Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
1995-11-09
2004-04-13
Moe, Aung (Department: 2612)
Television
Camera, system and detail
Solid-state image sensor
C348S311000, C348S243000
Reexamination Certificate
active
06721009
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of driving a solid state imaging device, and particularly to a method of driving an aspect ratio variable solid state imaging device. Specifically, the aspect ratio variable solid state imaging device includes an image area having light receiving elements arranged in a matrix in accordance with a specified aspect ratio (for example, 16:9) and vertical registers for vertically transferring signal charges in respective vertical lines of the light receiving elements, and at least one horizontal register for horizontally transferring signal charges transferred from respective vertical registers. In this imaging device, a signal according to the above aspect ratio (for example 16:9) is outputted in a usual manner while a signal according to another aspect ratio (for example, 4:3) smaller than the above aspect ratio can be also outputted by discharging signal charges in right and left unnecessary portions in the image area in a horizontal blanking period.
2. Description of the Related Art
The television broadcasting is mainly carried out at an aspect ratio of 4:3 at present. However, high definition broadcasting at an aspect ratio of 16:9 is also carried out, and a television receiver for receiving high definition broadcasting tends to be popularized. In addition, a television receiver called a wide vision which reproduces high definition broadcasting at an image quality slightly lower than the original high image quality of the high definition broadcasting is also extensively used because of its low cost. In other words, television receivers different in aspect ratio are present in the market and homes. As a result, a video camera and the like have been required to be matched with the above two aspect ratios.
To meet such a requirement, there has been known a technique applied to a CCD solid state imaging device used for a video camera as imaging means, wherein light receiving elements and the like are arranged in an image area in accordance with an aspect ratio of 16:9. When a signal is outputted at the 16:9 mode, the imaging device is read out in a usual manner, that is, signal charges from effective pixels in the image area are all read out. On the other hand, when a signal is outputted at an aspect ratio of 4:3, signal charges in right and left unnecessary portions in the image area (each side portion having a width of being about one-eighth of the total width of the image area) are discarded by the function of the solid state imaging device.
Such a prior art aspect ratio variable CCD solid state imaging device is shown in
FIGS. 6A and 6B
.
FIG. 6A
is a plan view showing the schematic configuration of the solid state imaging device, and
FIG. 6B
is a time chart showing a horizontal blanking pulse, and a horizontal drive pulse for driving a horizontal register.
In these figures, reference numeral
1
designates an image area in which light receiving elements
2
, . . . ,
2
constituting pixels are arranged in a matrix. Reference numeral
3
designates a vertical register provided in the image area
1
for each vertical line of the light receiving elements, which is adapted to vertically transfer signal charges from the light receiving elements in each vertical line.
The light receiving elements
2
, . . . ,
2
and the vertical registers
3
, . . . ,
3
are arranged in the image area
1
in accordance with an aspect ratio of 16:9. In this example, specifically, the number of effective pixels in the horizontal direction is 948, while the number of effective pixels in the vertical direction is 486. The effective pixels in the number of 948×486 are all to be reproduced when the solid state imaging device is used at the aspect ratio of 16:9. On the other hand, when the solid state imaging device is used at the aspect ratio of 4:3, signal charges in a left side unnecessary portion
1
L and a right side unnecessary portions
1
R in the image area are discharged, that is, they are not outputted as signals for the solid state imaging device. The signal charges from a middle portion (necessary portion)
1
C are not discharged even when the solid state imaging device is used at the aspect ratio of 4:3.
It is to be noted that in
FIG. 6A
, the light receiving elements
2
, . . . ,
2
and the vertical registers
3
, . . . ,
3
are shown to be present only in the middle portion
1
C; however, they are actually arranged at the same pitches in the left side unnecessary portion
1
L and the right side unnecessary portion
1
R. Each of the left side unnecessary portion
1
L and the right side unnecessary portion
1
R has a width being about one-eighth of the total width of the image area
1
; while the middle portion
1
C has a width being about three-fourth of the total width of the image area
1
.
Reference numeral
4
designates a horizontal register for transferring signal charges vertically transferred from the vertical registers
3
, . . . ,
3
in the horizontal direction. The horizontal register
4
may be provided either on the upper side or on the lower side of the image area
1
, and in this embodiment, it is provided on the lower side of the image area
1
. Reference numeral
5
designates an output section provided on the output end side of the horizontal register
4
for converting signal charges into electrical signals (voltages). The output section
5
also serves as means for discarding unnecessary signal charges outputted from the horizontal register
4
.
Next, the operation of the CCD solid state imaging device will be described with reference to FIG.
6
B.
In the mode of the aspect ratio of 16:9, horizontal transfer is carried out by the horizontal register
4
during the horizontal scanning period in the same manner as in the usual CCD solid state imaging device. At this time, the frequency of a horizontal drive pulse for driving the horizontal register
4
, that is, a horizontal drive frequency is, for example, 18 MHz. Then, during a horizontal blanking period, vertical transfer, that is, transfer of signal charges by the vertical registers
3
, . . . ,
3
in the vertical direction is carried out. By such one vertical transfer, signal charges in the vertical registers
3
, . . . ,
3
on one horizontal line are transferred into the horizontal register
4
.
In the mode of the aspect ratio of 4:3, the operation is complicated more than the 16:9 mode. During the horizontal scanning period, signal charges in the middle portion
1
C of the image area
1
, that is, only the necessary signal charges are horizontally transferred and outputted. Then, during the horizontal blanking period, signal charges in the right side unnecessary portion
1
R are discharged, followed by vertical transfer, and signal charges in the left side unnecessary portion
1
L are discharged. Specifically, signal charges in the necessary portion
1
C for the n-th horizontal line are first transferred. Subsequently, during the horizontal blanking period, signal charges in the right side unnecessary portion
1
R for the n-th horizontal line are discharged, followed by vertical transfer for transferring signal charges for the (n+1)-th horizontal line into the horizontal register
4
, and signal charges in the left side unnecessary portion
1
L for the (n+1)-th line are discharged.
In summary, during the horizontal blanking period, drive of the horizontal register, vertical transfer, and drive of the horizontal register must be carried out.
After the above horizontal blanking period is ended, that is, in the subsequent horizontal scanning period, signal charges in the necessary portion
1
C for the (n+1)-th line are horizontally transferred. It is to be noted that in the 4:3 mode, the frequency of the horizonal drive pulse of the horizontal register
4
in the horizontal scanning period, that is, the horizontal drive frequency is 13.5 MHz, and the frequency of the horizontal drive pulse for discharging signal charges in the horizontal blanking period is, for example, 54 MHz.
The above-de
Moe Aung
Sonnenschein Nath & Rosenthal LLP
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