7. OTHERS (Cont’d)
TECHNICAL INFORMATION (Cont’d)
Operations Principles of the Electronic Shutter (with the 1/500 sec. setting)
Electric charge is stored in the CCD image sensing device only for a 1/500 sec. before the signal is read from the CCD image sensing device. At this time the electric charge stored previ- ously is discharged to another electrode. This process enables
shutter operations with 1/500 sec.
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Vertical sync. |
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CCD device | Signal discharging timing | Signal reading timing | ||
signal reading |
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timing |
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| Unnecessary | 1/500 sec. |
| 1/60 sec.[U Ver.] |
CCD electric | charge | Effective charge | 1/50 sec.[E Ver.] | |
charge |
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storage |
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Electric charge |
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to be stored |
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Video output |
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●Caution for electric shutter mode
•On a monitor, the movement of the object looks like the ones taken under a strobe shot because an image of 1/500 sec. is detected every 1/60 sec. [U Ver.] or 1/50 sec. [E Ver.].
•Flicker occurs under a light such as fluorescent lamp which lights cyclically. Adopting a light like an incandescent lamp which lights constantly is therefore necessary.
•With the 1/500 sec. shutter mode, the storage time of the CCD image device is approx. 1/8 [U Ver.] or 1/10 [E Ver.] of that of normal the mode, and also the sensitivity is 1/8 [U Ver.] or 1/10 [E Ver.] of that of the normal mode.This causes a shortage of light, so that it is recommended to increase the light volume by increasing the illumination to 800% [U Ver.] or 1000% [E Ver.] or opening the lens iris about 3 steps.
SLOW SHUT Function
This function is used to record an object brighter than it ap- pears in a dark place.
This function adopts a system which acquires higher electric charge by taking a longer time for storing electric charge into the CCD image device, not that the system increases GAIN electrically. This enables the recording of an image with high sensitivity even under conditions of less light.
The max. storage time is approx. 8 sec. (240 frames [U Ver.] or 200 frames [E Ver.] ). One frame image is output for several frames, therefore, the video output signals are latched into a memory by using a WEN signal which is output at the same time. On a monitor, the movement of the object looks like the ones taken under a strobe shot
●When the SLOW SHUT is set to 3FRM
CCD storage electric charge
Video output signal
WEN output signal
Note:
•With the AUTO IRIS MODE, the normal video level can- not be used. Set to the MANUAL IRIS MODE and adjust the diaphragm of the iris.
•By switching the
•When the flame number is increased, noise may also increase. Set it to the appropriate value.
ALC and EEI Operations
ALC stands for automatic level control, and EEI means shutter iris control.With FULL AUTO mode, it adopts a system for maintaining a certain level of video by combining the lens auto iris, the continu- ous variable electronic shutter (EEI) and the automatic sensitivity adjustment circuit (ALC).
The automatic sensitivity adjustment circuit works under low illumi- nance, and the electronic shutter works under high illuminance. Moreover, when the iris is set to AUTO, sensitivity, the iris and the electronic shutter change continuously to acquire the appropriate signal level automatically at any time.
In the ALC mode, there is sensitivity from 0 dB to +18 dB under low illuminance.In the EEI mode, the electronic shutter varies the shutter speed automatically from 1/60 [U Ver.] or 1/50 [E Ver.] to 1/1920 [U Ver.] or 1/1600 [E Ver.] sec.The signal level is adjusted in the range of 3 ( dark) to 5 ( bright).
When the iris is set to the manual mode, the sensitivity and the electronic shutter vary continuously without varying the iris setting. This function enables recording an object without varying its depth under variable illuminance.
Illuminance: lx | This is the calculated value, which is different from the actual |
value displayed on the screen. |
8
16
32
62.5125
250 | 500 | 1000 | 2000 | 4000 | 8000 | 16000 |
32000 64000 128000 256000
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+18dB +12dB +6dB
EEI
1/120[U Ver.] 1/240 | 1/480 | 1/960 1/1920[U Ver.] |
1/100[E Ver.] |
| 1/1600[E Ver.] |
| F1.4 | F2 | F2.8 | F4 | F5.6 | F8 | F11 |
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+18dB +12dB +6dB |
| 1/120[U Ver.] 1/240 | 1/480 | 1/960 1/1920[U Ver.] | ||||||||
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Revised in August 1998 27
