JP3203791B2 - Character arrangement inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a keyboard manufacturing facility in which a plurality of key tops displaying characters are arranged in a predetermined order, and more particularly to a method for detecting a character arrangement error from a video signal input via a camera. The present invention relates to a character arrangement inspection device that automatically detects a character arrangement.

2. Description of the Related Art A keyboard used as an input device is usually provided with key tops for displaying characters and symbols in a predetermined order. An operator confirms the characters and symbols and presses the corresponding key tops. And the like.

The colors and arrangement order of such characters and symbols, the colors of key tops serving as backgrounds, and the like are diversified according to the purpose of use and preference of the keyboard. In a keyboard assembling process, predetermined keys are arranged in accordance with the set arrangement order. The tops are each inserted into key switches.

[0004] However, even if great care is taken at the time of assembling, a wrong character or an incorrect insertion direction of the inserted key top often occurs. Therefore, there is a demand for the development of a character arrangement inspection apparatus that can automatically detect a character arrangement error in an assembly process at a high speed.

[0005]

2. Description of the Related Art FIG. 8 is a plan view showing an example of a keyboard to be inspected, FIG. 9 is a block diagram showing a conventional character arrangement inspection apparatus, and FIG. 10 is a diagram showing video signals output from a camera.
FIG. 11 shows a video signal subjected to offset correction.

In the keyboard 1 to be inspected in FIG. 8, key tops 12 on which different characters and symbols 11 are displayed are arranged in a predetermined order, and the operator confirms the characters and symbols 11 and presses the corresponding key tops 12. Can input information to a computer or the like.

A conventional character arrangement inspection apparatus for inspecting the character arrangement of the keyboard 1 is composed of eleven blocks as shown in FIG. 9, and the whole image of the keyboard 1 is taken by the camera 2 and corresponds to the brightness of each pixel. Are sequentially output from the camera 2.

For example, when the key top 12 shown in FIG. 10A is imaged, the image is sequentially scanned from the top to the bottom by a plurality of horizontal lines, and when the key top 12 is scanned by a horizontal line indicated by an arrow, it corresponds to the horizontal line. The video signal shown in FIG.

That is, the color of the displayed characters and the color of the key top as the background are diversified according to the purpose of use of the keyboard and the like, and the level of the video signal output from the camera 2 is not uniform. It varies depending on the color of the character, the color of the key top, the contrast, and the like.

When such a video signal is binarized with the same threshold value as shown in FIG. 10 (c), all video signals having a low level fall below the threshold value and are formed based on the binarized video signal. As shown in FIG. 10 (d), the image of the low-level portion disappears from the resulting image.

Therefore, in the conventional character arrangement inspection apparatus, as shown in FIG. 9, an offset correction circuit 30 is provided after the camera 2 for imaging the keyboard 1, and the video signal output from the camera 2 can be binarized with the same threshold value. As described above, the level is corrected for each keytop.

For example, when imaging the key top 12 shown in FIG. 11 (a), a plurality of horizontal lines are sequentially scanned from the top to the bottom of the image. The video signal shown in FIG.

When the video signal is binarized by the same threshold value S _L , the low-level video signal falls below the threshold value and disappears as described above. However, the optimal threshold value for binarizing the video signal is used. Can be set for each keytop from the color of the display character, the color of the keytop, and the like.

That is, the difference S _LOFF between the optimum threshold value for binarization and the same threshold value S _L is set in advance for each _keytop , and is output from the camera 2 as shown in FIG. The video signals to be _output are corrected by S _{LOFF for} each key top so as to have the same level.

When such video signals are binarized at the same threshold value S _{L as} shown in FIG. 11C, all the video signals are binarized at the optimum threshold value, and as shown in FIG. An image including all key tops can be formed regardless of the level based on the coded video signal.

The analog signal level correction is performed for each key top is digitized in AD converter circuit 31 as shown in FIG. 9, the same in the binary circuit 32 threshold S _L
The video signal binarized in is stored in a frame memory 33 provided thereafter.

Next, an inspection character extracting circuit 34 sequentially extracts video signals of the characters to be inspected from the entire image stored in the frame memory 33, and stores the video signals in a data file 36 in advance in a pattern matching circuit 35. Check with the reference character pattern.

A mismatch point between the video signal and the reference character pattern is counted by a mismatch point counting circuit 37 provided after the pattern matching circuit 35, and an erroneous insertion determination circuit 38 is provided by a mismatch point counting circuit.
The count value of 37 is compared with the reference value stored in the data file 39 to determine good or bad.

[0019]

FIG. 12 is a diagram showing a problem in a conventional character arrangement inspection apparatus. When the contrast between the displayed character color and the key top color is small Figure 12
When binarized with an appropriate threshold as shown in (a), the image formed from the binarized video signal is almost the same as the character or symbol displayed on the keytop as shown in FIG. 12 (b). Become equal.

However, when the threshold value is slightly lowered as shown in FIG. 12 (c) due to an error or the like, a part of the character is blurred as shown in FIG. 12 (d), and as shown in FIG. If the height is slightly higher, the line becomes thicker as shown in FIG.

An object of the present invention is to provide a character arrangement inspection apparatus which is hardly affected by a threshold error or the like when binarizing.

[0022]

FIG. 1 is a block diagram showing a main part of an inspection apparatus according to the present invention. The same object is denoted by the same symbol throughout the drawings.

The above problem has a camera for capturing an entire image of a keyboard in which a plurality of key tops are arranged in a predetermined order, and automatically changes the character arrangement of the keyboard based on video signals sequentially output from the camera. In the inspection device, a means for correcting the amplification factor in accordance with the contrast between the brightness of the character displayed on the keytop and the brightness of the background is provided. An amplification circuit 4 for amplifying the sequentially output video signal is provided after the camera 2. This is achieved by the character arrangement inspection apparatus of the present invention provided.

[0024]

In FIG. 1, there is provided means for correcting the amplification factor in accordance with the contrast between the brightness of the character and the brightness of the background.
By providing an amplifying circuit for amplifying the sequentially output video signal between the camera and the offset correction circuit, it is possible to enlarge the difference in the level of light and dark at the keytop where the contrast between the character and the background is small. It is possible to realize a character arrangement inspection apparatus which is hardly affected by a threshold error or the like.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a block diagram of an amplifier circuit provided with amplification factor correction means, FIG. 3 is a flowchart showing a procedure for setting amplification factor correction data, FIG. 4 is a diagram showing a method for setting amplification factor correction data, and FIG. FIG. 6 is a flowchart showing a procedure for setting data, FIG. 6 is a diagram showing a method for setting offset correction data, and FIG. 7 is a diagram for explaining a noise removal method.

Referring to FIG. 1, one embodiment of the character arrangement inspection apparatus according to the present invention has an amplifier circuit 4 between a camera 2 and an offset correction circuit 30, and the amplifier circuit 4 includes a character displayed on a keytop, a background, and the like. Means for correcting the amplification factor based on the brightness contrast.

That is, as shown in FIG. 2, the amplifying circuit 4 has a compensating circuit 41 and a gain correcting circuit for setting the maximum amplitude of the video signal V _{IN to} , for example, 1 V, a synchronizing circuit 42 and a data storage memory 43.
The amplification factor correction circuit having the DA conversion circuit 44 outputs amplification factor correction data.

The data storage memory 43 stores the correction data of the amplification factor set for each keytop in accordance with the contrast, and the correction data sequentially cut out from the data storage memory 43 at the time of inspection is converted by the DA conversion circuit 44. It is converted to an analog signal.

The correction data analog signal by the DA converting circuit 44 is synchronized to the video signal V _IN by the synchronization circuit 42, the amplified video signal V _IN and the analog signal of the correction by the compensation circuit 41 Data is a multiplication circuit
Synthesized at 45.

That is, assuming that the input voltage to the amplifier circuit 4 is V _IN , the gain of the compensation circuit 41 is GAIN, and the gain correction data of the corresponding key top is A, the output voltage V _O calculated by the following equation is obtained. The signal is output via a buffer circuit 46 provided on the output side of the amplifier circuit 4.

V _O = (GAIN · V _IN ) × A (where V _IN is 1 V or less) In FIG. 1, collection of the amplification factor correction data is performed by directly digitizing the video signal output from the camera 2 by the AD conversion circuit 31. A video signal corresponding to the entire image of the keyboard 1 without passing through the binarization circuit 32;
Is stored in

As shown in FIG. 3, the amplification factor correction data is set by sequentially cutting out the video signal of the key top to be inspected from the frame memory 33, and setting the upper limit value V _UP and the lower limit value V _{LOW of the} video signal.
To calculate the contrast V _i of the key top from the difference between the V _UP and the V _LOW together to pick up the pieces.

The gain for small keytop amplification factor is smaller V _i for large keytop V _i should be large. Therefore, in A _i = 1 / kV _i becomes equation stored in the data storage memory 43 to calculate the gain correction data A _i from the contrast V _i.

For example, one of the key tops 12 shown in FIG.
When a video signal corresponding to a horizontal line (indicated by an arrow) is cut out from the frame memory 33, a video signal in which the upper limit value V _UP and the lower limit value V _LOW are different depending on the key top is output as shown in FIG.

The upper limit value V _UP and the lower limit value V _{LOW of the} video signal
Contrast V _i of each of the key top shown in FIG. 4 (c) is calculated from FIG. 4 from such contrast V _i
gain correction data A _i for each of the key top shown in (d) is further calculated.

When the key top 12 is inspected, the video signal shown in FIG. 4C is input to the amplifier circuit 4 and amplified by the compensating circuit 41. At the same time, the amplification factor for each key top shown in FIG. The signal shown in FIG. 4E is output after being synthesized with the correction data _Ai .

On the other hand, the collection of the offset correction data is shown in FIG.
Thus, the output signal of the amplifier circuit 4 is directly digitized by the AD conversion circuit 31, and the video signal corresponding to the whole image of the keyboard 1 is stored in the frame memory 33 without passing through the binarization circuit 32.

The setting of the offset correction data is performed by storing the video signal of the key top to be inspected as shown in FIG.
33, the optimum threshold value S _L for binarizing each key top is collected, and the maximum threshold value S _L is searched for as a reference threshold value S _LST .

Next, the difference S _LOFF between the optimum threshold value S _L and the reference threshold value S _LST for binarizing the video signal of each _keytop is calculated. The offset correction circuit 30 has a data storage memory not shown, and the calculated S _LOFF is stored in the data storage memory.

That is, the video signal cut out from the frame memory 33 at the time of setting the offset correction data is converted into a video signal corresponding to one horizontal line (indicated by an arrow) of the key top 12 shown in FIG. Has already been corrected as shown in FIG.

The threshold value S _L most suitable for binarizing each video signal differs for each key top as shown in FIG. 6C, and the optimum threshold value S _L for all key tops is obtained. And the maximum threshold value _SL is searched to be set as a reference threshold value S _LST .

The difference S _LOFF between the reference threshold value S _LST and the optimum threshold value S _L of each key top is stored in the data storage memory, and when the key top 12 is inspected, the image shown in FIG. The signal is corrected as shown in FIG. 6D and output from the offset correction circuit 30.

Thus, means for correcting the amplification factor in accordance with the contrast between the brightness of the character and the brightness of the background is provided, and an amplification circuit for amplifying the sequentially output video signal is provided between the camera and the offset correction circuit. Thus, it is possible to enlarge the level difference between light and dark at the key top where the contrast between the character and the background is small, and it is possible to realize a character arrangement inspection apparatus which is hardly affected by a threshold error or the like when binarizing.

However, in the character arrangement inspection apparatus according to the present invention, since the video signal is greatly amplified as the key top has a smaller contrast, even if the signal is caused by noise, the signal is amplified. The number of points increases.

Therefore, in the character arrangement inspection apparatus according to the present invention, the noise elimination circuit 5 for eliminating the noise signal included in the digitized video signal is replaced with a binarization circuit for binarizing the video signal as shown in FIG. 32 and frame memory 33 for storing video signals
And is provided between them.

The noise elimination circuit 5 has a noise elimination filter for discriminating the state of the central pixel from the state of the surrounding pixels in the 3 × 3 pixels, and the 3 × 3 pixels have any one of the states shown in FIG. Is satisfied, the level of the center pixel is inverted by regarding the noise.

That is, for example, an 8-bit bit number is assigned to each of the 3 × 3 pixels as shown in FIG. 7A, and a signal is output from the hatched pixel in FIG. 7B. A code corresponding to the bit number is attached to the output pattern.

The size of each of the 3 × 3 pixels is extremely small as compared with the thickness of the character displayed on the key top, and the state of the surrounding pixels is one of those shown in FIG. When the code is applicable, the output signal of the central pixel may be regarded as noise.

[0049]

As described above, according to the present invention, it is possible to provide a character arrangement inspection apparatus which is hardly affected by a threshold error or the like when binarizing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an inspection apparatus according to the present invention.

FIG. 2 is a block diagram of an amplifier circuit including an amplification factor correction unit.

FIG. 3 is a flowchart showing a procedure for setting amplification factor correction data.

FIG. 4 is a diagram illustrating a method of setting amplification factor correction data.

FIG. 5 is a flowchart showing a procedure for setting offset correction data.

FIG. 6 is a diagram illustrating a method of setting offset correction data.

FIG. 7 is a diagram illustrating a noise removal method.

FIG. 8 is a plan view showing an example of a keyboard to be inspected.

FIG. 9 is a block diagram showing a conventional character arrangement inspection apparatus.

FIG. 10 is a diagram illustrating a video signal output from a camera.

FIG. 11 is a diagram illustrating a video signal subjected to offset correction.

FIG. 12 is a diagram showing a problem in a conventional character arrangement inspection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Keyboard 2 Camera 4 Amplification circuit 5 Noise removal circuit 11 Character 12 Key top 30 Offset correction circuit 31 AD conversion circuit 32 Binarization circuit 33 Frame memory 34 Inspection character extraction circuit 35 Pattern collation circuit 36 Data file 37 Mismatch point counting circuit 38 Mis-insertion judgment circuit 39 Data file 41 Compensation circuit 42 Synchronization circuit 43 Data storage memory 44 DA conversion circuit 45 Multiplication circuit 46 Buffer circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-208528 (JP, A) JP-A-64-53270 (JP, A) JP-A-60-29876 (JP, A) JP-A 63-208 8986 (JP, A) Fully open 1986-60364 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 7/18 G06T 1/00 300 G06T 1/00 460

Claims (2)

(57) [Claims] 1. A camera for capturing an entire image of a keyboard in which a plurality of key tops displaying characters are arranged in a predetermined order, and based on video signals sequentially output from the camera, characters on the keyboard are displayed. In an apparatus for automatically inspecting an array, an amplifier circuit for amplifying an amplification factor in accordance with a contrast between the brightness of a character displayed on a keytop and the brightness of a background, and amplifying a sequentially output video signal ( 4) A character array inspection device, wherein is provided after the camera (2). 2. A binarizing circuit (3) for binarizing a digitized video signal in the character arrangement inspection apparatus according to claim 1.
A character arrangement inspection apparatus characterized in that a noise removing circuit (5) for removing a noise signal from the video signal is provided after 2).