JPH0389329A - Light emission controller for camera - Google Patents

Abstract

PURPOSE:To accomplish appropriate TTL dimming in light emission by detecting a brightness state and classifying a field by a field classifying means, extracting the area of the field where high brightness is present thereon from the photometry of ordinary light when the field is classified as the bright one and cutting the area at the time of performing the dimming in regular light emission. CONSTITUTION:The field is classified by the field classifying means 22. When the field is classified as the bright one, the area where the high brightness is present thereon is extracted from the photometry of the ordinary light and the area is cut or weighted to be low at the time of performing the dimming in the regular light emission. When it is classified as the dark one, preliminary light emission is performed by a flashing means 33 and the photometry of the reflected light is performed to detect the reflectance distribution of the field and the area considered as the one which has an adverse effect on the TTL dimming is extracted and the area is cut or set weighted to be low at the time of performing the dimming in the regular light emission. Thus, the appropriate flash light emission is performed all over the area from the bright area to the dark area.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light emission control device for a camera.

[Conventional technology]

FIG. 7 is a diagram showing the configuration of a conventional camera.

Conventionally, this type of camera has had a configuration as shown in FIG. First, to explain the state when observing the camera's viewfinder, the light flux (in this case, steady light) that has passed through the photographic lens structure 2 is reflected by the mirror 4 (in this case, the dotted line position) of the single-lens reflex camera body l, and is reflected on the screen. 5. Pentaprism After passing through the prism 6, a portion is guided to the eyepiece 7,
The other part is arranged so as to pass through the condenser lens 8 and be guided to the first photometry means 9.

Next, the state of the camera during photographing operation will be explained. For example, when performing strobe photography against backlight on a clear day, the light emitted from the flash unit 3, reflected back to the subject, and the steady light both pass through the photographic lens structure 2, and then 4 reaches the film surface 11 because it is retracted to the position indicated by the solid line. The reflected light and the constant light are reflected by the film surface 11, pass through the condenser lens 12, and are guided to the second photometric means 13.

[Problem to be solved by the invention]

Conventional cameras as described above have the following problems in dark situations such as at night, even when the angle of view of the photographic lens and the distance to the main subject are the same, for example when the main subject is a person. In other words, ■ the percentage of the screen occupied by the person differs due to differences in the number of people or the composition, ■ the distance from the person to the wall in the background varies indoors, ■ there is a wall in the background, or If the background is a landscape, there will be a blank area, or if the background situation is different, ■ If there is a difference in the screen where there is a highly reflective area, such as a wedding cake or a gold folding screen, etc. However, due to these different conditions, there was a problem in that the amount of light emitted in TTL dimming control varied.

In addition, in bright conditions such as during the daytime, for example, if a very bright object such as the sun enters a part of the screen, if TTL dimming is performed using the second photometry means, the amount of light by the flash means 3 will be reduced. There was a problem in that the main subject was underexposed due to insufficient exposure.

This is because the TTL light control method simultaneously measures the light emitted from the flash unit 3, reflected back to the subject, and the ambient light, and detects that the amount has reached a predetermined amount. Since the principle is to stop the light emission of the flash unit 3, if a high-luminance object enters a part of the screen and the steady light component increases, the amount of light emitted by the flash unit 3 will be reduced accordingly! :,
This is because they will be controlled.

In view of the problem that the conventional TTL adjustment method is greatly affected by the subject to be photographed and its background, the present invention solves this problem and provides a light emission camera capable of TTL light adjustment that can always perform appropriate light emission. The purpose is to provide a control device.

[Means to solve problems]

The light emission control device for a camera according to the present invention is a flash light that causes the flash unit to selectively perform main light emission for exposure and preliminary light emission for detecting the brightness state of the object field before the main light emission. a control means and a light control device having a separate light control device, a light control device for controlling the light emission of the flash device based on the output of the light control device, a light measurement device for photometering a field, and using the output of the light measurement device. a field classification means for classifying the brightness state of the field into at least a first state and a second state; and a field classification means that classifies the brightness state of the field into the first state. When classified, the flash control means prohibits preliminary light emission by the flash flash means, and weighting processing is performed on the output of the divisional light control element based on the photometry means, When classified into states, the flash control means causes the flash control means to perform preliminary light emission by the flash light control means and, based on the result, performs a weighting process on the output of the divisional light control element.

[For production]

In the present invention, the field classification means classifies the field by detecting its brightness state, and when the field is classified as bright (first state), the photometry of the ambient light is performed. Since the area of the object where high brightness exists is extracted from the image, and that area is cut or given a low weight when the main flash is dimmed, the control means can realize TTL dimming operation of appropriate light emission. .

In addition, in bright scenes, the aperture becomes small when shooting, and the ratio of the flash to the steady light also decreases, making preflash metering difficult in terms of light quantity. However, using the above method, you can shoot bright scenes without preflash It is possible to solve the problems in

Next, the field is dark according to the field classification means (second state)
When it is classified as such, a preliminary flash is emitted by the flash unit, and the reflected light is photometered to detect the reflectance distribution of the object field. We have extracted the area of the subject that is considered to have a negative effect on the TTLIIg light operation, and cut that area or set it to a low weight when the main flash of the flash unit is adjusted. However, the flash control means realizes a TTL dimming operation that enables appropriate light emission control.

In this way, the camera automatically classifies the subject using the subject classification means and automatically selects whether or not to fire a preliminary flash. The flash mode is automatically switched to the preliminary flash mode, and appropriate flash light is emitted over the entire range from bright to dark areas.

〔Example〕

FIG. 1 is a block diagram of a camera according to the invention. The light receiving element (first photometric means) 21 is composed of five regions 21a to 21e, and when the flash means 33 does not emit light, it divides the field into five regions and outputs each photometric value. The arrangement in the camera is approximately the same as the first photometric means 9 in FIG. 7.

The five outputs of the light receiving element 21 are input to the field classification means 22. This field classification means 22 classifies the field into two patterns: "bright J" and "dark". The details will be described later using FIG. 2.

The calculating means 23 determines the degree of weighting during TTL dimming (main light emission) according to an algorithm described later with reference to FIGS. 3 and 4, and outputs it to the weighting dimming circuit 31.

Further, from the five outputs of the light receiving element 21, an appropriate exposure value is calculated by the calculation means 23 and sent to the exposure control means 27, where the shutter 28 and the aperture 29 are controlled.

Further, the light receiving element (second photometric means) 30 also includes 30a to 3
It is composed of five areas of 0e, and when the flash unit 33 emits light, the reflected light from the object is measured by dividing the object into five areas. The arrangement of the camera is as shown in Figure 7.
The position is approximately the same as that of the photometric means 13. This light receiving element 3
0 is arranged so that the field divided by these five areas corresponds to the field divided by the five areas of the light receiving element 21.

The flash means 33 is controlled by the flash control means 32,
Performs preliminary flash and main flash.

Next, the operation will be explained in detail using FIGS. 2 to 5. 2 shows an example of the algorithm of the field classification means 22, FIGS. 3 and 4 show examples of the algorithm of the calculation means 23, and FIG. 5 shows an example of the weighting dimming circuit 31. and,
Each of the above means is controlled by a microcomputer.

First, referring to FIG. 2, the operation of the object scene classification means 22 will be explained. When the release button 24 is turned on in step Sl (hereinafter "step" is omitted), the process proceeds to S2, where each brightness value B V m (n =
1 to 5) are read.

Then, in S3, the average brightness value Σ BVn BM= is calculated from them. In S4, it is determined whether the average brightness value BM is 7 or more. If BM≧7, the process goes to Sll, and if BV<7, the process goes to S31.

Next, when the brightness state of the field is determined by the field classification means 22 as described above, the calculation means 23 performs the control shown in FIGS. 3 and 4 based on the determination.

FIG. 3 shows the case where the process proceeds to Sll.

In S12, the initial value of nsM is set to 0, and in 813, n=n+
Set to 1.

Then, in S14, BV and 11'8 (Bv) are compared. When BY≦11'8 (BV), the value is set to P and 1 in S15, and M-M+1 is set in S17.

This M represents a number not exceeding 11'/s with a BV of 511.

BV, >11'/s (BV) (S 16 TeP at D time.

−〇. Then, in 31B, the above S until n exceeds 5
Repeat the routines 13-818.

If n exceeds 5, compare M and 5 at 319, and if M-5, there is no ultra-high brightness output exceeding 11'/s (BV) in (7). , as is S
The process advances to large luminance difference blocks consisting of S21 to S24.

When S　l　9teM+5(1), BY, 11v.

Since this is a case where there is one or more ultra-high brightness outputs exceeding (BV), the process advances to S20 and the degree of weighting is determined. In S20, the calculations -P, /M are performed, and 11
The weighting corresponding to the photometry area that outputs ultra-high brightness exceeding '/s (BV) is O.

-0, weighting corresponding to other areas is D, , -1
/ (number of regions exceeding l l l/3 (BV)). This result is then sent to S25.

In a large luminance difference block consisting of 521-824, 521
The maximum brightness difference between the 5 outputs Δ Δ−MAX (BV, ) − MIN (BV, ) h< is calculated, and Δ and 3 are compared in S22. When Δ is less than 3, that is, when the maximum brightness difference Δ is small, , the process advances to S24, where the degree of weighting is set to 5, which is -115, and is sent to S325. Further, when Δa3, that is, when the maximum luminance difference Δ is large, the process advances to S23, and the maximum luminance (B
Y, -MAX) i: corresponding weighting degree, -
1/10), the degree of weighting corresponding to the minimum luminance (BY, -MIN) is 3/10, and the degree of weighting corresponding to the remaining three outputs is -2/10, then 325 send to

In S25, the above-mentioned weighting degree 8 is calculated, and the corresponding voltage value E is set to E, and the weight K (1-D,)E.

Calculated according to the formula: Note that here, K is a value corresponding to the ISO information and is input from S26.

Further, E is a predetermined constant voltage, the details of which will be explained in FIG. 5.

FIG. 4 shows a case where the field is classified as dark by the field classification means of FIG. 2 and the process proceeds to S3L.

Proceeding to step 332, the mirror 4 (FIG. 7) is moved up and the aperture 29 is stopped down to the photographing aperture. Moshite S33
Then, the flash unit 33 emits a preliminary light, and the light reflected from the subject due to the preliminary light is transmitted to the photographic lens 2 (see FIG. 7).
, is reflected by the shutter curtain surface 10 (Fig. 7), passes through the condensing lens 12 (Fig. 7), and is reflected by the photometric means 13 (Fig. 7).
The light reaches the light receiving element 30 located at the position shown in the figure. The element surface of the light-receiving element 30 is divided into five areas 30a to 30e, and photometry is performed by dividing the field into five areas.

In S34, an integral amount C7 corresponding to the photometric output of each photometric area of the light receiving element 30 is determined.

In S35, the reflectance distribution R of the object field is calculated using the following formula (% formula %) Detected as .

Between S36 and 342, the reflectance distribution R1 (n-1 to
5) Extract a photometric region with a very high value (R, >0°8) and a photometric region with a very low value (R, <0.1), and cut them. This is because in the photometry region where the reflectance distribution R1 is very high, it is thought that there is something in the background of the main subject (person), such as a gold folding screen or a white wall, that adversely affects the TTL adjustment. Also, the reflectance distribution R
The photometric area where 1 is very low is, for example, the main subject (person).
The reason for this is that the background of the image may be a landscape or something that is omitted, and this is also considered to be a factor that adversely affects TTL dimming.

When a cut is made, the reflectance distribution R of the cut area
(nm1-5) is replaced with O and no longer contributes to subsequent calculations.

In S43, the reflectance distribution R1 (n=1~
5), the weighting amount D0R1D, tsu(nx1~5)ΣR11 is calculated.

Next, proceed to step 344 and S45, and perform the weighting described above.
Voltage E.

E, -K (1-D,')E.

, and outputs it to the weighting dimming circuit 31. Note that here, K is a value corresponding to ISO information, 81
It is input from 4. Further, E is a predetermined constant voltage, the details of which will be explained in FIG. 5.

The voltage E corresponding to the weighting amount is the weighting dimming circuit 3.
1, in S46, the flashing means 3
3, the main light emission is performed. At this time, main mirror 4 (
Figure 7) shows the mirror up, and the aperture 2 of the lens.
9 is also narrowed down to the shooting aperture value. The reflected light from the subject of the main light emission passes through the lens 2 (Fig. 7), is reflected by the film surface 11 (Fig. 7), passes through the condenser lens 12 (Fig. 7), and then passes through the lens 2 (Fig. 7). The light reaches the light-receiving element 30 placed at the position of the light-receiving element 13 . The light receiving element 30 includes 30a~
It is divided into five areas of 30e, and the light reflected from the main light emission from the subject is divided into the five areas and dimmed. Note that the shape of the division of the field by the light-receiving element 30 is approximately the same as the division shape of the field by the light-receiving element 21.

In S47, the reflected light divided and measured by the light receiving element 30 is sent to the weighting dimming circuit 3! is weighted and integrated. Then, when the sum of the integral amounts of the five regions reaches a predetermined amount, a light emission stop signal is issued, and the light emission of the flash means 33 is stopped via the flash light control means 32, and the process proceeds to 848 and ends.

Next, a circuit diagram of the weighting dimming circuit 31 will be explained using FIG.

When light hits the five photodiodes 30a to 30e that laterally diaphragm the second photometric means 30, a potential corresponding to the amount of light is output from the OP amplifiers 35a to 35e and applied to the bases of the transistors 37a to 37e. Then, Vcc4
0 through the capacitor 39, the amount of which changes depending on the potentials of the variable power supplies 38a to 38e. The potentials of the variable power supplies 38a to 38e are set by the voltage values E and l outputted from the CPU section 23a of the arithmetic means 23 via the D/A converters 23b to 23f. For example, when the 21a portion of the first photometric means 21 is BY=1
When the brightness exceeds 1'/s, DI-0 becomes DI-0, and El
is set to a large value. Then, the transistor 37a
The collector current flowing into the capacitor 39 becomes smaller.
This means that it does not contribute much to the accumulation of charge. The comparator 42 outputs a light emission stop signal to the flash control means 32 when the potential on the non-inverting input terminal side exceeds the reference potential on the inverting input terminal side. The fact that it does not contribute means that a low weight is given to the output of the photodiode 30a, and the influence of ultra-high brightness is eliminated. The photodiodes 30b to 30e include 34a as shown in the figure.
The same circuit as that consisting of .about.38a is attached to each circuit, and each circuit is connected to a capacitor 39 by integrating the collector of a transistor 37. Therefore, the output of the photodiode in the highly weighted photometric region contributes to the accumulation of charge in the capacitor 39, and dominantly determines the timing of output of the light emission stop signal.

FIG. 6 is a diagram showing an example of a combination of element patterns of the first and second photometric means. Case l is the same as the embodiment shown in FIG. 1, and when the shaded area 21b has super high brightness, if the weighting of the output of the corresponding shaded area 30b is lowered, that is, the output of the photodiode 30b is of,
This indicates that it is sufficient to reduce the contribution of the flash device to the dimming operation. Alternatively, the influence of the shaded portion 21b may be removed by prohibiting the output of the photodiode 30b.

In case 2, the first photometric means is a 5-segment type, whereas
The second photometric means is of a two-part type, and only the central portions 43a and 44a correspond to each other. In this case, either of the peripheral parts (
For example, when 43b) has super high brightness, the degree of weighting of the entire peripheral portion 44b is lowered during TTL dimming. Such a combination is useful when the photometric optical system of the second photometric means cannot divide the field of view very accurately.

Case 3 is an example in which the first photometry means is not of the split photometry type, and when the first photometry means detects ultra-high brightness, the degree of weighting of the peripheral area 46b where the probability of the main subject being present is low. This indicates that the

In case 4, the first photometric means is of a five-segment type, whereas the second photometric means is of a three-segment type.

When part 47b detects ultra-high brightness, the surrounding sky side 4
This indicates that all of 8b are weighted to a low degree. When the photometric optical system on the second photometric device side looks at the film surface from a considerably oblique position, as shown in Figure 7, this combination allows the field of view to be accurately viewed in the vertical direction. It is effective in cases where it is difficult to accurately divide the image in the left and right directions.

Although embodiments of the camera according to the present invention have been described above with reference to the drawings, the present invention should not be interpreted as being limited to the above embodiments, and can be modified and improved as appropriate without departing from the spirit thereof. Of course it is.

〔Effect of the invention〕

In the present invention, the field is classified by the field classification means, and when the field is classified as bright, the area where high brightness exists is extracted from the photometry of the constant light, and the main flash is emitted. At the time of dimming, that area is cut and given a low weight, so that appropriate TTLIi light emission can be achieved. In addition, in bright scenes, the aperture becomes small when shooting, and the ratio of the flash to the steady light also decreases, making preflash metering difficult in terms of light quantity. However, using the above method, you can shoot bright scenes without preflash It is possible to solve the problems in

Next, when it is classified as dark, preliminary light is emitted by the flash means, and the reflected light is photometered to detect the reflectance distribution of the field. We have extracted the area that is considered to have a negative effect on the TTLIm light by monitoring the main flash, and when controlling the main flash, we have cut that area or set it to a lower weight, so we can achieve the appropriate TTLII light emission here as well. be done.

In this way, the camera automatically classifies the subject using the subject classification means, and automatically selects the weighting method for light control from the constant light method and the pre-flash method. Appropriate flash light is emitted over the entire area from dark to dark.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a camera according to the present invention. FIG. 2 is a flowchart showing an algorithm executed within the object scene classification means of FIG. 3 and 4 are flowcharts showing algorithms executed within the calculation means of FIG. 1. FIG. 5 is a detailed circuit diagram of the weighted dimming circuit of FIG. 1. FIG. 6 is a diagram showing an example of a combination of element patterns of the first and second photometric means. FIG. 7 is a sectional view showing the configuration of a conventional camera. [Explanation of symbols of main parts] 21...First photometric means, 22...Scene classification means, 23...Calculating means, 30...・Second photometry means, 31... Weighting dimming circuit, 32... Flash 1IllII+ means, 33...
...Flash means.

Claims (4)

[Claims] (1) Flash means; Flash control means for causing the flash means to selectively perform main light emission for exposure and preliminary light emission for detecting the reflectance distribution of the object field before the main light emission. A light control means having a divided light control element and controlling the light emission of the flash means based on the output of the light control element; A light measurement means for photometering a field; a field classification means for classifying the brightness state of the field into at least a first state and a second state; the field classification means classifies the field into the first state; When classified, the flash control means prohibits preliminary light emission by the flash flash means, and weighting processing is performed on the output of the divisional light control element based on the photometry means, The present invention is characterized by comprising control means for causing the flash control means to perform preliminary light emission by the flash light means and weighting the output of the divided light control element based on the result. Camera light emission control device. (2) The light emission control device for a camera according to claim 1, wherein the photometry means is of a split photometry type. (3) If the output of the photometric means is in a BV value region including at least a value of BV7, the field classification means
2. The camera light emission control device according to claim 1, wherein the camera light emission control device determines that the state is in the second state, and in any other state, the second state is determined. (4) The object field classification means performs classification using an average value of two or more brightness values from among a plurality of brightness values that have been subjected to split photometry. Camera light emission control device.