JPS6343486A - Image pickup device - Google Patents

Abstract

PURPOSE:Not to dislocate the spectral sensitivity characteristic of both sensors even if the color of a light source changes suddenly by limiting the accumulation of charges in a colorimetric coloring matter sensor using an image pickup system element and an element having the same characteristic as a said element. CONSTITUTION:An incident light limited by an iris 1 and a shutter 2 in converted into electrical signals such as a red signal R, a green signal G and a blue signal B by the image pickup element 3. At this time, a pulse (a) is transmitted from a pulse generating unit 10 to the element 3 and the charges are accumulated only for the duration of accumulating charges. And the pulse (b) is transmitted to the shutter 2, which is made to open while the pulse is high. Therefore the charges accumulated in the element 3 corresponds to the incident light while the shutter 2 opens. And the pulses (c) and (d) are transmitted to the colorimetric coloring matter sensor 8 from the pulse generating unit 10 and its accumulation period is the same as the duration of accumulating charges in the element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an imaging device such as a puppy camera, and particularly relates to white balance adjustment of an imaging device.

[Prior Art] Three types of white balance 33g in imaging devices are known: (1) manual type, (2) feedback type automatic adjustment method, and (2) automatic adjustment method using colorimetric sensor, so-called automatic tracking type. . Among these methods, ■ is a method in which the white balance is adjusted by manually adjusting the gains of the red signal R, green signal fi, Q, and blue signal B from the imaging system to a predetermined value, and ■ is when white objects are detected. The signal taken at the specified ratio (R:G:B=1:1:1)
The white balance is adjusted by using a feedback loop to set the gains for these, and then shooting with the set gains.
■By arranging a colorimetric sensor independent of the imaging system and always supplying correct light source information to the pseudo-imaging system circuit,
This is to adjust the balance.

Among these methods, the automatic adjustment method using a color sensor (■) is the one that does not require much effort and still allows you to adjust the white balance, which is expected to become mainstream in the future. Conceivable.

As a colorimetric sensor in the conventional automatic tracking type white balance 3I adjustment, a silicon photodiode, a photoconductor, or the like is used. Furthermore, solid-state imaging devices such as CCD, MOS, and SIT are increasingly being used as imaging sensors.

In that case, both the colorimetric sensor and the m-type sensor have some differences in spectral sensitivity characteristics due to differences in physical properties, structures, etc. The white balance will be disrupted.

Therefore, it is desirable to use the same type of CCD, MOS, and SIT calculation as the image sensor for the colorimetric sensor for white balance, but these elements are not suitable for dynamic and
Since the range is narrow, if a conventional color sensor is replaced with one of these sensors, it will not be able to compensate for all changes in external light.

[Problems to be Solved by the Invention] As described above, in the conventional white balance "A%" installation, due to the lack of dynamic range of the sensor, the colorimetric sensor is combined with the imaging sensor. It is not possible to use the same type of solid-state image sensor, and as a result, the spectral sensitivity characteristics of both sensors differ, and depending on the light source used, white
There was a problem with losing balance.

In view of these problems, it is an object of the present invention to provide an imaging device that maintains the white balance no matter what kind of light source is used and that allows for highly accurate white balance adjustment. It is something to do.

[Means for solving the problem] In order to achieve this purpose, in this development, an imaging system element, a colorimetric sensor using an element having the same characteristics as the imaging system element, and an imaging system element and means for limiting the accumulation of charge in the colorimetric sensor.

[Function] In this way, the period during which charges are accumulated in the embellishing sensor and the period during which light is irradiated to the imaging system element and charges are accumulated in the imaging system element can be appropriately controlled. Therefore, even when the color of the light source changes rapidly, the amount of charge accumulated in both the 4M image system and colorimetric system sensors can always be matched, and the spectral sensitivity characteristics of both sensors will not deviate. It becomes possible to do so.

[Example] The present invention will be described in detail below based on one drawing. FIG. 1 is a circuit block diagram for explaining a first embodiment of the invention, and FIG. 2 is a timing diagram for explaining the operation of this circuit. In Fig. 1, l is a rim that limits incident light, 2 is a shutter, 3 is a solid-state image sensor that stores optical information as a charge and converts it into an electrical signal, and 4 and 5 are red signals of image sensor 3, respectively. R2 Red signal # that amplifies the output of green signal B
II++a unit, a blue signal amplifier, 6 a process unit that derives a color difference-luminance signal from the output of the amplifier 4.5 and the output of the green signal G of the image sensor, 8 a color embellishment sensor that embellishes the color of the light source, and 7 a color embellishment sensor. 8 is a pattern that restricts the incident light, and 9 is P? from the output of the colorimetric sensor 8. A side control voltage derivation unit that derives a voltage to control the I% converter 4.5, IO is the image sensor 3.5. This is a pulse generator that sends timing pulses to each block such as the color sensor 8.

Reference numerals 11 and 12 are step motors that respectively drive the fins 1 and 2, and are driven by the output e of the pulse generator IO.

The image sensor 3 and colorimetric sensor 8 include CCD, MOS, and SI.
Although solid-state imaging devices such as T can be used, it is preferable to use devices of the same type for both devices, having the same substrate, electrode structure, etc., and having completely the same characteristics. .

Next, the operation of this imaging device will be explained.

First, the color sensor 8. i Prior to the accumulation of the signal in the image element 3, by a pulse e as shown in FIG.

The step motors 11 and 12 bring the strokes 1 and 7 into predetermined states. The incident light limited by the frit l and shutter 2 is converted into electrical signals of a red signal R9, a green signal G, and an n signal B by the image sensor 3. At this time, as shown in FIG. :1112, the image sensor 3 receives a pulse a from the pulse generator
is sent, and charges are accumulated only during the charge accumulation period. Also,
Pulse b is sent to shutter 2, and shutter 2 is opened only during its high period.

Therefore, the charge accumulated in the pseudo-imaging element 3 corresponds to the incident light during the period when the shutter 2 is open. Also, the third
．． Figure 4.5 is a diagram explaining the colorimetric sensor 8 in more detail. Figure 3 is a configuration diagram of the colorimetric sensor, and Figure 4 is a diagram of the MOS capacitor when the sensor is cut at A-8. The energy level diagram, FIG. 5, is a timing pulse diagram necessary for operation.

In FIG. 3, 13 is a block that detects the red component of incident light and converts it into an electric charge, and 14 and 15 are converters for green and blue components. Numeral 6 is an amplifier section that converts the charge corresponding to the red component of the incident light into a voltage, and 17 and 18 are amplifier sections for the green component;

In FIG. 4, a portion 23 indicates a light receiving area corresponding to 13, 14, and 15, and converts incident light into an electric charge 29. Note that 22 is a train that absorbs excess charge overflowing from 23. 24 and 27 are parts where the energy level changes in order to transfer the signal "charge", and the electrode 41
．． 32 by adding pulses c and d.

25, 26, 27, 28 are amplifiers A (floating diffusion amplifiers) that change charge into voltage.
25 is a floating diffusion section, 26 is a buffer for the output of the floating diffusion section 25, 27 is a reset gate for discarding the charge accumulated in the floating diffusion section 25, and 28 is a reset gate. It's a train. Further, 30 is a light shielding part that prevents light from entering other than 23. Next, the operation will be explained using FIGS. 4 and 5.

In FIG. 5, a indicates a signal applied to the image sensor 3, and during the period shown as T1, the signal is transferred from the image sensor 3, and during the period shown as T2, the signal is accumulated in the #M image sensor 3. controlled as it is done.

c and d indicate the levels of the signals applied to the electrodes 31 and 32 shown in FIG. 4, respectively, and out is the output output shown in FIG.
shows.

During the accumulation period T2 in FIG. 5, the energy level of the sensor is in the state (1) shown in FIG. 4, and the incident light is converted into charge 29. When the transfer period begins, the pulse d becomes high, and the energy level of the reset gate 27 is lowered by the electrode 32 as shown in FIG. Charge is absorbed into train 28 and reset. Note that the symbols (1) to (6) shown in Figure 4 are the same as (1) shown in Figure i5.
) to (6). Due to the above-described operation, the output OUT shown in FIG. 5 becomes the reset potential. In (3), the pulse d becomes low level and the energy level of the reset gate 27 rises.

Next, at (4), pulse C becomes high level and electrode 3
1 lowers the energy level of the portion 24 and the charge is transferred to the floating diffusion portion 25. As a result, the output OUT becomes the signal level 1.

Next, in (5), the pulse C becomes a low level and the pulse d becomes a high level, which is the same as the state of (2), so that the signal charge is absorbed into the train 28. Therefore, the output beam becomes the cellar 1-potential.

Furthermore, in (6), the state returns to (j) and starts accumulating charges in 23 again. The signal level obtained in this way is
As shown in the output of FIG. 5, this is the difference between the signal potential and the no-signal potential.

In this way, the light restricted by the fringes 7 enters the colorimetric sensor 8, and each of the red, green, and blue components of the light R= , G
,,B, are output. Furthermore, the output R of the colorimetric sensor 8,
,,G,,B,, the control voltage introduction unit 9 generates R,:=G,,/Rv B,,=Gw/B.

are determined, Rc is sent to the red signal amplifier 4, B1 is sent to the green signal amplifier 5, and R' = RxRc B' = BXBc are output. Each signal of R', G, B' is processed by process 8.
! The signal is input to I6 and converted into a luminance signal and a color difference signal.

As described above, pulses c and d are sent from the pulse generator 10 to the colorimetric sensor 8, and! The same period as the charge accumulation period in the M image element 3 is the accumulation period. That is, the accumulation period of the colorimetric sensor 8 coincides with the period during which light is incident on the image sensor by the shutter 2, that is, the accumulation period T2 of the element 3 during photographing.

Furthermore, since elements with the same characteristics are used for both the image sensor 3 and the one-color sensor 8, and the exposure periods are also the same, the amount of charge accumulated is the same. Therefore, even if the color of the light source suddenly changes, both the imaging system and sub-color system sensors 3 and 8
The amount of charge stored in the two is always the same and is not affected by this.

Furthermore, in the imaging system, the lack of dynamic range of the m-image beam 3 is compensated for by restricting light by the pattern 91. Therefore, by setting the pattern value of the pattern 1 and the pattern value of the pattern 7 to be the same value, the amount of light of the embellished color sensor 8 will not exceed the dynamic range of the element. That is, the step motors 11 and 12 for controlling the fringes set the respective fringing values of the twills 1 and 7 to the same value by the pulse e from pulse generation=10.

In this embodiment, an embodiment in which a fringe is provided on the front surface of the colorimetric sensor 8 or an embodiment in which the fringe on the primary side is unnecessary will be described with reference to FIG. 6, ': FS7. FIG. 6 is a circuit block diagram for explaining another embodiment of the present invention, and FIG. 7 is a pulse waveform diagram for explaining the operation of this circuit. In FIG. 6, 33 is the output R, , BC of the control voltage deriving section 9.
This is an integrator that integrates over a certain period of time. The rest of the configuration in FIG. 6 is the same as that in FIG. 1, so explanation r#I will be omitted.

Next, the operation of this imaging device will be explained.

A pulse f is sent from the pulse generator 10 to the image sensor 3, and the incident light during the charge accumulation period of the pulse f is converted into charges and accumulated. Further, a pulse g is sent to the shutter 2, and the shutter is opened for the duration of the pulse g. Therefore, the charge accumulated in the image sensor 3 corresponds to the incident light during the period when the shutter 2 is open.

On the other hand, a pulse C and a pulse d are applied to the colorimetric sensor 8. As shown in FIG. There will be a transfer period several times.

If the pulses c and d are pulses with continuous charge EIn periods like the pulse f, the colorimetric sensor 8 of this embodiment is provided with a stripe like the colorimetric sensor of the first embodiment. Therefore, more charge is generated in the sensor 8 than the amount of charge that can be accumulated.

Five saturated thoughts arise. Therefore, in this embodiment, a plurality of transfer periods [111] are provided during the period when the shutter 2 is open, and the output signal is read out and sent to the integrator 11.

Here, the number of times a transfer period is provided is determined by the value of 1. In other words, if the fringe value is small, increase the number of times,
By shortening the one-time accumulation period, reducing the number of times when the fringe value is large, and lengthening the one-time accumulation period,
It is possible to prevent the charge of the colorimetric sensor from exceeding the dynamic range, that is, to prevent the charge from being saturated. Furthermore, the output for each listening period is provided by 11 integrators. Since which pulse 1 is sent to the integrator 11 and the integrator integrates only during its high period, a control signal corresponding to the incident light accumulated during the period when the shutter 2 is open is obtained. Note that by making the transfer period as short as possible, it becomes possible for the colorimetric sensor 8 to detect almost all of the incident light during the period when the shutter 2 is open as electric charges.

[Effects of the Invention] As is clear from the above description, according to the present invention, elements having the same characteristics are used as the image sensor and the colorimetric sensor,
Furthermore, by adding the same fringes to the colorimetric sensor as the image sensor, or by dividing the charge storage period to the colorimetric sensor to limit the product of the charges, the dynamic performance of the colorimetric sensor can be improved. Without exceeding the range, also jiI
l&! Even if any light source is used, such as a light source with a spectrum or a light source with flicker, the white balance will not be distorted, and a highly accurate white balance JJ can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram for explaining a first embodiment of the imaging bag according to the present invention, FIG. 2 is a pulse waveform diagram for explaining the operation of this circuit, and FIG. 3 is a configuration of a colorimetric sensor. Fig. 4 is an energy level diagram when the sensor shown in Fig. 3 is cut along A-B, Fig. 5 is a timing chart explaining the operation, and Fig. 6 is a second implementation. A circuit block diagram for explaining an example, and FIG. 7 are pulse waveform diagrams for explaining the operation of this circuit. During IA. 1.7・Fringe 2・Shutter 3 Image sensor 8: Colorimetric sensor 10: Pulse generator ll: Integral agent Patent attorney 1) Haru Kitatake】U Figure 1 also Figure 2

Claims (3)

[Claims] (1) An imaging system element, a colorimetric sensor using an element having the same characteristics as the imaging system element, and means for limiting charge accumulation in the imaging system element and the colorimetric sensor to substantially the same state. An imaging device provided. (2) The imaging device according to claim (1), characterized in that fringes are provided on the front surface of the imaging system element and on the front surface of the colorimetric sensor, and the frit values of both fringes are matched. (3) Divide the charge accumulation period in the colorimetric sensor into multiple periods according to the frit value of the frit provided on the front of the imaging system element, and calculate the output of the colorimetric sensor in each period into the imaging system. 2. The imaging device according to claim 1, wherein integration is performed during a period during which a shutter is open.