JPH0373871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for reading a latent image formed on a detector, such as an electrostatic latent image, and obtaining a proper electrical signal.

A method of forming an electrostatic latent image by imagewise exposure on a multilayer detector including a photoconductive layer and reading out the electrostatic latent image as a time-series electric signal by scanning the detector with light is disclosed in Japanese Patent Application Laid-Open No. 54-31219. Already known by the number and other names.

Here, one of the well-known methods will be explained, and then its problems will be pointed out and an attempt will be made to solve them.

Figure 1 is a block diagram of the electrostatic latent image reading method.
01 is a transparent electrode, 102 is a photoconductor layer, 103 is an insulator layer, 104 is an interface between 102 and 103, 1
05 is an electrode, 106 and 107 are switches, 108
is a DC power supply, 109 is an output terminal, 110 is an output resistor, 111 is a full-surface irradiation light, 112, 113, 11
4 is electric charge. 115 is a negative film, 115-(1) is a transparent part, and 115-(2) is an opaque part. 116 is transmitted light, 117 is a beam light such as a laser, 118 is a rotating mirror or a vibrating mirror, 117-(1) and 117-(2) are 1
17, the reflected light by the vibrating mirror 118, I101 is the current, and V101 is the output voltage. In Figure 1 A, 1
06 on, 107 off, 108 on 10
1 and 105 as shown, layer 1
Charge 02 and 103. In this state, when the entire surface is irradiated with light 111, the resistance of 102 decreases,
Charge injection occurs, and the charge at 101 reaches 104 as shown, and the charges are accumulated as at 112 and 113. This is called primary charging.

Next, remove the light 111, that is, make it dark, and
When 06 is turned off and 107 is turned on, 114 appears in 101 as shown in FIG. 1B.

In this state, as shown in FIG. 1C, when the entire surface is irradiated with light 111 through the negative film 115, 1
The light 116 reaches the electrode 101 at the part 15-(1), and the resistance of the part of the photoconductive layer 102 irradiated by 116 decreases, and the resistance of the part 112 of the interface 104 and the electrode 101 decreases.
The charges at 114 and 113 of 105 disappear. Therefore, only the portion corresponding to the portion 115-(2) remains charged. This is called image exposure, and the remaining charge pattern is called an electrostatic latent image.

After this, as shown in FIG. 1D, the switch 10
With 6 off and 107 on, 117 is applied to 118, and the reflected light 117-(1), 117-
If 101 is irradiated in (2), 10 of the irradiated part
The resistance of 2 decreases, the charge 112 of the insulating layer 103 is discharged through the output resistor 110, I101 flows, and V101 occurs at 109. Figure 1 D is 1
The state in which the reflected light of No. 17 scans from 117-(1) to 117-(2) is shown. In this way, the electrostatic latent image can be read out as a current I101 or a voltage V101.

As is clear from the figure, the current I101 is 11
It does not flow in the irradiated area 6, but flows only in the area 116 that is not irradiated. That is, no current flows in the bright areas of the image, but current flows in the dark areas of the image.

In the above explanation, it is assumed that the charge completely disappears in bright areas and is completely retained in dark areas, but in this method, if there are intermediate tones between bright and dark, the electrostatic latent image is is formed, and a current or voltage corresponding to the electrostatic latent image can be obtained.

FIG. 2 shows an example of the output according to the method shown in FIG. 1, where the horizontal axis is time, that is, the scanning direction of the light beam 117, and the vertical axis is the current I101 or the voltage V101.

201 is the liquid form in the bright area, 202 is the waveform in the dark area,
Reference numeral 203 indicates an example of a halftone waveform.

Note that although the above explanation has only shown the case where optical scanning is performed in one dimension, if optical scanning is performed in two dimensions, a time-series electrical signal of a two-dimensional image can be obtained in the same way as a video signal.

Figure 3 shows two-dimensional optical scanning of the conventional example described above.
This shows how an electrostatic latent image is read out. 301 corresponds to the transparent electrode 101 in FIG. 1 viewed from below. 3
02 to 306 are trajectories of optical scanning. The main scan of the optical scan is performed in the direction of the arrow, that is, from the left to the right in the figure. The sub-scanning is 302, 303 from the top to the bottom on the diagram.
304 and 305 are scanned in this order, and a large number of lines (not shown) are scanned, and finally, 306 is scanned and the process ends. Following this time lapse, 307, 308,
309, 310, 311, 312, 313, 31
It is clear that the order of 4 ends with 315 and 316.

FIG. 4 shows an ideal current waveform when two-dimensional light scanning is performed as shown in FIG. 3 with image exposure dark and uniform over the entire surface in the conventional example shown in FIG. The horizontal axis is time and the vertical axis is current. 402 to 406 correspond to the optical scanning of 302 to 306, respectively, and 407 to 41
6 corresponds to positions 307 to 316, respectively.
Further, 417 indicates a state where the area outside the detector is being optically scanned and there is no signal. 418 omits the time during which multiple main optical scans are performed. In the ideal state shown in Figure 4, 402~
The currents obtained by each optical scan of 406 are all equal, and all of 407 to 416 are I401.

FIG. 5 shows the temporal change in the amount of charge per unit area of 112 in FIG. 1C. The horizontal axis is the time; the vertical axis is the amount of charge per unit area, and the amount of charge per unit area attenuates as time passes, as shown in 501. This is because the dark resistance of the photoconductive layer 102 in FIG. 1 is finite, so even if it is left in a dark room, the charges 112 and 114 in FIG. 1 will be neutralized over time, and the amount of charge 112 will be reduced. This is because it is attenuated. This is called Dark Decay.

Further, 502 indicates a temporal omission corresponding to 418. Here, as an example, consider the size of the detector.
400 x 400 mm, optical scanning is performed at 0.1 mm intervals, and in each optical scan, 0.1 mm interval is taken as one pixel, and it takes 1 μsec per pixel, 307 to 31
The time T from 6 or 407 to 416 is T=400/0.1×400/0.1×1 μsec=16 seconds without taking the part 417 into consideration. If the optical scanning is made very fast, the dark decay shown in Figure 5 can be ignored to some extent, but the numbers obtained from the common-sense calculations mentioned above show that dark decay cannot be ignored. It shows.

Therefore, the actual current waveform obtained by the optical scanning shown in FIG. 3 is a composite of FIGS. 4 and 5, and is shown in FIG. 6. The horizontal axis shows time and the vertical axis shows current. Partial waveform 602~
616 corresponds to 302-346 and 402-416, respectively. 617 is similar to 417. 6
18 indicates a temporal omission corresponding to 418,502. Similar to FIG. 4, this figure shows the case of the conventional example shown in FIG. 1, and it is determined that the larger the current, the darker the image. I601-609 are current values corresponding to portions 607-616, which decrease in the order of I601-609. Therefore, even though the entire surface of the detector was imagewise exposed with the same illuminance as described above, as is clear from FIG. Even so, it is perceived as bright. That is, in FIG. 3, the lower part is perceived to be brighter than the upper part, and shading development occurs in the reproduced image.

Although the occurrence of dark decay has been predicted so far, it has not been linked to actual image deterioration. This is because in the case of experimental machines, the detector dimensions are much smaller than those shown in the example, and the energy of the scanning light is increased to increase the scanning speed, or expensive materials with less dark decay are used. This is because you can choose. However, from a practical point of view, larger screen dimensions are desirable, and the energy of the scanning light may be suppressed or the use of materials may be limited to low-cost materials to increase the lifetime of the detector. Become.

It is an object of the present invention to deal with the phenomenon that information regarding the latent image changes over time and to compensate for this in order to obtain a desired signal. The example described above as the prior art uses the exposure process of a copying machine that uses a negative film as an original to give a latent image, but it is also possible to use a device that projects an original with a projection lens, or even a projection of a three-dimensional object. Alternatively, it can also be applied to the exposure process of a device that records transmitted images. Further, the exposure energy may be any energy that can form a latent image, such as visible light, invisible light such as infrared light, or radiation such as X-rays. In particular, it is well known from xeroradiography that photoconductors are sensitive to X-rays, and the use of electrophotographic means in X-ray examination equipment, especially medical X-ray examination equipment, is important for recording media. There is no need to use large silver halide film, and the amount of X-rays can be reduced by improving sensitivity.
Alternatively, there is a strong demand for it due to the advantage that the read signal can be immediately observed as a video image or subjected to various electrical operations. Even if the photoconductor has very low or almost no sensitivity to X-rays, a latent image can be formed by intervening an image converter such as a fluorescent screen.

On the other hand, regarding the readout scan for reading out the latent image, in the embodiments described below, two-dimensional scanning using laser light is adopted as the most desirable example, but irradiation with another radiant energy may be used. Furthermore, during scanning, instead of fixing the detector and moving the energy point, the detector may be moved, or the movement of the energy point and the movement of the detector may be combined.

The embodiment of the present invention is required to correct the output waveform of FIG. 6 into the waveform of FIG. 7. Signal portions 702 to 708 in FIG. 7 correspond to signal portion 6 in FIG.
02 to 608, respectively, and if the waveforms shown by broken lines in FIG. 7 are corrected as shown by solid lines, a proper image can be obtained.

Here, FIGS. 6 and 7 explain the case where the entire surface of the detector is image-exposed with the same illuminance.
Under normal usage conditions, the entire surface of the detector rarely has the same illuminance, and the illuminance distribution and the obtained electrical signals are random. Therefore, as it is, there is no standard for correction.

Examples of the present invention will be described below.

In FIGS. 8A and 8B, reference numeral 801 is a layered transparent electrode made of Nesa glass or the like, where "transparent" means that the used radiant energy is transmitted. 802
803 is an insulator layer, and 804 is an interface between the two layers. Reference numeral 805 is a layered electrode, which is a transparent electrode when reading and scanning from the back side. These members 801 to 805 are integrated to constitute the detector 800. Further, 806 and 807 are switches, respectively, which are connected in parallel and coupled to the electrode 805, while the switch 806 is coupled to the cathode of the DC power supply 808, and the switch 80
7 is grounded. 809 is an output terminal, and 810 is an output resistor.

Furthermore, 811 is an exposure light source, for example, supplied from a halogen light bulb (not shown). 815 is a negative film, 815a is a transparent area, and 815b is an opaque area. 816 is transmitted light that has passed through the negative film, and has a light distribution corresponding to the pattern of the negative film. Then, an electrostatic latent image corresponding to the pattern of the negative film is formed on the detector 800.
There is a charge 8 in the dark area blocked by the opaque area 815b.
12 to 814 are accumulated, and the brighter the light, the smaller the amount of charge per unit area.

Next, reference numeral 820 denotes a shielding plate that is characteristic of the present invention, and is placed outside the area where the electrostatic latent image is formed and close to the detector 800, blocking the incidence of exposure light and detecting This area (reference area) of the device 800 is always kept in a dark state. Therefore, charges 821-823 are always accumulated in the shielded area of detector 800. The above process corresponds to C in FIG.

Next, remove the shield plate 820 and set the optical scanner in front of the detector 800, or set the optical scanner in front of the detector 800.
If you remove it and set it in front of the optical scanner of a read-only machine, or scan it two-dimensionally from the back side with a laser beam as shown in Figure 1D and Figure 3, you will see an example of the current waveform as shown in Figure 9. can get. As for the optical scanner, an ordinary scanner equipped with a galvanometer mirror and a polygon mirror may be used.

The waveforms in FIG. 9 are for the case where the latent image is a vertical striped pattern of arbitrary halftones, and partial waveforms 902 to 918 correspond to partial waveforms 602 to 618 in FIG. 6, respectively. 9
Reference signals 20, 921, 922, 923, and 924 appear at the beginning of horizontal scanning and are obtained when the area shielded by the shielding plate 820 is optically scanned. These reference signals would have the same magnitude if there was no dark decay in the detector, so the ratio of signals 920 and 921 or 921 and 9
The ratio of 22, etc. indicates the rate at which the charge that formed the latent image dark decays and decreases. Partial waveform 902,
903...906 decrease rate and reference signal 920
etc. are decreasing at the same rate.

That is, FIG. 10 is a diagram showing dark decay, which, like FIG. 5, relates to the amount of charge per unit area. 1001a is a dark decay in a dark area, 1001b is a dark decay in an area slightly irradiated with light, and 1001c is a dark decay in a case where strong light is irradiated. However, 1002 indicates a temporally omitted portion. 1001a,b,c
decreases at the same rate with respect to time, and the amount of charge and the current value obtained by optical scanning are proportional, so reference numbers 920 to 924 and partial waveform 902
It can be seen that ˜916 decreases at the same rate over time.

Therefore, by correcting the partial waveforms 902 to 916 to the desired intensity using reference numbers 920 to 924 as reference standards, the electrical waveform in FIG. 9 can be corrected as the waveform in FIG. 11. However, the horizontal axis in FIG. 11 represents time, and the vertical axis represents voltage, and the waveforms indicated by broken lines in the diagram are shown by converting the current waveforms in FIG. 9 into voltage waveforms for comparison.

Signals 1120, 1121 to 1124 in Fig. 11
correspond to the reference signals 920 to 924, and V ₁₁₀₂ to V ₁₁₀₆ along the vertical axis correspond to the signal 11, respectively.
Indicates a voltage of 20 to 1124. highest voltage
V ₁₁₀₁ is a reference voltage, which should be generated in the dark state region, but voltage V ₁₁₀₂ may be substituted.

Here, the voltage V ₁₁₀₁ is used as the reference voltage, and V ₁₁₀₁ and
By the amount corresponding to the difference between V ₁₁₀₂ and _{V 1106} ,
By successively adjusting the gain of the amplifier in the signal processing circuit, a corrected voltage waveform shown by the solid line is obtained. If the image of the negative film 815 has a uniform vertical striped pattern, the corrected partial waveforms 1102' to 1102' to 11
06' are all equal.

FIG. 12 shows an example of an electrical circuit for correcting the output signal from the detector. Reference numeral 800 is the aforementioned detector, and 830 is a galvanometer mirror, which rotates back and forth around an axis and serves to scan a beam from a laser light source (not shown) in a direction perpendicular to the drawing. 831 is a polygon mirror that rotates at a constant speed around an axis and serves to scan the beam in the drawing. The scanner can be modified in various ways.
An acoustic deflection element may be used, or a two-dimensional array of LEDs may be projected and the LEDs may be blinked in sequence.

Ref is the reference area shielded from light during image exposure, OP ₁ ~
OP ₄ is an operational amplifier, OM ₁ and OM ₂ are one-shot multivibrator, FET ₁ ~
FET ₄ is an N-channel field effect transistor, R ₁
~ _R7 represents a resistor, _C1 to _C6 represent a capacitor, and _D1 to _D4 represent a diode. Further, in this electric circuit example, a current-voltage converter consisting of an operational amplifier OP ₁ and a resistor R ₁ is used in place of the output resistor 810 in FIG. 8A.

Now, if the detector 800 is scanned by a laser beam, the charge accumulated in a certain minute part of the detector is discharged through the resistor R ₁ and the operational amplifier OP ₁ as shown by the current I ₁₂₀₁ indicated by the arrow. . An example of the output of the operational amplifier _OP1 is as shown in FIG. 13a. The voltage V becomes V=I ₁₂₀₁ ×R ₁ .

Output waveform a in FIG. 13 corresponds to the first and second partial waveforms in FIG.
The signal corresponding to the second signal is omitted. The voltages of the signals 1320 to 1324 corresponding to the reference signals in FIG. 9 are set to V ₁₃₀₁ to V ₁₃₀₅ , and the scanning time thereof is set to T ₁ .
In addition, the scanning time of the effective area where the electrostatic latent image is recorded, excluding the light-blocking area Ref of the detector, is T ₂ , the scanning time from the current horizontal scan to the next horizontal scan, that is, the time of the part without image signal Let be T ₃ . This scanning is performed by, for example, a constant velocity scanning lens (-θ lens) 83.
2, the surface of the detector is scanned at a constant speed, so the times T ₁ , T ₂ , and T ₃ in each main scan (horizontal scan) can be made equal. If scanning is performed through an ordinary imaging lens, electrical correction may be required for both main scanning and sub-scanning.

The one-shot multivibrator OM ₁ has a pulse width that varies from the rising edge of reference signals 1320 to 1324.
The one-shot multivibrator OM 2 generates a negative pulse of T ₁ (signal lines in FIG. 13b and FIG. 12, and the same goes for others), and the one-shot multivibrator OM ₂ generates a positive pulse c of pulse width T ₂ from the rising edge of the negative pulse b. to occur. Waveform signal a includes operational amplifier OP ₂ , field effect transistor FET ₁ , resistors R ₂ and R ₃ , and capacitor
It is input to the sample hold circuit consisting of _C3 . The gate of the field effect transistor FET ₁ is connected to the output b of the one-shot multivibrator OM ₁ via a diode D ₁ and a capacitor C ₁ , and is conductive only when the pulse b is negative, and is open when the pulse b is positive. .

Therefore, a voltage corresponding to the difference between the voltages V ₁₃₀₁ to V ₁₃₀₅ and the preset reference voltage Vref is sampled and held, and its inverted voltage waveform becomes the output d of the operational amplifier OP ₂ . The other side of the waveform signal a is attenuated by an attenuator made up of a resistor _R4 and a field effect transistor _FET2 , and invertedly amplified by an inverting amplifier made up of an operational amplifier _OP3 and _a resistor _R5R6 . The gate of the field effect transistor FET ₂ is connected to the output d of the operational amplifier OP ₂ via a parallel diode D ₂ and a capacitor C ₂ . This field effect transistor FET ₂ functions equivalently as a variable impedance depending on the gate voltage, and the higher the gate voltage, the higher the impedance, and the lower the gate voltage, the lower the impedance. Therefore, signal e equivalently resists waveform signal a.
This corresponds to resistance division between _R4 and field effect transistor _FET2 , and since the waveform d is added to the gate of field effect transistor _FET2 , the signal e is the waveform a.
The larger the voltage of the reference signals 1320 to 1324 is, the more the waveform is attenuated, and the smaller the voltage is, the more the waveform is attenuated. As a result, the voltage drop in the reference signals 1320 to 1324 due to dark decay can be corrected.

On the other hand, the signal f obtained by inverting and amplifying the signal e is regenerated by a synchronous clamp circuit comprising a capacitor _C5 and a field effect transistor _FET3 . The gate of field effect transistor FET ₃ is connected to signal line b via diode D ₃ and capacitor C ₃ , and as in the case of field effect transistor FET ₁ , conducts only when pulse b is negative, and when pulse b is positive. When , it is in an open state. Therefore, waveform signal f is clamped to zero volts when pulse b is negative, ie, during time T ₁ corresponding to reference signals 1320-1324, resulting in waveform signal g. The waveform signal g is synthesized by a resistor R ₇ and a field effect transistor FET ₄ during a blanking period T ₃ .

The gate of the field effect transistor FET ₄ is connected to the output line c of the one-shot multivibrator OM ₂ via a diode D ₄ and a capacitor C ₄ in parallel, and the field effect transistors FET ₁ ,
As in the case of FET ₂ , the signal h conducts when the signal c is negative and makes the time T ₃ of the waveform signal g zero volts.
make. The phase of this signal h is reversed compared to the original signal a, and the voltage is high in bright areas during image exposure.
The voltage is lower in the dark areas.

Also, this signal h is the operational amplifier
It becomes a time-series electric image signal as a video (VIDEO) signal via the buffer of OP ₄ . Signal b can be treated as a horizontal synchronizing signal H similar to a negative horizontal synchronizing signal of television or the like.

The video signal VIDEO and the horizontal synchronization signal H can be stored in the still image disk file,
Video signals can be A/D converted and stored in electronic digital files. In addition, the signal can be read out directly or from a storage device, displayed on a display device such as a cathode tube or liquid crystal display panel, or reproduced as an image using various recording devices such as a laser printer.

In addition, before the effective screen of image exposure, that is, Fig. 8B
It is possible to shield the upper part shown in , and use the signal of the shielded part as the vertical synchronization signal at the beginning of optical scanning, or it is also possible to use the first reference signal 1320 as the vertical synchronization signal.

In this embodiment, an example has been described in which the shielded part is scanned at the beginning of the main scan, but the correction can also be made by scanning at the end of each main scan, or by temporarily storing the read signal.
If a correction method is adopted after that, the correction process can be performed at any time when the occluded portion is scanned.

Furthermore, in the above example, the shielding plate 820 was attached and detached, but the eighth
It is also possible to make one end of the transparent electrode 801 shown in the figure an opaque band-shaped electrode, and in this case, light scanning is performed from the transparent electrode 805 side. Alternatively, if image exposure is performed from the transparent electrode 805 side, the insulating layer 805
It can be substituted by making the end of 03 opaque.

Furthermore, although the screen of the above-mentioned detector had the area where the latent image is formed and the reference area continuous, they may have separate structures and the outputs may be taken out from separate signal lines, or the imaging device and the reading device may be connected. As a separate entity,
The reference part is fixed to the readout device, and the other steps except image exposure are performed in parallel, and after the image exposure is completed by the imaging device, the detector is placed adjacent to the reference part, and these steps are continued. You can also scan. If the material, structure, and dimensions of the detector are determined, it will exhibit certain characteristics.
It is also possible to detect the dark date characteristic for each main scan using an experimental method and store it, and to correct the entire image from the signals from only a portion of the light-shielded area and the stored information.

In the example explained above, the reference signal was obtained by blocking light during image exposure, but if the latent image formation process is different, that is, in the process described next according to FIG. 14, the reference signal is obtained during image exposure. The entire area will be irradiated. Switch 107 at A in Figure 14.
When the switch 106 is turned off and the switch 106 is turned on, charges 112 and 113 are applied to the transparent electrodes 101 and 105, respectively.
is charged. In this process, unlike in FIG. 1, the entire surface is not irradiated, so the charge 112 is transferred to the photoconductive layer 1.
It stays at the electrode without being injected into 02.

In this state, when image exposure is performed through the negative film 115 as shown in B, the resistance of the photoconductive layer 102 decreases in the area irradiated with the transmitted light 116 and charges are injected, and the charges 112 move to the boundary surface 104. charge 3
It becomes 12-(1). The charge 112 in the portion not irradiated with the transmitted light 116 remains on the electrode as it is.

Next, switch 106 is turned on in the dark state as shown in FIG. 14C.
When the switch 107 is turned off and the switch 107 is turned on, the two electrodes 101 and 105 are short-circuited, so the charge 11
2 is released through the output resistor, and the charges in the range not irradiated with the transmitted light 116 disappear. Further, negative charges 114 appear in the irradiated area. The subsequent reading process is the same as the process described above, but
The remaining part of the charge is in the opposite direction. Therefore, the output waveform in FIG. 15 is also reversed, 201' is the bright part, 201' is the bright part,
02' is a dark part waveform, and 203' is a halftone waveform.

FIG. 16 shows the image exposure process for another embodiment of the invention. In the figure, the same members as in FIG. 8 are given the same numbers. However, the on/off states of the switches 806 and 807 are reversed, and the states of charges are also different.

The newly added numeral 834 is an exposure lamp for reference signals, which is rod-shaped as shown in FIG. 8 again
A light shielding plate 35 is provided to prevent light from the exposure lamp 834 from entering the latent image forming area. The lighting of the exposure lamp 834 is performed in synchronization with the irradiation of the exposure light 811, and as a result, the charge in the area irradiated by the exposure lamp 834 becomes the same as the charge tendency in the area corresponding to the transparent area of the negative film 815. .

Note that instead of the rod-shaped exposure lamp 834, it is also possible to transmit the light from a xenon discharge tube to the entire reference area using a light transmission member such as an optical fiber to expose the entire surface. It is preferable to insert a diffuser plate 836 between the light emitting end and the detector transparent electrode 801.

The detector after electrostatic latent image formation and reference signal exposure is thus read out with a configuration similar to that shown in _FIG . Change as shown in Fig. 17, and make operational amplifier OP ₃ a non-rotating amplifier. The explanation of the operation of the processing circuit is largely the same as in the case of FIG. 12, so it will be omitted, but each output signal is as shown in FIG. 18. The waveform signal of FIG. 18 has the brightness and darkness reversed with respect to the waveform signal of FIG. 13.

FIG. 19 shows an embodiment in which the present invention is applied to a photographing device. Figure A shows a cross section of the camera, and Figure B shows a cross section of the reader, in which a process is used to shield a reference area forming part of the detector from light during image exposure.

800 is the multilayer detector described above, and 820 is a shielding plate. Reference numeral 1401 denotes a subject, which is either a three-dimensional object such as a human body as shown in the figure, or a flat original such as a manuscript.
1402 is an illumination light source, 1403 is a photographic lens, 1
404 is a shutter. The illumination light source 1402 may be a xenon discharge tube and emit light in synchronization with the opening of the shutter 1404. 1407 is a case, 1407' is a lid of the case, and the lid 1407' is provided for inserting and carrying out the detector 800. Note that it is practical to use a cassette to protect the detector on which the electrostatic latent image is formed from external light. Also, the electrical system etc. have been omitted. Reference numeral 1409 denotes a light source for full-surface exposure, which is placed inside the case 1407 facing the detector.

As already explained using FIG. 1, operate the switch to cause the light source 1409 to emit light, and then
After realizing the process, focus the photographic lens 1403 on the subject 1401 or
When a subject is placed at the focus position 03, the illumination light source 1402 is turned on, and the shutter 1404 is opened, the image of the subject 1401 is projected onto the photographing lens 14.
03, an image is formed on the detector 800, and the process described in FIG. 1C and FIG. 8A is realized. The detector 800 stores an electrostatic latent image of the subject and reference information in a region facing the shielding plate.

Next, in FIG. 19B, 1409 is a case, 140
9' is a case inlet/outlet cover. Reference numeral 1411 denotes a laser beam generator, which, although not shown in the drawing, generates a beam perpendicular to the drawing from bottom to top. This beam is made incident on a beam expander to slightly expand the beam diameter. Reference numeral 1412 denotes a galvanometer mirror, into which the beam from the laser generator 1411 enters and is scanned in a plane perpendicular to the drawing (sub-scanning). 1413 is a polygon mirror that rotates at a constant speed.
The beam reflected by the galvano mirror 1412 is scanned in a direction parallel to the drawing (main scanning). 1414 is a scanning lens.

Detector 80 on which a latent image was formed in the camera shown in Figure A
0 is taken out from the case 1407 by opening the lid 1407', and inserted into the case 1409 by opening the reader lid 1409'. Here, by operating the laser generator 1411, galvano mirror 1412, and porin mirror 1413, the laser beam scans the detector 800 two-dimensionally, and the electrostatic latent image can be read out. This signal readout is as already explained in FIG. 12.

Note that in the camera shown in FIG. A, the center of the detector and the optical axis of the camera are displaced by half the width of the reference area (shielding plate). Further, even if the shielding plate 820 is not particularly provided, a recess may be formed in a part of the case 1407 and the detector may be inserted into the recess to block light.

Furthermore, when the detector 800 is stored in a cassette, a lid is provided on the side of the cassette, and during image exposure and readout, the cassette is attached to the camera and reader, and the detector is inserted into the machine from the cassette, or the front side of the cassette is This can be achieved by attaching a sliding lid to the cassette, inserting the entire cassette into the machine, and opening the lid when exposing the image. Also, the shielding plate can be replaced with a cassette case.

Figure 20 shows the camera when using the process of inputting reference information with full exposure.
34 is an exposure lamp for reference signals, and 835 is a light shielding plate. It is assumed that the exposure lamp 834 is turned on in synchronization with the opening of the shutter. Note that the light source 1408 for illuminating the entire surface has been moved to a position where it illuminates the detector 800 from the back side. Subject 1401 in this case
is a reflective manuscript.

FIG. 21 shows an overview of the entire system related to the device to which the present invention is applied. 1501 and 1502
are the camera and reader as described above, and 800 is a detector. A reader 1502 converts the electrostatic latent image into an electrical signal, and the electrical signal is processed by an electrical signal processing unit including the electrical signal processing system described in FIG. 12, and then stored in a storage unit 1505. It is displayed on a television receiver (1506) or recorded as an image using a laser printer or inkjet recording device (1507). Or storage unit 150
5 is read out via the electrical signal processing unit 1504 at a desired time and displayed on the display 1506.
It can also be displayed on the computer or recorded on the storage device 1507.

FIG. 22 shows an example in which the present invention is applied to a medical X-ray imaging apparatus. In the figure, 1601 is a subject.
Further, 1602 is an X-ray generator, which has a function of irradiating the subject 1601. 1603 is the front panel,
It is made of a material that transmits X-rays and blocks light.
Contact with the subject. A shielding plate 1605 is made of a material such as lead to block X-rays. The shielding plate is fixed to the front panel 1603. 1606 is an outer box, and 1607 is a lid for taking the detector 800 in and out. 1608 is an illumination light source for illuminating the entire surface of the detector 800.

In the case of this example as well, the processes explained in FIGS. 1A and 1B are carried out in advance, and then the X-ray generator 160
2 is activated to irradiate the subject with X-rays. The X-rays that have passed through the subject 1601 pass through the front panel and form an electrostatic latent image on the detector 800 that corresponds to an X-ray fluoroscopic image. The subsequent steps are the same as those described in FIG. 19B and FIG. 12, so the explanation will be omitted.

FIG. 23 is a modified example of the example shown in FIG. 22. Here, 1609 is a light source for illuminating the reference area, and is turned on in synchronization with the drive of the X-ray generator. Further, reference numeral 1601 denotes a light-scattering reflective slope, which reflects the light coming from the light source 1609 toward the detector 800 . In this example, an X-ray-to-light converting material layer 1608, such as a fluorescent layer, is provided on the front surface of the detector 800 so that not only the X-rays act on the photoconductive layer, but also the fluorescent light enhances the effect. . Note that this X-ray-light conversion material layer 1608 may be provided on the opposite surface of the detector.

FIG. 24 is an example in which a signal reader is coupled to the X-ray direct imaging device of FIG. 22. Here, outer box 16
A laser generator 1611 and a polygon mirror 1613 are placed inside the laser beam 161.
2 to scan the detector 800. Note that the lens system and sub-scanner are omitted.

As described above, an electrostatic latent image equivalent to an X-ray transmission image of the subject 1601 is formed in the effective area of the detector 800 by X-ray exposure, but the X-rays directed toward the reference area of the detector 800 is blocked by a lead shielding plate 1605, so this area is kept in the dark and provides a reference signal when the detector is optically scanned, making it possible to compensate for electrical signal degradation due to dark decay. Become.

[Brief explanation of drawings]

1A, B, C, and D are diagrams for explaining a well-known electrostatic latent image formation and readout process. FIG. 2 is a diagram of read waveforms. FIG. 3 is a diagram showing two-dimensional scanning of the detector. Figure 4 is an ideal waveform diagram when performing two-dimensional scanning. FIG. 5 is a diagram showing the dark decay of the amount of charge per unit area. FIG. 6 is an actual output waveform diagram during two-dimensional scanning. FIG. 7 is an output waveform diagram after correction. FIGS. 8A and 8B are process explanatory diagrams showing an embodiment of the present invention. FIG. 9 is a current waveform diagram of the output electrical signal. FIG. 10 is a diagram showing dark decay when the light amount of image exposure is different. FIG. 11 is a voltage waveform diagram after correction. Figure 12 is an electrical circuit diagram. Figures 13a to 13h are voltage waveform diagrams at various stages of electrical processing. FIGS. 14A, 14B, and 14C are diagrams showing another well-known electrostatic latent image forming process. FIG. 15 is a diagram of read waveforms. FIGS. 16A and 16B are process explanatory diagrams showing another embodiment. 1st
Figure 7 is the main electrical circuit diagram. Figures 18a to 18h are voltage waveform diagrams at various stages of electrical processing. 19A and 19B are cross-sectional views of a photographing device and a reader, which are examples of application of the present invention. FIG. 20 is a cross-sectional view of another application example. FIG. 21 is a block diagram showing the entire system. Figure 22 is a cross-sectional view of a direct X-ray imaging device, which is another example of application;
This figure and FIG. 24 are cross-sectional views showing modified examples, respectively. In the figure, 101 and 801 are transparent electrodes, 102 and 8
02 is a photoconductive layer, 103 and 803 are insulating layers, 10
4 and 804 are interfaces, 105 and 805 are transparent electrodes, 106 and 107 and 806 and 807 are switches, 108 and 808 are DC power supplies, 109 and 809
is the output terminal, 110 and 810 are the output resistances, 115
and 815 are negative films, 111 and 811 are full-surface irradiation lights, 118 is a scanner, 820 is a shielding plate, and 92
0 and 921 to 924 are reference signals, 800 is a detector, 830 is a galvano mirror, 831 is a polygon mirror, 832 is a constant velocity scanning lens, OP ₁ to _{OP 4} are operational amplifiers, OM ₁ and OM ₂ are one shot multi Vibrator, FET ₁ to _{FET 4} are field effect transistors, 834 is an illumination light source, 835
1602 is a light shielding plate and an X-ray generator.

Claims (1)

[Scope of Claims] 1. In a latent image reading device that scans an image detector on which image information is recorded as a latent image with radiant energy and reads out an image signal corresponding to the latent image, the information recorded on the detector is provided. 1. A latent image reading device comprising: means for generating a reference signal corresponding to a change over time; and means for correcting the image signal by referring to the reference signal. 2. The means for generating the reference signal is a reference part that is adjacent to the image forming part of the image detector and has the same structure as the image forming part in which a uniform latent image is recorded, and by scanning with the radiant energy. A latent image reading device according to claim 1, which generates a reference signal. 3. The reference section is a part of the image detector,
The latent image reading device according to claim 2, which is placed in a shielded state during latent image recording. 4. The reference section is a part of the image detector,
The latent image reading device according to claim 2, wherein the entire surface is exposed before reading out the latent image. 5. The latent image reading device according to claim 1, wherein the correcting means includes means for adjusting an amplification factor of the image signal according to the reference signal. 6. X-ray imaging means for recording X-ray image information of the object as a latent image on an image detector, scanning means for two-dimensionally scanning the image detector with a light beam, and an image corresponding to the latent image. In a latent image readout device having a readout means for reading out a signal and an output means for forming and outputting an image based on the readout image signal, the reference information corresponding to changes over time of information recorded on the detector is provided. A latent image reading device comprising: means for generating a signal; and means for correcting the image signal by referring to the reference signal. 7. The latent image reading device according to claim 6, wherein the X-ray photographing means is a medical X-ray photographing device that photographs an X-ray image of the subject. 8. The latent image reading device according to claim 6, wherein the scanning means includes a laser light source and a scanning optical system. 9. The latent image reading device according to claim 6, wherein the output means includes a printer for recording and outputting an image. 10. The latent image reading device according to claim 6, wherein the output means includes a display device for displaying and outputting an image.