JP2001350174A - Light quantity controller and optical apparatus incorporating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light quantity controller which can deal with a device where a high shutter speed is required by controlling the light quantity accumulated in an image pickup device (CCD) on the basis of the opening/closing position of a light quantity controlling member, and which can yield a photographed image of high quality by preventing a smear phenomenon, and to provide an optical apparatus incorporating the light quantity controller. SOLUTION: An exposure control signal for starting/finishing accumulation of the exposure quantity to a light receiving means constituted of a CCD 105 and a CCD driving control part 110 is outputted on the basis of a detection signal by an opening quantity detecting means installed in the light quantity controller 100, and also the accumulation is started/finished by making the light quantity received by the CCD 105 effective based on the exposure control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount control device and an optical device incorporating the light amount control device, and more particularly to a light amount control device for controlling a light amount taken into an image pickup device (hereinafter referred to as a CCD) used in a digital camera or the like. And an optical device with a built-in light amount control device.

[0002]

2. Description of the Related Art Conventionally, a CCD has been used as an image pickup medium of a digital camera. In this CCD, a large number of light receiving elements (pixels), which are minute photoelectric conversion materials, are arranged in a grid pattern, and an optical lens is placed there. And project the light image, and take out the amount of light as a change in electric charge, which is photoelectric energy. When taking out the photoelectric energy, the charge of each light receiving element is sequentially transferred through a common charge transfer path and output to the outside.

As for the charge transfer method, an interline method is currently used in many digital cameras. In this method, a light-shielded transfer path is provided between each pixel, and charges accumulated in each pixel are instantaneously transmitted to this transfer path and transferred by a bucket brigade method. There are two types of CCDs driven by the interline method, namely, interlace control and progressive control, due to the difference in the transfer method. Interlace control CC
In D, the charge accumulated in the pixel is output and transferred to the outside twice every other line. On the other hand, in the progressive CCD, electric charges of all pixels are output and transferred to the outside at a stretch.

As is generally known in television scanning, the interlace control CCD captures one image every 1/60 second (16.6 ms) by scanning every other line. In the shooting of a subject, a slight time difference between two transfers can easily cause a shift in imaging, but since the transfer time is reduced by half compared with a progressive control CCD, it is generally used for an optical device such as a video camera for capturing moving images. Have been. However, if the interlace control CCD is used for capturing a still image such as a still camera, the scanning is performed every other line as described above, so that the image quality is halved to half. There is a big problem.

On the other hand, since the progressive CCD outputs and transfers all the pixels at once, the time required for electrical processing during the transfer becomes enormous, and during the processing time, the next image cannot be captured and a moving image is captured. It is inappropriate in some cases. Therefore, this progressive CCD is generally widely used in still cameras such as digital cameras.

FIG. 7A shows a relationship between a shutter opening value (F value) and an opening / closing speed (t) in a general digital camera. The brightness of a lens can be represented by an F value obtained by dividing the focal length by the effective aperture of the lens. Therefore, if the focal length is the same, the larger the aperture value of the shutter, the smaller the F value, the more the light path is opened, and the greater the amount of light hitting the CCD. Conversely, the smaller the aperture value of the shutter, the greater the F value, the narrower the optical path, and the smaller the amount of light that strikes the CCD. As shown in the figure, as the aperture value of the shutter increases, the light amount also increases in proportion thereto, and after a certain period of time, the shutter is closed, and the light amount also decreases and approaches zero. (B) is an enlarged view of a change in the amount of light when the shutter is closed at that time. As shown in the figure, when the shutter is closed, the ideal closing operation immediately operating at the position of Φ2 at which the closing signal is output is, as compared with the shutter time t0 indicated by the dotted line, the actual closing timing is as shown by Φ3. The shutter time varies depending on the degree of delay of the closing timing, such as t1 to t3.

[0007]

Therefore, the higher the shutter speed, the more difficult it is to obtain an appropriate exposure amount due to the above-mentioned delay in closing timing greatly affecting the amount of light. However, when the CCD is continuously exposed, there is a problem that a smear phenomenon in which a peripheral portion of a point having a high light amount value is blurred occurs.

However, as shown in FIG. 7 (b), when the variation of the exposure amount S from a certain opening value F0 in the closing operation is observed, the exposure amount S is S1 to S3 as shown in FIG.
And has been maintained almost constant.

Therefore, the present invention focuses on the relationship between the exposure amounts in the closing operation, and is particularly applicable to an apparatus which requires a high shutter speed, and is capable of preventing a smear phenomenon and obtaining a high quality photographed image. An object of the present invention is to provide a light quantity control device and an optical device having a built-in light quantity control device.

[0010]

According to a first aspect of the present invention, there is provided a light amount control device for opening and closing an optical opening to regulate an exposure amount, and a light amount adjusting member for controlling an exposure amount. A light amount control device having an opening amount detecting means for detecting an opening amount of the adjustment member, wherein an exposure control signal for starting or ending accumulation of the exposure amount is output based on a detection signal of the opening amount detecting means. I do.

According to the present invention, since the amount of light to be taken into the optical device is defined by the information from the open / close position of the light amount adjusting member, the taking in of an extra amount of light is cut, and the subject can be recorded with the optimum exposure amount. .

According to a second aspect of the present invention, there is provided an optical device with a built-in light amount control device, which opens and closes an optical opening of the optical device and regulates an exposure amount to a light receiving means. In an optical device including a light amount control device having an opening amount detection unit for detecting an opening amount, the light amount control unit starts or ends accumulation of the exposure amount of the light receiving unit based on a detection signal of the opening amount detection unit. In addition to outputting the exposure control signal, the light receiving means of the optical device comprises an image sensor, and the light quantity captured by the image sensor is made effective based on the exposure control signal to start or end the accumulation.

According to the present invention, it is possible to control so as to start or end the charge accumulation in the image pickup device at the moment when the light amount adjusting member is closed.

According to a third aspect of the present invention, in the optical device with the built-in light amount control device according to the second aspect, the image pickup device validates a light amount captured by the image pickup device based on the exposure control signal, and stores the remaining light amount. It is characterized by comprising erasing means capable of erasing data.

According to the present invention, it is possible to prevent a smear phenomenon due to excessive exposure without performing exposure during opening / closing operation of the light amount adjustment member in a state where the light amount is separately reduced by using a stop device or the like. A high quality captured image can be obtained.

According to a fourth aspect of the present invention, in the light amount control device according to the first aspect, the opening amount detecting means includes a plurality of detecting portions provided in the light amount adjusting member and corresponding to a predetermined opening amount, and And a sensor unit for detecting the detection unit, and the sensor unit outputs a position signal corresponding to each detection unit at the time of the closing operation of the light amount adjusting member as the exposure start or end signal. .

According to this invention, since the plurality of detecting portions are finely provided along the opening / closing direction of the light amount adjusting member (shutter blade), the current position of the shutter blade can be detected accurately and accurately. The detected information is transmitted to the CCD drive control unit of the light receiving means. Therefore, appropriate exposure control according to the subject is performed, and a high quality captured image can be obtained.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a light quantity control device according to the present invention; FIG. 1 is a block diagram of a digital camera incorporating the light amount control device of the present invention, FIG. 2 is an assembled view in which the light amount control device is incorporated in an optical unit of the camera, and FIG.
FIG. 4 is a perspective view of the light amount control device, FIG. 4 is a perspective view showing the configuration of a light amount adjustment member and an opening amount detection unit of the light amount control device, and FIG. 5 is a graph showing the relationship between the open / close position of the light amount adjustment member and the light amount. FIG. 6 is a graph showing the relationship between the open / close position of the light amount adjusting member and the light amount according to another embodiment.

As shown in FIGS. 1 and 2, the light amount control device of the present invention comprises an optical unit 10 of a digital camera 103.
1 is disposed between the front lens 104 and the rear lens 106 for condensing the light on the light receiving element of the CCD 105. As shown in FIG. 3, two or more shutter blades 10 are provided in the light quantity control device 100.
7, each of which is provided with an opening 115 and a notch-shaped detection unit 108. Then, the shutter blade 107 is fitted to the operation lever 111 and moves while sliding on the exposure hole 116 provided in the base member 114 in synchronization with the swing of the operation lever 111. The swing of the operating lever 111 is based on the magnet 112 disposed at a position where a magnetic field is generated in a direction crossing the direction of the magnetic attraction magnetic field generated by the current flowing through the coil 113 in the swing range of the operating lever 111. This is performed by a magnetic action with the magnetic attraction magnetic field generated from the coil 113 wound around the member 114. In other words, a magnetic force is generated in the magnet 112 such that the direction of the magnetic field of the magnet 112 is in line with the direction of the inductive magnetic field generated in the coil 113.
Is pivoted. Then, the reversal of the swing direction of the operation lever 111 is performed by switching the direction of the current flowing through the coil 113.

FIG. 4 shows the structure of the opening amount detecting means for detecting the opening amount of the shutter blade 107. The opening amount detecting means includes a plurality of detecting sections 108 provided on the shutter blade 107 and a photo interrupter 109. As shown in FIG.
A plurality is provided along the moving direction of 07 and has a cutout shape. The photo interrupter 109 includes a light emitting unit 118 and a light receiving unit 119.
9 is provided in the gap facing the detecting portion 1 of the shutter blade 107.
08 so that the cutouts (a to e) provided therethrough can pass through. The photointerrupter 109 includes the light emitting unit 1
Two types of states (ON / OFF) are distinguished when the light emitted from 18 reaches the light receiving unit 119 or when the light emitted from the light emitting unit 118 is not blocked by the shutter blades 107 and does not reach the light receiving unit 119. By detecting sequentially,
This ON / OFF information is transmitted to the light receiving means. This light receiving means comprises a CCD 105 and a CCD drive control unit 110 as shown in FIG. The CCD drive control unit 110 instructs the CCD 105 to start taking in the incident light based on the ON / OFF information. The CCD drive control unit 110 includes a CCD 105
Erasing means for forcibly erasing the electric charge accumulated in the memory. This erasing means can set the charge of the CCD 105 to zero regardless of the opening / closing operation of the shutter blade 107 in a state where the light amount is separately reduced using a diaphragm device or the like. For this reason, a smear phenomenon due to excessive exposure can be prevented, and a high-quality captured image can be obtained. The memory 117 has CC
A control program for driving D105, position information of the detection unit 108, and the like are stored, and read out to the CCD drive control unit 110 as needed. As described above, since the shutter blade 107 is detected in a non-contact state by the optical sensor such as the photo interrupter 109, the shutter blade 10
7 can be detected without hindering the opening / closing operation of the switch 7.
Further, since the photointerrupter 109 has a high response speed, it is possible to accurately detect an object that moves at a high speed such as opening and closing a shutter. In addition,
The detection unit 108 is formed on both the shutter blades 107, but detection can be similarly performed by using only one of the shutter blades 107.

Next, a method for detecting the open / close position of the shutter blade 107 will be described with reference to FIGS. 1, 3 and 4. FIG. Normally, the shutter blade 107 is stopped at a position to close the exposure hole 116, and the exposure hole 116 is
After moving in the opening direction, the operation to return to the first stop position after a predetermined time has elapsed is quickly performed. Shutter blade 1
The opening amount of 07 is detected in advance by an exposure meter (not shown) or the like provided in the digital camera 103, and the shutter blades 1 perform the shutter opening / closing operation corresponding to the detected amount.
07 is driven. A control signal for opening and closing the shutter blade 107 is output from the CCD drive control unit 110. The operating lever 111 swings the shutter blade 107 based on the control signal. At this time, the control signal is applied to the number of counts transmitted through the notch-shaped detectors 108 (a to e) passing through the photointerrupter 109. Then, the shutter opening amount at that time is detected from the position of the predetermined notch. The light incident from the exposure hole 116 up to the detection position is changed so that the accumulation in the CCD 105 is temporarily erased.
The control is performed on the D drive control unit 110 side, and then the shutter blade 1
Only at the moment when 07 closes to the original position, the CCD 105
Is controlled so as to accumulate charges corresponding to the light incident on the.

FIG. 5 shows a change in the light amount (F value) according to the aperture value up to the notches (a to e) of the detection unit 108.
In each case, the change in the amount of light accumulated in the CCD 105 while the shutter blade 107 moves from the open state to the close direction is shown. Plotted on the curve in the figure (a ′
To e ′) are detection units (a to e) of the shutter blade 107.
Is the starting point in the closing direction from the position detected at. The time from the start point in the closing direction to the time when the F value becomes 0 corresponds to the shutter speed. For example, the position of e is set to 1/60 second, the slowest, and a is set to 1/1000 second, the fastest. You. The light amount actually accumulated in the CCD 105 is obtained by integrating the F value with the shutter speed. The shutter speed is adjusted automatically or manually as appropriate according to the movement and brightness of the subject.

As described above, the exposure due to the lapse of extra time until the shutter blade 107 opens is prevented, and the light amount is limited from the moment when the subject is captured to the moment when the shutter blade 107 closes, so that the smear phenomenon occurs. This makes it possible to shoot with the proper exposure always maintained.

FIG. 6 is a graph showing the relationship between the F value and the shutter speed of the light amount control device according to another embodiment of the present invention. In the above embodiment, a high shutter speed is obtained by using the closing operation of the light amount control device. However, as in this embodiment, a high shutter speed is obtained by using the opening operation of the light amount control device. Is also possible. That is, as shown in the drawing, the shutter opening start position is captured by the release operation, and exposure to the CCD 105 is started. At that time, the position (a
~ E), and the exposure to the CCD 105 is stopped, thereby quickly shifting from the opening operation to the closing operation. Also in this embodiment, high-speed control of the shutter speed is possible without causing any mechanical delay as in the above-described embodiment. The light amount control device according to the present invention includes a progressive CCD, an interlaced CCD, and the like.
Can be applied to all CCDs without distinction.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital camera incorporating a light quantity control device according to the present invention.

FIG. 2 is an assembly diagram showing a state in which the light amount control device is incorporated in an optical unit of a digital camera.

FIG. 3 is a perspective view of the light quantity control device.

FIG. 4 is an enlarged perspective view of a light amount adjusting member in the light amount control device.

FIG. 5 is a graph showing a relationship between an F value and a shutter speed by the light amount control device.

FIG. 6 is a graph showing a relationship between an F value and a shutter speed by a light amount control device according to another embodiment of the present invention.

FIG. 7 is a graph showing a relationship between an F value and a shutter speed in a conventional shutter device.

[Explanation of symbols]

 100 light intensity control device 105 CCD 110 CCD drive control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/235 H04N 5/235 5/238 5/238 Z

Claims (4)

[Claims] 1. A light amount control device comprising: a light amount adjusting member for opening and closing an optical opening to regulate an exposure amount; and an opening amount detecting unit for detecting an opening amount of the light amount adjusting member. An exposure control signal for starting or ending the accumulation of the exposure amount based on the detection signal. 2. A light amount control device comprising: a light amount adjustment member for opening and closing an optical opening of an optical device to regulate an exposure amount to a light receiving unit; and an opening amount detection unit for detecting an opening amount of the light amount adjustment member. Wherein the light quantity control device outputs an exposure control signal for starting or ending accumulation of the exposure amount of the light receiving means based on the detection signal of the aperture amount detecting means, and the light receiving means of the optical device includes An optical device with a built-in light amount control device, comprising an image pickup device, wherein the light amount captured by the image pickup device is validated based on the exposure control signal, and accumulation is started or terminated. 3. The image pickup device according to claim 2, wherein the image pickup device includes an erasing means for making the amount of light captured by the image pickup device effective based on the exposure control signal and erasing other accumulated data. Optical device with built-in light intensity control device. 4. The sensor according to claim 1, wherein the opening amount detecting means includes a plurality of detecting units provided on the light amount adjusting member and corresponding to a predetermined opening amount, and a sensor unit for detecting the plurality of detecting units. 2. The light amount control device according to claim 1, wherein the unit outputs a position signal corresponding to each detection unit when the light amount adjustment member is closed, as the exposure start or end signal.