Semiconductor image pickup device having function circuit block

Details Semiconductor image pickup device having function circuit block Semiconductor image pickup device having function circuit block

2002-06-05

2004-04-06

Allen, Stephone B. (Department: 2878)

Radiant energy

Photocells; circuits and apparatus

Photocell controlled circuit

C348S230100

Reexamination Certificate

active

06717127

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor image pickup device such as a complementary metal oxide semiconductor (CMOS) image sensor, a charge coupled device (CCD) or a semiconductor device including the CMOS image sensor or CCD.
2. Description of Related Art
FIG. 7
is a block diagram showing the configuration of a conventional CMOS image sensor representing a conventional semiconductor image pickup device.
In
FIG. 7
,
1
indicates a conventional CMOS image sensor.
2
indicates each of a plurality of pixel cells for respectively converting an optical signal into an electric signal indicating pixel data.
3
indicates a pixel array which is composed of the pixel cells
2
arranged in a two-dimensional array on a chip surface of the CMOS image sensor
1
. The optical signals sent from an object, of which an image is picked up, are received in the pixel array
3
and are convened into the electric signals.
4
indicates a logic input/output terminal for receiving an operation clock signal and data from the outside of the chip and outputting a data output start signal and the like to the outside of the chip.
5
indicates a data set unit for controlling the CMOS image sensor
31
according to the data received in the logic input/output terminal
4
.
6
indicates a set point register block for registering the data received in the logic input/output terminal
4
, producing a set point for each of a plurality of function circuit blocks according to the data and supplying the set point each function circuit block.
7
indicates a row scanner for selecting a series of pixel cells
2
placed on an arbitrary row of the pixel array
3
.
8
indicates a column scanner for selecting a series of pixel cells
2
placed on an arbitrary column of the pixel array
3
.
10
indicates a color tone correcting circuit for correcting a color tone (a red component, a green component and a blue component) of the electric signals converted in the pixel array
3
according to the set point sent from the set point register block
6
.
11
indicates a gain circuit for correcting the electric signals output from the color tone correcting circuit
10
at a gain (a ratio of the level of each output electric signal to the level of the input electric signal) corresponding to the set point sent from the set point register block
6
.
12
indicates a gamma correcting circuit for correcting the electric signals output from the gain circuit
11
to a degree corresponding to the set point sent from the set point register block
6
so as to fit the sensibility of the pixel array
3
to the sensibility of the naked eye.
13
indicates a digital-to-analog (D/A) converter for performing the D/A conversion by using the set point sent from the set point register block
6
and producing a reference voltage Vref.
13
a
indicates an adder, arranged in the gamma correcting circuit
12
, for adding the reference voltage Vref produced in the D/A converter
13
to each electric signal to change the level of the electric signal to a level suitable for a circuit connected to the chip of the CMOS image sensor
1
. A group of function circuit blocks
9
is composed of the color tone correcting circuit
10
, the gain circuit
11
, the gamma correcting circuit
12
with the adder
13
a
and the D/A converter
13
.
14
indicates an analog-to-digital (A/D) converter for performing the A/D conversion for each electric signal corrected in the gamma correcting circuit
12
.
15
indicates an output terminal through which each electric signal obtained in the A/D converter
14
is output.
16
indicates an analog pixel output terminal through which each electric signal obtained in the gamma correcting circuit
12
is output.
Next, an operation of the conventional CMOS image sensor
1
will be described below.
In the check of the function of the conventional CMOS image sensor
1
, circuit characteristics of the group of function circuit blocks
9
are checked. In this check, many set points ranging from several set points to tens of set points are sent one after another from the set point register block
6
to the group of function circuit blocks
9
. Therefore, many gains ranging from one-fold gain to several-fold gain or tens-fold gain are, for example, set in the gain circuit
11
.
In a check process of circuit characteristics of a desired function circuit block, data indicating a known set point is sent from the outside of the chip of the conventional CMOS image sensor
1
to the data set unit
5
through the logic input/output terminal
4
, the data is registered in the set point register block
6
, and the known set point is sent from the set point register block
6
to the desired function circuit block. In this case, a prescribed set point has been already sent to each of the function circuit blocks
9
other than the desired function circuit block. Thereafter, a plurality of optical signals input from the image pickup object to the pixel cells
2
of the pixel array
3
are converted into a plurality of electric signals, the electric signals are corrected in the group of function circuit blocks
9
such as the color tone correcting circuit
10
, the gain circuit
11
, the gamma correcting circuit
12
with the adder
13
a
and the D/A converter
13
according to the known set point and the prescribed set points to produce a plurality of corrected analog electric signals, the corrected analog electric signals are converted in the A/D converter
14
into a plurality of corrected digital electric signals, and the corrected digital electric signals are output to the outside of the chip of the conventional CMOS image sensor
1
through the output terminal
15
. Also, the corrected analog electric signals are output to the outside of the chip of the conventional CMOS image sensor
1
through the analog pixel output terminal
16
.
Thereafter, circuit characteristics of the desired function circuit block are checked according to the optical signals input to the pixel array
3
, the corrected analog or digital electric signals and the known set point supplied to the desired function circuit block in the outside of the chip of the conventional CMOS image sensor
1
. Therefore, in cases where a plurality of known set points different from each other are sent to the desired function circuit block, circuit characteristics of the desired function circuit block can be precisely checked.
FIG. 8
is an explanatory view of a check sequence of circuit characteristics of a desired function circuit block performed in the conventional CMOS image sensor
1
.
As shown in
FIG. 8
, a first set point is set in the data set unit
5
and is sent to a desired function circuit block in a data set unit setting time period T
1
. In this case, a prescribed set point has been already sent to each of the function circuit blocks
9
other than the desired function circuit block. Thereafter, when electric signals are prepared in the pixel array
3
during an accumulating time period (or a standby time period) T
2
, the data outputting is started in the pixel array
3
. In detail, in a data outputting time period (or an image pickup time period, for example, corresponding to one frame) T
3
, all the electric signals are sent from the pixel cells
2
of the pixel array
3
to the group of function circuit blocks
9
, and corrected electric signals are output from the group of function circuit blocks
9
to the outside of the conventional CMOS image sensor
1
. For example, one electric signal D is acquired in the group of function circuit blocks
9
and is output to the outside in a part of the data outputting time period T
3
. Thereafter, in a calculating and judging time period T
4
, the calculation for the electric signals and the judgment (or check) of circuit characteristics of the desired function circuit block are performed in the outside of the conventional CMOS image sensor
1
.
Therefore, in this check sequence, in cases where circuit characteristics of the desired function circuit block are checke

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