JPH0366875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reproducing device using an optical fiber bundle, which transmits an optical image using an optical cable constructed of the fiber bundle and reproduces it as a television image.

FIG. 1 is an explanatory diagram of the principle of conventional optical image transmission using an optical fiber. In the same figure, 1 is an optical cable consisting of an optical fiber bundle (bundle of optical fibers),
F is its leading edge and R is its trailing edge. The optical image is transmitted by a cable 1 consisting of a bundle of optical fibers arranged so that each fiber occupies the same geometric position at the tip F and the rear end R. For example, from the tip F to the end surface This is done by sending light at the position of the image formed by a lens or the like through a fiber to create an optical image on the other end surface R.

Such an optical cable 1 needs to be arranged so that each fiber at both ends occupies the same geometric position. By the way, when manufacturing a cable with long dimensions or a large number of fibers, it is possible to twist individual fibers or bundles of fibers together for convenience in handling the cable when it is wound around a drum or the like. Efforts are being made to make it flexible. However, when the fibers are twisted together in this way, the geometric positions of the fibers at both ends are inevitably not the same. Under these circumstances, conventional optical image transmission uses a short, small-sized fiber bundle as a fiberscope (for example, an endoscope).
It was only used for medical purposes such as observing the inside of the stomach and esophagus.

On the other hand, there is a demand for using optical image transmission technology using optical cables to monitor conditions in places that are difficult for humans to access, such as inside nuclear reactors and molten metal reactors, from a remote location. For this reason, optical cables with the same geometrical position of each fiber at both ends cannot be manufactured in long dimensions.
The above requirements were difficult to meet.

The inventors of the present invention have overcome these difficult circumstances and created an image display device that makes it possible to transmit and display optical images even using optical cables that are twisted together to give them flexibility and a sufficient length. has been proposed in another patent application, and will be explained next.

FIG. 2 is a block diagram showing an image display device proposed by the present inventors. In the same figure,
21 is an object to be monitored, 22 is a lens, and 2 is a long flexible optical cable. 10 is a photoelectric conversion circuit, which is actually a color TV camera consisting of an image pickup tube and a control unit, and converts the optical image of the object to be monitored 21 transmitted through the optical cable 2 into analog R (red), G (green), B (blue) This is a circuit that converts into an electrical signal. The A/D conversion circuit 12 converts the analog RGB electric signal from the photoelectric conversion circuit 10 into a digital signal of gray level (6 bits) for each pixel with a resolution of 512 (dots) x 512 (dots).
This is a circuit that converts to RGB signals. A/D conversion work is performed at extremely high speed in accordance with the order of addresses generated from the two-dimensional coordinate generation circuit 11.

The two-dimensional coordinate generation circuit 11 generates the two-dimensional address (X coordinate address and Y coordinate address) of the famous pixel (dot) when dividing the photoelectric conversion surface in the circuit 10 into 512 (dots) x 512 (dots). This is a circuit that does this. These two-dimensional coordinate addresses are generated so that the display screen can be scanned correctly. The write control circuit 13 is a circuit that causes the data buffer memory 14 to store pixel information (RGB signals and their gradation information) digitized for each pixel in the A/D conversion circuit 12.

The coordinate conversion circuit 15 is a conversion table prepared in advance that can convert the positional coordinates of each fiber at the eyepiece side terminal R of the optical cable 2 to the positional coordinates of each fiber at the objective side terminal F. A method for creating this coordinate conversion circuit will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a conceptual diagram of the coordinate conversion circuit creation means, and FIG. 4 is an explanatory diagram of its operating principle. In FIG. 3, reference numeral 2 denotes a long flexible optical cable, and an adjustment jig 3 is attached to the tip F thereof.

Although the adjustment jig 3 will not be described in detail, its function is basically a device that generates light and inputs the light into each fiber by moving it from one side to the other at the tip F of the optical cable 2. It is.

In FIG. 4, S indicates a bright line having a width Δt (approximately the same dimension as the thickness of one optical fiber), which is generated by the adjustment jig 3.

Now, in FIG. 4A, the bright line S is located at the left end of the tip F of the optical cable, and inputs light to three optical fibers. At this time, at the rear end R, light should be recognized in three corresponding optical fibers, so the coordinates of these three fibers are memorized. Next, as shown in FIG. Since each fiber should glow, memorize the coordinates of these fiber positions. Below, in the same way, the emission line S is x
It is moved sequentially in the axial direction to cross the tip F.

Next, turn the emission line S sideways and move it in the y-axis direction,
The coordinates of the position of the glowing fiber at the rear end R are stored at each time the fiber is moved by a minute distance Δt.
Above, the x-axis direction and y-axis direction of the emission line S with respect to the tip F
By organizing the coordinates of the glowing fiber positions obtained at the rear end R as a result of a total of two scans in the axial direction, it is possible to find the correspondence between the coordinates of the fiber position at the tip F and those at the rear end R. . Note that the light emitted from the adjustment jig 3 does not need to be visible light, and may of course be invisible light. The same result can also be obtained by gradually enlarging the bright portion of the tip F that is illuminated by the light instead of moving the bright line S.

Determining the correspondence between the coordinates of the fiber position at the tip F and the coordinates of the fiber position at the rear end R from the results of the above-mentioned two scans will be explained in more detail with reference to FIG. Figure 5 shows the cable tip F and rear end R.
FIG. 2 is a diagram explaining the principle of coordinate transformation of each fiber position in FIG.

Now, to make the discussion easier to understand, in Figure 5A, the cable tip F is made up of nine fibers a to i, and as shown in Figure 5B, the rear end R is
Let the fiber positions in be expressed by A to I.

First, assume that the bright line at the tip F is scanned in the x-axis direction.

In the first stage, the fiber position a(x ₁ ,
Suppose that when light is input to y ₁ ), b (x ₁ , y ₂ ), and C (x ₁ , y ₃ ), G, E, and C light up at the rear end R. Then, since a, b, and c have a common coordinate x ₁ , G, E, and C are found to have at least a coordinate x ₁ on the F side.

In the second stage, similarly, the fiber position d at the tip F
Assume that when light is input to (x ₂ , y ₁ ), e (x ₂ , y ₂ ), and f (x ₂ , y ₃ ), lights A, H, and F are emitted at the rear end R. Then, it can be seen that A, H, and F have at least the coordinate x ₂ on the F side.

In the third stage, the fiber position g(x ₃ ,
Suppose that when light is input to y ₁ ), h (x ₃ , y ₂ ), and i (x ₃ , y ₃ ), B, D, and I light up at the rear end R. Then, B, D, and I are at least the coordinates on the F side.
It turns out that there is something with x ₃ .

Next, it is assumed that scanning is performed from top to bottom in the y-axis direction with the bright line horizontally.

As the fourth step, the fiber position a(x ₁ ,
Suppose that when light is input to y ₁ ), d (x ₂ , y ₁ ), and g (x ₃ , y ₁ ), E, F, and B light up at the rear end R. Then E, F, B are at least the coordinates y ₁ on the F side
It turns out that it has the following.

In the fifth step, the fiber position b(x ₁ ,
y ₂ ), e (x ₂ , y ₂ ), and h (x ₃ , y ₂ ), and if we assume that A, G, and I are illuminated at the rear end R, these will be at least on the F side. It can be seen that it has the coordinate y ₂ .

In the sixth stage, the fiber position c(x ₁ ,
y ₃ ), f (x ₂ , y ₃ ), and i (x ₃ , y ₃ ), and assuming that C, D, and H shine at the rear end R, these are at least on the F side. It can be seen that it has the coordinate y ₃ .

When the above is summarized, the correspondence relationship between the positions of each fiber at the rear end R and the front end F can be obtained as follows.

A (X ₁ , Y ₁ ) → e (x ₂ , y ₂ ) B (X ₁ , Y ₂ ) → g [x ₃ , y ₁ ) C (X ₁ , Y ₃ ) → c (x ₁ , y ₃ ) D (X ₂ , Y ₁ ) → i (x ₃ , y ₃ ) E (X ₂ , Y ₂ ) → a (x ₁ , y ₁ ) F (X ₂ , Y ₂ ) → d (x ₂ , y ₁ ) G (X ₃ , Y ₁ ) → h (x ₂ , y ₂ ) I (X ₃ , Y ₃ ) → h (x ₃ , y ₂ ) The tip F and rear edge R found above The coordinate conversion circuit 15 is a table of the coordinate relationships of each fiber position. Using this, at the rear end R of the optical cable, the information obtained at fiber position A is placed at address (x ₂ , y ₂ ), the information obtained at fiber position B is placed at address (x ₃ , y ₁ ), and so on. The optical image formed at the tip F can be correctly reproduced by storing the information obtained at I at addresses (x ₃ , y ₂ ) and reading and displaying the information in the order of the addresses.

Returning to FIG. 2, the memory 16 includes the coordinate conversion circuit 1
This is a circuit that stores the information after the coordinate transformation in step 5 in the order of scanning addresses, and is a refresh memory. The TV synchronization signal generation circuit 17 is a circuit for generating horizontal and vertical synchronization signals when performing raster scanning in the CRT 20. The read control circuit 18 is a circuit that reads out information written in the refresh memory 16 in synchronization with the TV synchronization signal from the circuit 17 and reads it out to the D/A converter 19. D/A
The conversion circuit 19 is a circuit that reads out the refresh memory 16 and converts the input digital level pixel signal string into a color video signal and inputs the same to the CRT 20.

The operation is probably already clear, but I will briefly explain it. An image of an object to be monitored 21 located in a place that is difficult for humans to approach, such as inside a nuclear reactor, is formed on the tip F of the optical cable 2 by a lens 22 or the like. The optical image is transmitted through the optical cable 2 and sent to the photoelectric conversion circuit 10.
It is converted into an electrical signal under the control of the coordinate generation circuit 11, and converted into a digital signal in the A/D conversion circuit 12, and then written to the data buffer memory 14 under the control of the write control circuit 13. be included. The information read out from the data buffer memory by a readout control means (not shown) is processed in the coordinate conversion circuit 15 according to the predetermined coordinate relationship of each fiber position at the tip F and rear end R of the optical cable 2. Refresh memory 1 after address conversion
6 is written. The read control circuit 18 reads out information from the refresh memory 16 under the control of the TV synchronization signal generation circuit 17, and reads out information from the D/A conversion circuit 1.
After converting to analog signal in step 9, CRT2
Enter 0 to display. As a result, an optical image of the object to be monitored 21 can be displayed on the CRT 20 and monitored.

The image display device proposed by the present inventors as described above has the following problems. That is, since the optical cable 2 is long, if there is a fiber that is broken in the middle, only that part will be displayed in black and the image quality will deteriorate. Furthermore, the optical cable 2 is manufactured by using a fiber bundle consisting of a certain number of fibers as a unit, and further twisting and drawing a plurality of these units, but when looking at the optical image at the end of the cable,
The disadvantage is that the light transmission level is reduced in the periphery of each unit, creating shadows and making it difficult to see the image.

This invention was made in order to solve the above-mentioned problems in the image display device proposed by the present inventors, and therefore, the purpose of this invention is to:
To provide an image correction method capable of providing an easy-to-see image by eliminating black dots on a displayed image even if an optical cable contains fibers that are broken in the middle and eliminating shadows generated from the periphery of a unit. be.

The gist of the configuration of the present invention is that when there is a pixel consisting of a black dot or a pixel with a particularly low luminance level in a displayed image, the value obtained by taking, for example, the average of the luminance levels of a plurality of pixels surrounding the pixel, is calculated from the defective pixel. The aim is to improve the image quality by using the brightness level as the brightness level.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a block diagram showing one embodiment of the present invention. The circuit configuration shown in this figure differs from the circuit shown in FIG. 2 in a circuit portion S surrounded by a chain line. That is, by adding the S portion to the circuit of FIG. 2, the circuit of FIG. 6 is obtained. The S part includes a level determination circuit 31, a surrounding coordinate generation circuit 32, a read control circuit 33, an arithmetic circuit 35, and a data register 3.
It consists of 4.

In FIG. 6, a level determination circuit 31 is a circuit that determines the level of data provided from the coordinate transformation circuit 15 after completing the coordinate transformation, and when it is at a predetermined level, writes it to the refresh memory 16,
If it is not at a predetermined level, the address of the data is transferred to the surrounding coordinate generation circuit 32. The surrounding coordinate generation circuit 32 generates coordinate addresses of data points around the transferred address as the center. Based on the address given from the circuit 32, the read control circuit 33 reads data from the data points (for example, four points) around the defective data point whose level is not at a predetermined level from the refresh memory 16, and stores the data in the register. Store it in 34. The arithmetic circuit 35 calculates, for example, an average value (not necessarily an average value) of the data at four locations from the data register 34, and writes it to the address of the defective data point in the refresh memory 16.

In this way, even if a defective data point is at the black level due to, for example, a break in a fiber in an optical cable, if the surrounding data points are normal, the defective data can be corrected with normal data. Therefore, image quality can be improved. Correction is made in exactly the same way for shadows around the unit.

As explained above, according to the present invention, in the image display device proposed by the present inventors, there is an advantage that even if there is some defect in the optical cable, deterioration of image quality due to the defect can be prevented. .

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of conventional optical image transmission using optical fibers, Figure 2 is a block diagram showing the image display device proposed by the present inventors, and Figure 3 is a coordinate diagram used in the proposed image display device. FIG. 4 is a conceptual diagram of the conversion circuit creating means, FIG. 4 is a diagram explaining its operating principle, FIG. 5 is a diagram explaining the principle of coordinate transformation, and FIG. 6 is a block diagram showing an embodiment of the present invention. Description of symbols, 1... Optical fiber bundle, 2... Flexible long optical cable, 3... Adjustment jig, 10...
...Photoelectric conversion circuit, 11...Coordinate generation circuit, 12...
...A/D conversion circuit, 13...Write control circuit, 14
...Data buffer memory, 15...Coordinate conversion circuit, 16...Refresh memory, 17...TV
Synchronizing signal generation circuit, 18...Reading control circuit, 19
......D/A conversion circuit, 20...CRT, 21...
...object to be monitored, 22...lens, 31...level judgment circuit, 32...surrounding coordinate generation circuit, 33...
...Read control circuit, 34...Data register, 35
...Arithmetic circuit.

Claims (1)

[Scope of Claims] 1. A means for reading an optical image transmitted through an optical cable formed by bundling a large number of optical fibers as digital data corresponding to each of the coordinates of a large number of dots constituting the image; a coordinate conversion means for generating an address corresponding to the dot arrangement of the optical image of the input end face of the optical cable from each dot coordinate of the image data read by this means; a memory means for storing data corresponding to each of the dot coordinates according to the address; and a memory means for determining the level of each data corresponding to each of the dot coordinates input to the memory means, and determining whether the level is below a set level. a level determining means for detecting the dot coordinates of defect data of the dot; a surrounding coordinate generating means for generating addresses of a plurality of coordinates around the dot coordinate determined to be below a set level by the level determining means; a calculation means for reading data corresponding to a plurality of coordinate addresses generated by the surrounding coordinate generation means and forming data to replace the defective data based on the read data; An image reproducing apparatus using an optical fiber bundle, characterized in that the image data stored in the memory means is reproduced by writing to the address of the defect data in the memory means.