuit 9 will be briefly described below with reference to FIG. C output from the line sensor 2
The CD signal is separately output for each of the red (R), green (G), and blue (B) signals. Each output signal is inverted and amplified by the head amplifier 91 and output (FIG. 6 (g)). Dark uniformity (hereinafter referred to as “DU”) correction circuits 92R, 92G, and 92 for each color signal (R, G, B)
Input to B respectively. This DU correction circuit 92R, 9
In 2G and 92B, noise caused by dark current is corrected. Since this error differs for each pixel, each value is read from the DU memory 92M and corrected for each pixel. At this time, since each correction amount is digitized and stored, the memory value is D / A converted, and then the correction amount for each pixel is input to the DU correction circuits 92R, 92G, and 92B.

Next, the CCD signal is supplied to the white uniformity (hereinafter referred to as "WU") correction circuits 93R and 93G.
It is input to 93B respectively. This WU correction circuit 93
In R, 93G, and 93B, noise caused by the sensitivity difference for each pixel is corrected. Since this correction amount differs for each pixel, each value is read from the WU memory 93M and corrected for each pixel. At this time, since each correction amount is digitized and stored, after the memory value is D / A converted, the correction amount for each pixel is calculated by the WU correction circuits 93R and 93G.
Input to 93B.

Next, the CCD signal is input to shading (hereinafter referred to as "SD") correction circuits 94R, 94G and 94B, respectively. Since the intensity of the light source differs depending on the position of the pixel, the SD correction circuits 94R, 94G, and 94B perform nonuniform correction of the optical system such as the light source and the lens. Since this correction amount varies depending on the position of each pixel, each value is read from the SD memory 94M and corrected for each pixel. At this time, since each correction amount is digitized and stored, after the memory value is D / A converted, the correction amount for each pixel is set to the SD correction circuits 94R and 94G.
Input to 94B.

Next, the CCD signal is supplied to the automatic white balance (hereinafter referred to as "AWB") circuits 95R, 95G, 95.
Input to B respectively. This AWB circuit 95R, 95
In G and 95B, the sensitivity difference and the change in color temperature of the light source are corrected for each of the R, G, and B signals. This is each A
This is performed by variably adjusting the amplification degree of the WB circuits 95R, 95G, and 95B. These AWB circuits 95R and 9R
The variable adjustment of the amplification degree between 5G and 95B is made by the AWB control circuit 95C.

Next, the CCD signal is input to the density correction circuit (hereinafter referred to as "γ correction circuit") 96R, 96G, 96B. This γ correction circuit 96R, 96G, 96
In B, the γ characteristic is corrected according to the output device, and the recordable dynamic range is expanded.

The operation of the above process is controlled by the system control 10. This system control 10
It is operated externally via the operation panel 10a. The CCD signals processed as described above are input to A / D conversion circuits 97R, 97G, and 97B, respectively. Each of the R, G, and B CCD signals is converted into a digital signal and, for example, as shown in the drawing, is transmitted to the high-definition frame memory simultaneously by the interface 15 for each color.

Alternatively, it is output to the photographing monitor system 16. In the imaging monitor system 16, R, G,
The B signals are transmitted to the frame memories 16R and 16R, respectively.
The information is input to G and 16B, processed into information in which the number of pixels is reduced to, for example, 1/10 in accordance with the TV monitor, and output to the monitor 16b via the D / A conversion circuit 16a.

Alternatively, information may be recorded by inputting it to the hard disk drive device 18a or the magneto-optical disk device 18b via the SCSI circuit 17. further,
It may be input to a personal computer (PC) or an engineering workstation (EWS) 18c and output to the monitor 19.

Incidentally, each of the A / D conversion circuits 97R and 97R
G and 97B are respectively connected to the average value calculation circuit 13, and the digital signals of the CCD signals of R, G and B are input to the average value calculation circuit 13. The average value calculation circuit 13 calculates the average value of the digital signal output, inputs it to the system control 10, and uses it for exposure control.

The system control 10 controls the iris motor 5 based on the signal from the average value calculation circuit 13.
Controls the drive of the iris drive system including 32, and the iris 5
The aperture of 31 is controlled to an appropriate value. Such control of the iris 531 is performed when the average amount of transmitted light of the film F varies depending on the type of document. For example, in the case of reading an orange-based color negative film and the case of reading a color positive film, the former requires four times as much light as the latter case. The signal from the average value calculation circuit 13 may be used to adjust the amount of flashing light of the strobe device 4 itself, as described below.

Here, a configuration example of the strobe drive circuit 14 will be described with reference to FIG. When the stroboscopic light emission trigger signal P output from the system control 10 is input to the thyristor 62 of the trigger circuit 61, the thyristor 62 is turned on, and the discharge from the capacitor 63 causes a current to flow to the primary side of the transformer 64. , A high voltage is applied to the excitation electrode 65 connected to the secondary side thereof.

On the other hand, a high voltage (for example, about 300 V) is applied between both electrodes of the light emitting portion (xenon discharge tube) 41 by the main capacitor 66, and the xenon is excited by the application to the excitation electrode 65. Electric discharge occurs in the tube, and strobe light is emitted. The electric charge boosted by the booster circuit 67 is accumulated in the main capacitor 66. The amount of strobe light is always constant if the charging voltage of the main capacitor 66 is controlled to be constant.

Further, the strobe light emission trigger signal P is
It is also input to the switch 71 of the dimming circuit 7, whereby
The switch 71 is in the open state, and the integration of the light amount is started. That is, a current is generated in the light receiving element 70 installed at a predetermined position, and an electric charge according to the received light amount is accumulated in the capacitor 72 via the operational amplifier 73. When the switch 71 is closed, the electric charge accumulated in the capacitor 72 is released and reset (the integrated value becomes 0).

The output of the operational amplifier 73 is input to the negative terminal of the comparator 74, but the capacitor 7
When the output voltage of the operational amplifier 73 decreases due to the accumulation of electric charges in 2, and becomes equal to or lower than the reference voltage (input voltage to the plus terminal) of the comparator 74, the quench signal Q is output from the comparator 74.

The quench signal Q is input to the thyristor 75 connected in parallel with the main capacitor 66, and the thyristor 75 is turned on. As a result, the current supplied from the main capacitor 66 flows through the thyristor 75,
Since the power supply to the light emitting unit (xenon discharge tube) 41 is cut off, the light emitting unit 41 stops emitting light.

The light receiving element 70 is provided, for example, in the vicinity of the light emitting portion 41 and receives the strobe light before passing through the film F. As a result, the amount of light emitted from the strobe device 4, that is, the amount of light emitted from the film F can be controlled to be constant. Therefore, it is possible to prevent unevenness in the amount of light in the sub-scanning direction, and it is possible to perform uniform reading. It should be noted that the dimming circuit 7 may not be present in the illustrated strobe drive circuit 14.

The strobe drive circuit 14 shown in FIG.
In the above, the adjustment of the flash light amount of the strobe device 4 based on the difference in the type of the original can be performed by appropriately changing the reference voltage of the comparator 74 in the light control circuit 7, for example.

Further, when the light quantity is changed drastically or when the dimming circuit 7 is not provided, the capacity of the main capacitor 66 in the strobe drive circuit 14 may be changed. For example, when the image input of the color positive film is switched to the image input of the color negative film, the capacity of the main capacitor 66 is changed. To change the capacity of the main capacitor 66, a variable capacitor may be used to change the capacity, or a circuit configuration having a plurality of capacitors having different capacities may be used, and these may be appropriately switched and used.

FIG. 9 is a circuit diagram showing another embodiment of the strobe drive circuit. The strobe drive circuit of this embodiment is
It has a booster circuit 80, a main capacitor 81 connected in parallel to the booster circuit 80, and a xenon discharge tube 41 also connected in parallel. One terminal of the xenon discharge tube 41 is provided with a switch means. The collector of an IGBT (insulated gate bipolar transistor) 83 is connected in series.

Further, the emitter has a light emission trigger circuit 84.
The coil terminal on the primary side of the transformer 87 constituting the above and one output terminal of the booster circuit 80 are connected. Further, the coil 871 on the primary side of the transformer 87 has a capacitor 8
6 and a resistor 85 are connected in series, and these are connected in parallel to the booster circuit 80 and the xenon discharge tube 41.

The n-side terminal of the diode 88 is connected to the IG
It is connected to the emitter of BT83 and the p-side terminal is connected to the resistor 85. The excitation electrode 89 is connected to one terminal of the secondary coil 872 of the transformer 87, and the terminal of the primary coil 871 is connected to the other terminal. In this way, the capacitor 86, the transformer 87, the diode 88, and the IGBT 83 constitute the light emission trigger circuit 84.

The booster circuit 80 is controlled by the system control 10, and the light emission control signal input to the base of the IGBT 83 is also controlled by the system control 10.
Sent from. A voltage of about 300 V is applied to the main capacitor 81 by the booster circuit 80.

When the light emission control signal is input from the system control 10 to the IGBT 83, the IGBT 83 is turned on, and the main capacitor 8 is connected to the xenon discharge tube 41.
The voltage from 1 is applied, the light emission trigger circuit 84 is turned on, and the capacitor 86 is discharged.
By this discharge, the primary coil 871 of the transformer 87
A current flows through the electrodes, and a high voltage is applied to the excitation electrode 89 connected to the secondary side.

In the xenon discharge tube 41 excited by applying a voltage to the excitation electrode 89, a discharge is generated between the electrodes in the tube and strobe light is emitted. When the output of the light emission control signal is stopped, the IGBT 83 is turned off and the light emission is stopped. The control of the light emission time is performed by adjusting the output time of the light emission control signal input to the IGBT 83.

According to the above configuration, the xenon discharge tube 41
Since the electric charge accumulated in the main capacitor 81 is not released when the strobe light is emitted from the device, the electric charges can be re-accumulated in a short time, the light emission time interval can be shortened, and the power saving can be achieved. You can also Further, the light amount sensor may monitor the amount of light emitted from the xenon discharge tube 41, and when the amount reaches a predetermined value, the system control 10 may turn off the IGBT 83 to stop the light emission.

With the above arrangement, in the line sensor 2, it is possible to prevent the charge from reaching the saturation level or more and overflowing, and the light amount adjustment by the iris 531 is not performed, and the flash light amount from the strobe device 4 is adjusted. The average amount of light in the line sensor 2 can be adjusted only by adjusting.

According to the embodiment of the present invention configured as described above, since the accumulation time of the line sensor 2 can be extremely shortened, the sub-scanning time can be further shortened, and the entire scanning time can be shortened. Can be shortened. Further, it is not necessary to stop the sub-scanning mechanism each time main scanning is performed,
Since the sub-scanning can be performed by continuous movement, there are advantages that the mechanical load is small and the sub-scanning can be performed at higher speed.

In the device of the above-mentioned embodiment, a xenon (Xe) discharge tube is used as the light emitting section. The spectral distribution of light emitted from the xenon discharge tube has a relatively high proportion on the short wavelength side and a relatively small proportion on the long wavelength side (high color temperature). Therefore, in order to improve color reproduction, when orange is used as the basic tone (orange base), that is, when it is used to read a color negative film with high spectral transmittance on the long wavelength side, the input spectrum of the line sensor It is particularly useful because the distribution is compensated.

In the embodiment described above, the line sensor moves with respect to the set original, but the line sensor (reading section) and the flashing means are stationary,
On the other hand, the document may be moved by the transport system. In any case, the optical system may be configured to move relative to the line sensor as a unit.

The image input apparatus of the present invention is not limited to the reading of the above film, but may be, for example, a normal image scanner,
It can also be applied to various image input devices such as facsimiles and copying machines.

[0084]

As described above, according to the image input apparatus of the present invention, the motion blur is suppressed and the image can be read in high definition, and in particular, a small-sized original such as a photographed film can be read. Even in this case, it is possible to read in high definition.

Since the reading time is short, the sub-scanning speed can be further increased, the scanning time can be shortened, the influence of dark current generated during reading can be reduced, and the reading can be performed. If the unnecessary accumulated charges are swept out immediately before the start of, the influence of the dark current can be further reduced. Furthermore, since it is not necessary to stop the sub-scanning mechanism each time main scanning is performed, the mechanical load is small and high-speed reading is possible.

If a strobe light source is used as the flashing means, the color temperature is high and the color rendering is excellent.
Color reproduction faithful to the original can be obtained. Further, since the light emission efficiency is high, heat generation is small, the temperature rise of the device is suppressed, the size can be reduced, and the power consumption can be reduced.

Further, there is an advantage that there is little variation in color temperature which is likely to occur in other light sources, and a waiting time until the light source stabilizes is unnecessary.

[Brief description of drawings]

FIG. 1 is an overall internal perspective view showing the structure of an image input device of the present invention.

FIG. 2 is a diagram showing an array of pixels of a CCD.

FIG. 3 is an enlarged sectional view showing a part of a CCD.

FIG. 4 is a simplified block diagram of electric circuits of a drive system and a data transmission system of the image input device of the present invention.

FIG. 5 is a flowchart showing the operation of system control when controlling speed control and reading by a line sensor.

FIG. 6 is a timing chart showing the drive timing of each circuit.

FIG. 7 is a block diagram showing a configuration of a signal processing circuit.

FIG. 8 is a circuit diagram of a flash drive circuit.

FIG. 9 is a circuit diagram showing another embodiment of a strobe drive circuit.

[Explanation of symbols]

1 Image Input Device 2 Line Sensor 20 CCD 21 Slit 22 Drive Circuit 23 Substrate Voltage Control Circuit 24 Photoelectric Conversion Element (Photodiode) 25 Charge Transfer Shift Register 27 Substrate 28 P Layer 29 Depletion Layer 3 Transfer System 31 Carriage 310 Base 311 Reading sensor mounting part 312a, 312b Insertion part 32a, 32b Guide member 33 Nut 34 Lead screw 35 Coupling member 38 DC motor 381 Encoder 4 Strobe device 41 Light emitting part 42 Reflecting part 421 Opening 50 Film holding body 51 Holder 511 Mounting part 52 Mount 521 Window 53 Optical System 531 Iris 532 Iris Motor 61 Trigger Circuit 62 Thyristor 63 Capacitor 64 Transformer 65 Excitation Electrode 66 Capacitor 67 Booster Circuit 7 Dimming Circuit 7 Light receiving element 71 Switch 72 Capacitor 73 Opamp 74 Comparator 75 Thyristor 80 Step-up circuit 81 Main capacitor 83 IGBT 84 Light emission trigger circuit 85 Resistance 86 Capacitor 87 Transformer 871 Primary coil 872 Secondary coil 88 Diode 89 Excitation electrode 9 Signal processing circuit 91 Head amplifier 92 Dark uniformity (DU) correction circuit 93 White uniformity (WU) correction circuit 94 Shading (SD) correction circuit 95 Auto white balance (AWB) circuit 96 Density correction circuit (γ correction circuit) 97 A / D conversion circuit 10 System Control 10a Operation Panel 10b Memory 11 Counter 12 Detection Circuit 13 Average Value Calculation Circuit 14 Strobe Drive Circuit 15 Interface 1 6 System for photography monitor 16a D / A conversion circuit 16b Monitor 17 SCSI circuit 18a Hard disk drive device 18b Magneto-optical disk device 18c Personal computer (PC), engineering workstation (EWS) 19 Monitor F film (original) P Strobe flash trigger Signal Q quench signal 101-108 steps

Claims (7)

[Claims] 1. A flash unit that intermittently emits a flash, and a reading unit that is provided so as to face the document and that has a photoelectric conversion element that reads reflected light or transmitted light from the document due to the flash arranged in the main scanning direction. A conveyance system that moves the reading unit relative to the document in a sub-scanning direction orthogonal to the main scanning direction, and the flash unit causes the reading unit and the document to move relative to each other. An image input device, which emits a flash of light intermittently and reads by the reading unit in synchronization with the flash of light. 2. The image input device according to claim 1, wherein the document is stationary, and the reading unit moves in the sub-scanning direction with respect to the document. 3. The image input device according to claim 1, wherein the flashing unit moves in the same direction as the reading unit moves in the sub-scanning direction. 4. The image input device according to claim 1, wherein the unnecessary charges accumulated in the photoelectric conversion element are swept out immediately before the flash of the flash unit. 5. The image input device according to claim 1, wherein the flash means is a strobe device. 6. The image input device according to claim 1, wherein the average amount of received light in the reading unit can be adjusted according to the type or characteristics of the original. 7. The image input device according to claim 1, wherein the adjustment is performed by adjusting an amount of light emitted from a flash unit.