JPH03127035A - Shutter device - Google Patents

Abstract

PURPOSE:To determine an exposure time regardless of the variance at the beginning of a shutter movement by giving a control signal to an image-pickup element after the shutter has been released until a prescribed stop blade value is completely reached, and starting exposure. CONSTITUTION:A stop blade driving circuit 6 is operated by a stop blade control circuit 23, a pulse signal is obtained from an effective aperture detecting means 3 according as stop blades 2 are released, and the operation of the stop blades is stopped when a value which is counted by a stop value calculating circuit 22 agrees with an Av value determined by an AE value calculating circuit 21. A Tv value . Vp timing circuit 24 is given a shutter speed Tv determined by the AE calculating circuit 21, power is supplied to the image-pickup element 4 from an image-pickup control circuit 25 after a timing Vp, and image is started to be picked up. A stop signal is given to the stop blade control circuit 23 from the Tv value . Vp timing circuit 24 after the shutter is released at a shutter speed Tv, and the blades 2 are closed through the stop blade control circuit 23. Thus, the shutter speed is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shank device used in electronic still cameras and the like.

[Conventional technology]

In recent years, electronic still cameras have become smaller, lighter, and less expensive for consumer use, and shutter devices are also required to be smaller, smaller, and lighter. FIG. 4' is a schematic diagram showing an example of a conventional shank device. In this figure, an aperture blade 2 is provided within a lens system 1, and an effective aperture detection means 3 for detecting the effective aperture of the aperture blade 2 is connected thereto. lens system l
An image sensor 4 is provided on the optical axis. The output of the effective aperture detection means 3 is then given to the aperture blade control circuit 5.

The aperture blade control circuit 5 measures the brightness of the subject in advance using a photometric element (not shown) and determines the aperture value and shutter speed based on a set program diagram, and the aperture value Av and shutter speed Tv are determined by the aperture blade control circuit 5. given to. Based on this signal, the aperture blade control circuit 5 provides an opening command signal a to the aperture blade drive circuit 6 via the aperture blade drive circuit 6 as shown in FIG. In this way, the aperture blades 2 are opened and their effective aperture is detected by the effective aperture detection means 3. When this effective aperture reaches a predetermined aperture value Av, the opening operation is stopped by the aperture blade control circuit 5, and the opening of the aperture blades is completed at the set position. After a time corresponding to the shutter speed Tv determined by the program diagram, the aperture blades 2 are closed by a closing command signal d shown in FIG.

[Problem to be solved by the invention]

However, such conventional shutter devices have a drawback in that the responsiveness of the aperture blades is not sufficient during the opening process. Furthermore, since the response speed varies, it is difficult to realize a high shutter speed or stabilize the shank speed.

That is, as shown in FIG. 6, the shutter speed Tν indicates the time during which the aperture blades 2 are open relative to the set value of the aperture amount of the aperture blades, and in the opening process, the areas A and A'
It is defined as the time from time t, when the areas B and B' are equal, to a point 1h, where the areas B and B' are equal in the closing process. However, in the process of opening the aperture blades 2, variations occur as shown in FIG. 7, so the shutter opening times t□, t change. Therefore, the achieved shank-velocity ↑v,, Tv
.

This has the disadvantage that the shutter speed fluctuates due to variations in the shutter speed, making it difficult to accurately control the shutter speed.

The present invention has been made in view of the problems of the conventional shutter device, and its technical object is to stabilize the shutter speed regardless of variations in the opening process of the aperture blades.

[Means to solve the problem]

The present invention includes an image sensor, a lens system part provided on the front surface of the image sensor and having aperture blades, an aperture blade opening/closing means for opening and closing the aperture blades in the lens system, and an aperture blade opening/closing means provided in the lens system for controlling the effective aperture by the aperture blades. After the effective aperture detection means to detect and the aperture signal obtained from the effective aperture detection means reach a predetermined value, a control signal is given to the imaging device to start imaging,
The present invention is characterized in that it includes an aperture blade/imaging element control means for applying an opening signal to the aperture blade opening/closing means to close the aperture blades when a predetermined exposure time has been reached.

[Effect]

According to the present invention having such features, when opening the shutter, an opening signal is given to the opening/closing means, and when the aperture signal obtained from the effective aperture detection means reaches a predetermined opening amount, the shutter is opened. It's stopped. Thereafter, a control signal is given to the image pickup device to start imaging, and when a predetermined exposure time is reached, an opening signal is given to the opening/closing means.

〔Example〕

FIG. 1 is a diagram showing the overall configuration of a shutter device according to an embodiment of the present invention. In this figure, the same parts as in the conventional example described above are designated by the same reference numerals and their explanations are omitted. In this embodiment, the effective aperture The output of the detection means 3 is given to the aperture blade/image sensor control circuit 10. The aperture blade/imaging element control circuit 10 receives the brightness signal E of the subject using an external photometric element 11.
v is given, and when an image according to the NTSC system is obtained, a vertical synchronizing pulse Vp is given by the vertical synchronizing signal generating circuit 12. Aperture blade/image sensor control circuit
O is AE to which the luminance signal Ev is given as shown in FIG.
It has an arithmetic circuit 21. The AE calculation circuit 21 calculates the aperture value Av and the shutter speed Tv based on a program diagram.
2. The Tv value is applied to the aperture blade control circuit 23 and the Tv value/Vp tie determining circuit 24, respectively. Also, the aperture value calculation circuit 22
is given the output of the effective aperture detection means 3, for example, the output of a rotary encoder, and counts its pulses to detect coincidence with the aperture blade value Av. When a coincidence occurs, a drive stop signal is sent to the aperture blade control circuit 23. give. The aperture blade control circuit 23 opens the aperture blades 2 after receiving a signal from the AE calculation circuit 21, and controls the opening to stop in response to a matching signal from the aperture value calculation circuit 22. It is applied to the blade drive circuit 6. xTv value・V
Based on the given Tv value and the vertical synchronization pulse Vp, the p timing circuit 24 starts imaging via the image sensor drive circuit 25 from the time when the timing pulse Vp is given after the aperture value reaches a predetermined aperture value Av. Let it start. Then, when the shutter speed Tv time has elapsed, a stop signal is given to the aperture blade control circuit 23, and the image sensor control circuit 2
An imaging end signal is given to the image sensor 4 via the image sensor 5.

Next, the operation of this embodiment will be explained with reference to FIG. During imaging, as shown in FIG. 2(a), the aperture blade drive circuit 6 operates in response to an aperture blade opening command signal given by the aperture blade control circuit 23, and starts opening the aperture blades 2. As the aperture blades 2 are opened, a pulse signal is obtained from the effective aperture detection means 3 from a rotary encoder or the like as shown in FIG. If it matches the Av value, the operation of the aperture blades is stopped as shown in FIG. Now, the Tv value/Vp timing circuit 24 is given the shutter speed Tv value determined by the AE calculation circuit 21, and as shown in FIG.
As shown in , after the timing of Vp, the image sensor control circuit 2
5, power is applied to the image sensor 4 to start imaging. Then, after the time when the shutter speed Tv has elapsed, the Tv value/Vp
A stop signal is sent from the timing circuit 24 to the aperture blade control circuit 2.
Give to 3.

In this way, the aperture blade m2 is closed via the aperture blade control circuit 23. Therefore, the actual exposure time is as shown in Figure 2.
A stable shutter speed Tv can be obtained.

In this embodiment, the operation of the aperture blade/image sensor control circuit 10 is realized by a hardware circuit as shown in FIG. 1, but it can also be realized by software-based function realization means using a microcomputer. It is. In this case, the aperture blade/image sensor control circuit 10 is composed of a human output interface, a memory for storing its processing program, and a microprocessor. In this case, as shown in the flowchart in FIG. 3, when the operation starts, first a luminance signal is obtained from the external photometric element 11, then the process proceeds from step 31 to step 32, where AE calculation is performed and the aperture value A.
v, calculate the shutter speed Tv.

Then, in step 33, the opening of the aperture blades is started,
The pulse counts obtained from the effective aperture detection means 3 are read and it is checked whether they match (steps 34 and 35). This opening operation is repeated until they match, and if they match, the process proceeds to step 36 and the opening action of the aperture blades 2 is stopped. Then, the image sensor 4 is energized to prepare for exposure, and a tying signal of the vertical synchronization signal Vp is awaited (steps 37 and 38). When this timing signal is given, exposure of the image sensor is started. Then, generate the timing of the shunter speed Tv time (
Step 39), this signal causes the aperture blade drive circuit 6 to
(Step 40). In this way, the shutter speed can be accurately defined by combining function realizing means using software.

〔Effect of the invention〕

According to the present invention having such characteristics, when the shunter is opened, a control signal is given to the image sensor to start exposure after the shutter has completely reached a predetermined aperture blade value. Exposure time can be determined regardless of variations in Therefore, even if a normal shutter device with relatively low precision is used, it can be made into a high precision shutter device, and the shunter device can be provided at low cost. Furthermore, since exposure is started by energizing the image sensor, it is possible to achieve an ultra-high shutter speed that is impossible with a lens shutter used in conventional compact cameras.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a shutter device according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing waveforms of each part, FIG. 3 is a flowchart showing its operation, and FIG. A block diagram showing the configuration of a conventional shutter device, FIG. 5 is a waveform diagram showing the waveforms of each part of the conventional shutter device, FIG. 6 is a diagram showing the opening amount when the shutter is opened, and FIG. 7 shows the variation. FIG. 1--11--Lens system 2--Aperture blades 3--Effective aperture detection means 4--Image sensor 10--Aperture blade/image sensor control Circuit 11-----Photometering element 12------Vertical synchronization signal generation circuit 21-----AE calculation circuit 22--------Aperture value calculation circuit 23----
One aperture blade control circuit 24---Tv value/Vp
Timing circuit 25-... Image sensor control circuit

Claims (1)

[Claims] (1) an image sensor; a lens system section provided on the front surface of the image sensor and having aperture blades; an aperture blade opening/closing means for opening and closing the aperture blades within the lens system; and an aperture blade provided within the lens system. an effective aperture detection means for detecting an effective aperture according to the present invention; and after an aperture signal obtained from the effective aperture detection means reaches a predetermined value, a control signal is given to the image sensor to start imaging, and a predetermined exposure time is reached. 1. A shutter device comprising: aperture blade/imaging element control means for applying a closing signal to the aperture blade opening/closing means to close the aperture blades when the aperture blade opening/closing means is opened/closed.