JPH01180189A - Image pickup device - Google Patents

Abstract

PURPOSE:To suppress the effect of a faulty brightness part onto the entire pattern with respect to an object including partially the fault bright part and to obtain an image pickup signal with proper exposure by blocking the input to an arithmetic means of a relevant exposure evaluation circuit when an exposure evaluation value includes a value larger or smaller than the permissible range with respect to a reference value. CONSTITUTION:Arithmetic circuits 10a-10f as an evaluation value detection means of an image pickup device output a brightness level of an image pickup video signal subjected to A/D conversion 6 in plural separated sampling areas on the pattern by the switching means 8 as the exposure evaluation value for each area. The evaluation value is given to error discrimination means 11a-11f, it is compared with a reference value of a reference memory 16 to apply weighting in the permissible range due to the difference of the both. The sum of the evaluation values subject to weighting is obtained by a mean value calculation means 12 and an aperture mechanism and its variable gain amplifier 5 are controlled so that the output is made coincident with the value of the object memory 18 set in advance.

Description

[Detailed description of the invention]

A] Field of Industrial Application The present invention relates to an imaging device such as a video camera having a lens diaphragm mechanism. 1. Prior Art In imaging devices such as video cameras, exposure adjustment, which is achieved by controlling the optical aperture of a lens or the like and the amplification factor of a one-handed amplifier that amplifies the level of the captured video signal, has been widely praised. However, this method has a problem in that the main donor cannot obtain appropriate brightness when the m-plane includes a high-luminance area such as a light source or when the background is very dark. To solve this problem, an exposure compensation method has been proposed that takes advantage of the fact that the main subject is placed in the center of many screens. For example, JP-A-62-11
Publication No. 0369 (HO4NS/243) discloses that the screen is divided into two areas, a central area and a peripheral area, and the signal level of the captured video signal in each area is detected as an evaluation value, and the evaluation value of the edge area is calculated. By weighting the evaluation value of the central region (l: 0 in the extreme case) and controlling the aperture amount of the lens and the amplification gain of the captured image No. 16 according to the ratio of both evaluation values. , a technique is disclosed to increase the contribution of the central region to the exposure decision. (/9 Problems to be Solved by the Invention According to the above-mentioned prior art, optimal auto-iris operation is performed in response to changes in the brightness of the entire screen, but for example, when a high-brightness part enters only the central area. Or, if only the peripheral area contains an extremely bright subject such as the sun, it is inevitable that the aperture will increase, the gain will decrease, and the main subject will not be bright enough. Ninth Means for Solving the Problem The present invention provides a plurality of 11 screens divided on the screen! evaluation value detection means for outputting the luminance signal level of each imaged video signal in the sampling areas of l as an exposure evaluation value for each area; a calculation means for calculating the sum of the exposure evaluation values; In order to match the set target value,
and an exposure adjustment means for controlling the aperture amount of the lens or the amplification factor of the captured image signal, and when the exposure evaluation values include those that are larger than or smaller than the allowable range with respect to the reference value, it is applicable. The method is characterized in that input of the exposure evaluation value to the calculation means is inhibited. (E) Function Since the present invention is configured as described above, it is possible to suppress the contribution of the luminance signal level of the area including a special object such as a light source to the exposure determination of the entire screen. (f) Examples Examples of the present invention will be described below according to the ninth page. FIG. 81 is a circuit block diagram of the first embodiment. (1) an α lens, (2) a mechanical diaphragm 'a<exposure adjustment means), (3) an imaging device composed of a C0D (solid-state image sensor), and (4) a preamplifier. Lens 11)KThe incident light from the subject is adjusted by the aperture mechanism <21, the photoelectricity of which is adjusted, and then photoelectrically converted by the imaging device (3) to form an imaged video signal. Output. This imaged video signal is serially taken out by horizontal and vertical scanning, amplified with a predetermined gain by a preamplifier (41), and then applied to a variable gain amplifier (B output adjustment means) (5) at the subsequent stage.
The A/D conversion circuit (6) and the synchronization separation circuit convert it into a total value, which is selected by the switching circuit (8) and input to the next calculation circuit. The synchronization separation @J path (7) separates the vertical and horizontal synchronization signals from the imaging video signal, and the subsequent switching control circuit (9) is used to control both synchronization signals and the imaging device (3). The switching circuit (9) is controlled based on the notes, and the sampling area (A) is divided as shown in Figure 2.
a) Switch corresponding to (Ab)...(Af). B.I.
] Then, the A/D conversion value of the imaged video signal in area (Aa) is sent to the integration circuit C10 &) in the same way as area (Ab) (Ac
) (Ad) (Ae) (Af) are integrated into the integration circuits (10b) (10e) (lod) (10e) (1
0f) and integrated manually. It should be noted that each of the integration circuits is composed of an arithmetic unit that adds a new A/D conversion value and the output of a latch circuit at the subsequent stage, and a latch circuit that latches the addition result. In this way, +II calculation route (FF value detection means) (10&
) (10b) - (10f) respectively σ area (Aa)
The luminance signal level of the captured video signal for l fields corresponding to (Ab) . . . (Af) is held as a digital value. This digital value is called an exposure evaluation value for each template area. Incidentally, since all of the integration circuits are reset at the vertical synchronization signal, the integration is always performed for one field. The above integration results are input to the respective abnormality discrimination circuits (weighting is a reduction means) (lla) (llb) - (llf), and if there is a high brightness area such as a light source or a low brightness area such as a deep green area within the corresponding sampling area. It is determined whether or not there is an abnormal brightness part such as the part, and if it exists, the input to the subsequent average value calculation circuit (calculation means) α is blocked. Specifically, as shown in Figure 3, this abnormality discrimination circuit (lla) is comprised of a measurement output path 13a), a comparison circuit (14 and 14), a gate circuit (15a), and a VC circuit. The exposure evaluation value (L, a) from (10a) is calculated by the density calculation circuit (13a) in the corresponding sampling area (
Density (Da) at area C8&) of Aa) LJL/SJ
Calculate L, store this in advance in the reference value memory 〇61, compare it with the nine criteria II (PJ, and if the difference between the two is within the allowable range, open the subsequent gate circuit (15a),
If the permissible range is exceeded, or if there are abnormal brightness areas such as high brightness areas such as light sources or low 4 degree areas such as deep green areas only within the corresponding sampling area, the density (Da) will be set to the standard value [
F] Since it is extremely large or small compared to K, the gate circuit (15a) is closed, and passage of the exposure evaluation value CL& from the integration circuit (101) is blocked. The abnormality determination circuits (llb), (lie), . . . (llf) also have the same configuration as the abnormality determination circuit C1l&). However, the area of each sampling area is set in advance and is not necessarily the same. The average value calculation circuit σ4 is a gate circuit (15&) (15b
)... 7I21.4) - Calculate the average value per unit area of the exposure evaluation value for each sampling area and the average value of the part density. For example, if we consider a case where there is an abnormal brightness part such as a light source only in the Templing area (Ac), only the exposure evaluation value (Sc) is blocked in the abnormality determination circuit (lie), and the average value calculation circuit α4 is Exposure evaluation value (LA) (
Lb) (Ld) (Le) (Lf) are input, and the sum (LX) of these exposure evaluations 11 is determined as the sampling area (A a ) that was not determined to be abnormal by the abnormality determination circuit.
The sum of the areas of (A b ) (Ad) (Ae) (Af) (S
X) T is divided and the ratio value is calculated as an average value (N1). This average value (N) is input into the comparison circuit aD and compared with the target value (Q) stored in advance in the target value memory α&. ,
The error signal corresponding to the difference between the two is a variable gain amplifier (5)
and is input to the input value σ3. Based on this error signal, the drive circuit α9 drives the iris motor etc. to operate the aperture mechanism (2) and aperture! 7t
The variable gain amplifier (5) is operated based on the error signal so that the average value approaches the target value. In this way, when an abnormal brightness portion exists in some area, automatic iris adjustment can be performed while eliminating the influence of this abnormal component. Next, a second example 711h will be explained with reference to FIG. Incidentally, the same parts as in the first embodiment are given the same reference numerals and the explanation thereof will be omitted, and the sampling area is divided into five parts at the center and the periphery as shown in FIG. The stage up to the stage before the switching circuit (8) is the same as the first embodiment,
The switching control circuit (9) controls the sampling area (Ag
) (Ah) (At) (Aj) (Ak) The respective exposure evaluation values (mug) (Lh) (Ll) (Lj) (Lk) are integrated into the integration circuit (10g) (10h) (10f) (10j) (10k
)! Output. Next, the exposure evaluation value (Lg) of the central sampling area (Ag) is divided by the area (Sg) of the area (Ag) in the density calculation circuit (■), and the density (Dg) is divided by the area (Sg) of the area (Ag).
) is calculated and further compared with the reference value 0 of the reference value memory 11B in the ratio IIR circuit, and based on the comparison result, the subsequent switching circuit! 211 switching control is performed. 5-μchi,
If the density (Dg) is within the allowable range with respect to the reference value [F]K, it is assumed that no abnormal brightness portion exists in the area (Ag), and the fixed contact (21b) ijt! Instead of IKgJ, the density CDg) is input to the comparator circuit α, and is compared with the target f[(Q), and as in the first practical example, this comparison result is output as an error signal.
Used for door iris operation. In addition, if the density (Dg) is larger or smaller at the end than the reference value 0, the switching path 1 +211 is connected to the fixed contact (21
cllll, and the comparison circuit (17) Krs and the output of the average value calculation circuit fi3 are input. The average value calculation circuit I is the average value calculation circuit α of the N1 embodiment.
1 integration circuit (10h) (lot) (10j)
(10k) K integrated sampling area (Ah) (
Exposure evaluation value (Lh) (Ll) of Ai) (Aj) (Ak)
(In the Lin (L, k), the abnormality determination circuit (11h)
111](llj)(llk) excluding the area containing the abnormal brightness portion, and calculates the average density l1l(N2) in the same manner as in the first embodiment. Follow. If there is no abnormal brightness area in the central sampling area (Ag), priority is given to the exposure evaluation value (Lg) of this area (Ag), and if there is an abnormal brightness area in the surrounding area, priority is given to the exposure evaluation value (Lg). The average value of the evaluation values per unit area of the area without is used for auto iris operation. In addition, regarding igJ works below comparison @U circuit n! This is the same as the first embodiment. Next, a third embodiment will be described with reference to FIG. The method of setting the sampling area is the same as in the second embodiment, and the same parts as in FIG. The comparison output of the comparison circuit Ω executes the switching control of the switching circuit (weighting is a reducing means) @■. That is, the exposure evaluation value (Ll) of the central sampling area (Ag) is ai * 1
11 (E'), move the movable contact (24&) (25J11) to the fixed contact (24b).
(25b) Fix it to @, input the exposure evaluation value (Lf) to the average value calculation circuit t43, and at the same time input the exposure evaluation value (muh) (Li) (Lj) (Lk) of other Templing areas.
), respectively, are integrated L! ! Circuit (10h) (101) (lo
j) (lok) The average value (N3) of the exposure evaluation values per unit area of the entire area is calculated by inputting it to the F average value calculation circuit, and is compared with the target value in the comparison circuit. In addition, if it is determined that the exposure evaluation value (Lg) C) density (Dg) of the central sampling area (Ag) is within the allowable range with respect to the reference value 0, the movable contact piece (24&)
(25a) is a fixed contact (241 (25C) flKW), and the evaluation value of the central sampling area (Ag) is weighted in the circuit (to) and input into the hole diameter to the average value calculation circuit I. For weighting, the circuit ■ is 1, for example, the input digital value is 2
It is a multiplication circuit that multiplies and outputs the multiplication signal. Therefore, if there is no abnormal brightness area in the central ten-ring area (Ag), weighting is performed with more emphasis on this center than on the periphery, and the abnormal brightness area is (Ag), exposure evaluation 11 [(
It is possible to reduce the influence of the automatic iris operation caused by the automatic iris operation. Note that the average value calculation circuit corresponds to the average value calculation circuit σ2 of the first embodiment, and the following four functions and operations are the same. Next, a fourth embodiment will be described with reference to jN71k. In this fourth embodiment, the integration circuit (lOg)...
・The exposure evaluation values of each sampling area held in (10k)K are all input to the average value calculation circuit QK, and the average exposure evaluation value per unit area for each sampling area [(Ml) is calculated, and this average The value is input as a reference value during the comparison circuit, and the exposure is evaluated using this comparison circuit! 1
1 (Lg) per unit area of the sampling area (Ag), that is, the density (Dg), and based on the comparison result, switching control of the subsequent switching circuit □□□ is performed. That is, v! ! ! If the degree (Dg) is within the allowable range with respect to the average value (M1), the movable contact piece (38a) is fixed to the fixed contact (38b) and the first target value memory (to) K
The first target value (R1) stored in advance is the comparator circuit C3.
9 as the target value, and the density (Dg) is set to the average value (M
l) If the value exceeds the allowable range, the movable contact (381) is switched to the fixed contact (38b), and the second target value (R2) stored in advance in the second target value memory can is compared. The density (D3) is input to the circuit (to) and the density (D3) is the average value (M
1], it is possible if it is smaller than the allowable range.
Replace the J contact piece (38a) with a fixed contact (38d), and connect the third
The third target value (R3) previously stored in the target value memory C (7) is input to the comparator circuit (2). ) has R2<R1
<R3 holds true. Also, the weighting of the exposure evaluation value (Lg) is doubled in the circuit diagram, and the exposure evaluation value (Lh) of other sampling areas...
- The average value of the exposure evaluation values per unit area in each sampling area is input together with (Lk) to the average value calculation circuit 53

[M2] is calculated and compared with any one of the first to M3 targets described above in a comparison circuit (2). Therefore, in this fourth embodiment, the reference value 0 and the target value (Q), which were always fixed in the previous embodiments, change depending on the situation.In addition, there are no abnormal brightness areas on the screen. In this case, the comparison low and low outputs have an average density ff (Dg) of 1 shift (
The first target value memory (R1) is selected as being within the allowable range for M1], while the average value calculation circuit 63 calculates a weighted average value of only the first evaluation value (Lg) of the central sampling area (Ag). (M2) and comparator circuit (3
9 compares the two, issues an error signal, and executes an auto-iris operation. For example, if the light intensity of the entire Im surface increases from this state, both inputs of the comparison circuit (to) will increase by the same amount, so that the switching circuit C! 8th stile 1st target value (R1)
However, since the average +1 (M2) increases, 1Ml
The difference between the target value (R1) and the average value (M2), that is, the error signal, increases, and the aperture amount increases.Next, there are extremely low brightness areas such as deep green only in the central sampling area (mug). If the average @[(M2)
When the density (Dg) decreases significantly compared to , and exceeds the allowable range, the switching circuit Ω selects the prefecture 2 target value (R2). On the other hand, although the average ([L(M2)) decreases, since the second target value (R2) is set smaller than the first target value (R1), the error signal does not increase significantly.Similarly, When an extremely bright area such as the sun exists only in the central sampling area (Ag), if the density CDI) increases significantly compared to the average value (Ml) and exceeds the allowable range, the switching circuit will Select the third target value (R3). On the other hand, although the average value (M2) increases, the error signal does not increase significantly because the third target value (R3) is set larger than the first target value (R1). Even if there is an abnormal brightness area only in the sampling area (Ag), the target value will change accordingly, the error signal will not change significantly, and the influence of the abnormal brightness area will be suppressed. Example comparison circuit C3!]
corresponds to the comparison circuit 03 of the first embodiment, and the following configuration and operation are the same. As described above, in the ml example, the exposure evaluation values are weighted 0:1 for areas where abnormal brightness parts exist and areas where there are no abnormal brightness parts. A method is adopted in which the 11 existing areas are completely ignored, and in the second embodiment, priority is given to the central area. Furthermore, in the third implementation flJ, a method is adopted in which the first exposure evaluation of the central area is weighted with respect to the surrounding areas depending on whether or not there is an abnormal brightness portion in the central area. In the fourth embodiment, by changing the target value depending on whether or not there is an abnormal brightness part in the central area, the amount of weighting of the exposure evaluation value in the central area is changed in a chain manner. . Furthermore, each of the circuit blocks in this example! It goes without saying that If'F: can be processed by software using a microcomputer. Furthermore, in the above-mentioned embodiment, when comparing with the reference value or target value, the exposure evaluation value per unit area of the sampling area is used, but the amount per unit area is set as the reference value and target value. ,
Multiply the area of the corresponding Nangling soil! It may also be compared with the direct exposure evaluation value. It is possible to obtain a captured video signal with strict exposure while suppressing the influence on the image as much as possible.

[Brief explanation of the drawing]

Figure 1 is all related to the present invention, Figure 1 is a block diagram of the conduit embodiment, Figure 2 and Figure 5 are division diagrams of the sampling area, and Figure 3 is a block diagram of the main circuit of Figure 1. , Figure 4 is N
The circuit block diagram of the second embodiment, the sixth factor is a circuit block diagram of the third embodiment, and FIG. 7 is the circuit block diagram of the fourth embodiment.

Claims (4)

[Claims] (1) Evaluation value detection means that outputs the brightness signal level of each captured video signal in a plurality of sampling areas divided on the screen as an exposure evaluation value for each area, and calculating the sum of the exposure evaluation values. a calculation means; and an exposure adjustment means for controlling the aperture amount of the lens or the amplification factor of the captured video signal so that the output of the calculation means coincides with a preset target value; An imaging apparatus characterized in that when an exposure evaluation value that is larger than or smaller than a reference value by more than an allowable range is included, input of the corresponding exposure evaluation value to the calculation means is blocked. (2) If the exposure evaluation value of the area at the center of the screen in the sampling area is within the allowable range with respect to the reference value, only this exposure evaluation value is used by the exposure adjustment means instead of the output of the calculation means. 2. The imaging apparatus according to claim 1, wherein the image capturing apparatus inputs the information to the user. (3) If the exposure evaluation value of the area at the center of the screen in the sampling area is within an allowable range with respect to a reference value, weighting is performed only on this exposure evaluation value. The imaging device according to scope 1. (4) Depending on the relationship between the exposure evaluation value of the area at the center of the screen in the sampling area and the reference value,
The imaging device according to claim 1, wherein the target value is changed.