JPH04188968A - Electronic still camera - Google Patents

Abstract

PURPOSE:To execute simultaneous exposure with simple constitution by obtaining a still picture by comprising one image of field images for two times of image data in the simultaneous exposure on a CCD by executing the start of exposure on the CCD by the electronic shutter function of the CCD and executing the completion of the exposure by a mechanical shutter. CONSTITUTION:Frame image data is generated from field image data for two times with simultaneity and without generating time difference in exposure time. In such a case, the charge sweeping function of an overflow drain that is the electronic shutter function of the CCD 9 is inverted from an on-state to an off-state at the start time of light reception on the CCD 9, and a closing function to shield projection light on the CCD 9 of the mechanical shutter 3 is used at the closing time of light reception on the CCD 9. Thereby, the structure of the mechanical shutter loaded on a camera can be simplified, and miniaturization, light weight, and low pricing can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic still camera, and particularly to a frame image generation method.

(Prior art) Solid-state charge transfer device (Charge C,
There is a known method in which one image is constructed and transferred in one frame scan using an electronic shutter function that creates a shutter effect by sweeping out the charge of an image sensor (hereinafter referred to as CCD). There is.

However, this method has a more complicated CCD transfer structure than the current state of the art method in which one image is constructed by two field scans and then transferred.

Therefore, when taking out a charge pattern image signal corresponding to an optical image of a subject generated on a CCD in imaging with an electronic still camera, a method is used in which one image is constructed by two field scans. However, when one image is composed of two field scans using only the electronic shutter function that sweeps out the charge of an image sensor composed of a CCD, due to the limitations of solid-state scanning of the image sensor, one frame image is Odd-numbered field images and even-numbered field images (hereinafter referred to as simple sentence odd-even 2
Each field image (hereinafter referred to as "field image") is composed of exposure data at different times. Therefore, when one frame image composed of two odd and even field images obtained from exposure data with time differences is observed as a still image of a video image, the exposure data will shift for each field image. Observed as an image.

Conventionally, to deal with this problem, the optical image of the subject was
Simultaneous exposure is performed for each frame, and one field image is selected from two odd and even field images of charge images on the image sensor obtained by this simultaneous exposure.
A method of constructing two frame images was used.

In this simultaneous exposure method, the shutter function for the simultaneous exposure is not dependent on the electronic shutter function of the image sensor, but is realized by interposing a mechanical shutter that blocks or passes light beams projected onto the image sensor. There is.

That is, a focal brain shutter is used as the mechanical shutter, and the function of the focal brain shutter is used to expose the image sensor, and after blocking the light, two odd and odd field images are sequentially obtained to form one frame image. ing.

However, the frame image constructed in this way is
Since these are obtained from two odd and even field images based on the charge images on the image sensor during simultaneous exposure with no time difference, when the frame image is observed as a still image of a video image, no shift between field images will be observed. .

However, the focal-brain shutter, which is a mechanical shutter used in the conventional method described above, is not suitable for electronic still cameras that aim to be small and lightweight.In other words, the focal-brain shutter is extremely complex in structure, and is therefore low-priced. There were also limits to this.

(Objective of the Invention) Therefore, the present invention starts exposure on a CCD using the electronic shutter function of the CCD, and ends the exposure using a mechanical shutter, thereby displaying two images of image data in simultaneous exposure on the CCD.
An object of the present invention is to provide an electronic still camera that can realize simultaneous exposure with a simple configuration by forming one image from multiple field images to obtain a still image.

(Structure of the Invention) In order to achieve the purpose of this technology, there is an imaging lens that images the object, and the start of the exposure time is regulated by the optical image of the object that is incident and imaged through this imaging lens. an imaging element having a means for converting the optical image into a charge signal corresponding to the optical image; a shutter located between the imaging lens and the imaging element to regulate exposure to the imaging element by the optical image; and an exposure by the optical image. The apparatus further comprises a setting means for setting a time, and a shutter drive control means for driving the shutter based on the exposure time set by the setting means to regulate the end of the exposure time of the optical image. an imaging lens that captures an image of a photographic field; a photometer that meters the field; an exposure calculation unit that calculates exposure based on the photometry data measured by the photometer; and an exposure calculated by the exposure calculation unit. an aperture control means for controlling an aperture that regulates the brightness of an optical image of a subject incident and formed through the imaging lens based on the data; and an exposure time of the optical image based on the exposure data. shutter drive control means for driving and controlling a shutter to be regulated; and means for regulating the start of exposure time, which is disposed behind the diaphragm and the shutter on the optical axis;
an image sensor that converts the image charge signal into a signal, and a frame image data generation means that reads out the video charge signal converted by the image sensor for each field data on the image carrier and generates frame image data based on the field data. , and video signal processing means for processing the video signal generated by the frame image data generation means.

Hereinafter, the present invention will be explained in detail based on the embodiments shown in FIGS. 1 to 3.

FIG. 1 is a functional block diagram showing one embodiment of the present invention.

A photometric lens 11 and a light-receiving element 13 are arranged so that their respective optical axes coincide with the optical axis X of the photometric system, and a light receiving element 13 receives the amount of subject light that is incident on the photometric lens 11 and has passed through the lens.

Based on the output of the light receiving element 13, a photometric circuit 15 measures the amount of light that has entered the photometric lens 11.

The analog output of the photometric circuit 15 is converted into a digital output by an analog-to-digital converter 17.

Central calculation bag! A CPU 19 (hereinafter abbreviated as CPU) receives the output of the analog-to-digital converter 17 and transfers control data to each circuit section to be described later.

The aperture control circuit 21 outputs an aperture control command based on aperture control data that is calculated by the CPU 19 and output. The diaphragm mechanism 5 is controlled by the diaphragm control circuit 21 and controls the amount of incident light of an optical image projected onto a CCD 9 (described later) by changing the aperture diameter.

The mechanical shutter drive control circuit 27 controls the mechanical shutter drive which is calculated by the CPU 19 and outputted! III @Outputs a shutter drive control command based on the data. The mechanical shutter 3 is drive-controlled by a mechanical shutter drive control circuit 27 and controls the amount of incident light of an optical image projected onto the CCDQ by a shutter function.

Along the optical axis
CD9 is arranged.

The CCD drive circuit 23 drives the CCD 9 based on control data from the CPU 19 and outputs a video signal.

The video signal processing circuit 25 performs processing to generate a video output from the video signal output by the CCD drive circuit 23.

FIG. 2 shows the timing of the electronic shutter operation in the embodiment shown in FIG. 1 and the field scanning of the charge pattern of the optical image of the object generated on the CCDQ based on the amount of light controlled by the mechanical shutter 3 and the aperture mechanism 5. This is a timing chart showing the following.

FIGS. 3(a), 3(b) and 3(c) show the structure of a part of the mechanical shutter 3 and the mechanical shutter drive control circuit 27 in the embodiment shown in FIG.

The step motor 51 rotates in steps in response to commands from the control output of the CPU 19 shown in FIG. Binion 53
is fixed to the rotating shaft of the step motor 51. The sector gear 55 meshes with the pinion 53. The aperture 57 is coaxially attached to the sector gear 55 and the shaft 59 . Engagement bin 6
1 is implanted in the aperture 57 and engages with a hole 63 formed in the sector gear 55. Aperture aperture 57a157b, 57
c and 57d are provided on concentric circles passing through the optical axis centered on the rotation axis 59 of the diaphragm 57.

The rotation shaft 35 is the rotation shaft of the shutter blade 31 installed in the shutter lever 33. Further, the engagement pin 37 engages with a perforation 39 formed in the upper part of the shutter blade 31, which is implanted in the shack lever 33 and formed in a crankbell shape, on the side that does not cross the optical axis. The rotation shaft 41 is the shutter blade 31
This is the axis of rotation when the shutter is open.

The plunger 43 is controlled by control commands from the CPU 19 shown in FIG. The engagement pin 45 is the plunger 4
The drive body 43a of No. 3 is implanted to engage with a perforation 47 formed in the shutter lever 33.

FIG. 3(b) shows the configuration with the shutter blade 31 open. FIG. 4(C) shows the configuration shown in FIGS. 12(a) and 22(b) in the upper and lower directions along the optical axis.

In each figure, the same components are given the same reference numerals.

Next, the operation of the embodiment of the present invention will be explained using FIGS. 1 to 3. The photometric light beam from the subject that enters the photometric lens 11 passes through the photometric lens 11 and is received by the photodetector 13. The conversion output charged and converted by the photodetector 13 is measured in the photometric circuit 15 and is detected as a counterfeit. The luminance analog output is converted to a digital output by an analog-to-digital converter 17.

This digital output is transferred to the CPU 19, where exposure calculation is executed. Exposure control data for controlling the diaphragm mechanism 5 obtained as a result of the exposure calculation is transferred to the diaphragm control circuit 21 and shown in FIGS.
) or the step motor 51 shown in FIG. The signal is transmitted to the sector gear 55 which meshes with the sector gear 55.

This driving force is transmitted to the aperture 57, and the aperture 57 is connected to the shaft 59.
It rotates around the optical axis of the imaging light.

Each aperture opening 57a, 57b formed in the aperture 57,
57c and 57d are selected based on the exposure control data calculated by CP019 shown in FIG. 1 at a rotational position where the aperture center coincides with the optical axis each time the stepper motor 5 rotates one step.

Exposure control data for controlling the mechanical shutter 3 obtained as a result of exposure calculation by the CPU 19 shown in the same figure is transferred to the mechanical shutter drive side@circuit 27, and is transferred to the mechanical shutter drive side @ circuit 27, as shown in FIGS. 3(a) and 3(b).
Alternatively, the plunger 43 shown in FIG. 3(C) is driven, and the controlled driving force of the plunger 43 is transferred from the driving body 43a of the plunger 43 shown in FIG. 3(a) to the driving body 4.
The signal is transmitted to the shutter lever 33 via the engagement pin 45 installed in the shutter lever 3a. The transmitted driving force is transmitted to the mechanical shutter 3.
The shutter lever 33 shown in FIG.
1 to open and close the mechanical shutter for the beam of light that forms the captured optical image.

Next, the operation of determining the exposure time (shutter speed) by the cooperation between the electronic shutter function and the mechanical shutter function of the CCD, which is the core of this technology, will be explained.

FIG. 2 shows a timing chart of the shutter of this technology. Figure 2 (a) shows the overflow drain that belongs to the CCD shutter function.
drain) indicates the timing when the overflow drain is turned ON or OFF.When the overflow drain is in the ON state, the first
Unnecessary charges on the CCD shown in the figure are swept away to the N-type substrate of the CCD during each horizontal blanking period, and the accumulated charges corresponding to the captured optical image are always empty. When the overflow drain is in the OFF state (tz~1.), the corresponding storage 8! ! Scavenging of the charge is prevented and the accumulation of charge corresponding to the captured optical image is preserved.

FIG. 2(b) shows the timing of the mechanical shutter of this technique.

When in the closed state (~1+), the shutter blade 31 of the mechanical shutter is in the position shown in FIG. 3(a), blocking passage of the imaging light beam.

When the oven is in the state (1+ to 1.), the shutter blade 3 is at a level that allows the imaging light beam to pass through, as shown in FIG. evacuate to.

FIG. 3(c) shows the light reception timing of the CCD 9 (FIG. 1).

Light reception starts when the overflow drain, which is the electronic shutter function of the CCD 9, is turned off.t2) Light reception ends when the shutter blade 31 of the mechanical shutter (Fig. 3 (a)) blocks the projection of the imaging light beam onto the CCD 5. (t,), the light reception period (tx~1.) is an exposure period and corresponds to the shutter speed.

FIG. 2(d) shows the timing at which one field readout gate is turned ON or OFF for a charge pattern corresponding to the captured optical image generated on the CCD 9 during the exposure period.

FIG. 5(e) shows the timing at which the field read gate is turned on or off twice for the charge pattern.

When the CPU 19 shown in FIG. 1 sets the aperture value as a result of exposure calculation based on the photometric output of the analog-to-digital converter 17, the mechanical shutter 3 is in the state shown in FIG. 3(a), and the shutter blades 31 is CC shown in FIG.
lol to D9! It blocks the image carrier ray east captured by the I image lens group 1.7. This state is at the closing timing (~t) of the mechanical shutter 3 shown in FIG. 2(b). In this timing state, the overflow drain for the electronic shutter function of the CCD 9 shown in FIG. 1 is in the ON state, and the charges existing in the CCD 9 are swept out as unnecessary charges, and the charges on the light-receiving surface of the CCD 9 become empty. There is.

The mechanical shutter drive control circuit 27 shown in FIG. 1 is driven in conjunction with a shutter button (not shown) of the camera, and the drive output drives the plunger 43 shown in FIG. 3(a), so that the driver 43a moves in the direction of arrow C. , shutter lever 3
3 rotates clockwise (in the direction of arrow B), and the shutter blade 3
1 is a mechanical shutter 3 that rotates clockwise around a shaft 35.
opens. At this point (from Figure 2 (bl t, ) to 3
As shown in FIG. 2(b), the Isoshiro shutter 3 is in an open state (t1 to t in FIG. 2(b)). In this state, the first
The optical image of the subject that has passed through the aperture aperture 57a, 57b, 57c or 57d corresponding to the exposure calculated by the CPL 119 is projected onto the CCD 9 shown in the figure, but the overflow drain of the CCD 9 is shown in FIG.
At the timing of the ON state (~tx) shown in a), the accumulated charges due to projection are swept out as unnecessary charges, so the CCD 9 is in a state where it is not substantially in the light receiving state (Fig. 2 (cl~t2)). Following the opening timing of the mechanical shutter 3 ((b)t in the same figure), the CP shown in FIG.
U19 transfers an electronic shutter opening command signal to the CCD drive circuit 23. The CCD drive circuit 23 turns off the overflow drain of the CCD 9 based on the command signal.
The command signal to be transmitted is transmitted. The overflow drain of the CCD 9 is connected to the timing of receiving the command signal (Fig. 2 (a)).
tz), it is reversed to the OFF state ((alt2 to tg) in the same figure.The CCD 9 starts substantially receiving light from this point ((cJt2) in the same figure) and accumulates a charge pattern corresponding to the optical image projected on the CCD9. The time when the electronic shutter is opened (Fig. 2 (alto)), that is, the time when charge accumulation starts in response to substantial light reception by the CCD 9 (Fig. 2 (cl ti))
) to the end point of the exposure time determined based on the exposure calculated by the CPU 19 shown in FIG.
In l t a-), the CPU 19 transfers a mechanical shutter closing command signal to the mechanical shutter drive control circuit 27 . Driving body 43a of plunger 43 shown in FIG. 3(b)
moves in the direction indicated by the arrow, the shutter lever 33 rotates counterclockwise (direction of arrow A), the shutter blade 31 rotates counterclockwise about the shaft 59, and the mechanical shutter 3 closes.

From this point (also in FIG. 2(b)), the mechanical shutter 3 is in the closed state (FIG. 2(b)) as shown in FIG. 3(a).
~) becomes.

Timing 1g (second
In Figure (a)), the electronic shutter of the CCD opens and the CCD starts accumulating the charge of the optical image in response to the light reception. The charge accumulation time up to the timing ti ((C) in the same figure) at which light reception on the CCD is interrupted and charge accumulation ends at the closing timing ts ((B) in the same figure) is the charge accumulation time corresponding to the CCD. This corresponds to the shutter speed of a hybrid shutter that is the core of this technology, which combines an electronic shutter function that starts charge accumulation and a mechanical shutter that ends charge accumulation. charge accumulation time) is the shutter speed corresponding to the digital output in the relationship between the aperture value and the shutter speed from the exposure calculated by the CPU 19 based on the photometric digital output output from the analog-to-digital converter 17 shown in FIG. The hybrid shutter is closed (timing t shown in FIG. 2(b)).
, after the exposure to the CCD 9 (Fig. 1) is completed (timing t shown in Fig. 2 (cl)), the charge pattern corresponding to the optical image accumulated on the CCD 9 during the exposure time is shown in Fig. 2 (d) and Field image data is read out by two field scans at the timing shown in (e), and one frame image data corresponding to the optical image is generated from the field image data of M2 times.

The mechanical shutter drive control circuit 27 shown in FIG. 1 transfers the timing when the mechanical shutter 3 closes as shown in FIG. 3(a) (FIG. 2(bl t)) to the CPU 19 as a mechanical shutter closing timing signal.

The CPU 19 receives the timing signal and outputs a drive command to the CCD drive circuit 23. After receiving the drive command, the CCD drive circuit 23 turns on (opens) the first field readout gate of the CCD 9 (Fig. 2(d)).
l tx ) command is transferred to the CCD 9.

From this point on, the CCD drive circuit 23 starts reading out the first field image data of the accumulated charge pattern on the CCD 9, and the field period (FIG. 2(d) ts to t
The field image data read in step 4) is output to the image processing circuit 18 as an output of the CCD drive circuit 23. After the timing at which the successive output of the first field image data is completed (second section (d) t), the CCD drive circuit 23 turns the second field readout gate of the CCD 9 on.
Timing to turn to N (open) [Figure 2 (el ts)
The command is transferred to the CCD 9.

From this point on, the CCD drive circuit 23 starts reading out the second field image data of the charge pattern accumulated on the CCD 9, and the field period (Fig. IJ2 (alt++
The field image data read out in ~ta) is sent to the image processing circuit 18 as an output of the CCD drive circuit 23.
is output to.

There is a difference of about one field period in the readout time between the first field image data and the second field image data, but the charges accumulated on the CCD 9 corresponding to the optical image of the subject maintain simultaneity in the exposure time and there is no time difference. It is image data.

The first field image data and the second field image data shown in FIG. 1, which are taken into the video signal processing circuit 18, are combined into frame image data in the processing circuit and processed as image data. The output is recorded on a memory card (not shown) attached to the electronic still camera.

After the timing at which the successive output of the second field image data ends ((dlta) in FIG. 2), the CCD drive circuit 23 instructs the timing ((alty) in FIG. 2) to invert the overflow drain of the CCD 9 from OFF to ON. In the ON state (11~), unnecessary accumulated charges in the CCD 9 continue to be swept out, and the CCD 9 enters a standby state for the next photographing.

The image data recorded on the above-mentioned memory card or the like is reproduced as a video signal and presented for viewing as a still image.

(Effects of the Invention) When frame image data is generated from two field image data that are simultaneous and have no time difference in exposure time, the charge is swept out of the overflow drain, which is the electronic shutter function of the CCD, at the start of light reception to the CCD. By reversing the function from ON to OFF and using a closing function that blocks the light projected onto the CCD by the mechanical shutter when the light reception is closed to the CCD, the structure of the mechanical shutter installed in the camera is extremely simple, making it compact and lightweight. This has the effect of greatly contributing to lower prices and lower prices.

[Brief explanation of drawings]

Fig. 1 is a block functional diagram showing the optical, electrical, and mechanical configuration of an embodiment of this technology, and Figs. FIGS. 3(a), 3(b), and 3(c) are diagrams showing the cooperation with the shutter and the timing of field image readout, which are block diagrams of the mechanical shutter. 1... First imaging lens group, 3... Mechanical shutter,
5... Aperture mechanism, 7... Second image carrier lens group, 9...
... CCD, 15... Photometric circuit, 17... Analog-to-digital converter, 18... Video signal processing circuit, 19
...CPU, 21...Aperture control circuit, 23...C
CD drive circuit, 27... mechanical shutter drive control circuit.

Claims (2)

[Claims] (1) It has an imaging lens that images a field, and a means for regulating the start of an exposure time based on an optical image of the field that is incident and formed through this imaging lens, and has a charge corresponding to the optical image. an image sensor that converts into a signal; a shutter that is located between the image sensor lens and the image sensor and regulates the exposure of the optical image to the image sensor; a setting device that sets an exposure time of the optical image; An electronic still camera comprising: a shutter drive control means for driving the shutter based on a set exposure time to regulate the end of the exposure time of the optical image. (2) an imaging lens that captures an image of a subject; a photometer that measures the light of the subject; an exposure calculator that calculates exposure based on photometric data measured by the photometer; an aperture control means for controlling an aperture that regulates the brightness of an optical image of a subject incident and formed through the imaging lens based on the calculated exposure data; shutter drive control means for driving and controlling a shutter that regulates the exposure time of the optical image; and a means for regulating the start of the exposure time that is disposed behind the diaphragm and the shutter on the optical axis, an image sensor that converts into a charge signal; a frame image data generation means that reads out the video charge signal converted by the image sensor for each field data on the image sensor and generates frame image data based on the field data; An electronic still camera comprising video signal processing means for processing the video signal generated by the frame image data generation means.