Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
1999-07-02
2004-11-02
Christensen, Andrew (Department: 2615)
Television
Camera, system and detail
Solid-state image sensor
C348S362000
Reexamination Certificate
active
06812965
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to imaging apparatuses having an imaging element, which are used for electronic still cameras, digital cameras and the like. More particularly, the present invention relates to an imaging apparatus having an imaging element for accumulating signal charge corresponding to an incident scene light flux in a photo-electric converting element section and transferring the accumulated signal charge through a vertical shifter to a horizontal shifter so as to be read out therefrom, and a shutter means for selectively blocking the scene light flux to be incident on the imaging element.
BACKGROUND OF THE INVENTION
Hitherto, various imaging apparatuses have been proposed as a digital still camera and a digital camera. The imaging elements applicable to such imaging apparatuses have also been proposed. Among such imaging elements is an inter-line CCD solid-state imaging element having a vertical overflow drain structure as schematically shown in FIG.
14
.
The CCD shown in
FIG. 14
comprises a two-dimensional array of photo-diodes
1
arranged in both horizontal and vertical directions and each constituting a photo-electric converting cell for accumulating charge according to light incidence, a plurality of vertical shift registers
3
constituting vertical shift paths for receiving charge accumulated in associated photo-diodes
1
via a transfer gate
2
and progressively vertically shifting the received charge, a horizontal shift register
4
constituting a horizontal shift path for receiving shifted charge from the vertical shift registers
3
and progressively horizontally shifting the received charge, and a signal detector
5
for amplifying the output signal of the horizontal shift register
4
and outputting the amplified signal.
FIG. 15
is a block diagram showing the construction of a prior art imaging apparatus with the CCD shown in FIG.
14
. The illustrated imaging apparatus comprises a focusing lens
11
, a shutter means
12
, a CCD
13
, as a signal processor
14
, a shutter driver
16
, a signal generator
17
, and a CPU
18
. The focusing lens
11
focuses a light beam of a scene on a light incidence surface of the CCD
13
. The shutter means
12
is constituted by, for instance, a mechanical shutter for either passing or blocking the scene light flux. The CCD
13
converts the scene light beam flux having passed through the shutter means
12
to an electric signal. The signal processor
14
performs various processes on the electric signal from the CCD
13
and outputs an image signal thus generated. The shutter driver
16
controls the shutter means
12
. The signal generator
17
supplies pulses for controlling the period of charge accumulation in the photo-diodes
1
, pulses for driving the vertical shift registers
3
and pulses for driving the horizontal shift register
4
and also supplies pulses for driving the signal processor
14
in synchronism with the CCD
13
. The CPU
18
collectively controls circuits including the driver
16
and signal generator
17
. The signal processor
14
and the signal generator
17
together constitute a digital signal processor (DSP)
19
.
FIG. 16
is a timing chart illustrating a conventional imaging operation in the imaging apparatus shown in FIG.
15
. Specifically, the Figure shows a vertical sync signal VD, a transfer gate pulse train TG, a sub-pulse train SUB, a vertical shift register shift pulse train VT, a clamp pulse train CLP, opening/closing operation of the shutter means
12
, and a CCD signal, i.e., a signal read out from the CCD
13
.
The vertical sync signal VD is a pulse train prescribing a predetermined unit period of time for obtaining a signal representing one image (i.e., one frame image). Here, periods prescribed by the individual pulses are labeled V
1
, V
2
, . . . .
The transfer gate pulse train TG consists of pulses for determining the timing of the transfer of charged stored in the photo-diodes
1
to the vertical shift registers
3
, and is applied to the transfer gate
2
in synchronism with the vertical sync signal VD. The transfer gate pulses TG corresponding to the periods, V
1
, V
2
, . . . of the vertical sync signal VD are labeled TG
0
, TG
1
, . . . .
The sub-pulse train SUB consists of pulses for discharging charge generated in the photo-diodes
1
in the vertical direction of the substrate. The charge discharge is done while sub-pulses SUB are outputted. That is, the charge is accumulated in the photo-diodes
1
during periods tb
1
, tb
2
, . . . in which the sub-pulses SUB are stopped in the periods V
1
, V
2
, . . . of the vertical sync signal VD. Thus, it will be seen that a so-called element shutter is realized, in which the effective exposure time is controlled through control of the charge accumulation period. The charge accumulation time is determined as a result of measurement of light of the scene image with a measuring means (not shown), and it is measured by counting sub-pulses SUB.
The vertical shift register shift pulse train VT consists of pulses for causing progressive shift of charge in the vertical shift registers
3
toward the horizontal shift register
4
.
The clamp pulse train CLP consists of pulses for clamping the CCD signal corresponding to an optical black portion of the CCD. By the clamping, the potential level of the image signal is stabilized to hold a stable black level.
The shutter means
12
is normally open, and is closed (light-shuttered or -blocked) when causing the transfer of charge accumulated in the photo-diodes
1
in response to a recording trigger signal. As the recording trigger signal, in the case of a shutter release button (not shown) providing a two-stage trigger signal, that is, in the case when a first trigger pulse is generated in a preparatory stage of lightly depressing the shutter release button for AF locking and a second trigger pulse is generated by further depressing the shutter release button for starting the recording of a still image, the second trigger pulse corresponds to the recording trigger signal.
The CCD signal has time sections to
1
and to
2
corresponding to optical black portions in the vertical direction and an effective time section intervening as a scene image period between these time sections. Normally the optical black signal is at a higher level than the effective period signal level.
As is seen from the timing chart of
FIG. 16
, in the prior art imaging apparatus upon generation of a recording trigger signal in, for instance, the period V
3
, vertical shift register shift pulses VT are continuously outputted during a subsequent time section ta for fast sweep-out of unnecessary charge in the vertical shift registers
3
. In the subsequent period V
4
, the charge is accumulated in the photo-diodes
1
by suspending the application of sub-pulses SUB for a time section tb
4
corresponding to the exposure period, which has been determined on the basis of the CCD signal until the recording trigger signal generation. Accordingly, the time section tb
4
constitutes an exposure time for one frame image.
In the subsequent period V
5
, the image obtained by the exposure during the time section tb
4
in the period V
4
is outputted as signal CCD
4
, which is outputted as a result of the exposure in response to the recording trigger signal from the signal amplifier
5
. Also, in synchronism with the start of the period V
5
, the shutter driver
16
is caused to drive the shutter means
12
for closing and in the subsequent period v
6
the shutter means
12
is opened. The image obtained by exposure as a result of the closing operation of the shutter means
12
in the period V
5
, is outputted as signal CCD
5
in the subsequent period V
6
. Since the signal CCD
5
is obtained while the shutter means is blocking incident light, the signal levels in the optical black portion time sections and the effective period are substantially equal.
As shown above, in the prior art imaging apparatus, fast sweep-out of charge from the vertical shift registers
3
is performed in the period V
Ide Masataka
Kijima Takayuki
Christensen Andrew
Harris Tia M.
Olympus Corporation
Volpe and Koenig P.C.
LandOfFree
Imaging apparatus with detectors for judging the operating... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Imaging apparatus with detectors for judging the operating..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Imaging apparatus with detectors for judging the operating... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3351567