Hitachi HV-D25 operation manual Long-Time Store Mode, Ab+ Ac+

Long-Time Store Mode

In case that illumination on the subject is insufficient, just increasing the gain of the camera may cause an increase in noise, resulting in an unclear image. In such a situation, it is advisable to select the long-time store mode using the external memory. Thereby, the image can be brighter and clearer according to the stored amount of image. This camera is provided with two kinds of image store functions (CCD MODE:FLD/FRM in SUB MENU 1). When one of these image store functions is used, video signal output is delivered from the camera with the timing shown below.

Since the degree of after-image increases for a moving subject because of image storing, it is recommended to use the image store function when taking a still picture or scene.

	Field store mode
Even field	CCD line A
odd field	CCD line B
Even field	CCD line A
	CCD line B

In the field store mode, both the CCD lines A and B are read out simultaneously. After completion of storing, video signal output is made on the next field. Immediately before the field on which video signal output is made, the WE signal is delivered from the D-SUB connector equipped on the rear panel.

Store time: 1/15 s (Example)

VD signal
Store charge
	Aa		Ab		Ac		Ad
on CCD line A
Store charge
	Ba		Bb		Bc		Bd
on CCD line B
Video signal		Aa+		Ab+		Ac+
		Ba		Bb		Bc
WE signal

	Frame store mode
Even field	CCD line A
Odd field	CCD line B
Even field	CCD line A
	CCD line B
Odd field

In the frame store mode, each of the CCD lines A and B is read out individually. Therefore, the vertical resolution is superior. After completion storing, video signal output is made between two fields. Immediately before the field on which video signal output is made, the WE signal is delivered from the D-SUB connector equipped on the rear panel.

Store time: 1/15 s (Example)

VD signal

Store charge	Aa	Ab	Ac	Ad
on CCD line A
Store charge
	Ba	Bb	Bc	Bd
on CCD line B

Video signal

Aa Ba

Ab

Bb

Ac

Bc

WE signal

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