JP3387573B2 - Imaging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus such as a video camera, and more particularly, to control a light according to the illuminance of a subject and the control state of the image pickup apparatus to obtain a proper exposure. The present invention relates to an imaging device.

[0002]

2. Description of the Related Art Conventionally, when a proper light exposure cannot be obtained due to a shortage of light quantity, a method of performing exposure control using a light so that an output signal amplitude of an image pickup device has an appropriate value is disclosed in, for example, Japanese Patent Laid-Open No. It is disclosed in JP-A-2-241276.
Further, in the conventional image pickup apparatus, the brightness information is used to determine whether or not the light is emitted. When the light is emitted, the aperture is different from the normal control mode for lighting the light. It was controlled by.

[0003]

In the above-mentioned conventional method, when the light is turned on, it is necessary to control the aperture by a control different from the normal control. This is because it is necessary to determine whether the change in the brightness information after the light is emitted is due to the reflectance of the subject, the change in the light source, or the change in the control state of the imaging device. Is. Further, in the above-mentioned conventional example, when the light is turned on, the aperture is basically fixed, and the light amount of the light is controlled instead of the aperture to control the exposure. Therefore, it is necessary to use a light whose light amount can be continuously changed. .

[0004] The purpose of the present invention, by using the object illuminance estimated from the control state of the imaging device, and a distance to the object,
Properly turn on or off the light
Then, it is providing an imaging device which obtains appropriate exposure.

[0005]

[0006]

[0007]

[0008]

An image pickup apparatus according to the present invention
In order to achieve the above-mentioned purpose, incident light is converted into an electric signal.
Adjust the image sensor to be converted and the amount of light incident on the image sensor
Aperture control means for controlling the aperture to be used, and the output from the image sensor.
A gain control circuit for controlling the gain of a signal to be applied, and the imaging
Signal amount detecting means for detecting the amount of signal output from the element
And an electronic shutter for adjusting the charge accumulation time of the image sensor.
Controller and an aperture value control output from the aperture controller.
Control information and signal gain control output from the gain control circuit
Information and signal amount information output from the signal amount detecting means
And an electronic shutter output from the electronic shutter control means.
Subject that estimates the illuminance of the subject from the speed control information
Body illuminance estimation means, a light for illuminating the subject, and the subject
A distance detecting means for detecting the distance to, the subject illumination estimation
Depending on the estimation result of the determining means and the detection result of the distance detecting means.
Light control to control the light to turn on or off
Control means, the light control means is the distance detection means
As the distance to the subject increases,
Therefore, the illuminance of the illuminance that is the criterion for turning off the light
Control the extinction of the light by decreasing the threshold value
Is configured.

[0009]

[0010]

[0011]

[0012]

[Operation] As described above, the illuminance of the subject and the
Since the light control means is driven according to the distance,
The timing of turning on / off can be set appropriately.
It

[0013]

[0014]

[0015]

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to each embodiment shown in FIGS.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration diagram of the image pickup apparatus according to the present embodiment, and FIG. 2 is a processing flow chart for explaining an algorithm for generating the write control signal 104.

In FIG. 1, 1 is a lens, 2 is a diaphragm, and 3 is a diaphragm.
Is an image sensor, 4 is a signal processing circuit, 5 is an output terminal, 6 is an aperture control circuit, 7 is an electronic shutter control circuit, 8 is a light for illuminating an object, 9 is a light control circuit, and 10 is the control of the entire system. It is a microcomputer. Here, the microcomputer 10 is actually an I / O interface, a ROM in which a main control program and fixed data are stored, and an RA in which various data and flags are read and written.
M is provided with a CPU that controls the overall control, and various control processes are executed by various predetermined programs. The signal processing circuit 4, the aperture control circuit 6, the electronic shutter control circuit 7, and the light control circuit 9 are provided with various control signals (signal gain control signal 102, aperture value control signal 100,
It is controlled by an electronic shutter speed control signal 101 and a light control signal 104).

In the structure shown in FIG. 1, the light incident on the image pickup device 3 through the lens 1 and the diaphragm 2 is converted into an electric signal and then inputted to the signal processing circuit 4. Signal processing circuit 4
Then, the input electric signal is converted into a video signal of a broadcasting standard such as NTSC and output to the output terminal 5, and at the same time, the signal amount information 103 is output to the microcomputer 10. The microcomputer 10 manages / controls each unit by various control signals such as an aperture value control signal 100, an electronic shutter speed control signal 101, a signal gain control signal 102, and the like, and also controls the signal amount information 103, the aperture value 100, and the electronic value. Shutter speed 1
01, the illuminance L ₀ of the subject is calculated / estimated from each control state (each control command) value of the signal gain 102. Further, the microcomputer 10 generates the light control signal 104 for turning on or off the light 8 by the algorithm shown in FIG. 2 based on the estimated value of the illuminance L ₀ . It should be noted that the microcomputer 10 performs the iris control of the diaphragm 2 as usual when the light 8 is turned on as in the case where the light 8 is turned off. Is also the same).

In FIG. 2, L _a and L _b are values indicating a predetermined illuminance that satisfies the relationship of L _a <L _b . In the algorithm of FIG. 2, first, in step ST1, the write 8
The process is divided into two depending on whether or not is already lit. If the light 8 is already turned on (YES in step ST1)
In the case of S), it is determined in step ST2 whether or not L _b <L ₀ , and if L ₀ exceeds L _b (YES in step ST2), the light 8 is turned off. As described above, the light control signal 104 is generated to turn off the light 8 (step ST5), and if L ₀ is equal to or less than L _b (if NO in step ST2), the light control is performed so that the light 8 continues to be lit. The signal 104 is generated and the light 8 is turned on (step ST3). On the other hand, N in step ST1
In the case of O, in step ST4, it is determined whether or not L _a > L ₀ , and if L ₀ is less than L _a (step ST 4
4 if YES) generates a write control signal 104 so as to turn on the light 8 turns on the light 8 (step ST3), if L ₀ is L _a or more (step S
If NO in T4), the light control signal 104 is generated so that the light 8 continues to be turned off, and the light 8 is turned off (step ST5).

As described above, according to the present embodiment, the light control signal 104 is generated according to the illuminance of the subject and the ON / OFF state of the light 8 is controlled. Therefore, when the illuminance of the subject is insufficient, the automatic control is performed. It is possible to realize an image pickup device that obtains a proper exposure by turning on the light 8 and automatically turning off the light 8 when sufficient illuminance is obtained. Further, since the value to be compared with the illuminance L ₀ of the subject is changed depending on whether the light 8 is already turned on, it is possible to prevent hunting in which the light 8 is turned on / off periodically.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a configuration diagram of the image pickup apparatus according to the present embodiment, and FIG. 4 is a process flow diagram for explaining an algorithm for generating the write control signal 104,
FIG. 5 shows the function f used in determining the threshold value in FIG.
1 shows an example of (D ₀ ).

The image pickup apparatus of this embodiment shown in FIG. 3 has basically the same configuration as that of FIG. 1, but a distance detection circuit 11 for newly detecting the distance to the subject is added. The distance detection circuit 11 detects the distance from the position of the zoom ring attached to the zoom lens. The distance information 105 detected by the distance detection circuit 11 is input to the microcomputer 10.

As described above, in the first embodiment, after turning on the light 8, the light 8 is not turned off unless the illuminance L _{0 of} the subject becomes larger than L _b . However, when the distance to the subject is long, the proportion of the light from the light 8 reflected by the subject and returning to the lens 1 is low, so the timing of turning off the light need not necessarily wait until L ₀ becomes larger than L _b. There is no. Therefore, in the present embodiment, the distance detection circuit 11 detects the distance D ₀ to the subject, and the microcomputer 10 calculates the light control signal 104 from the illuminance L ₀ and the distance D _{0 of} the subject estimated in the same manner as in the first embodiment. I am trying to generate. In the generation of the light control signal 104, the threshold value when the state is changed from lighting to extinguishing is made variable according to the subject distance by using the function f (D ₀ ) shown in FIG. Do not wait for the light to turn off until the illuminance of the subject becomes large.

The algorithm for generating the write control signal 104 shown in FIG. 4 is basically the same as that shown in FIG. 2, and the changed point is that the threshold value at the time of transition of the light from ON to OFF in step ST2 of FIG. 4 is a fixed value L _b , a threshold value “f (D ₀ ), which is variable according to the distance, is used as in step ST2 ′ (in this embodiment) using the function f (D ₀ ). ₀ ) · L + L _a ”. It should be noted that L in the variable threshold value shown in step ST2 ′ is a value indicating an increase in illuminance when all the light of the light 8 that is turned on is reflected, and f (D ₀ ) is a value As shown in FIG. 5, this is a function that approaches 0 from a value near 1 as the subject distance D ₀ increases. That is, as the distance to the subject becomes distant, illumination turns off the lights 8 is that gradually becomes closer to the threshold L _a at the time of lighting the lights 8.

According to the present embodiment, as described above, the threshold value for changing the state from the lighting to the extinguishing in the generation of the light control signal 104 is variable according to the distance to the subject, so that it is appropriate. It is possible to realize an imaging device in which the light 8 is turned on or off at a timing and an appropriate exposure is obtained.

Next, a modification of this embodiment will be described. In the above description, the method of simply changing the threshold value when the light 8 is turned on and off according to the distance has been described. This is because the distance L ₀ and L _a described above increase as the distance D ₀ increases.
It is equivalent to the operation to bring _b closer. Therefore, the function f (D ₀ )
Depending on the situation, hunting may occur when the distance D ₀ increases. As an example of a method for preventing this, when the light 8 is turned on in a state where the distance to the subject is more than a certain distance, the turned-on state is maintained until a sufficient illuminance is obtained.

In this way, when the subject is far, the light 8 is kept on, so hunting is prevented, and the light 8 is turned on or off at an appropriate timing to obtain an appropriate exposure. An imaging device can be realized.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a configuration diagram of the image pickup apparatus according to the present embodiment.

The image pickup apparatus of this embodiment shown in FIG. 6 is basically the same as that shown in FIG. 3, but in this embodiment, a color temperature sensor that outputs different voltage values depending on the color temperature of the light source is used. A color temperature detection unit 12 is added, and the color temperature information 106 is input from the color temperature detection unit 12 to the microcomputer 10. Further, in this embodiment, a memory (for example, RAM) for storing the control state (imaging state) of the image pickup apparatus is provided in the microcomputer 10, and, for example, the color temperature 106 and the aperture value 10 are set.
0, the electronic shutter speed 101, the signal gain 102, the signal amount 103, the subject distance 105, and the like are stored in the memory (the state information at a plurality of time points is stored at appropriate sampling intervals). Is supposed to do). Then, the microcomputer 10 analogizes the change of the shooting environment from the comparison between the current control state (shooting state) and the past control state (shooting state) stored in the memory, and the light 8 is changed according to the change of the shooting environment. Is turned on or off.

Specifically, for example, when the amount of light is insufficient, the electronic shutter control circuit 7 is driven to set the electronic shutter speed 101 to the minimum speed, and even when the diaphragm 2 is fully opened, the signal amount 103 satisfies the desired value. Light 8 if none
Lights up. Color temperature 106 when this light 8 is turned on
Since the light 8 attached to the image pickup device is used as a light source, when the color temperature 106 stored immediately after the light 8 is turned on and the color temperature 106 at a certain point after the light 8 is turned on are different, a new light source is used. Appears (the shooting environment has changed), the light 8 is turned off. Although the signal amount 103, the aperture value 100, and the electronic shutter speed 101 are used as the conditions for turning on the light 8, the subject illuminance used in each of the above-described embodiments may be used as the conditions for turning on the light 8. Note that the illuminance of the subject itself may be stored as a value indicating the control state of the imaging device.

As described above, according to the present embodiment, the change of the photographing environment is estimated by storing the control states of the image pickup apparatus at a plurality of points in the past, and the light is controlled according to the change of the photographing environment. Therefore, it is possible to realize an imaging device that always obtains an appropriate exposure.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a configuration diagram of the image pickup apparatus according to the present embodiment.

The image pickup apparatus of this embodiment shown in FIG. 7 is basically the same as that of FIG. 3, but in this embodiment, the light 8 is used.
A reflection plate 15 for adjusting the irradiation angle is provided after the light 8, and a mechanism (not shown) for adjusting the mutual distance is provided between the reflection plate 15 and the light 8. The distance between the reflector 15 and the light 8 is adjusted by driving the irradiation angle control circuit 13 by the irradiation angle control signal 108 from the microcomputer 10, and when the distance between the light 8 and the reflector 15 is the shortest, the irradiation angle becomes the minimum. The irradiation angle increases as the distance increases. Further, in this embodiment, the light quantity of the light 8 is the light quantity control signal 107 from the microcomputer 10.
Thus, it can be adjusted by driving the light amount control circuit 14.

In the present embodiment, the illuminance of the object is estimated in the same manner as in the first embodiment, and if the estimated result does not reach the desired value, the light 8 is turned on with the minimum light amount. Then, when the subject illuminance is less than the desired value, the light amount is increased, and when the subject illuminance exceeds the desired value, the light amount control signal 107 is generated so as to decrease the light amount.
The light amount control circuit 14 is driven. Further, when the light 8 is turned on, the irradiation angle control signal 108 is generated according to the detection result of the distance detection circuit 11 and the irradiation angle control circuit 13 is driven to irradiate the subject with light at an appropriate irradiation angle. It is like this.

In this embodiment, the irradiation angle is adjusted by using the reflection plate 15. However, the irradiation angle can also be adjusted by disposing a lens in front of the light 8 and changing the distance between the light 8 and the lens. Can be adjusted.

As described above, according to the present embodiment, the light amount of the light 8 is increased or decreased according to the illuminance of the subject, and the irradiation angle is adjusted according to the distance to the subject, so that the battery consumption is suppressed and Thus, it is possible to realize an imaging device that obtains appropriate exposure.

In each of the above-mentioned embodiments, the light 8 is attached to the body of the image pickup apparatus, but it goes without saying that the light 8 may be detachable from the body of the image pickup apparatus.

[0039]

As described above, according to the present invention, since the light is controlled according to the image pickup state such as the illuminance of the subject and the distance to the subject, an image pickup apparatus which can always obtain a proper exposure to the subject is provided. Can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an image pickup apparatus according to a first embodiment of the present invention.

FIG. 2 is a process flow diagram for explaining an algorithm for generating a write control signal according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an image pickup apparatus according to a second embodiment of the present invention.

FIG. 4 is a processing flow chart for explaining an algorithm for generating a write control signal according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a function used in determining a threshold value for determining whether or not to perform a state transition from turning on a light to turning off a light according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an image pickup apparatus according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an image pickup apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 lens 2 aperture 3 image sensor 4 Signal processing circuit 5 output end 6 Aperture control circuit 7 Electronic shutter control circuit 8 lights 9 Light control circuit 10 Microcomputer 11 Distance detection circuit 12 Color temperature detector 13 Irradiation angle control circuit 14 Light intensity control circuit 15 Reflector 100 Aperture value control signal 101 Electronic shutter speed control signal 102 signal gain control signal 103 Signal amount information 104 Light control signal 105 distance information 106 Color temperature information 107 Light intensity control signal 108 Irradiation angle control signal

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Tarumi, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi Image Information Systems, Inc. (72) Inventor Tamiya Imade, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi, Ltd., Video Media Research Laboratory (72) Inventor Ken Hojo, 1410 Inada, Katsuta City, Ibaraki Prefecture Hiritsu Manufacturing Co., Ltd., AV Equipment Division (56) Reference JP 4-70071 (JP, A) JP HEI 4-70069 (JP, A) JP-A-6-14227 (JP, A) JP-A-3-229578 (JP, A) JP-A-2-241276 (JP, A) JP-A-60-10882 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 5/238

Claims (2)

(57) [Claims] 1. An image pickup device for converting incident light into an electric signal, an aperture control means for controlling an aperture for adjusting the amount of light incident on the image pickup device, and a gain for controlling a gain of a signal output from the image pickup device. A control circuit, a signal amount detection means for detecting a signal amount output from the image sensor, an electronic shutter control means for adjusting a charge accumulation time of the image sensor, and an aperture value control output from the aperture control means. The illuminance of the subject based on the information, the signal gain control information output from the gain control circuit, the signal amount information output from the signal amount detection means, and the electronic shutter speed control information output from the electronic shutter control means. Subject illuminance estimation means, a light for illuminating the subject, a distance detection means for detecting a distance to the subject , an estimation result of the subject illuminance estimation means, and a distance detection means of the distance detection means.
The light is controlled to turn on or off according to the detection result.
Control means for controlling the light , and the light control means is responsive to the detection result of the distance detecting means.
Turn off the light as the distance to the subject increases.
Decrease the threshold of illuminance that is the criterion for lighting
Image pickup device characterized by controlling the turning off of the light.
Place 2. The image pickup device according to claim 1, wherein the distance to the subject is long and the illuminance of the subject is desired.
If the value is less than, turn on the light.
An image pickup device characterized by keeping.