JPH02177777A - Exposure controller for still video camera - Google Patents

Abstract

PURPOSE:To make an appropriate light quantity of flash light attribute on exposure by computing the emission time of flash superposed on the accumulation time of a signal charge on an image pickup element based on distance information. CONSTITUTION:A means value BVc is found by photometric data inputted from a phtometry part 22, and shutter speed TV value is calculated from CCD sensitivity SVc and the diaphragm value AVc of an optical system. When the TV value is larger than hand-blurring limit shutter speed TVh, an appropriate diaphragm value AV at the time of emitting the flash is found from the guide number IVc of the flash, the sensitivity SVc of a CCD, and distance data obtained from a range finding part. And appropriate emission time Tf is calculated by comparing the AV value with the opening diaphragm value AV0 of the optical system. The emission timing Ttrg of the flash is found from the time Tf obtained in such a manner, exposure time TVc, and a time DELTAT until a state where a vertical transfer CCD can receive the signal charge is set, and the emission of the flash is permitted by setting FL.EL at H.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure control device for a still video camera using an image pickup element such as a COD having a shutter function.

[Prior Art] In a still video camera equipped with a so-called CCD shutter function, the timing of flash emission is disclosed in Japanese Patent Application Laid-open No. 63-2.
As shown in Japanese Patent No. 17882, the flash emission timing is determined based on the brightness information of the subject, the flash is fully emitted at a predetermined timing after the signal charge accumulation starts, and the signal charge is fully emitted when the proper exposure is achieved. There is something that ends the accumulation. In addition, as shown in Japanese Patent Application Laid-open No. 58-147722, a flash is emitted at a predetermined time after the accumulation of signal charges begins, and when proper exposure by flash light is achieved, the flash is forcibly stopped and the charge is charged. There is something that ends the accumulation.

By the way, although the amount of light contributed to exposure by flash light differs depending on the distance to the subject, conventionally C
No example is shown in which flash control is performed using distance information in exposure control using an OD shutter function.

[Problems to be Solved by the Invention] The present invention has been made based on the above background, and provides exposure control by determining the overlapping period of flash emission time and signal charge accumulation time based on distance information. Accordingly, an object of the present invention is to provide an exposure control device for a still video camera that can perform appropriate exposure control.

[Means for Solving the Problems] The present invention provides an exposure method for a still video camera equipped with an image sensor having a shutter function, a flash device that emits light as necessary, and a distance measuring device that obtains object distance information. The control device includes means for calculating, based on the distance information, a flash emission time that overlaps with the signal charge accumulation time in the image sensor.

[Operation] According to the above configuration, it is determined based on the distance information whether the flash emission time and the signal charge accumulation time overlap, and therefore the flash emission timing is also determined.
It is possible to make an appropriate amount of flash light contribute to exposure.

[Effects of the Invention] According to the present invention, when flash light is required in the exposure control of an image sensor equipped with a shutter function, the overlap between the signal charge accumulation time and the flash emission time is determined using distance information of the subject. By determining the period and performing flash control, it is possible to make an appropriate amount of flash light contribute to exposure, and it is possible to easily perform appropriate exposure control.

[Example] (Example 1) FIG. 1 shows the configuration of Example 1 of the present invention, and the following description will be made based on the same figure.

The central control circuit 1 controls the entire device, has multiple timers for time management of signal output for control, and performs predetermined calculations based on photometry data obtained by controlling the photometry section 2. Then, based on the calculation result, the CCD driver 3
, controls the flash control unit 4.

The photometry section 2 is located at the center i! In response to the control signal from lJ# circuit 1, pre-photometering is performed before photographing, and the photometry results are sent back to central control circuit 1 as surrounding subject brightness value B V a and main subject brightness value BVs. 1 IN
Upon receiving the REL signal and the FSP signal from the CCD driver 3, it outputs the EXP 1 signal to the central control circuit 1 and the CCD driver 3, which enables dimming in real time.

The CCD driver 3 receives E output from the central control circuit l.
In response to the XP2 signal and the ExP1 signal from the photometer 2, the CCD 5 accumulates signal charges and sweeps out unnecessary charges, furthermore, transfers the signal after accumulating the signal charges to the memory and synchronously sends it to the video processing circuit. It controls the

The flash $1J911 unit 4 receives the flash light emission signal FTR, flash stop signal FLS, and flash light emission enable signals PL and EN from the central fiIJ control circuit 1 and controls the light emission of the flash. Solid-state image sensor (C
The OD) 5 operates under the control of the CCD driver 3, and the video processing circuit 6 processes the signal charge accumulated by the CCD 5 as a video signal. The recording unit 7 is a block for recording the signal processed by the video processing circuit 6 to the still video FLO/B.

Next, each signal will be explained.

Release signal A signal that starts the exposure sequence at the rising edge of H (high) → L (low) when the release switch (SW) is pressed.

Real-time dimming of the photometer 2 becomes H-L after the time Tw necessary for scraping out unnecessary charges by highway transfer (n-1) times has elapsed from the time of H-+L of the INREL release signal. Start signal.

FSP: Vertical transfer of charges accumulated in the photoelectric conversion unit
Pulse to move to D.

EXPI: Controls the timing of the start of signal charge accumulation,
Also, a signal that gives a command to stop flash emission when the appropriate exposure amount is reached.

EXP2: A signal giving the stop timing of expressway transfer and the start timing of high-speed transfer.

φ■: Vertical transfer COD drive pulse.

FTR: A signal that gives the flash emission timing at the rising edge of L→H.

FLS: A signal that gives the flash emission stop timing at the rising edge of L-H.

PL, EN: Flash emission permission signal, H allows permission.
prohibited.

BVa: Surrounding subject brightness value measured by the photometer.

BVs: Main subject brightness value measured by the photometer.

Next, the exposure sequence during flash emission in Example 1 will be explained based on FIGS. 1, 2, and 4.

By pressing the release SW, the COD driver 3 will switch to FSP.
After outputting a pulse and a φV pulse and transferring the accumulated unnecessary charge to the vertical transfer COD using an FSP pulse, the operation of transferring it to a high-speed road using a φV pulse and sweeping it out to a sweep train is started, and this operation is repeated. At the same time, when the release SW is turned on, an interrupt is generated in the central control circuit 1, and the timer O counts the time Tw required to repeat the sweeping operation (n-t) times and waits so that there is no residue left after sweeping out due to highway transfer. (#
21.22.23).

When the timer O finishes counting and the Tw waiting time has elapsed, the INREL signal is turned off (#24).

In synchronization with the fall of the first FSP pulse after the INREL signal becomes low (Nth sweep operation), the EXPI signal from the photometer 2 changes from H to L, and spot photometry is started. Vertical transfer COD with FSP pulse at this time
The unnecessary charges transferred to the COD driver 3 are transferred to the expressway and are swept out to the drain (shutter open).
After the aforementioned n-th FSP pulse is output in response to the fall of the EXP1 signal, the FSP pulse is not output until the EXP2 signal becomes t.

After that, the reverse transfer continues until the EXP2 signal is output from L to H from the central control circuit 1, and the EXPI signal is changed to H to sweep out the smear component (unnecessary charge) generated in the vertical transfer CCD.
-L is received (#25), central control port Fjf! ! 1 is
Set timer 1 to the Ttrg value obtained from the result of the flash metering and start subtraction (#26, 27>. Wait until the content of timer 1 becomes 0, and when timer 1 becomes 0, set FT
Start flash emission by changing the R signal from L to H (#2
8). The photometer 2 sets the EXP 1 signal to L-H when the main subject area reaches an appropriate amount of light. At this time, upon receiving the EXP1 signal L → I (#29), the central control circuit 1
The S signal is set to L-H, the flash light emission is stopped, and the timer 2 is set to a time Ts that is sufficient to perform one expressway transfer of the vertical transfer COD, and the timer 2 is started (#30).

When the contents of timer 2 become 0 (#31), EXP2
The signal is set to L-H (#32), and in response to this, the COD driver 3 stops expressway transfer. After the time ΔT from the stop of expressway transfer until the potential of the vertical transfer COD reaches a state where it can transfer charges, a H→L-H pulse is generated in the FSP and the accumulated signal charge is transferred to the vertical transfer CCD (
shutter closed).

Thereafter, the signal charge is transferred to the memory section of the CCD 5 by the φV pulse, and sent to the video processing circuit 6 in synchronization with the video synchronization signal (reading of the video signal).

After setting the EXP2 signal to H, the INRBL signal is set to L-H,
EXP2 signal H-, L, FTR signal H-L, FLS
The signal is set to F (→L) to return each signal to its initial state before photographing (#33) (end of exposure sequence).

The photometric calculation sequence of the first embodiment will be explained based on FIG. 3.

Assuming that the difference between the pre-photometered values BVs and BVa sent from the photometer 2 to the central control circuit 1, that is, the brightness difference, is α, (
#1), in the case of α≧2, the main subject brightness is 2Ev lower than the peripheral subject brightness, so it is determined that it is backlit, and the sequence from #9 is performed (#2), if α≧2, the main subject is backlit , find the average value of BVa and BVs, and use this as B
Vc (#3), where the above brightness value BVc, CCD
Determine the shutter speed TV value from the sensitivity Svc and the aperture value AVc of the optical system (#4), determine whether the determined TV value is faster than the shutter speed value TVh that limits camera shake (#5), and determine whether the determined TV value is a value that is faster than the shutter speed value TVh that limits camera shake. If the shutter speed is fast, the flash light emission permission signal is set to L to prohibit light emission and expose using natural light (#8).

When the TV value is slower than the camera shake limit, the Franche light emission timing Ttrg is determined as the time from the time point of H-+L of the EXP1 signal. Ttrg is the time Ts equivalent to one unnecessary charge sweep-out operation of the vertical transfer COD from the camera shake limit time 2-TVh, the potential stabilization waiting time ΔT for the vertical transfer COD to switch from highway transfer to high-speed transfer, Light emission time TfO when the flash is fully fired
(#6). This is because signal charges are accumulated during the periods Ts and ΔT in FIG.
This is because it is necessary to subtract the time Ts+ΔT in advance because the amount of time will be exceeded, and it is also necessary to consider the total light emission time of the flash so that the exposure time does not exceed the camera shake limit. After determining Ttrg, the flash light emission enable signals FL and EN are set to H to permit flash light emission.

If backlight is determined in #2, the TV value is determined so that the surrounding subject brightness exceeds IBv (#9).

If the Tv value is later than the camera shake limit ffI Tvh, the flash emission timing Ttrg (Y in #10)
ES), Ttrg=2-TVh-TfO (#11), and if it is faster than the camera shake limit TVh (No in #10), Ttrg=2-TV-Ts-ΔT-TfO (#1
2) After correcting the Ts + ΔT time and the flash emission time TfO described above (and obtaining Ttrg), the flash emission permission signals FL and EN are set to H to permit the emission of the flash.

Note that FIG. 3(b) is a flowchart when the flash is emitted at the same time as the signal charge accumulation starts when the signal charge accumulation time is short because the surroundings are extremely bright. In addition, FIG. 4(b) is a flowchart for limiting the exposure (storage) time to 2-TVh determined by the camera shake limit when proper exposure is not achieved even when the flash fires. ) is an exposure sequence in high-brightness front lighting in the first embodiment.

(Example 2) The exposure sequence during flash emission in Example 2 of the present invention will be explained based on FIGS. 1, 5, and 7.

By pressing down the release SW, the COD in Figure 1 is released.
The driver 3 outputs FSP and φ■ pulses, transfers unnecessary charges accumulated in the photoelectric conversion section of CCD 5 to the vertical transfer COD using the FSP pulses, transfers them to the highway using the φ■ pulses, and starts sweeping them out to the drain. do. When this release SW is turned on, an interrupt is generated to the central control circuit 1, and the sweeping operation (n
The timer 0 counts the time Tw that can be repeated -1) times and waits (#121, 122, 123>).

After timer 0 finishes counting and Tw time has elapsed, I
Set the NREL signal to L (#124).

After the INRBL signal becomes L, the BXP1 signal from the photometer 2 changes from H to L in synchronization with the fall of the first FSP pulse (FSP for the n-th sweep operation).
Spot metering starts (#125), at this time F
Unnecessary charges transferred to the vertical transfer COD by the SP pulse are transferred to the drain and drained out.

Upon receiving the falling edge of the EXPI signal, the COD driver 3 outputs the nth FSP pulse and then outputs the EXP
The output of the FSP pulse is stopped (shutter is open) until 2 rises to L-H.

At the timing when the EXP1 signal falls from H to L, the central control circuit 1 sets the TVc determined by the photometry calculation to the timer 1, and starts the timer 1 (#126).
At the same time, the FTR signal is set to H and the flash starts firing (#127).When the light intensity of the main subject becomes appropriate, the photometry unit 3 changes the EX21 signal from L to H, so the BXPI
In response to the rising edge of the signal (#128), the central control circuit 1 sets the FLS signal to H to stop the flash emission, and at the same time sets the timer 2 to a time Ts that is sufficient to perform one high distance reverse transfer of the vertical transfer COD. Then, timer 2 is started (#129), and the content of timer 2 becomes O (#130).
), and after the elapse of time Ts, the EXP2 signal is set to HL (#131).

The COD driver 3 stops the expressway transfer that was being performed up to then at the timing of this falling edge of EXP2.

After this, the central control circuit 1 waits for timer 1 to become 0 (#132), and when timer 1 becomes 0, it raises the EXP2 signal to L-H (#133). Driver 3 is FSP's H-L-
Outputs an H pulse and transfers the accumulated signal charge to the vertical transfer CCD (shutter closed).The signal charge transferred to the vertical transfer COD is transferred to the memory section by the φ■ pulse and synchronized with the video synchronization signal. The images are processed by the image processing unit circuit 6. After setting the EXP2 signal to H, each signal INREL
is set to H, FTR is set to L, and FLS is set to L to return to the initial state before photographing (#134) (end of exposure sequence).

Next, the shortest shutter speed will be explained.

In Examples 1 and 2, after the flash stops emitting light, in order to remove the smear component of the vertical transfer CCD, the expressway transfer is continued for a time Ts during which the vertical transfer COD can be swept out once during the expressway transfer. .

Further, a time ΔT is required from when the expressway transfer is stopped until it becomes possible to read the signal by high-speed transfer, that is, until the potential of the vertical transfer COD is in a state where it can receive the signal charge. Therefore, the shortest shutter speed is constrained by (Ts+ΔT) and [(EXP
L period of I)+(Ts+ΔT)].

In addition, in the case of Example 2, EXP2 during TVc-ΔT
Expressway transfer may be performed by leaving the signal at H.

The photometry calculation sequence of Embodiment 2 will be explained based on FIG. 6. As a result of the blurring photometry input from the photometry section 2 of FIG. Let α be (#101), the brightness difference α is α×2,
That is, if the main subject brightness is 2 Ev or more lower than the surroundings, it is determined that the subject is backlit, and otherwise it is determined that it is frontlit (#102). When there is direct sunlight, calculate the average value of BVa and BVs and calculate it as BVC #103), and calculate this BVc and C
The shutter speed TV value is determined from the CD sensitivity SVc and the aperture value AVc of the optical system (#104). Determine whether the obtained TV value is faster than the camera shake limit shutter speed value TVh #105) When the TV value is faster than Tvh, set the flash emission permission signals FL and EN to L to prohibit flash emission. Then, expose with natural light (#108). If the TV value is slower than TVh, the signal charge accumulation time, that is, the exposure time, is set as TVc and T.
V c -2-TVh binding (#106), set PL, EN to H, fire the flash and take a picture (#10
7).

If backlighting is determined in #102, the TV value is determined so that the surrounding subject brightness exceeds IEv (#109
), and the exposure time TVc is the camera shake limit time T.
If the value is faster than Vh, set TV 2, and if TV h is slower than the camera shake limit time 'r v h, set 2 (#110.1
11,112) Next, since the photo was taken against the light, PL
, set EN to H to permit flash emission (#113
).

(Embodiment 3) FIG. 8 shows the configuration of Embodiment 3, and the following description will be made based on this figure.

The central control circuit 11 controls the photometry section 12 and the distance measurement section 18, and calculates the main subject brightness value BV as photometry data before shooting.
s and the surrounding subject brightness value BVa are taken in from the photometry section 12, and the distance measurement section 18 takes in DVc which indicates the distance to the subject.
Also, this central control port F! ? 111 is
It has a built-in plurality of timers (timer 0, timer 1, timer 3), and can time-manage the control output signals of the COD driver 13 and flash control unit 14 during shooting.
It is also connected to counter 19, and the count number C-D
By setting it as ATA, FSP pulses from the COD driver 13 can be counted.

The photometric section 12 is controlled by the central control circuit 11 and sends photometric data values BVs and BVa back to the central control circuit 11.

The CCD driver 13 receives the ON signal of the release SW, the EXP2 signal from the central control circuit 11, and the E signal from the counter 19.
Upon receiving the XP1 signal, it controls the accumulation of signal charges in the CCD 15, the sweeping out of unnecessary charges, and the transfer of the signal charges after accumulation of signal charges to the memory section and sending them to the video processing circuit.

The flash control unit 14 receives signals from the central control circuit 11 to PL and E.
Input the N signal and FTR signal, and when the PL and EN signals are H, the FTR signal is accepted and the flash is emitted, and the P
When the L and EN signals are L, the FTR signal is not received, the flash is not emitted, and the solid-state image sensor (CCD
) 15 operates under the control of the CCD driver 15,
The video processing circuit 16 processes the signal charge accumulated by the CCD 15 as a video signal. The recording unit 17 is
The video signal processed by the video processing circuit 16 is recorded on a still video floppy disk.

The distance measuring section 18 performs distance measurement upon receiving a distance measurement start control signal from the central control circuit 11 and outputs a distance measurement data value DVc to the central control circuit 11. The counter 19 is reset by the RESET signal from the central control circuit 11 and counts the number of pulses of the FSP signal from the CCD driver 13.

The number of pulses of the PSP signal is changed from the central control circuit 11 to C-D.
When it becomes equal to the value set as ATA, EXP
1 signal falls to H-L. EXP at reset
1 signal is in the H state.

The fogging sequence during flash emission in Example 3 will be explained based on FIGS. 8, 9, and 11.

By turning on the release SW, the CCD driver 13 outputs an FSP pulse and a φV pulse, and after transferring the unnecessary charge accumulated in the photoelectric conversion section of the CCD 15 to the vertical transfer CCD using the FSP pulse, it is transferred to the highway using the φV pulse. Then, start the action of hoisting the material to the sweep-out train, and repeat this process. Further, at the timing of turning on the release SW, an interrupt is generated in the central control circuit 11, and the flash emission timing T r g obtained by the photometric calculation is set in the timer O, and the timer 0 is started (#230
．． 231), when the content of timer O reaches 0 and Ttrg time has elapsed since the release switch was turned on, the FTR pulse is set to L-H and the flash starts firing (#2
33).

The counter 19 counts the number of FSP pulses and lowers the EXPI signal from H to L in synchronization with the fall of the n-th FSP pulse after the release switch is turned on.
When this EXPI signal falls in response to 9 (#234>,
The central $IJ control circuit 11 sends (Tf+Ts) to timer 1,
Tie 72 c: Set the TV C and start each (#235, 236> (shutter open)
, the CCD driver 13 outputs the nth FSP pulse in response to the falling edge of EXPI, and then outputs the low level of EXP2.
→Stop FSP pulse output until H rises.

Note that Tf is the flash light emission time obtained by photometric calculation, Ts is the time required to sweep out unnecessary charges from the vertical transfer CCD once, and T V c is the signal charge accumulation time obtained by photometric calculation.

After starting timer 1 and timer 2, the central control circuit 11 first waits for the content of timer 1 to become O (#
237), when the content of timer 1 becomes 0 after (Tf+Ts) time has elapsed, the EXP2 signal is lowered to H-L (
#238), at this timing the CCD driver 13
First, the central control circuit 11 stops the V pulse output and stops the high distance reverse transfer. Next, the central control circuit 11 waits for the content of timer 2 to become O (#239), and when the content of timer 2 becomes 0, EXP
2 signal to L-H (#240). In synchronization with the fall of EXP2, the CCD driver 13 outputs an FSP pulse and transfers the accumulated signal charge to the vertical transfer COD (shutter closes).

The signal charge transferred to the vertical transfer COD is transferred to the memory section by the φV pulse, processed as a video signal by the video processing circuit 16, and then recorded.

Finally, the FTR signal is turned on to return to the initial state and the exposure sequence is completed.

Next, the shortest shutter speed will be explained.

In Example 3, after the time Tf has elapsed from the start of signal charge accumulation,
In other words, after the flash has finished emitting light, during the time Ts during which the smear component of the vertical transfer CCD can be removed and the vertical transfer COD can be swept out once during expressway transfer, expressway transfer continues, and expressway transfer is stopped. In order to transfer the accumulated signal charges from the photoelectric conversion section to the vertical transfer COD, a time ΔT is required to stabilize the potential of the vertical transfer COD.

For this reason, the shortest shutter speed is (T s + ΔT
), and (Tf+Ts+ΔT
) is the shortest shutter speed time.

The photometric calculation sequence in the third embodiment will be explained based on FIG. 10.

The difference between the main subject brightness value BVs and the peripheral subject brightness value BVa, which are the results of the preliminary photometry input from the photometry section 12 in FIG. 8, is taken and this is set as α (#201).
If the main subject brightness is 2 EV or more lower than the surrounding brightness, it is determined that the subject is backlit, and otherwise, it is determined that it is frontlit (#202).

If it is determined that there is direct sunlight, calculate the average value of BVa and BVs and use it as BVc.
Vc, shutter speed T from optical system aperture value AVc
Calculate the V value (#204), determine whether this TV value is faster than the camera shake limit shutter speed Tvh (#205), and if it is faster than TVh,
In addition to setting TV c = 2-TV, flash emission permission signals FL and EN are changed from H to L to prohibit flash emission and take pictures using natural light (#20
6.207), when the TV value is a value slower than the TVh value and jl, knee G, t, TVc-2-TVh) and proceed with the sequence from #209 onwards. TVc is the charge accumulation time of the CCD.

If backlighting is determined in #202, set the TV value so that the peripheral object t*brightness exceeds IEV (#2
18) If the obtained TV value is faster than the camera shake limit shutter speed TVh, set 2, and if it is slower, set 2 - TVh to TVcV and proceed with the sequence from #209 (#219.
220, 221>.

From #209 onwards, the sequence for determining the flash firing timing is determined from the flash guide number IVc, CCD sensitivity SvC, and distance data DVc input from the distance measuring section. (#209), compare the obtained AV value with the open aperture value AVO of the optical system (#210), and find that AV≦
In the case of AV (1), the distance to the subject is too far for the flash light to reach, so the flash emission time Tf is set to the total emission time TfO (#217), AV>
In the case of AVO, the appropriate aperture value AV and the open aperture value AV
The difference ΔAV from O is calculated (#211). Since the light emission characteristics of the flash are known in advance, a light emission time Tf corresponding to ΔAV can be calculated (#212). From the Tf thus obtained, the total light emission time TfO, and the time Tw required to sweep out unnecessary charges after turning on the release SW, calculate the time Ttrg from turning on the release SW to the timing of flash emission ($213). Furthermore, FL, EN
→H to enable flash emission (#214).

Next, the central control circuit 11 outputs a RESET signal to reset the counter 19. When the counter 19 is reset, the E X P 1 signal is set to H. After resetting the counter 19, the central control circuit 11 controls the FSP to be counted.
The number n of pulses is set in the counter 19 as C-DATA (#216).

Note that FIG. 9(b) and FIG. 11(b) respectively show the exposure operation timing and exposure sequence during high-brightness front lighting in the third embodiment.

(Embodiment 4) FIG. 12 shows the configuration of Embodiment 4, and the following description will be given based on this figure.

The central control circuit 21 controls the photometry section 22 and the distance measurement section 28, and calculates the main subject brightness value BV as distance measurement data before photographing.
s, surrounding subject brightness value BVa from the photometry section 22, and
The DVc values indicating the distance to the subject are respectively fetched from the distance measuring section 28, and based on these inputs, an appropriate exposure time and flash emission timing are determined. Moreover, this central control circuit 21 has a plurality of built-in timers (timer 0, timer 1, timer 3), and when shooting, the C, CD driver 23
, the control output to the flash control unit 24 can be time-managed.

The photometry section 22 sends back the photometry data values BVs and BVa to the central control circuit 21 under control from the central control circuit 21 .

The COD driver 23 receives the ON signal of the release SW and the EXP signal from the central control circuit 21, and controls the accumulation of signal charges in the C0D 25, the sweeping out of unnecessary charges, and the transfer of signal charges after accumulation of signal charges. It is.

The flash control unit 24 receives PL and E from the central control unit 21.
When the N signal and FTR signal are input, and the PL and EN signals are H, pTR, (receives No. 8 and fires the flash, and when the PL and EN signals are L, it does not accept the FTR signal, Do not fire the flash.

The solid-state wk image device (CCD) 25 is a COD driver 23
The video processing circuit 26 operates under the control of C0D2.
The signal charge accumulated in step 5 is processed as a shadow one-image signal.

The recording section 27 is. The video signal processed by the video processing circuit 26 is recorded on a still video floppy disk. The distance measuring unit 28 performs distance measurement in response to distance measurement start control from the central control unit 1i21, and sends the distance data DVc to the central control circuit 2.
Send it to 1.

Note that the EXP signal provides the timing to start accumulating signal charges and the timing to stop the operation of sweeping out unnecessary charges by high-speed transfer.

The exposure sequence during flash emission in the fourth embodiment will be explained based on FIGS. 12, 13, and 15.

By turning on the release SW, the COD driver 23
After outputting SP and φV pulses and transferring the unnecessary charges accumulated in the photoelectric conversion section of the CCD 25 to the vertical transfer C and CD using the FSP pulse, the operation is started to perform high-speed transfer using the φV pulse and sweep it out to the drain. . In addition, the central control circuit 21 generates an interrupt at the timing when the release switch is turned on, and performs an interrupt (n
Set timer 0 to a time TW that is long enough to repeat the sweeping operation -1> times, and start timer 0 (#3
30), wait for the contents of timer O to become O (#331
), then detects the falling edge of the FSP pulse (#
332), and sets the EXP signal to HL (1333) (shutter open).

When the EXP signal is in the L period, the COD driver 23 does not output the FSP pulse, and only the sweeping operation for expressway transfer is performed using the φV pulse.

Furthermore, at the same time as the EXP signal falls, the central control circuit 21 sends timers 1 and 2 Ttrg, (TV
c-ΔT) and start each timer (#
334), when the content of timer 1 becomes 0 (#335)
, First, set the FT P signal to 1--H to fire the flash (#336), and when the time TVC has elapsed and the content of time 2 becomes O (#337), the EXP signal is set to L →
Set H (#338) to stop sweeping out unnecessary charges by expressway transfer. After Δ]゛ hours due to expressway transfer stop,
The potential of the vertical transfer CCD becomes ready to receive signal charges, and the signal charges accumulated by the FSP pulse are transferred to the vertical transfer COD (shutter closed).

The signal charge transferred to the vertical transfer COD is transferred to the memory section by the φV pulse, processed as a video signal by the video processing circuit 26, and then recorded.

Finally, the FTR signal is set to L to return to the initial state and the exposure sequence is completed.

Next, the shortest shutter speed will be explained.

In Embodiment 4, ΔT is set in order to create a state in which the potential of the vertical transfer COD can receive and receive signal charges from the time the expressway transfer is stopped to the start of signal charge readout by high-speed transfer.
time is required. During the period of this ΔT, the photoelectric detection section continues to accumulate signal charges, so the shortest shutter speed is limited by this ΔT.

The photometry calculation in Embodiment 4 will be explained based on the block diagram in FIG. 12 and the flowchart in FIG. The difference in Va is taken and this is set as α (#301). If the brightness difference α is α minus 2 and the main subject brightness is 2EV or more lower than the surroundings, it is determined that the subject is backlit, otherwise it is determined that it is frontlit (#30
2).

If it is determined that there is direct sunlight, calculate the average value BVc of B V a,, BVs (#303>, BVc, and CCD
A shutter speed TV value is calculated from the sensitivity SVc and the aperture value A V c of the optical system (#304).

Determine whether the value is faster than the camera shake limit shutter speed TVh (#305), and if the value is faster than the camera shake limit shutter speed TVh, set the exposure time TV to 2.
c, set FL and EN to L to prohibit flash emission, and take pictures using natural light.<#306,30
7) If the TV value is slower than TVh - TV)i value, set 2 to exposure time TVc and #30
Proceed with the sequence from 9 onwards (#308).

On the other hand, if it is determined that the subject is backlit, the TV value is set to a value that causes the surrounding subject brightness to exceed IEV (#316). , 2-T for slow values
Set Vh as the exposure time T V c, respectively, and #
Proceed with the sequence after 309 (#317.318.
319).

The sequence after #309 is for determining the flash emission timing. Based on the flash guide number IVc, CCD sensitivity SV (and the distance data DVc obtained from the distance measuring unit), the appropriate aperture value A when firing the flash
Find V (#309), compare this AV value with the open aperture value AVO of the optical system (#31.0>, AV≦AVO
In this case, the distance to the subject is too far for the flash light to reach, so the appropriate flash firing time Tf is the total firing time TfO6 (#315), and when AV>AVQ, the appropriate aperture @AV. Find the difference ΔAV between the open aperture 1iii AVO (#311). Since the light emission characteristics of the flash are known in advance, an appropriate light emission time of 1゛f corresponding to ΔAV can be calculated (#312).

From Tf thus obtained, exposure time T V c, and time ΔT until the vertical transfer CCD receives signal charges, the flash emission timing T t r
Find g (#31.3), and finally set FL and EN to H to allow the flash to fire.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of Embodiment 1.2 of the present invention, Figure 2 (
a) is an operation timing diagram of Embodiment 1, FIG. 2(b) is an exposure operation timing diagram in high brightness front light in Embodiment 1, and FIG. 3 (a>(b) is a photometry calculation of Embodiment 1) Sequence flowchart, FIG. 4 (a>(b) is a 70-chart of the exposure sequence during flash emission in Example 1,
Figure (C) is a flowchart of the exposure sequence at high brightness 11n light in Example 1, Figure 5 is an operation timing diagram of Example 2, Figure 6 is a flowchart of the photometry calculation sequence of Example 2, and Figure 7. 9 is a flowchart of the exposure sequence during flash emission in Embodiment 2, FIG. 8 is a block diagram of Embodiment 3, FIG. 9(a) is an operation timing diagram of Embodiment 3, and FIG. 9(b) is an embodiment. 10 is a flowchart of the photometry calculation sequence of Example 3, FIG. 11(a) is a flowchart of the exposure sequence of Example 3, and FIG. 11(b) 12 is a block diagram of Embodiment 4, FIG. 13 is an operation timing diagram of implementation pA4, and FIG. 14 is a photometry calculation sequence of Embodiment 4. The flowchart in FIG. 15 is for Example 4.
3 is a flowchart of the exposure sequence of FIG. 1.11.21...Central control circuit, 3,13.23.
・・COD driver, 4,14.24・・Flash system w part, 5,15.2'5・・COD, 18.28・
...Distance measurement section.

Claims (1)

[Claims] (1) In an exposure control device for a still video camera that includes an image sensor with a shutter function, a flash device that emits light as necessary, and a distance measuring device that obtains object distance information, an image is captured based on the distance information. 1. An exposure control device for a still video camera, comprising means for calculating a flash emission time that overlaps with a signal charge accumulation time in an element.