JPH08111800A - Light quantity controller for camera - Google Patents

Abstract

PURPOSE: To prevent the deterioration of image quality due to a diffraction phenomenon that is caused by the excessive stop-down of an iris diaphragm in a camera having a CCD sensor provided with micro lens arraies. CONSTITUTION: When a subject of high luminance is photographed, the image quality is deteriorated by a diffraction phenomenon due to the excessive stop- down of an iris diaphragm. Thus a transparent glass plate 16 is placed in front of a micro lens array 12 so that a sealed space 24 is formed in front of the array 12. The oil can be poured into and discharged out of the space 24 by a pump 18. Then the oil is poured into the space 24 when the subject of high luminance is photographed. As a result, the refraction effect of the array 12 is suppressed and the sensitivity of a CCD sensor can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount adjuster for a camera, and more particularly to a light amount adjuster for a camera which adjusts the light amount by changing the aperture efficiency of a CCD sensor in a camera image pickup section.

[0002]

2. Description of the Related Art Conventionally, an iris diaphragm is used as a light quantity adjuster for a video camera and a still camera, but an ND filter is used on the diaphragm blade so that the iris diaphragm does not become a small diaphragm when photographing a subject having high brightness. It is attached (a small aperture causes deterioration of image quality due to diffraction phenomenon).

[0003]

By the way, in order to increase the sensitivity of the CCD sensor on the array surface of the CCD elements in the camera image pickup section, a microlens array 12 is provided on the CCD element 10 as shown in FIG. There is. That is, the microlens array 12 locally collects the incident light on the CCD pixels 14, and the adjacent CCs
The sensitivity of the CCD element is increased by condensing the light incident on the gap between the D pixels on the CCD pixel 14.

As a result, when photographing a high-brightness subject, the iris diaphragm may not be sufficient with the ND filter alone. The present invention has been made in view of such circumstances, and when photographing a high-brightness subject, it is possible to adjust the light amount of the subject light without causing deterioration of image quality due to excessive narrowing of the iris diaphragm. An object is to provide a light quantity adjuster.

[0005]

In order to achieve the above object, the present invention converts the subject light, which is taken in through a taking lens, into an electric signal by an image pickup device having a microlens array on the pixel array surface. In the camera having the means for performing, a transparent plate is provided in front of the microlens array, and a space portion between the microlens array and the transparent plate is formed into a closed structure, and a refractive index of the microlens array is provided in the space portion. It is characterized in that a medium equivalent to the above can be injected or discharged.

[0006]

According to the present invention, a medium having a refractive index equivalent to that of the microlens array can be injected into or discharged from the space provided in front of the microlens array of the image pickup device, and the iris diaphragm is used. When the aperture adjustment reaches the limit (when photographing a high-brightness subject), the medium is injected into the space, and the aperture efficiency of the image sensor, that is, the sensitivity is reduced.

On the other hand, when the diaphragm can be adjusted by the iris diaphragm, the medium is discharged from the space to improve the sensitivity of the image pickup device.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a light quantity controller for a camera according to the present invention will be described in detail below with reference to the accompanying drawings. First, FIG. 1 shows the configuration of a photographing optical system in a video camera to which the light amount adjuster of the camera according to the present invention is applied.

In the figure, the taking lens system and the CCD element 10 are shown.
It is shown. The taking lens system includes a focus lens 100 arranged in a lens barrel 118 for focus adjustment, a zoom lens 112 for changing the magnification, a correction lens 114 for correcting a focus shift during zooming, and a relay lens 116. . The CCD element 10 is installed behind the taking lens system and converts an image formed by the taking lens system into an electric signal.

FIG. 2 shows the CCD element 10 of the above video camera.
3 is a cross-sectional view showing a light amount adjuster of a camera according to the present invention applied in FIG. As shown in FIGS. 2A and 2B, the light amount adjuster of the camera is mainly composed of a CCD element 10 provided with a microlens array 12, a transparent glass plate 16,
It is composed of a pump 18 and an oil tank 20.

The transparent glass plate 16 is C by the outer frame 15.
It is supported with a space between it and the CD element 10, and a space 24 is formed between the transparent glass plate 16 and the CCD element 10. A part of the outer frame 15 is provided with an oil inlet / outlet port, from which the pump 1 is connected via a pipe 22.
8 suction / discharge ports are connected. Also, the pump 18
The oil tank 20 is connected via a pipe 23 from the other suction / exhaust port. For oil, for example, CAR
GILLE OIL # 1160 is used.

The oil is stored in the oil tank 20, and when the oil is injected into the space 24, the oil is sucked from the oil tank 20 by the pump 18 and the space 24 is filled.
Inject into When the oil injected into the space 24 is discharged, the pump 18 sucks the oil in the space 24 and discharges it into the oil tank 20. The oil has a refractive index of a value between about 1.4 and 1.8, and the same refractive index as that of the microlens array 12 (about 1.5) is used. This prevents the condensing action of the microlens array 12 when oil is injected into the space 24.

Next, the operation of the light quantity adjuster of the camera will be described. In a normal photographing state (when the diaphragm can be adjusted by the iris diaphragm), oil is not present in the space 24 as shown in FIG. 2 (A). In this state, there is no difference from a normal CCD sensor. Therefore, the microlens array 1 on the array surface of the CCD elements
Reference numeral 2 locally collects light to enhance the sensitivity of the CCD element.

On the other hand, when the brightness of the subject is high and it is necessary to limit the amount of light, and when the iris diaphragm is closed further, image quality deterioration due to diffraction occurs, the control unit of the video camera main body (not shown) operates the pump 18. It is operated to inject the oil stored in the oil tank 20 into the space 24. The locus of the incident light beam at this time is shown by the arrow in FIG.

According to the figure, the oil is filled in the space 24, and the refractive index of the space 24 becomes equivalent to the refractive index of the microlens array 12, so that the light incident on the microlens array 12 is made incident on the microlens array 12. It goes straight without refracting on the surface. As a result, the amount of light detected by the CCD element is reduced because it is not condensed by the microlens array 12.

That is, when oil is injected into the space 24,
CCD increased by microlens array 12
The aperture efficiency of the element is reduced to the aperture efficiency of the CCD element in which the microlens array 12 is not provided, and the amount of light incident on the CCD pixel 14 is reduced. After the shooting is performed by injecting oil into the space 24 as described above, when returning to the normal shooting state (a state in which the iris diaphragm can be used to adjust the aperture), the oil in the space 24 is pumped by the pump 18 contrary to the above. Suction and discharge to the oil tank 20.

[0017]

As described above, according to the light quantity controller for a camera of the present invention, it is possible to smooth the front surface of the microlens array with a medium equivalent to the refractive index of the microlens array. It is possible to adjust the light amount without deteriorating the image quality when photographing a subject of brightness.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a photographing optical system in a video camera or the like.

FIG. 2 is a configuration diagram showing a configuration of a light amount adjuster of a camera according to the present invention.

FIG. 3 is a sectional view of a CCD element provided with a microlens array.

[Explanation of symbols]

 10 ... CCD element 12 ... Micro lens array 14 ... CCD pixel 16 ... Transparent glass plate 18 ... Pump 20 ... Oil tank 24 ... Support frame

Claims (1)

[Claims] 1. A camera having means for converting an object light, which is taken in through a taking lens, into an electric signal by an image pickup device having a microlens array on a pixel array surface, wherein a transparent member is provided in front of the microlens array. A plate is provided, a space between the microlens array and the transparent plate is formed into a closed structure, and a medium equivalent to the refractive index of the microlens array can be injected or discharged into the space. And the light control of the camera.