JP2003037709A - Method and device for reading image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image read method and device, which employs an image sensor that records image information as an electrostatic latent image and generates a current, in response to the electrostatic latent image by being scanned with a reading purpose electromagnetic wave, that can enhance the read efficiency through the reading of the image with a proper power of the read-purpose electromagnetic waves. SOLUTION: The image reading device of records a solid image whose density is uniform, by emitting uniform radiant rays to the image sensor 10, uses a reading light emission means 20 to apply scanning and exposure to the image sensor, while changing the power of the reading light, obtains a relation between the luminous quantity of the read light and the read efficiency, sets the read luminous quantity, when the read efficiency reaches 90% of the maximum efficiency to a control means of a control printed circuit board 80 and controls a current flowing through a light source 101 of the reading light emission means 20, according to the set reading luminous quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading method and apparatus, and more particularly to an image reading method and apparatus having an image pickup device (image detector) for recording an image as an electrostatic latent image. is there.

[0002]

2. Description of the Related Art Conventionally, as an apparatus using an image detector, a facsimile, a copying machine, a radiation image pickup apparatus and the like have been known.

Particularly, in medical X-ray photography, in order to reduce the exposure dose to the subject and to improve the diagnostic performance, a photoconductive material such as a selenium plate made of, for example, a-Se, which is sensitive to radiation such as X-rays. A radiation solid-state detector (electrostatic recording body) having a body is used as an image detector, the radiation solid-state detector is irradiated with X-rays, and an amount of electric charge according to the dose of the irradiated X-rays is applied to the radiation solid-state detector. The radiation image information is recorded as an electrostatic latent image in the power storage unit by accumulating it as a latent image charge in the power storage unit inside, and the radiation solid-state detection in which the radiation image information is recorded by the laser beam or the line light as the reading light A method and apparatus for reading radiation image information from the solid-state radiation detector by scanning the device have been proposed (for example, US Pat. No. 5,268,569).
International Publication No. 59261 of 1998, JP-A-9-
5906, Japanese Patent Application No. 10-232 by the applicant of the present application
No. 824, No. 11-242876, No. 11-8792.
No. 2).

Further, since the applicant of the present invention practically uses the radiation image recording / reading apparatus using the radiation solid-state detector as described above, the radiation solid-state detector and the image detection before the irradiation of the recording light are performed. Pre-exposure light source unit that irradiates the image detector with electromagnetic waves to eliminate unnecessary charges accumulated in the container, and performs primary exposure to perform pre-charge before actual recording, and solid-state detection of read light A reading exposure light source unit for scanning and exposing the container, and a current detecting unit for detecting a current generated according to the electrostatic latent image by the scanning exposure of the reading light,
A chest imaging apparatus that is provided in the same housing and has a compact and portable configuration as a whole is proposed (Japanese Patent Application No. 20
00-113944).

Here, when a radiation image is recorded by using the radiation solid-state detector as described above and the electrostatic latent image is read by irradiation of the reading light, theoretically, when the light amount of the reading light is increased. , The magnitude of the image signal read increases with the change in the magnitude, that is, the reading efficiency (ratio of the magnitude of the image signal read to the magnitude of the charge of the recorded electrostatic latent image) After it becomes large and reaches the amount of light equivalent to read all the electrostatic latent images,
It is considered that even if the light amount of the reading light is increased more than that, the reading efficiency does not increase and a constant value of the image signal is output.

[0006]

However, when the amount of read light is gradually increased, the amount of read light decreases when the amount of read light exceeds a certain value as shown in FIG. Became clear by the experiment of the applicant. This tendency is not limited to the experimental result shown in FIG.
The same tendency is seen in other radiation solid state detectors,
Furthermore, it was also clarified that the amount of read light that maximizes this reading efficiency differs depending on the solid-state radiation detector.

In view of the above situation, the present invention records image information as an electrostatic latent image and scans it with an electromagnetic wave for reading such as reading light to generate a current according to the electrostatic latent image. In the image reading method and apparatus using the image detector, it is possible to improve the reading efficiency by reading with an electromagnetic wave for reading having a more appropriate size. To do.

[0008]

According to the image reading method of the present invention, image information is recorded as an electrostatic latent image and scanning exposure is performed with an electromagnetic wave for reading to generate a current corresponding to the electrostatic latent image. An image to be read by scanning and exposing this image detector with an electromagnetic wave for reading using an image detector and detecting the current generated according to the electrostatic latent image by the scanning exposure of the electromagnetic wave for reading as an image signal. In the reading method, the reading efficiency of the image detector is 80 to the maximum value of the reading efficiency.
The reading is performed by scanning and exposing an image detector on which image information is recorded as an electrostatic latent image by an electromagnetic wave for reading having a value within a range of 100%.

Here, the above-mentioned "image detector" records image information as an electrostatic latent image and generates a current according to the electrostatic latent image by scanning with an electromagnetic wave for reading. That is, for example, the electrostatic recording body described in Japanese Patent Application No. 10-232824 mentioned above. The image detector may be a device capable of recording image information as an electrostatic latent image by irradiating light carrying image information (not limited to visible light), or transmitting a subject. The radiation image information may be recorded as an electrostatic latent image by irradiating radiation carrying radiation image information such as the above radiation.

The "reading electromagnetic wave" may be anything that can read an electrostatic latent image from an image detector, and is specifically light or radiation.

The above-mentioned "scanning exposure" means irradiating a planar image detector with a two-dimensional electromagnetic wave for reading, for example, a beam-shaped electromagnetic wave for reading.
The scanning may be performed dimensionally, or the line light linearly extending in the main scanning direction may be scanned in the sub scanning direction.

Further, the "magnitude of the reading electromagnetic wave" means the intensity of the reading electromagnetic wave irradiated per unit area and unit time on the surface of the image detector irradiated with the reading electromagnetic wave.

The above "reading efficiency" means the ratio of the image signal read by the irradiation of the reading light to the charge amount of the electrostatic latent image recorded on the image detector. Further, for example, when an image detector recorded with a solid image having a uniform density by being irradiated with uniform radiation is read, the current value itself detected at that time is included.

Further, the "maximum value of the reading efficiency" means the peak value of the reading efficiency detected when the magnitude of the reading electromagnetic wave with which the image detector is irradiated is changed.

Further, based on the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency in the image detector, the magnitude of the reading electromagnetic wave at which the reading efficiency is a value within the range of 80 to 100% of the maximum reading efficiency. It is possible to read by performing scanning exposure of the image detector on which the image information is recorded as an electrostatic latent image by the reading electromagnetic wave having the selected size.

Here, "to select the magnitude of the reading electromagnetic wave having a reading efficiency within the range of 80 to 100% of the maximum reading efficiency" means, for example, the magnitude of the reading electromagnetic wave. When the relationship between the reading efficiency and the reading efficiency has a peak value, the magnitude of the reading electromagnetic wave having a value within the range of 80 to 100% of the maximum reading efficiency on both sides of the peak value as a boundary. Can exist (but 100%
However, it is desirable to select a smaller reading electromagnetic wave magnitude.

Further, the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency in the image detector, the image detector on which the reference image for setting the magnitude of the reading electromagnetic wave is recorded, the magnitude of the reading electromagnetic wave is set. It is possible to obtain the value by scanning and exposing while changing the reading.

Here, the "reference image for setting the magnitude of the reading electromagnetic wave" means, for example, an image having a uniform density recorded by irradiating the image detector with uniform radiation. means.

Further, the reading electromagnetic wave having a magnitude that makes the reading efficiency within the range of 80 to 95% of the maximum value of the reading efficiency scans the image detector in which the image information is recorded as an electrostatic latent image. It can be exposed for reading.

Here, when reading the image detector,
It is desirable to irradiate the reading electromagnetic wave so that the reading efficiency is as high as possible. For example, when an image detector having a relationship between the reading efficiency and the reading light amount as shown in FIG. There is not much difference in the magnitude between 95% and 100%, but there is a great difference in the amount of reading light at this time. Therefore, considering the reduction of power and the cost, the reading efficiency is about 95%. It is desirable to perform reading with the magnitude of the reading electromagnetic wave.

Further, for example, when the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency has a peak value as described above, the maximum reading efficiency of 80 to 95 on both sides of the peak value is set. Although there may be a reading electromagnetic wave having a value within the range of%, it is desirable to select a smaller reading electromagnetic wave.

The image reading apparatus of the present invention records an image information as an electrostatic latent image, and an image detector that generates a current according to the electrostatic latent image by scanning and exposure with an electromagnetic wave for reading, and an image. An electromagnetic wave for reading that scans and exposes an electromagnetic wave for reading on an image detector in which information is recorded as an electrostatic latent image, and a current flowing according to the electrostatic latent image is detected as an image signal by scanning exposure of the electromagnetic wave for reading. In the image reading apparatus including the image signal detecting means, the reading electromagnetic wave irradiating means reads the reading efficiency of the image detector within a range of 80 to 100% of the maximum reading efficiency. The electromagnetic wave is used to scan and expose an image detector in which image information is recorded as an electrostatic latent image.

Further, the reading efficiency selected by the reading electromagnetic wave irradiating means on the basis of the relationship between the size of the reading electromagnetic wave in the image detector and the reading efficiency is within the range of 80 to 100% of the maximum value of the reading efficiency. It is possible to scan and expose the image detector in which the image information is recorded as an electrostatic latent image by the electromagnetic wave for reading having a value of.

Further, the reading electromagnetic wave irradiation means scans and exposes the image detector on which the reference image for setting the size of the reading electromagnetic wave is recorded while changing the size of the reading electromagnetic wave to perform reading. Thus, the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency in the image detector is obtained, and the reading efficiency is a value within the range of 80 to 100% of the maximum value of the reading efficiency based on the obtained relationship. The magnitude of the electromagnetic waves can be chosen.

Further, the reading electromagnetic wave irradiating means records the image information as an electrostatic latent image by the reading electromagnetic wave having a reading efficiency within a range of 80 to 95% of the maximum reading efficiency. The scanning image exposure may be performed on the image detector.

Radiation image information can be applied as the image information.

[0027]

According to the image reading method and apparatus of the present invention, the reading efficiency of the image detector is set to a value within the range of 80 to 100% of the maximum value of the reading efficiency by the reading electromagnetic wave. Since the image detector in which the image information is recorded as an electrostatic latent image is scanned and exposed for reading, the reading efficiency can be improved by performing reading with a more appropriate reading electromagnetic wave size. it can.

Since the size of the reading electromagnetic wave can be made more appropriate, it is possible to reduce the cost of the apparatus without consuming unnecessary power for emitting the reading electromagnetic wave.

Further, based on the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency in the image detector, the magnitude of the reading electromagnetic wave at which the reading efficiency is a value within the range of 80 to 100% of the maximum reading efficiency. If the reading electromagnetic wave of the selected size is selected and scanning is performed by the image detector in which the image information is recorded as an electrostatic latent image for reading, the reading electromagnetic wave is further read. It is possible to optimize the size of the.

Further, the relationship between the magnitude of the reading electromagnetic wave and the reading efficiency in the image detector can be measured by setting the magnitude of the reading electromagnetic wave in the image detector on which the reference image for setting the magnitude of the reading electromagnetic wave is recorded. In the case where scanning exposure is performed while changing and reading is performed, the above effects can be obtained with a simpler configuration and method.

Also, the electromagnetic wave for reading having a size such that the reading efficiency becomes a value within the range of 80 to 95% of the maximum value of the reading efficiency scans the image detector in which the image information is recorded as an electrostatic latent image. When reading is performed by exposing, it is possible to suppress unnecessary irradiation of electromagnetic waves for reading and further reduce cost.

Further, when the radiation image information is used as the image information, the reading efficiency is improved, so that the radiation image with the improved image quality can be used for the image diagnosis.

[0033]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of a chest imaging apparatus 1 to which an embodiment of an image reading apparatus for carrying out the image reading method of the present invention is applied. As shown in FIG. 1, the chest imaging apparatus 1 includes an imaging support column 3
In addition, the image pickup unit 4 is supported so as to be able to move up and down through an actuator (not shown) such as a ball screw or a cylinder.

The image pickup section 4 includes a radiation image detector 10 which is an image pickup device formed on a glass substrate 5, a base 6 which further holds the glass substrate 5 on which the image detector 10 is arranged, and image detection. The reading light irradiation means 20 used at the time of reading the radiation image information recorded in the container 10, and the reading electromagnetic wave (hereinafter, referred to as an electromagnetic wave for reading to the image detector 10 by the reading light irradiation means 20.
Image signal detecting means 30 for obtaining a current as an image signal by detecting a current generated in the image detector 10 by scanning exposure of reading light), and a predetermined voltage is applied to the image detector 10. A high-voltage power supply unit 45, a pre-exposure light source unit 60 that irradiates the image detector 10 with pre-exposure light before starting image capturing,
A grid 70 disposed on the side facing the object of the image detector 10 that absorbs scattered radiation generated by scattering of the radiation transmitted through the object (not shown), and the grid 7
0, a pre-exposure light source unit 60, and a control printed circuit board 80 having control means for controlling the reading light irradiation means 20 are arranged in the same housing 2.

Further, the image pickup section 4 includes an image signal detecting means 30.
A signal cable 90 for outputting an image signal from the inside of the support column 3 to the external image processing device 150, and a power cable 92 connected to an external AC (alternating current) power supply 152 through the inside of the support column 3. Is equipped with.

The image signal detecting means 30 is the printed circuit board 3
1, relatively short T with one end connected to the printed circuit board 31
An AB (Tape Automated Bonding) film 32 and a charge amplifier IC 33 mounted on the TAB film 32. The other end of the TAB film 32 is connected to the image detector 10.

FIG. 2 is a view showing an arrangement relationship between an example of the image detector 10 and the reading light irradiation means 20. In FIG. 2, a base 6 described later is omitted. Further, the reading light irradiation means 20 has a light source section and a scanning mechanism thereof, but the scanning mechanism is omitted.

The image detector 10 records radiation image information as an electrostatic latent image and generates a current according to the electrostatic latent image by scanning with the reading light. Specifically, FIG. As shown in FIG. 1, the first conductive layer 11 formed on the glass substrate 5 and transparent to electromagnetic waves for recording such as X-rays that have passed through the subject (hereinafter referred to as recording light),
As a substantially insulating material for the recording photoconductive layer 12 that exhibits electric conductivity by being irradiated with the recording light and exhibits conductivity, and the latent image polar charges (for example, negative charges) charged in the first conductive layer 11. A charge transport layer 13 that acts and substantially acts as a transporting charge (a positive charge in the previous example) having a polarity opposite to that of the latent image polar charge, and generates a charge by being irradiated with reading light. Then, the reading photoconductive layer 14 having conductivity and the second conductive layer 15 having transparency to the reading light are laminated in this order. Recording photoconductive layer 12
A power storage unit 19 is formed at the interface between the charge transport layer 13 and the charge transport layer 13.

The first conductive layer 11 and the second conductive layer 15 each form an electrode. The electrode of the first conductive layer 11 is a two-dimensional flat plate electrode, and the electrode of the second conductive layer 15 is As shown by the diagonal lines in the figure, a large number of elements (linear electrodes) 15a are stripe electrodes arranged in a stripe pattern at the pixel pitch (for example, Japanese Patent Application No. 10-2328).
See the electrostatic recording body described in No. 24). The arrangement direction of the elements 15a corresponds to the main scanning direction, and the longitudinal direction of the elements 15a corresponds to the sub scanning direction.

The reading photoconductive layer 14 has a high sensitivity to electromagnetic waves in the wavelength range from near ultraviolet to blue (300 to 550 nm), and has a wavelength in the red range (700 nm or more).
Having low sensitivity to the electromagnetic waves of, specifically,
_{a-Se, PbI 2, Bi} 1 2 (Ge, Si) O 20,
At least one of perylene bisimide (R = n-propyl) and perylene bisimide (R = n-neopentyl)
A photoconductive material containing two as a main component is preferable. In this embodiment, a-Se is used.

In this embodiment, each element 15a has a width of 50 .mu.m and is arranged at a pixel pitch of 100 .mu.m, and is made of a material such as ITO or thin film Al through which light having a wavelength of 550 nm or less is transmitted.

FIG. 3 shows the image detector 1 of the image pickup section 4 shown in FIG.
0 is a diagram more specifically showing the mounting portion of the base plate 6 for supporting 0 and the base 6 to the housing 2, (A) is a front view seen from the image detector 10 side, (B), (C). ) Shows the BB line sectional view and CC line sectional view of (A), respectively. The base 6 supports the glass substrate 5 on which the image detector 10 is formed as shown in the figure. In general, the glass substrate 5 is very thin with a thickness of 1.1 mm or less, whereas the base 6 is made of sufficiently thick glass so as not to bend even if it is arranged vertically as shown in the figure. Then, it is set to 5 mm or more. The base 6 is transparent to the light output from the reading light source and the pre-exposure light source, and has substantially the same refractive index and thermal expansion coefficient as the glass substrate 5. Further, in order to prevent light loss and stray light due to reflection of the reading light, the reading light incident surface 6a
AR (anti-reflection) coat is applied to. The base 6 and the substrate 5 are adhered to each other with an adhesive such as epoxy resin or Canadian balsam. As shown in FIG. 3, the base 6 is sandwiched at its four corners, left and right, and the lower end by mounting members 7 made of metal or the like, reinforced and fixed to the housing 2. In addition, between the upper end of the base 6 and the mounting member 7,
A gap 8 through which the above-mentioned TAB film 32 that connects the image detector 10 and the printed circuit board 31 is provided is provided. More specifically, as shown in the sectional view (B), a gap 8 is provided between the portion of the base 6 located above the image detector 10 and the mounting member 7, and is shown in the diagram (A). The upper right corner of the base 6 is sandwiched by mounting members 7 as shown in the sectional view (C).

The reading light irradiation means 20 comprises a light source composed of a plurality of LED chips arranged in a line, and an optical system for linearly irradiating the light output from the light source on the image detector 10. Use one. The reading light irradiating unit 20 scans the light source section in the longitudinal direction of the stripe electrode 15a of the image detector 10 with a scanning mechanism (linear motor) (not shown) while keeping a necessary distance from the image detector 10. The entire surface of the detector 10 is exposed.

As described above, the reading photoconductive layer 14 has high sensitivity to electromagnetic waves in the wavelength range from near ultraviolet to blue (300 to 550 nm), and has a wavelength in the red range (70).
Since it has a low sensitivity to electromagnetic waves of 0 nm or more), a light source that emits light having a wavelength in the near-ultraviolet to blue region of 550 nm or less is used.

A specific example of the light source of the reading light irradiation means 20 will be shown in FIG. Figure 4 (A)
FIG. 4B is a side view showing the detailed configuration of the light source unit of the reading light irradiation means 20 shown in FIG. 2, as viewed from the Y direction, and FIG.
[Fig. 3] is an XY cross-sectional view of a light source unit. In FIG. 4, the above-mentioned base 6 is omitted.

As shown in FIG. 4, the light source section of the reading light irradiating means 20 is composed of a plurality of LEs arranged linearly in the Z-axis direction.
A light source 101 including D chips 101a, 101b, ...
A slit 102 having an opening 102a extending in the longitudinal direction of the light source 101 and an opening 10 of the slit 102 for improving the quality of light emitted from the light source 101.
2a, a first optical means 106 composed of cylindrical lenses 104 and 105 which are optical members 103 for converging light, and light passing through the first optical means 106 is imaged in a direction orthogonal to the longitudinal direction of the light source 101. Cylindrical lens 107, 10 for focusing on the detector surface
And second optical means 109 composed of eight.

The slit 102 spatially filters the light output from the light source to suppress flare light, and determines the beam diameter on the detector. The slit may be any slit as long as it suppresses the spatial spread of light, and may be not only a mechanical slit having an opening as in the present embodiment but also an optical gap such as a density distribution filter.

Light emitted from each light emitting point of the light source 101, that is, each LED chip 101a, 101b, ... Is slit 102 by cylindrical lenses 104 and 105.
The light is focused and filtered in the longitudinal direction by the opening 102a of the optical system, and is then focused by the cylindrical lenses 107 and 108 of the second optical means 109 in the direction orthogonal to the longitudinal direction of the light source to irradiate the image detector 10. Each LED
Since the light beam from the chip spreads isotropically and diffuses, and is not focused in the longitudinal direction of the light source, the light from each chip diffuses in the longitudinal direction of the light source on the detector. Thereby, the light from the light source 101 irradiates the detector linearly, and the light from each chip simultaneously exposes a plurality of pixels lined up in the linear shape. That is, each pixel on the detector is simultaneously exposed by the light output from the plurality of LED chips. For example, although FIG. 4 is a schematic view, point A on the detector 10 is simultaneously exposed by seven LED chips.

More specifically, for example, the focal length of the optical system is 40 mm, the pixel size is 100 μm, the LED chip interval (light emitting point interval) is 200 μm, and the beam divergence angle from the LED chip in the longitudinal direction of the light source is 120 °. (Half), each pixel on the detector is simultaneously exposed to light from at least 700 or more LED chips.

Here, the light amount of the reading light output from the light source 101 is controlled by current control by the control means mounted on the control printed circuit board 80. The light amount of the light source 101 in this device is as follows. In this way, the control means is set.

First, a solid image having a uniform density is recorded by irradiating the image detector 10 with uniform radiation, and the reading light irradiating means 20 reads the solid image with respect to the scanning position as shown in FIG. The image detector 10 is scanned and exposed while changing the intensity of light. At this time, based on the image signal detected by the image signal detecting means 30, the magnitude of the reading light amount and the reading efficiency (the magnitude of the image signal detected by the image signal detecting means 30 is the radiation dose applied to the image detector 10). (A ratio based on a value divided by the size of the image signal calculated from the above). The relationship between the amount of reading light and the reading efficiency is theoretically such that when the size of the reading light becomes equal to or larger than a predetermined value, the reading efficiency gradually approaches a certain value. The relationship is as shown in FIG. 6, and there is a magnitude of the reading light amount that maximizes the reading efficiency. Therefore, the magnitude of the reading light amount when the reading efficiency is 90% of this maximum value is set in the control means by a predetermined input means. The control unit controls the light source 10 of the reading light irradiation unit 20 according to the set reading light amount.
The current is controlled to flow to 1.

In this embodiment, the reading light amount when the reading efficiency is 90% of the maximum value is set by a predetermined input means, but the control means automatically sets the reading light quantity. You may make it calculate and set the magnitude | size of the reading light amount.

Further, the light source 1 of the above-mentioned reading light irradiation means 20.
Although 01 is composed of a plurality of LED chips arranged side by side, a plurality of LD chips may be arranged side by side instead of the LED chips. Further, an LED array or an LD array in which a plurality of light emitting points are arranged in a line may be used as a light source.

Further, in the light source section of the reading light irradiation means 20 described above, a SELFOC lens may be used instead of the cylindrical lenses 104 and 105 of the first optical means 106.

FIG. 7 is a diagram showing details of the connection mode of the image detector 10, the image signal detecting means 30, and the high-voltage power supply section 45. As shown in the figure, each element 15a of the image detector 10 has a charge amplifier IC3 via a print pattern (not shown) formed on the TAB film 32.
3 and the charge amplifier IC33 is connected to TAB
It is connected to the printed board 31 via a print pattern (not shown) formed on the film 32. In the present embodiment, not all the elements 15a are connected to one charge amplifier IC33, but several to several tens of charge amplifier ICs 33 are provided as a whole, and each of the several adjacent elements 15a is sequentially charged. It is connected to the amplifier IC33.

The first conductive layer 11, which is a plane electrode of the image detector 10, is provided with a non-image area 11a which is partially formed larger than the image recording area. In the non-image area 11a, the hot side (core wire) of the cable 46 output from the high-voltage power supply unit 45 arranged near the image detector 10.
46a is directly bonded, and the ground side (sheath) 46b of the cable 46 is connected to the printed circuit board 31 by screwing 47. In this embodiment, the hot side 46a has a negative potential with respect to the ground side 46b. The ground side 46b connected to the printed circuit board 31 is
Each charge amplifier IC33 through the TAB film 32
Is commonly connected to the charge amplifier IC33.
It also becomes the reference potential of.

In this embodiment, the TAB connection is used to connect the image detector 10 and the printed board 31, but wire bonding or anisotropic conductive rubber may be used.

FIG. 8 shows the details of the image signal detecting means 30 and the high-voltage power supply section 45 provided in the housing 2, and these and the image detector 10, the image signal detecting means 30, and the device 1. FIG. 3 is a block diagram showing a connection mode with the image processing apparatus 150 and the like.

The high-voltage power supply section 45 is a circuit in which the high-voltage power supply 40 and the bias switching means 42 are integrated, and the high-voltage power supply 40 once switches the bias application / short-circuiting to the image detector 10. Therefore, it is connected to the image detector 10 via the bias switching means 45. This circuit is
It is designed to prevent excessive charging / discharging current in order to prevent the destruction of the portion where the current of the device is concentrated by limiting the peak value of the current flowing at the time of switching.

The charge amplifier IC 33 provided on the TAB film 32 is provided for each element 1 of the image detector 10.
It is provided with a large number of charge amplifiers 33a and sample-hold (S / H) 33b connected for each 5a, and a multiplexer 33c for multiplexing the signals from each sample-hold 33b. The current generated in the image detector 10 is converted into a voltage by each charge amplifier 33a, the voltage is sampled and held by the sample hold 33b at a predetermined timing, and the voltage corresponding to each sampled and held element 15a is converted into an element 15.
The signals are sequentially output from the multiplexer 33c so as to be switched in the arrangement order of a (corresponding to a part of main scanning). The signals sequentially output from the multiplexer 33c are input to the multiplexer 31c provided on the printed board 31,
Further, the multiplexer 31 is arranged so that the voltage corresponding to each element 15a is switched in the arrangement order of the elements 15a.
The main scanning is completed by sequentially outputting from c. The signals sequentially output from the multiplexer 31c are converted into digital signals by the A / D converter 31a, and the digital signals are stored in the memory 3
It is stored in 1b.

As the pre-exposure light source unit 60, a light source that emits / quenches light in a short time and has a very small afterglow is required. In this embodiment, an external electrode type rare gas fluorescent lamp is used. More specifically, the pre-exposure light source unit 60, as shown in FIG.
A plurality of external electrode type rare gas fluorescent lamps 61 extending in the depth direction in the drawing, a wavelength selection filter 62 inserted between the fluorescent lamps 61 and the image detector 10, and a fluorescent lamp 61.
And a reflecting plate 63 arranged behind the fluorescent lamp 61 for efficiently reflecting the light output from the fluorescent lamp 61 to the image detector 10 side. It should be noted that the pre-exposure light may be applied to the entire second electrode layer 15 of the image detector 10, and no particular focusing means is required, but the illuminance distribution is preferably small. Instead of the fluorescent lamp, a light source in which LED chips are arranged side by side can be used as the light source. Further, by providing the base 6 with wavelength selectivity, the wavelength selection filter 62
Can be omitted.

When the electrostatic latent image is read from the image detector 10, basically all the accumulated latent image charges can be read out, but in some cases the latent image charges cannot be completely read out and the image is It may be left as a residual charge on the detector 10. Further, when an electrostatic latent image is recorded on the image detector 10, a high voltage is applied to the image detector 10 before irradiation of recording light, but a dark current is generated at the time of this application, and a charge (dark The electric charge) is also accumulated in the image detector 10. Furthermore, the image detector 1 may be caused by other causes.
It is known that various charges are accumulated at 0 before irradiation with recording light. Unnecessary charges such as these residual charges and dark current charges accumulated before the irradiation of the recording light are added to the charges that carry the image information accumulated by the irradiation of the recording light, so that the image When the electrostatic latent image is read from the detector 10, the output signal contains a signal component due to unnecessary charges in addition to the signal based on the charges carrying the image information, which may cause an afterimage phenomenon or S / N deterioration. Cause problems.

The "pre-exposure" is for eliminating unnecessary charges accumulated in the image detector before irradiating the image detector with the recording light, and for solving problems such as an afterimage phenomenon and S / N deterioration. It is a thing.

Next, the operation of the chest imaging apparatus 1 thus constructed will be described. First, the imaging unit 4 is moved up and down and positioned according to the physique of the subject (patient). next,
The image detector 10 is irradiated with pre-exposure light to erase unnecessary charges accumulated in the image detector 10. The pre-exposure process may be performed before the voltage is applied to the image detector 10 or after the voltage is applied. Further, it may be a mode in which the pre-exposure lighting is turned on before the voltage application and the light is turned off after the voltage application.

At the time of photographing, first, the bias switching means 42.
Thus, the negative electrode of the power source 40 is connected to the first conductor layer 11 and a DC voltage is applied between the first conductor layer 11 and each element 15a to charge both conductor layers 11, 15. As a result, the first conductive layer 11 and the element 15a in the image detector 10 are
A U-shaped electric field that forms the U-shaped recess in the element 15a is formed between and.

Thereafter, when the photographer presses an irradiation button (not shown) in consideration of the timing, the grid 70 arranged on the side of the subject of the photographing section 4 starts to swing, and the swing speed of this grid 70 is a predetermined speed. Is reached, and X-rays are emitted at the timing when a sufficient voltage is applied to the image detector 10 by the voltage application described above.

When the image detector 10 is irradiated with X-rays transmitted through the subject, that is, recording light carrying radiation image information of the subject, positive and negative charge pairs are generated in the recording photoconductive layer 12 of the image detector 10. The negative charges therein are concentrated on the element 15a along the electric field distribution described above, and the negative charges are accumulated in the electricity storage unit 19 formed at the interface between the recording photoconductive layer 12 and the charge transport layer 13. Since the amount of the accumulated negative charges, that is, the latent image polar charges, is approximately proportional to the amount of radiation that has passed through the subject, the latent image polar charges carry an electrostatic latent image. In this way, the electrostatic latent image is detected by the image detector 1.
It is recorded at 0. On the other hand, the positive charges generated in the recording photoconductive layer 12 are attracted to the first conductive layer 11 and are recombined with the negative charges injected from the high voltage power source 40 to disappear.

After reading the electrostatic latent image from the image detector 10 after irradiating the X-ray and recording the image, the image detector 1
The bias switching means 42 short-circuits both conductive layers 11 and 15 of 0.

The reading light irradiation means 20 is activated, and the light source 101
The reading light L is output from the device and the element 15a is moved in the longitudinal direction, that is, the sub-scanning direction by a linear motor (not shown) to scan the entire surface of the image detector 10. As described above with respect to the operation of the reading light irradiation means 20, the linear reading light L output from the light source unit passes through the base 6 and the glass substrate 5, and each element 15a of the image detector 10 is detected.
Is irradiated.

The light amount of the reading light L output from the light source section of the reading light irradiating means 20 is the reading light when the reading efficiency is 90% of the maximum value as described above. The size of L is preset in the control means of the control printed circuit board 80, and accordingly, the control means causes a control current to flow to the light source 101 of the reading light irradiation means 20.

By controlling the magnitude of the reading light L as described above, it is possible to improve the reading efficiency by performing reading with a more appropriate reading electromagnetic wave magnitude.

Further, since the size of the reading light 1 is set to a more appropriate size, it is possible to reduce the cost of the apparatus without consuming unnecessary power for emitting the reading light L.

When the image detector 10 is irradiated with the reading light L as described above, positive and negative charge pairs are generated in the reading photoconductive layer 14, and the positive charges therein are accumulated in the electricity storage section 19. It rapidly moves in the charge transport layer 13 so as to be attracted by the negative charges (latent image polar charges), and is recombined with the latent image polar charges in the electricity storage unit 19 to disappear. On the other hand, the negative charges generated in the reading photoconductive layer 14 recombine with the positive charges injected into the second conductive layer 15 and disappear. In this way, the image detector 10
The negative charges stored in the image detector 10 disappear due to charge recombination, and a current is generated in the image detector 10 due to the movement of charges during the charge recombination.

The current detection charge amplifier 33a connected to each element 15a detects this current in parallel (simultaneously) for each element 15a. The signal detected by the charge amplifier 33a is sample-held by the sample-hold 33b, and the voltage corresponding to each sample-held element 15a is sequentially output from the multiplexer 33c so that the voltage is switched in the arrangement order of the elements 15a. The signals are further sequentially output by the multiplexer 31c, A / D converted by the A / D converter 31a, and stored in the memory 31b as a digital image signal.

With the scanning exposure of the reading light L, the image detector 10
The electric current flowing therein corresponds to the latent image charge, that is, the electrostatic latent image, and the image signal obtained by detecting this electric current represents the electrostatic latent image, so that the electrostatic latent image can be read.

The image signal once stored in the memory 31b is sent to the external image processing apparatus 150 via the signal cable 90, is subjected to appropriate image processing in this image processing apparatus 150, and is taken together with the photographing information to the network. 15
1 is uploaded and sent to the server or printer.

Although the electrostatic recording body described in Japanese Patent Application No. 10-232824 is used as the image detector in the above embodiment, the present invention is not limited to this. That is, it can be applied to any image detector as long as it generates a current according to the electrostatic charge carrying the image information by scanning with the electromagnetic wave for reading.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a schematic configuration of a chest imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of an image detector used in the chest imaging apparatus and a diagram showing a positional relationship between an exposure light source unit for reading.

FIG. 3 is a diagram showing a base supporting the image detector.

FIG. 4 is a diagram showing a detailed configuration of a reading exposure light source unit.

FIG. 5 is a diagram showing a relationship between a reading light amount and a scanning position.

FIG. 6 is a diagram showing the relationship between the reading light amount and the reading efficiency in the image detector used in the image reading method and apparatus of the present invention.

FIG. 7 is a diagram showing details of a connection mode of an image detector, a current detection unit, and a high-voltage power supply unit.

FIG. 8 is a block diagram showing details of a current detection unit and a high-voltage power supply unit and a connection mode between these units and an image detector.

[Explanation of symbols]

1 Chest imaging device 3 Supporting column for imaging 4 Imaging unit 10 Image detector 20 Exposure light source unit 30 for reading Current detection unit 40 High voltage power supply 45 High voltage power supply unit 60 Pre-exposure light source unit 70 Grid 80 Control printed circuit board 90 Signal cable 92 power cable 101 light source 101a, 101b, 101c, 101d LED chip

Claims (9)

[Claims] 1. An image detector using an image detector which records image information as an electrostatic latent image and generates a current according to the electrostatic latent image by scanning exposure with an electromagnetic wave for reading. In the image reading method, wherein the reading electromagnetic wave is scanned and exposed, and the reading is performed by detecting the current generated according to the electrostatic latent image by the scanning exposure of the reading electromagnetic wave as an image signal. Scanning exposure of the image detector in which the image information is recorded as an electrostatic latent image by the reading electromagnetic wave having a reading efficiency of 80 to 100% of the maximum reading efficiency. The image reading method is characterized by performing the reading. 2. The reading efficiency is a value within the range of 80 to 100% of the maximum value of the reading efficiency based on the relationship between the magnitude of the reading electromagnetic wave in the image detector and the reading efficiency. The magnitude of the reading electromagnetic wave is selected, and the reading is performed by scanning and exposing the image detector recorded with the image information as an electrostatic latent image by the reading electromagnetic wave of the selected magnitude. The image reading method according to claim 1. 3. The reading of the image detector in which a reference image for setting the magnitude of the reading electromagnetic wave is recorded as the relationship between the reading electromagnetic wave magnitude and the reading efficiency in the image detector. The image reading method according to claim 2, wherein the reading is performed by performing scanning exposure while changing the magnitude of the electromagnetic wave for use. 4. The reading efficiency is 8 which is the maximum value of the reading efficiency.
The reading is performed by scanning and exposing an image detector on which the image information is recorded as an electrostatic latent image with the reading electromagnetic wave having a value in the range of 0 to 95%. Item 4. The image reading method according to any one of Items 1 to 3. 5. An image detector that records image information as an electrostatic latent image and generates a current according to the electrostatic latent image by scanning and exposing with an electromagnetic wave for reading, and the image information is an electrostatic image. A reading electromagnetic wave irradiation means for scanning and exposing the reading electromagnetic wave to an image detector recorded as a latent image, and a current flowing according to the electrostatic latent image is detected as an image signal by the scanning exposure of the reading electromagnetic wave. In the image reading apparatus including the image signal detecting means, the reading electromagnetic wave irradiating means has a size such that the reading efficiency in the image detector is a value within a range of 80 to 100% of the maximum value of the reading efficiency. An image reading apparatus, which scans and exposes an image detector on which the image information is recorded as an electrostatic latent image by the reading electromagnetic wave. 6. The reading efficiency selected by the reading electromagnetic wave irradiating means based on the relationship between the reading electromagnetic wave size and the reading efficiency in the image detector is 80 to 80 which is the maximum value of the reading efficiency. 6. An image detector in which the image information is recorded as an electrostatic latent image is scanned and exposed by the reading electromagnetic wave having a value within a range of 100%. Image reading device. 7. The reading electromagnetic wave irradiating means scans and exposes the image detector on which a reference image for setting the size of the reading electromagnetic wave is recorded while changing the size of the reading electromagnetic wave. By performing reading, the relationship between the reading electromagnetic wave magnitude and the reading efficiency in the image detector is obtained, and the reading efficiency is 80 to 100% of the maximum value of the reading efficiency based on the obtained relationship. 7. The image reading device according to claim 6, wherein the magnitude of the reading electromagnetic wave having a value within the range is selected. 8. The image information is electrostatically generated by the reading electromagnetic wave by the reading electromagnetic wave irradiating means having a size such that the reading efficiency is a value within a range of 80 to 95% of the maximum value of the reading efficiency. 8. An image detector, which is recorded as a latent image, is scanned and exposed, and any one of claims 5 to 7 is characterized.
The image reading device described in the item. 9. The image reading apparatus according to claim 5, wherein the image information is radiation image information.