JPH0627920B2 - Imaging device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an image pickup apparatus capable of obtaining highly accurate photometric information in a short time.

(Prior Art) A conventional single-lens reflex camera using a silver salt film receives TTL (T
There is one that has performed photometry.

On the other hand, in an image pickup device for obtaining a still image using an image sensor, the brightness information of the object can be obtained by integrating the output of the image sensor, etc., so conventionally, the reflected light from such an image plane is detected. I've been told that I don't have to.

However, when an optical finder is used as an image monitor of such an image pickup apparatus, it can be easily constructed by separating the incident light into an image sensor and a finder using a half mirror, but the sensitivity of the image sensor decreases and the finder also becomes dark. There is a drawback that.

To solve this problem, a quick return mirror is provided to selectively guide the incident light to the finder and the image sensor to solve this problem.

However, in this case, even if the photometric information is immediately obtained from the image sensor due to the displacement of the mirror, the signal reading cycle from the image sensor is determined, and therefore NT
SC has a drawback that it takes 1/60 second PAL and SECAM takes 1/50 second.

Such a drawback has also been a problem when dimming the flash device by TTL.

That is, a very fast response is required for dimming the flash device, and the output of the image sensor cannot be used as it is.

On the other hand, when the image sensor surface reflection side light is to be emitted as in the case of the film surface reflection side light system, a color separation filter having a relatively low reflectance is generally provided on the surface of the color image sensor, so that the image sensor surface There is a problem that sufficient photometric sensitivity cannot be obtained by simply integrating the amount of reflected light from.

(Objective) The present invention aims to solve the above-mentioned drawbacks of the prior art.

Another object of the present invention is to provide an image pickup device capable of highly sensitive and highly accurate photometry. In order to achieve such an object, the image pickup apparatus of the present invention photoelectrically converts image pickup light from a subject incident through a predetermined optical path and also has an image having a periodic pattern of a predetermined pitch P on the surface. Means and _m arranged at the position of the m-th order reflection diffraction angle θ _m for detecting the m-th order reflection diffracted light component (m is an integer) of the imaging light formed by the periodic pattern on the surface of the image pickup means. Secondary reflection diffracted light detecting means (where θ _m = Sin ⁻¹ (mλ / P),
λ is the wavelength of the imaging light), and control means for controlling the amount of exposure to the imaging means according to the output of the m-order reflected diffracted light detection means.

(Example) Hereinafter, the present invention will be described based on the example of FIG. First
In the figure, 1 is a taking lens, 2 is a quick return mirror, 3 is a focusing screen, 4 is a condenser lens with a built-in semitransparent mirror, 5 is a photoelectric conversion element for photometry of natural light, 6 is a pentaprism, 7 is an eyepiece lens, Reference numeral 8 is an optical low-pass filter, 9 is a stripe color filter as a stripe pattern, 10 is a solid-state image sensor as an image sensor, 11 is a condenser lens, and 12 is a light-modulating photoelectric conversion element as a light receiving means. 13 is a photoelectric conversion element 12 for light control
, A photometric circuit for determining whether or not the integrated output of has reached a predetermined level, 14 is a γ correction for the output of the solid-state image sensor 10,
A process circuit 15 for adding aperture correction and the like is a recording device.

Reference numeral 16 is a driver for driving the image pickup device 10, and 17 is a clock generator for supplying various timing signals.

Reference numeral 18 is a sequence control circuit for controlling the sequence of the entire image pickup apparatus, and 19 is a flash device.

The configuration of the flash device is, for example, as shown in FIG.

That is, 200 is a battery, 21 is a main switch, 2
2 is a DC-DC converter, 23 is a backflow prevention diode, 24 is a main capacitor, 25 is a trigger switch, 26 is a trigger circuit, 27 is a xenon tube, 28 is a dimming switch, and X ₀ and X ₁ are switches 25 and 28, respectively. Is a control signal for controlling the output of the sequence control circuit 18. 20 is a motor for driving the quick return mirror, and X ₃ is a control signal for controlling this motor 20.

The operation of the present invention will be described below. The light flux that has passed through the taking lens 1 will be reflected by the quick return mirror 2 during natural light metering.
Is reflected by the finder portion, passes through the focusing screen 3, is partially reflected by the semitransparent mirror in the condenser lens 4, and is measured by the photoelectric conversion element 5. And
When a release button (not shown) is operated during flash photography, the signal X ₃ is output from the circuit 18, the quick return mirror 2 is repelled by the motor 20, and the signal X ₀ is output, whereby the flash device emits light. . Here, the voltage of the battery is boosted by the DC-DC converter through the main switch 21 in advance, and the capacitor 24 is charged as light emission energy.

Therefore, when the switch 25 is turned on by the signal X _{0, the} trigger circuit is activated, a high voltage is applied to the trigger electrode of the xenon tube, and the xenon tube 27 emits light.

The switch 28 is on until the signal X ₁ is output.

The reflected light from the subject illuminated by the flash light passes through the optical low-pass filter, and then the entire light flux passing through the photographing lens 1 is applied onto the stripe filter 9. The stripe color filters are arranged in stripes at a cycle equal to the cycle of a photosensitive surface cell of a solid-state image sensor such as a CCD placed immediately after the stripe color filter. When light is applied to such a surface from a certain direction, the light is reflected and diffracted at an angle θm according to the cycle of the stripe filter. Where θm is
It is the reflection diffraction angle of the m-th order reflection diffracted light, the wavelength of the irradiated light is λ, and B, G, R of the stripe color filter are used.
If the cycle of each color filter is p, then θm = sin
It is represented by ^-1 (mλ / p). Since the light flux that has passed through the taking lens generally contains light of various wavelengths, the reflected diffracted light spreads over a wide range as indicated by the broken line in FIG. This spread reflected diffracted light is in the plane where the reflected diffracted light is generated, that is, in the stripe color filter,
Through the condenser lens 11, a strobe light adjustment photoelectric sensor is provided at a position that does not block the light flux from the photographing lens in a plane including the filter array direction and the optical axis of the photographing lens, that is, in a plane perpendicular to the stripe direction. The conversion element 12 is arranged and detected. Then, when the output of the photoelectric conversion element exceeds a predetermined level, a signal X ₂ is obtained from the photometry circuit 13, and this signal X ₂ is supplied to the flash device 19 via the circuit 18 as the signal X ₁ .

Since the switch 28 is turned off by this signal X _{1, the} issuance of the xenon tube is stopped and the brightness of the subject becomes appropriate.

In the above embodiment, the photometric sensitivity can be increased by receiving the reflected and diffracted light of the stripe filter on the image pickup element rather than receiving the mere diffused reflected light.

The light receiving element of the present invention is not limited to the stripe pattern on the surface of the image pickup element, and may be any one that can detect the reflected diffracted light of the stripe pattern at an arbitrary position in the image pickup optical path.

For example, when an interference slit filter is provided as an optical low-pass filter, a device that detects reflected diffracted light from this filter is also included.

It goes without saying that the present invention can also be applied to a color separation filter having a plurality of types of stripe filters for diagonally intersecting each other for a frequency separation system.

Further, it is also applicable to the image sensor whose surface has stripe-shaped irregularities due to the manufacturing process.

(Effect) As is apparent from the above description, according to the present invention, the actual brightness of the front surface of the image pickup unit can be detected by TTL even when the flash unit is used, and in particular, the m-order reflected diffracted light can be detected. With the configuration for detecting, since the photometric sensitivity can be made higher and the accurate detection can be realized as compared with the case of detecting the irregular reflection, the accurate dimming can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an image pickup device of the present invention, and FIG. 2 is a schematic view showing a distribution of reflected diffracted light and an arrangement of dimming photoelectric conversion elements in the vicinity of a striped color filter attached to the surface of a solid-state image pickup element. FIG. 3 and FIG. 3 are diagrams showing a configuration example of a flash device. In the figure, 1 is a taking lens, 2 is a quick return mirror, 3 is a focusing screen, 4 is a condenser lens with a built-in semitransparent mirror, 5 is a photoelectric conversion element for natural light photometry, and 6
Is a penta prism, 7 is an eyepiece lens, 8 is an optical low-pass filter, 9 is a striped color filter, 1
Reference numeral 0 is a solid-state image sensor as an image sensor, 11 is a condenser lens, and 12 is a dimming photoelectric conversion element as a light receiving means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatake Kato 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Plant (56) References JP-A-50-93425 (JP, A) 59-90937 (JP, U) Actually opened 59-68323 (JP, U)

Claims (1)

[Claims] 1. An image pickup device for photoelectrically converting image pickup light from a subject which is incident through a predetermined optical path, and an image pickup device having a periodic pattern of a predetermined pitch P on the surface, and the periodic image on the surface of the image pickup device. An m-th order reflected diffracted light detecting means (where θ _m = Sin) arranged at the position of the m-th order reflected diffraction angle θ _{m in} order to detect the m-th order reflected diffracted light component (m is an integer) of the imaging light formed by the pattern. ^-1 (mλ / P),
(where λ is the wavelength of the imaging light) and a control unit that controls the exposure amount for the imaging unit according to the output of the m-order reflected diffracted light detection unit.