JPH06300707A - Foreign matter detection circuit of color filter - Google Patents

Abstract

PURPOSE:To provide a foreign matter detection circuit that detects a foreign matter without missing and outputs the accurate peak value indicating the size thereof. CONSTITUTION:The apparatus consists of a first and a second foreign matter detection sections, a division signal generating circuit that supplies a division signal Ts for dividing each photodetection signal into intervals s and a reference determining circuit that sets a reference value K. Each of the foreign matter detection sections comprises a peak value selection part 61 that selectively outputs a maximum or a minimum peak value from a pattern waveform i of each pixel in the arbitrary divisional interval, a divisional signal hindering part 62 that hinders the divisional signal Ts, a signal detection part 63 wherein the reference value K is subtracted from or added to each of the peak values to form threshold values Ls(n+1) for next interval s(n+1) and the threshold values are compared with photodetection signal of the interval s(n+1) so that a foreign matter detection signal R is outputted therefrom when a foreign matter p is detected and a peak level calculation part 64 that calculates the difference between the photodetection signal and the selected peak level and outputs the difference as peak level data Hp indicating the size of the foreign matter by an foreign matter detection data R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign substance detection circuit in a foreign substance inspection device for color filters used in liquid crystal panels.

[0002]

2. Description of the Related Art Due to advances in liquid crystal and its control technology, a liquid crystal panel capable of color display on a screen of considerable size with a small amount of power has been developed, and a color filter is used for this. FIG. 4 shows an example of the color filter 1. In FIG. 4 (a), a chrome thin film 12 is vapor-deposited on the surface of a glass plate 11, on which a pixel 13 of a square three primary colors having a side of about 50 μm is formed.
(R, G, B) are regularly planted at regular intervals. (b) shows a cross section of the color filter 1, and in order to protect each pixel 13, the entire surface of the color filter 1 is coated with a transparent and minute protective film (called top coat) 14 such as polyimide or acrylic. ing. Although illustration is omitted, a color liquid crystal panel is configured by stacking an alignment film, a liquid crystal film, a thin film transistor (TFT) and the like having a minute thickness on the color filter 1.

When foreign matter is present in the color filter 1 and the size thereof is, for example, several μm or more, not only the pixel itself becomes defective, but also the foreign matter continuously breaks through the alignment film or the liquid crystal film. May damage the TFT. TF
Although T is arranged in the number corresponding to each pixel, each of them is not independent in the circuit and a large number of Ts are connected to each other. Therefore, the damage of one TFT is not limited to one, and the connection is not limited to one. This is a serious problem because it causes a series of malfunctions of the TFTs thus produced and lowers the product yield. The foreign matter existing in the color filter 1 will be described with reference to FIG. (a) shows the state before the top coat 14 is coated, where the foreign matter is p, p ₁ is the middle of the pixel 13, p ₂ is the foreign matter attached to the surface of the pixel, and p ₃ is the inside of the pixel. It is a buried foreign object buried in. What should be noted here is that the surface of the pixel rises upward due to p ₃ to form the mountain-shaped projection 2. Next, in (b), the foreign matter p ₁ , p ₂ , p ₃ is buried in the top coat in a state where the top coat 14 is coated, and in this case also, the chevron projections 2 are formed on the top coat.
Is occurring. The foreign matter p ′ is attached to the top coat 14 after the coating is completed.

In order to efficiently detect the above-mentioned foreign matters,
This patent applicant has applied for a patent for "Japanese Patent Application No. 4-161952, Optical system for detecting foreign matter of color filter". Figure 6
The foreign matter detection optical system according to the above patent application will be described below. First, the principle of detecting the buried foreign matter p will be described with reference to FIG. The white light flux L _T is projected onto the surface of the color filter 1 at a projection angle θ _T. If the surface is smooth, the specular reflection light L _R has a direction of specular reflection angle θ _R equal to the projection angle θ _T , but if the chevron projection 2 is present, the reflection direction changes and the axially displaced reflection light L _R ′. Becomes When this is received by the CCD sensor and scanned, the received light signal shown in (b) is obtained, and in the pattern waveform i of the constant period generated by the pattern of each pixel 13,
The pulse p with respect to the chevron projection 2 is projected, and the buried foreign matter p is indirectly detected by detecting this with a proper threshold value. It should be noted that the foreign matter p'attached to the above-mentioned top coat 14 can be detected if it is larger than a certain degree.

FIG. 7 shows an embodiment of the above-mentioned foreign matter detecting optical system. In the optical system, the light projecting system 3 and the light receiving system 4 are symmetrically arranged at a narrow angle with respect to the perpendicular C of the color filter 1, and the white light from the light source 31 of the light projecting system 3 is slit by the light projecting lens 32 and the slit.
33, for example, the width W is about 30 mm and the thickness d is about 50
A light beam L _{T of} μm is projected on the surface of the color filter 1 mounted on the mounting table 5. In the light receiving system 4, the reflected light on the surface passes through the image forming lens 41 and is split by the half mirror 42, and one of them is extracted by the spatial filter 43 only the axially shifted light L _R ′ within the range of the light flux L _T. An image of the surface of is imaged on a first CCD sensor (hereinafter simply referred to as CCD) 44, and a light reception signal I ₁ is output by the scanning. In addition, the other divided light is reflected regularly by the spatial filter 45.
Only _R is extracted, and the same surface image is the second C
An image is formed on the CD 46, and the received light signal I ₂ is output. In addition,
Since the second CCD 46 is off-axis by the chevron projection 2, the intensity of the specularly reflected light L _R is reduced, and the embedded foreign matter p is detected by this reduction. Thus, the first and first CCD4
The combined use of 4,46 improves the detection sensitivity not only for the embedded foreign matter but also for the above-mentioned attached foreign matter p '.

A procedure for inspecting the color filter 1 in the above-mentioned foreign matter detecting optical system will be described with reference to FIG. The surface of the color filter 1 in the X direction, is divided into a plurality of areas S corresponding to the width W of the light beam L _T, the reflected light of the projected light beam L _T relative area S, the first and second, respectively CCD44,4
Imaged on 6 and inspected. By the XY movement mechanism 5a,
The color filter 1 is sequentially moved in the Y direction by the thickness d of the light flux L _T , and the inspection is performed for each Y position.
When the inspection is completed, the entire area of the color filter 1 is inspected by sequentially moving to the next area. Figure 8 (b) shows each CCD4
The pulse of the foreign matter p generated in the light receiving signals I ₁ and I ₂ of 4,46 is illustrated, and it is assumed that there are buried foreign matter (hereinafter simply referred to as foreign matter) p _a and p _{b in} the region S. _{If a} is imaged on the first CCD 44, the pulse p _a thereof projects above the pattern waveform i, and this is the threshold L _a.
Detected by. If the foreign matter p _b is imaged on the second CCD 46, its pulse p _b is the pattern waveform i.
Below, which is detected by the threshold value L _b . The crest value of each foreign substance is determined together with its detection, and the crest value is converted into the size of the foreign substance in the data processing unit.

[0007]

The above-mentioned CCDs will be described below.
The levels of the light reception signals I ₁ and I ₂ of 44 and 46 change slowly in the region S. The reason is that the intensity distribution of the light flux L _T is not always uniform, and the imaging lens 41 has a characteristic that the peripheral brightness is lowered with respect to the optical axis. FIG. 9 shows an example of the received light signal whose level changes slowly. In the case of the signal I ₁ shown in (a), the pattern waveform i is curved upward with the both ends of the region S as the hem, and near the top thereof. The foreign matter pulse p _a projects upward. The pattern waveform i of the signal I _{2 in} (b) is the same, but the foreign matter pulse p _b is projected downward in the opposite direction. If a light receiving signal whose level changes in this way is detected with a fixed fixed threshold value, a foreign object detection error will occur, and even if it is detected, the peak value will not be accurate, so there will be an error in the converted foreign object size. Has a drawback. On the other hand, if the threshold value is not set to a constant value and the level change of the pattern waveform i is followed, the above-mentioned drawback can be solved. However, if the received light signal contains a foreign substance pulse, the pulse interferes and inaccurate tracking makes it impossible to obtain a correct threshold value. Therefore, a means for avoiding the foreign matter pulse is necessary. This invention is based on the above idea.
It has a means for avoiding foreign matter pulses, sets an appropriate threshold value by following the level change of the pattern waveform i of each pixel, detects foreign matter on the color filter without error, and has an accurate crest value indicating its magnitude. An object is to provide a foreign matter detection circuit that outputs data.

[0008]

SUMMARY OF THE INVENTION The present invention is a foreign matter detection circuit for a color filter, comprising:
The first and second foreign matter detectors to which the light-reception signals of the first and second CCD sensors are respectively input, and the respective light-reception signals in the area S to the respective foreign matter detectors are divided into sections of appropriate lengths. It comprises a classification signal generation circuit for supplying a classification signal T _s for classifying into _s , and a reference value setting circuit for supplying a reference value K for the detection threshold value L _s of foreign matter. The first or second foreign matter detection unit selects and outputs the maximum or minimum crest value from the pattern waveform of each pixel included in the received light signal of the arbitrary section s _{n divided} by the division signal T _s. A reference value K is added to or subtracted from the peak value selection unit and each selected peak value to create a threshold value L _s (n + 1) for the next section s (n + 1) and a threshold value L _s. (n + 1) is compared with the light receiving signal in the section s (n + 1), and a detection signal unit that outputs a foreign material detection signal R when a foreign material pulse is detected, and the input light receiving signal and each selected wave The difference from the high value is calculated, and the difference at the output time of the foreign matter detection signal R is calculated as the peak value H _{p of the} foreign matter pulse.
Is provided on the output side of the crest value calculating section and the crest value selecting section, and outputs the sorting signal T according to the foreign object detection signal R.
prevents _s, constituted by a division signal blocking portion to suspend the updating of the threshold value L _s.

[0009]

In the first or second foreign matter detecting section of the foreign matter detecting circuit described above, the light receiving signals from the first and second CCD sensors inputted to the respective peak value selecting sections are classified by the dividing signal generating circuit. The signal T _s is divided into sections of appropriate length s, and the maximum or minimum peak value is selected and output from the pattern waveform of each pixel included in the light receiving signal of an arbitrary section s _n . In each detection signal section, for each selected peak value, the reference value K supplied from the reference setting circuit
Is added or subtracted to create a threshold value L _s (n + 1) for the next section s (n + 1), and this threshold value is compared with the received light signal in the section s (n + 1) to detect a foreign substance. When this is done, the foreign matter detection signal R is output. On the other hand, in each crest value calculation unit, the difference between the received light receiving signal and each selected crest value is sequentially calculated, and at the time when the foreign matter detection signal R is output, this difference is the crest value of the foreign matter pulse. This is output because it indicates H _p . Further, in each section signal blocking unit, since the section signal T _s is blocked by the foreign object detection signal R, the updating of the threshold value is temporarily stopped, and the threshold value L _s (n + 1) for the section _s (n + 1) is set. It applies to the next interval s (n + 2). As a result, the threshold value change due to the foreign matter pulse is avoided, and the threshold value L
_{Since s} correctly follows the pattern waveform, the foreign matter pulse can be detected well, and its accurate peak value H _p
Is output. In the above, if the length of the divided signal T _s is smaller than the width of the region S, and is, for example, several tens of minutes,
Since the level change of the pattern waveform i in the adjacent section s becomes minute, even if the threshold value L _s is applied to the next section s or the next section s as described above, a foreign matter detection error or the size of the detected foreign matter is detected. There is no error.

[0010]

1 is a block diagram of a foreign matter detecting circuit 10 according to an embodiment of the present invention, FIG. 2 is a block diagram of a first foreign matter detecting section 6A in FIG. 1, and FIG. 3 is a foreign matter detecting section. It is explanatory drawing of 6 A of foreign substance detection operations. The foreign matter detection circuit 10 shown in FIG. 1 includes the first and second foreign matter detection units 6
A, 6B, a division signal T _s for dividing the width of the region S into appropriate intervals, and a division signal generation circuit 7 for supplying to each foreign matter detection unit, and a reference value K for the foreign matter detection threshold L _s are set. The reference value setting circuit 8 supplies this to each foreign matter detecting section. The output side of each foreign matter detector 6A, 6B is connected to the data processor 9. The foreign matter detection unit 6A shown in FIG.
A peak value selection unit 61 including a comparison circuit 611, an OR circuit 612, and a latch circuit 613, an AND circuit 621, and a latch circuit 62.
2 and the phase inverter 632 and the divided signal blocker 62,
The detection signal unit 63 includes an adder circuit 631 and a comparison circuit 632, and the peak value calculation unit 64 includes a difference circuit 641 and a latch circuit 642. Although not shown, the configuration of the second foreign matter detection unit 6B is almost the same as that of the first foreign matter detection unit 6B. Hereinafter, referring to FIGS. 2 and 3, the first foreign matter detection unit 6A
Will be described.

In FIG. 2, the received light signals of the first CCD 44 are sequentially input to the comparison circuit 611 of the peak value selection unit 61. On the other hand, the division signal T _s supplied from the division signal generation circuit 7 triggers the latch circuit 613 via the OR circuit 611, and the peak value of the first waveform i _a of the pattern waveform i in the arbitrary section s _n shown in FIG. (Hereinafter, the peak value is omitted) is latched, transferred to the comparison circuit 611 and compared with the next waveform i _b . When i _a <i _b, the selection signal Q is output and O
Trigger the latch circuit 613 through the R circuit 611 to generate the waveform i _c
Are latched and the waveforms i _b and i _c are compared. Such comparison selection is repeated for each waveform, the maximum of the waveform i _max in the interval s _n is latched by the latch circuit 613. The waveform i _max is latched by the latch circuit 622 by the division signal T _s supplied to the AND circuit 621 of the peak value blocking unit 62, and then transferred to the adder circuit 631 of the detection signal unit 63, and the reference value setting circuit 631. The reference value K supplied from 8 is added to create a threshold value L _s (n + 1) for the section s (n + 1), which is given to the comparison circuit 632. The reference value K
Is added to prevent the pattern waveform i itself from being detected when the peak value of the waveform i _max is used as the threshold value L _s as it is. However, if the reference value K is too large, there is a risk of missing a foreign matter pulse having a small crest value, and if the reference value K is too small, it is detected that the pattern waveform i changes. In the comparison circuit 632, the threshold value L _s (n + 1) is compared with the received light signal I _{1 in the} next section s (n + 1), and when I ₁ > L _s (n + 1), the foreign matter pulse p Is detected, the foreign matter detection signal R is output. On the other hand, the waveform i _max and the signal I ₁ are the difference circuit of the peak value calculation unit 64.
Input into 641 and the difference between the two is calculated. When the foreign matter detection signal R is output, this difference is the foreign matter pulse p.
Since the peak value H _p of the signal is accurately indicated, it is latched in the latch circuit 642 with the signal R as a trigger. However, the foreign matter detection signal R
If is not output, the difference is meaningless and is ignored. Next, regarding the division signal blocking unit 62, since the light receiving signal I ₁ in the section s (n + 1) has the foreign matter pulse p, the maximum value of this section becomes the peak value of p, and the section s (n + 2) ), The correct threshold L _s cannot be obtained. On the other hand, the foreign matter detection signal R is phase-inverted by the phase inverter 65 and applied to the AND circuit 623 to block the input of the division signal T _s , and the pulse p of the section s (n + 1) of the pulse s (n + 1) to the latch circuit 622 is blocked. The latch is stopped.
Therefore, the threshold L _s (n + 1) is not updated and is applied to the section s (n + 2), and the influence of the foreign matter pulse p on the threshold L _s is avoided. The foreign object detection signal R detected as described above and the latched peak value H _p data are both data processing unit 9
And the peak value H _p is converted into the size of the foreign matter and output to an appropriate output device.

The above description is for the first foreign matter detection unit 6A, but the second foreign matter detection unit 6B is different in the following points. That is, in the foreign matter detection unit 6B, since the foreign matter pulse p to be detected is projected downward, the comparison selection by the comparison circuit 611 of the peak value selection unit 61 is the selection signal when i _a > i _b contrary to the above. Q is output and the latch circuit 613 latches the waveform i _min having the minimum peak value. Further, by using a subtraction circuit in place of the adder circuit 631, in which the threshold L _s is created by subtracting the reference value K from the waveform i _min, the operation of other portions are the same as those described above.

[0013]

As described above, in the foreign substance detecting circuit for a color filter according to the present invention, the threshold L _s is set so as to avoid the influence of the foreign substance pulse and correctly follow the level change of the pattern waveform of each pixel. The foreign matter is detected without any mistake, and the accurate crest value H _p of the foreign matter pulse is obtained together with the foreign matter detection signal R, and the effect of improving the reliability of the color filter inspection for the color liquid crystal panel is great. There is something.

[Brief description of drawings]

FIG. 1 is a foreign matter detection circuit 1 according to an embodiment of the present invention.
The block block diagram of 0 is shown.

FIG. 2 shows a block configuration diagram of a first foreign matter detection unit 6A in FIG.

FIG. 3 is an explanatory diagram of a foreign matter detection operation of a foreign matter detection unit 6A.

4A and 4B show an example of a color filter 1, FIG. 4A is an explanatory view of a pixel 13 of three primary colors, and FIG. 4B is a sectional view of the color filter 1.

5 is an explanatory diagram of a foreign substance p existing in the color filter 1. FIG.

FIG. 6 is an explanatory diagram of the detection principle of the foreign matter detection optical system according to the patent application.

FIG. 7 shows an example of a foreign matter detection optical system according to a patent application.

8 (a) is an explanatory view of a test procedure of the color filter 1 in the foreign matter detecting optical system in FIG. 7, (b) is a pattern waveform i of each pixel included in the received signal, the foreign matter p _a, the p _b threshold L _a with respect to the pulse, an illustration of L _b.

FIG. 9 is a waveform diagram showing an example of level changes of the received light signals I ₁ and I ₂ .

[Explanation of symbols]

1 ... Color filter, 13 ... Pixel, 2 ... Angle projection, 3 ... Projection system, 31 ... Light source, 4 ... Light receiving system, 41 ... Imaging lens, 42 ... Half mirror, 43, 45 ... Spatial filter, 44 ... 1 CCD
Sensor, 46 ... Second CCD sensor, 6A ... First foreign matter detecting section, 6B ... Second foreign matter detecting section, 61 ... Crest value selecting section, 61
1 ... Comparison circuit, 612 ... OR circuit, 613 ... Latch circuit, 62
... Classification signal blocking unit, 621 ... AND circuit, 622 ... Latch circuit, 623 ... Phase inverter, 63 ... Detection signal unit 631 ... Addition circuit, 632 ... Comparison circuit, 64 ... Crest value calculation unit, 641 ... Difference circuit, 642 ... Latch circuit, 7 ... Differential signal generating circuit, 8 ... Reference value setting circuit, 9 ... Data processing unit, 10 ... Foreign matter detection circuit of the present invention, I ₁ , I ₂ ... Light receiving signals of first and second CCD sensors , I ... Pixel pattern waveform, i _max , _imin ... Maximum value, minimum value of pattern waveform i in section s, p ... Foreign matter or its pulse, T _s ... Classification signal, Q ... Selection signal, K ... Reference value , R ... Foreign matter detection signal, _Hp ... Crest value data.

Claims (1)

[Claims] 1. A light projecting system for dividing a surface of a liquid crystal color filter in which pixels of three primary colors are arranged into a plurality of regions S, and projecting a white light beam to the regions S, and reflected light of the regions S. Is divided by a half mirror, one of the divided specularly reflected lights is removed to receive the axially displaced reflected light, and the second CCD sensor to receive only the other specularly reflected light is divided. Equipped with a foreign matter detection light receiving system consisting of a CCD sensor,
A foreign matter inspection device for inspecting a foreign matter of the color filter, comprising: a first foreign matter detecting section and a second foreign matter detecting section to which respective light receiving signals of the first and second CCD sensors are inputted; and the respective foreign matter detecting sections. On the other hand, a division signal T for dividing each received light signal in the area S into a section s having an appropriate length.
division signal generating circuit for supplying a _s, and more becomes a reference value setting circuit for supplying a reference value K for the detection threshold L _s of the foreign substance, the first foreign object detector or the second foreign object detection section, said section A peak value selecting section that selects and outputs the maximum or minimum peak value from the pattern waveform of each pixel included in the light receiving signal of the arbitrary section s _{n divided} by the signal T _s , and each of the selected peak values. The reference value K is added to or subtracted from the peak value to obtain a threshold value L _s (n +) for the next section s (n + 1).
1) is created, the threshold value L _s (n + 1) is compared with the light receiving signal in the section s (n + 1), and a detection signal for outputting a foreign matter detection signal R when the pulse of the foreign matter is detected Section and a peak value calculation for calculating a difference between the received light receiving signal and each of the selected peak values and outputting the difference at the time of outputting the foreign object detection signal R as a peak value H _p of the foreign object pulse. And a section signal blocking section which is provided on the output side of the peak value selecting section, blocks the section signal T _s by the foreign object detection signal R, and temporarily stops the update of the threshold value L _s . A foreign matter detection circuit for a color filter, comprising: