JPH01261626A - Photographing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application) The present invention relates to a photographing device most suitable for X-ray photography, TV photography, etc.

(Prior Art) An example of this type of imaging device is an Xm imaging device for nondestructively inspecting industrial products and the like.

This X-ray imaging device places a subject between an X-ray source and an X-ray detector, detects the X-rays that are emitted toward the subject, passes through the subject, and converts them into an optical image. , and further converts it into an electrical signal according to the light intensity, which is then subjected to TV signal processing to create an image of the subject. In addition, when converting it into a digital signal, it is binarized and gradated into 256 steps, 512 steps, etc. according to the above signal level, and image processing is performed at this digital value step, and then the 'r■ signal is converted into a digital signal. Even if you create a , you can image the subject in the same way.

In recent years, this type of X-ray imaging apparatus has also been put into practical use for photographing electronic components such as semiconductors, substrates for mounting electronic components, and the like.

(Problem to be Solved by the Invention) The brightness level or gradation level corresponds to the black level to white level displayed on the display, and in the case of digital PL scale, the photographing signal level is binarized. The corresponding value corresponds to the signal level itself.

Therefore, an image composed of only low signal levels ends up being an image with a gradation close to the black level as a whole.

Particularly in the case of non-destructive testing, there is a problem in that if the gain of the xios camera or signal amplifier is kept constant, only images that are not worthy of testing can be taken.

In other words, subjects made of materials that are difficult for X-rays to pass through! ! In the case of a shadow, the overall detected X-ray intensity is low, and the signal level when converted into an electrical signal via an optical image is also low.

Therefore, when this is displayed, the brightness level is low, resulting in an overall dark image, and in the case of a digital image, the image is very difficult to see with little gradation difference.

These current models are not necessarily limited to X-ray imaging devices;
In the case of TV photography as well, there is a problem in that images are taken under certain conditions determined by the surrounding brightness, etc., and images are converted as they are based on the photographic signals, resulting in disappointing images.

Therefore, the purpose of the present invention is to solve the above-mentioned conventional problems, and to solve the above-mentioned problems even if there are differences in subject structure, shooting conditions, etc. An object of the present invention is to provide a photographing device that can perform accurate imaging.

Arrangement 1 of the Invention (Means for Solving Problems) The present invention provides a standard for setting a reference value of a signal level in a photographing device that images a subject image based on subject image data output from an image sensor. a comparator that compares the signal level when the subject is photographed with the reference value; and a control means that changes and controls the photographing conditions and/or the signal processing conditions so that the comparison error of the comparator is reduced. It's 12 and has a configuration with .

Here, it is preferable that the reference value of the signal level is set to the value (self level) with the highest brightness level (gradation level in the case of digital images), and it is also possible to set it at the shooting position. In addition, a reference object that is imaged at the same brightness level as the reference value during proper imaging may be provided, and the imaging signal of this reference object may be compared with the reference value.

(Function) Due to differences in the structure of the subject or the imaging conditions (the amount of X-ray exposure, ambient brightness in the case of camera imaging, etc.), there is a possibility that a predetermined image quality may not be obtained.

Therefore, the present invention has a signal level reference value, and compares the photographed signal level when photographing an actual subject or a reference subject whose brightness level is known in advance with the reference value,
Control is performed to reduce this comparison error to obtain an optimal photographed image.

For example, if the signal level reference value (corresponding to the gradation level in the case of digital) is set to the maximum brightness level (self level), the maximum signal level when the subject is actually photographed is and the reference value. If the signal level is low, the imaging conditions (for example, increasing the light source intensity or X-ray exposure amount) are changed or the amplifier gain is increased, both of which result in an increase in the signal level. It will be controlled as follows.

Through such control, an appropriate photographed image with good contrast can be obtained.

On the other hand, if the signal level is greater than the reference value, -E
The optimum image is obtained by lowering the signal level of the subject using the control opposite to that described above. Particularly when the imaging signal level is high, saturation may occur, so such control is effective.

Furthermore, the above-mentioned control is not necessarily performed by photographing an actual subject, but can also be performed by photographing a reference subject whose brightness level is known at the time of proper photographing, before photographing the actual subject.
Control may be performed by comparing this signal level with the reference value. Since this reference subject is an image that has approximately the same level as the reference value when properly photographed, this subject is photographed, It can be said that the smaller the error output when comparing this with the reference device output, the more suitable the conditions are for photographing an image.

(Example) Hereinafter, the present invention will be described.
An embodiment applied to a ll inspection device will be specifically described with reference to the drawings.

This X-ray inspection device is XI! X of generator 10! 1 tube 1
14 on the tube! X-ray photography is performed by placing a subject 20 between an image sensor 40 that performs photography.

The X-ray generating section 10 includes the X-ray tube 11 that generates X-rays.
and a high voltage generator 1 that applies a high voltage to this X-ray tube 11.
It is composed of 2. The X-ray tube 11 is equipped with a cathode filament and an anode opposite to the cathode filament in its internal vacuum.Thermionic electrons ejected by heating the filament are accelerated by a high DC voltage and collided with the anode. ,
The kinetic energy of the thermoelectrons at this time is obtained as X-rays. Note that this X-ray exposure amount can be changed by varying the tube voltage or filament current of the X-ray tube 11.

In addition, in the nine embodiments in which a so-called minute focus X-ray source is adopted as the X-ray tube 11, the size of the focal point is 10.
A microfocus X-ray source of 0 microns or less, preferably 15 microns or less is used. In order to obtain such a minute focus, it is sufficient to cause the thermoelectrons to collide with a minute region on the anode, which is the target of the thermoelectrons, and this can be achieved by focusing the target region using a focusing electrode or the like.

In this embodiment, the subject 20 is an electronic component such as an IC,
It is a mounting board or a multilayer board for mounting electronic components, and can be set as an X-ray irradiation area by placing it on the X-Y table 21, for example.

Note that a reference object 22 is placed on the X-Y table 21.
is also installed, and is always set outside the X-ray emitting area.
If necessary, it can be placed in the xtiq radiation area by moving the table when setting imaging conditions. Note that details of this reference subject 22 will be described later.

In order to convert the above-mentioned X-ray image into an image,
The image sensor 40 that inputs Il is provided. In this embodiment, a vidicon is used as the image sensor 40, but the photoconductive surface of this vidicon, which is an X-ray input surface, is also sensitive to XIl, and an electrical signal corresponding to the X-ray intensity is generated. Output.

Further, a variable gain amplifier 50, for example, is provided downstream of the image sensor 40, and is configured to amplify and output the electric signal using a gain determined as described later.

Further, an image processing section 60 receives the output of the amplifier 50.
The image processing unit 60 divides the electric signal into 256 levels or 51 levels for each predetermined level range.
The signal is binarized in two stages, and the binarized gradation signal is subjected to image processing such as edge enhancement and output.

Furthermore, a 1゛v signal processing section 7 is provided after the image processing section 60.
0 is provided, and the digital signal output from the image processing section 60 is converted into an analog signal, and further processed such as superimposing a synchronization signal to become the 'r■ signal, which is then sent to the display 8 at the subsequent stage.
0 enables image display.

Next, the characteristic configuration of the device of this embodiment will be explained.

This device includes a reference device 90 for setting a signal level reference value corresponding to at least one brightness level, for example, a maximum level (white level), and a reference device 90 for setting a signal level reference value corresponding to at least one luminance level, for example, a maximum level (white level), and a subject 20 or a reference subject 2.
a comparator 100 that compares the signal level when photographing 2 with the reference value; and a control means for changing the photographing conditions and/or signal processing conditions so as to reduce the comparison error of the comparator 100. CPUll0 is provided.

In this embodiment, a switch SW is placed in the middle of the signal path input from the W2 amplifier 50 to the comparator 100, and the above-mentioned control is enabled only when this switch SW is ON. Further, a maximum level extraction circuit 120 such as a peak hold circuit is disposed at the subsequent stage of the switch SW so that a high level signal among the outputs of the amplifier 50 is input to the comparator 100.

Further, the CPU 11.0 includes the xi generation unit 10.
The tube voltage is varied by controlling the high voltage generating section 12 of the amplifier 50, and the gain of the amplifier 50 is also variably controlled.

Next, the effect will be explained.

Although the amount of xsiq radiation in the X-ray tube 11 and the gain of the amplifier 50 are usually set to constant set values, it may not be possible to display an appropriate image with these set values.

Therefore, in such a case, turn on the switch SW,
The automatic adjustment mode of the imaging condition and the gain of the amplifier 50 will be selected.

Here, after setting the above mode, X-rays are emitted from the X-ray tube 11 toward the subject 20. In addition, in this embodiment, since a fine focal point xm source is employed, a large amount of power is not required to increase the x-ray density.

Then, XIl transmitted through the subject 20 is input to the image sensor 40, where it is converted into an electrical signal corresponding to the X-ray intensity of the X-ray transmitted image. At this time, since this embodiment employs the X&I tube 11, which is a fine focus XIl source, a clear X-ray image without blur can be projected onto the photoconductive surface of the image sensor 40.

That is, as shown in FIG. 4(b), if the focal point is not minute, in addition to the original transmitted image A1 of the object, a blurred image A2, which occurs due to the large focal point, will occur.
As shown in a), in the case of a minute focus, only the transmitted X-ray image of the subject 20 will be incident on the image sensor 40, so a clear image without image blurring can be obtained.

The electrical signal output from the image sensor 40 is amplified by the amplifier 50 according to the initially set gain and input to the image processing section 60. This image processing unit 60 first converts the analog signal into a digital value and converts it to 1Wj111.
This digital signal is then subjected to predetermined image processing and output. Generally, the signal based on an X-ray image has a maximum level that transmits well through XIl, and a signal based on XIl.
There is a wide zone between the lowest level and the minimum level where it is difficult to transmit light, and if this is displayed as is, the image in the gray zone where the area to be inspected will be concentrated, will have the same gradation level even though they are made of different materials, and will be clearly visible. image cannot be obtained. Therefore, it is necessary to perform various types of image processing such as edge enhancement at the digital signal stage, and for this purpose, as in the above configuration, the digital signals are converted to digital values and various types of processing are performed.

The image-processed digital signal is converted into an analog signal in the TV signal processing unit and then subjected to TV signal processing, and an X-ray transmission image can be displayed on the display 80 in accordance with the TV signal.

On the other hand, in the adjustment mode in which the switch SW is turned on, the maximum level signal of the output of the amplifier 50 is transmitted to the comparator 10 through the maximum level extraction circuit 120.
It will be input to one input terminal of 0. Since the reference signal level of the reference device 90 is input as the other input of the comparator 100, this comparator 100 compares the signal level of the signal 211 mentioned above.

Here, as the setting value of the reference device 90, a signal level reference value corresponding to the maximum level (white level) on the display 80 is set, so that the maximum level in the photographing signal and this white level are different. will be compared.

The comparator 100 outputs the error level of both signals, which is input to the CPUll0. When the level of the imaging signal is low, the CPUll0 controls either or both of controlling the Xl1 generating unit 10 to increase the xmoi radiation amount and increasing the gain of the amplifier 50. will be executed. That is, if the error is small, it may be sufficient to just control the gain of the amplifier 50, and the xsi and ts radiation amounts are limited due to the influence on the human body and saturation, and in such cases, the gain rAW of the amplifier 50 may be sufficient. This is because there is a need to execute the above at the same time.

On the other hand, if the maximum level of the photographing signal is higher, one or both of the following controls is performed: conversely, the X&lO1 ratio is decreased, or the gain of the amplifier 50 is lowered.

As a result of such control, as shown in Figure 2, if the maximum level of the imaging signal is low as shown in Figure 2 (B), the 1@tonation of the X-ray transmission image is close to the black level. Although only the side is used, Xll[l
By controlling the withstand capacity or increasing the amplifier 50 gain, the figure (
As shown in A), the maximum level corresponds to the white margin of the display 80, making it possible to display an appropriate X-ray transmission image. Further, in this way, a large difference in gradation can be achieved in the gray zone region, so even materials having similar X-ray transmission characteristics can be displayed as images with differences in gradation.

The above embodiment is effective even when an appropriate image cannot be obtained due to the structure of the subject, etc., but if you simply want to set the general appropriate value of the X-ray exposure amount and the appropriate gain of the amplifier 50, it is actually This can be dealt with by setting the reference subject 22 as the photographing area instead of the subject 20 of .

As this reference object 22, for example, as shown in FIG.
55, material 22 that is difficult to transmit X-rays
a and a material 22b that satisfactorily transmits X-rays. Then, by performing the above control in the same way based on this imaging signal, if the amount of X-ray exposure is small, the cage level of the imaging signal will be lower than the reference level, and conversely, the X#l
If the 1qI radiation amount is small, it will be larger than the reference value, so control can be performed to correct this.

This is similarly effective for gain adjustment of the amplifier 50.

Here, in this embodiment, it is possible to change the imaging magnification. That is, the imaging magnification of the image displayed on the display 80 is determined by the distance from the X-ray tube 11 to the center of the subject 20, as shown in FIG. 1, and the distance from the center of the subject 20 to the input surface of the image sensor 40! 2, the magnification ratio of the subject image displayed on the display 80 is 11 +12 >711. In the present embodiment, since the position of the image sensor 40 in two directions is variable, the above-mentioned distance <11 +12 ) can be changed as desired, and as a result, the X-ray image displayed on the display 80 can be changed as desired. Shooting magnification can be varied.

In addition, as shown in the conventional figure 4(b),
When used as a source, parallel X-rays are emitted from this large focal point, so it was impossible to take X-rays without using something with a large input area, such as an X-ray fluorescence multiplier tube. However, in this embodiment, since the X-ray tube 11 with a minute focus is used, a vidicon or the like whose input surface has a small diameter of several inches can be used as the image sensor 40. In addition, even with such a small-diameter input surface, it is possible to scan electronic components by moving the X and Y positions of the subject 20 or by increasing the imaging magnification of the X-ray image as described above. It becomes possible to photograph the whole or part of it as desired. Furthermore, X
Linear photomultiplier tubes are extremely expensive compared to vidicons;
This embodiment is also advantageous in that the device can be made inexpensive.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible within the scope of the invention.

For example, although the above embodiment has been described using an X-ray imaging device as an example of the imaging device, the present invention is not limited to this, and can be similarly applied to other types of radiography as well as RV imaging. In this case, instead of controlling the X-ray exposure amount, it is sufficient to control the light source intensity at the time of imaging, which determines the imaging condition, and the same can be applied to the gain adjustment of the amplifier. Also, Tv
In the case of a wa shadow, conversion to a digital signal is often not required, so in this case, the reference value may be set for the luminance signal.

Also, the reference value does not necessarily need to be set to the maximum level, and it is sufficient to set at least one level as a comparison standard. can be configured as a filter or mask having multiple reference levels corresponding to all its tonal levels.

[Effects of the Invention] As described in F below, according to the present invention, the brightness level (gradation level in the case of digital gradation) of a captured image is compared with a reference value to determine the appropriate shooting conditions or signal processing conditions. Therefore, under this corrected condition, an easy-to-see image with good contrast can be obtained, and especially when used for non-destructive inspection of industrial products, the inspection can be carried out reliably.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram for explaining an embodiment in which the present invention is applied to an X-ray imaging device that is a non-destructive inspection device for electronic components, etc. FIG. Figure 3 (B) is a characteristic diagram showing the gradation processing when the shooting conditions etc. are not appropriate. Figure 3 (A) is a schematic explanatory diagram of the reference subject. Figure (B) is a characteristic diagram showing the photographing signal level, and Figures 4 (a) and (b).
) is a schematic explanatory diagram of y) illustrating an X-ray transmission image in the case of a minute focus and in a case where it is not. DESCRIPTION OF SYMBOLS 11... Microfocus X-ray source, 20... Subject, 22... Reference subject, 40... Image sensor, 50... Amplifier, 60... Image processing unit, 70... TV signal Processing unit, 80...Display, 90...Reference device, 100...Comparator, 110...Control means. Agent Patent attorney Inoue - (1 other person) Figure 4 (0) (b)

Claims (1)

[Claims] A photographing device that images a subject based on photographic data of the subject output from an image sensor, comprising: a reference device for setting a reference value of a signal level; and a signal level and a signal level when photographing the subject. A photographing apparatus comprising: a comparator for comparing the reference value with the reference value; and a control means for changing and controlling photographing conditions and/or signal processing conditions so as to reduce a comparison error of the comparator.