JPS61280529A - Colorimetric sensor - Google Patents

Abstract

PURPOSE:To obtain an image pickup apparatus capable of substantially instantaneouly picking up an image by simple constitution, by outputting specific color temp. information when the output of a color sensor is out of an A/D conversion range. CONSTITUTION:The output photocurrent of a colorimetric sensor 4 is converted to logarithmically compressed voltage by a logarithmic amplifying part 5 while said voltage is converted to a digital value by an A/D converter 11 through a final amplifying part 6, wherein offset to a level necessary for A/D conversion is controlled by an offset part 9, to be stored in a memory 12. The content of this memory 12 is processed by an operation means 13 to be brought to color temp. information which is, in turn, outputted through memories M2, M3, M5, M6. The input level of the converter 11 is detected by a level detector 14 and, when said level is out of the A/D conversion range of the converter 11, the specific color temp. information of the memory M1 or M4 is outputted through a system controller SC corresponding to the detection output of the detector 14 and the operation time of a microcomputer or a photocurrent and the time required in the change-over a current for correcting temp. are omitted and substantially instantaneous image pickup can be performed by a simple constitution.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a colorimetric sensor device, and particularly to a colorimetric sensor device that can appropriately adjust color balance even when the brightness range of a light source is very wide, and that can be used instantaneously. Concerning means to enable photographing.

(Prior Art) For example, as a colorimetric sensor device in an imaging device, color temperature information has conventionally been obtained using the output ratio of an R sensor that detects an R (red) color component and a B sensor that detects a B (blue) color component. What you get is known.

By the way, in a colorimetric sensor device that obtains color temperature information in this way, if you try to perform processing such as logarithmic compression on the output of each color sensor using two signal processing circuits, not only will the circuit configuration become complicated, but , large discrepancies occur in color temperature information due to differences in logarithmic compression characteristics, temperature characteristics, etc. between the two circuits.

In addition, since the target light source light has a very wide brightness range, the output of the color sensor described above can be applied over a wide level range.
In order to process accurately, it may be possible to convert it into a digital signal and perform arithmetic processing, but in that case, the performance of the A/D converter, which is the interface to the microcomputer, becomes an issue, and the amount of light that can be processed depends on that performance. It has been difficult to use inexpensive and less accurate A/D converters.

In order to eliminate the above-mentioned drawbacks, the present applicant first filed a patent application in 1973.
No. 9-64969 (filed on March 30, 1982), offset adjustment of the output of each color sensor according to the output of a level detection means that detects the output level of a plurality of color sensors that respectively detect different color signals. We proposed a colorimetric sensor device equipped with means for

(Problems to be Solved by the Invention) According to the colorimetric sensor device according to the above proposal, the output of each color sensor can be kept within a predetermined level range by adjusting the offset of the output of each color sensor. ,
Conversion into a digital signal becomes possible using an A/D converter with a simple configuration, and there is an effect that highly accurate color temperature information can be obtained at low cost.

However, even in the above device, if the number of switching stages for offset adjustment cannot be increased,
Alternatively, if the brightness range of the light source light is extremely wide and extends beyond the range that can be converted by the A/D converter, the purpose cannot be fully achieved as is, and the control and calculation in the above device Color balance adjustment takes some time due to the calculation time of the microcomputer as a means and the switching time of the photocurrent of the color sensor and the current for temperature correction. Therefore, this may become an obstacle when taking still images where instantaneousness is important.

Therefore, this invention is applicable to the above-mentioned Japanese Patent Application No. 59-6496.
The invention related to No. 9 is further improved to output appropriate color temperature information even when the brightness range of the target light source light is very wide and extends beyond the convertible range of analog-to-digital conversion means. The object of the present invention is to provide a colorimetric sensor device that can perform color measurement.

Furthermore, in cases where the brightness of the light source light is outside the range that can be converted from analog to digital, the present invention can improve the calculation time and color of the microcomputer as a control and calculation means by providing the above-mentioned colorimetric sensor device. It is an object of the present invention to provide an imaging device that can perform substantially instantaneous imaging by omitting the time required for switching the photocurrent of a sensor and current for temperature correction.

(Means for Solving the Problems) In order to solve the above problems, the colorimetric sensor device of the present invention includes a plurality of color sensors that respectively detect different color signals, and an analog output signal of the color sensors. - A colorimetric sensor device comprising means for digital conversion and means for outputting color temperature information for performing arithmetic processing on the output of the analog-to-digital conversion means to adjust the color balance of the video signal, means for detecting whether the output level of the color sensor is within a convertible range of the analog-to-digital conversion means; and detecting that the output level of the color sensor is outside the range that can be converted from analog to digital. and means for outputting specific information as the color temperature information.

(Function) (Fig. 1) The colorimetric sensor device of the present invention, based on the above configuration, detects whether the output level of the color sensor is within the convertible range of the analog-to-digital conversion means, and If it is within the convertible range, color temperature information for adjusting the color balance of the video signal is output by calculating the output of this analog digital conversion means, but if it is outside the above convertible range. If there is, specific information is output as color temperature information.

(Embodiment) Referring to FIGS. 2 to 8 below, the overall configuration of the embodiment of the colorimetric sensor device of the present invention, the offset adjustment means in the embodiment, the output level detection means of the color sensor, and the identification A detailed explanation will be given in the order of the information output means.

(Overall configuration of an embodiment of the colorimetric sensor device of the present invention) (Fig. 2) Fig. 2 shows the overall configuration of an embodiment of the colorimetric sensor device of the present invention. is the decoding section 1
3 is a switch section; 4 is a colorimetric sensor including, for example, an R sensor that detects red color and a B sensor that detects blue color; 5 is a log amplifier section; 6 is a final amplifier section, and the decode section 1 controls which signal is outputted from the final amplifier section 6 to the A/D converter 11 in accordance with a selection signal inputted to the input terminal 2.

The switch section 3 selects whether or not to transfer the photocurrent output from the colorimetric sensor 4 to the log amplifier section 5 under the control of the decoder section 1 . Note that when the photocurrent is not transferred to the log amplifier unit 5, the sensor is short-circuited to remove excess electron-hole pairs. The log amplifier section 5 is
The photocurrent outputted from the colorimetric sensor 4 via the switch unit 3 is converted into a logarithmically compressed voltage and output, and the final amplifier unit 6 converts the output of the log amplifier unit 5 into the next stage A/D converter 11. Amplify to match the input level.

7A is a reference current control section 1, for example, an external resistor R, which adjusts the magnitude of the reference current Iref, and cancels the offset of the final amplifier section 6, etc. A reference voltage setting section 7B sets a reference voltage Vref for the log amplifier section 5 and the final amplifier section 6. Reference numeral 8 denotes a current shunt section, which sets a current for canceling temperature fluctuations in voltage in the log amplifier section 5. 9
teeth.

The offset section serves as a signal source and offset adjustment means, and the output V of the final amplifier section 6 is used to convert the R signal and the B signal into signals within a convertible range of the A/D converter 11.
A current is generated to apply an offset voltage to out. The details will be described later with reference to FIG. 3. 10 is a mode setting input terminal for controlling the offset value of the offset section 9, and is connected to the system controller SC.
A mode setting signal is input from.

11 is an A/D converter for converting the output of the final amplifier section 6 into a digital signal; 12 is a memory for storing the output; and 13 is an arithmetic unit for forming color temperature information based on the output of the memory 12. circuit, memory Ml
-M8 is connected.

Reference numeral 14 denotes a level detection circuit which is an example of a level detection means, and is used to detect the level of the output V out of the final amplifier section 6.
It detects whether it is within the range of , and outputs the detection signal to the system controller SC. The details will be described later with reference to FIG. 6.

The system controller SC controls the operation and operation timing of each part of this colorimetric sensor device as shown in the figure.
The details will be described later with reference to FIG.

15 to 18 schematically show an imaging device whose gain is controlled by this colorimetric sensor; 15 is an image sensor;
Reference numerals 16 and 17 denote gain control amplifiers that relatively control the gains of R, G, and B signals, which are the respective color signals output from the image sensor 15. In this example, they are provided for the R and B signals respectively, and are The gain is controlled by the output of the circuit 13, and the level of each color signal is adjusted according to the color temperature of the subject. 18 is a process encoder which generates a standard television signal based on the R, G and B signals;
For example, an NTSC signal is formed.

Next, the operation of the colorimetric sensor device shown in FIG. 2 will be explained.

A photocurrent generated by the colorimetric sensor 4 consisting of an R sensor and a B sensor is selectively sent to the log amplifier section 5 or short-circuited by the decoder section 1 and the switch section 3. The photocurrent sent to the log amplifier section 5 is converted into a voltage, logarithmically compressed, and then amplified by the final amplifier section 6 and output. The above flow is called signal acquisition mode. Also, under the control of the decoding section 1, no current is sent from the colorimetric sensor 4 to the log amplifier section 5, and a constant current (described later) is sent from the current shunting section 8 to the log amplifier section 5, and the output is output from the final amplifier section 6 in the same manner as above. do. Since the ambient temperature is measured by this, the above flow is set as the temperature measurement mode. In other words, the select signal input terminal 2 from the system controller SC
When a (0, 0) signal is sent to each input terminal A, B of
The output of the sensor is outputted from the final amplifier section 6 via the log amplifier section 5, and when the (0, 1) signal is sent, the output of the R sensor is sent, and when the (1, 0) signal is sent, the output of the current shunt section 8 is When the (1,1) signal is sent to the output current 11, the output current 16i1 of the current shunting section 8 is similarly outputted from the final amplifier section 6. Therefore, since time division processing is performed on the outputs of each sensor and the current shunt section 8 as a constant current source, the circuit configuration can be simplified.

In this way, the outputs of the R sensor, the B sensor, and the current shunting section 8 are changed in time series to the log amplifier section 5. After passing through the final amplifier section 6, it is A/D converted by the A/D converter 11 and supplied to the memory 12.
The outputs of the sensor and current shunt section 8 are each temporarily stored. The calculation circuit 13 calculates the output ratio of the R sensor and the B sensor, excluding the influence of temperature fluctuation, based on these stored values, and this output ratio corresponds to one color area on a one-to-one basis.

Furthermore, in the colorimetric sensor device shown in FIG.
When it is outside the range where D conversion is possible, the above-mentioned arithmetic-processed information is not used, but is
Output specific information stored in memory M1 or M4.

(Offset adjustment means in the embodiment of the present invention) (Figs. 3 to 5) Next, the main points of the offset adjustment means in the above embodiment will be explained with reference to the specification of the above-mentioned Japanese Patent Application No. 59-64969. do. FIG. 3 shows an example of a specific circuit configuration of the final amplifier section 6 and offset section 9 in FIG. 2. In the final amplifier section 6, 21 is an operational amplifier whose (+) input terminal potential is Letting the signal voltage be Vs (Vs+V
ref), and the potential at the other end of the resistor R1 connected to its (-) input end is Vref. In the offset section 9, CMI, 0M2, and CM3 are current mirror circuits, and C, D, and E are input terminals forming the mode setting input terminal IO in FIG. IO is the output voltage V of the final amplifier section 6
This is the output current of the offset section 9 for adjusting the offset of out, and its value is determined by the input terminals C and C as described later.
The output currents 11, I2 . It is determined by the combination of I3. And 1. , I2. The ratio of I3 is 4:2
:1, the details of which will be described later. Further, I2 is set to I2=Ic with respect to constant current Ic.

Here, a mode of adjusting the offset of the final amplifier section 6 will be explained. In FIG. 3, the current Is flowing through the resistor R1 is Is = (Vs +Vref -Vref)
/R1=Vs/R1, but on the other hand, Is is expressed as l5=Is'-I□, where Is' is the current flowing through resistor R2, so Is' = Vs/R1+I O Therefore, the output The voltage Vout is expressed as Vout = Vs + Vref + (V s / R1 + I □ ) R2 * (R1 + R2) / R1 + Vref + I O1'12 @ @ * (1).

Therefore, 1. By changing the magnitude of V
For example, as shown in FIG. 4, when IoR2=0, the offset of out can be adjusted.
:Can only handle light intensity up to VlO, but Io6R2=1.
When 5V, EV2.5~EV7.5, I o 11
When R2=3V(7), the light amount of EVO to EV5 can be handled. That is, by adding the offset IoIIR2, the light amount from EVO to EVIO can be handled. Therefore 11. I2. I3 is set as described above, and the output current 1. and offset voltage vary as shown in Table 1.

Table 1 Here, in the devices shown in Figs. 2 and 3, in order to form color temperature information, it is sufficient to read the output signals of the R sensor and B sensor as Vs in equation (1) and find the ratio. However, since the above sensor offset is adjusted,
It is necessary that the two types of signals are both in the same mode, otherwise error effects will occur. That is, when redundancy is not provided to the offset as shown in FIG. 5(a), if the above two types of signals are R and B,
It is good when R and B are in the same mode as in 22 in the same figure, but R is in mode 1 and B is in the mode below it as in 2.3 in the same figure. When the ratio is within the range, even if the ratio between R and B is calculated in this state, a completely incorrect result will be calculated.

Therefore, in this device, this drawback is prevented by providing an overlapping portion between each mode as shown in FIG. 5(b). However, this overlapping portion is set to be larger than the difference between R and B.

In this way, for example, even if R is in mode (2) and B is lower than its lower limit, if (b) is set to mode (2), both R and B will be in this mode.

The mode setting procedure is automatically performed by the system controller SC, and details thereof will be described later with reference to FIG. 7, but an example of the mode setting procedure will be briefly described here. First, the mode as a reference mode■
and check whether R is within that range.

If R is larger than the upper limit of ■ (-5V), go to mode ■.

If it is smaller than the lower limit (-9V) of (2), it goes to mode (2). Further, when the mode reaches ■, the upper and lower limits of ■ are compared with R, and the mode is moved to mode ◎ or mode ■.

In this way, we search for a mode in which H can be entered, and when we find a mode in which R is found, we check whether B can be entered. Here, if B is also in that mode, in order to give an offset corresponding to that mode, a code signal is input from the system controller SC to the mode setting input terminal 10 to give a predetermined offset, and in this state, R sensor output,
The B sensor output and the output of the current shunt section 8 are each sequentially processed under the control of a select signal, A/D converted, stored in the memory 12, and then arithmetic processed to form color temperature information. Here, the current mirror circuit CMI-CM3
If the current values of the outputs 11 to I3 have an error, the offset voltage will also contain the error, making it impossible to cover the target light brightness range. The difference between R and B is
Assume that there are 5 stages of EVO0.

Two problems arise in this case. The first is the lower limit (mode ■
), it is necessary to provide a sufficient margin for error so that the range of target light brightness can be covered.
If the error is considered and Ic = 100 pots A, then I 1 = 200 pots A → 220 to 180 houses Al2 = 100
Hiro A → 110-90 pA I3 = 50 pA → 55-45% A.

If the maximum error occurs in mode (2), what should be 3504A becomes 385ILA or 315%A. In this case, one problem is 315 gA, but this problem can be solved by determining the lower limit EV value of mode (2) by taking into account the error voltage obtained by multiplying the error amount of 35 gA by R2. If the error voltage is lv, it corresponds to an EVI stage, so if the lower limit of mode 2 is set to EVI, it is possible to guarantee up to EV2.

The second problem occurs in the following cases. That is,
Suppose that in FIG. 5(b), R is in mode 2, but B is smaller than the lower limit of mode 2. In this case, mode ■ jumps ', and in mode ■, both R and B should enter due to the overlap, but at this time, due to an error, mode ■ becomes too high by 0.5V, and mode ■ If the voltage becomes lower by 0.5V, the above-mentioned overlap will disappear. In other words, even after subtracting the error, if the overlap is not larger than the difference between R and B,
A problem arises in that R and B are not covered in the same mode.

To deal with this problem, a constant current 1 for offset adjustment is used.
If 1 to I3 are set at equal intervals, the maximum error between each mode will vary even if the error is taken into account, and there is a possibility that a very large maximum error will occur. be.

Therefore, it is necessary to provide an extra amount of overlap between each mode, and as a result, the configuration and control of the constant current source for forming the current flow become complicated.

Therefore, in this embodiment, in order to reduce this error, the output of each reference signal source is set so that the above-mentioned error is averaged.

This can be explained theoretically as follows. That is, in order to minimize the conversion error to the adjacent mode, the ratio of the output currents of each signal source is not l:2:4:*II, but 1+α:2+β:4+γ:...fist, and l1= X1. I2"X2.I3"X3 x1=4x-t x2=2x+ (z-z') x3=2x+z' Assuming that there is an error of ±y% in X, the above formula is xl' = (4x-z) (1±y)
= (x+z')(1±y), and the difference from the adjacent mode is (x+z')(1+y) =x+xy+z'+zy (2) (between modes ◎ and ■) (2x+z-z ' ) (1+y) -(x+z' )
Fist (1-y) = x + 3xy + z-2z' +zy...
・(3) (Between modes ■ and ■) (4x-z) (1+y)-((2x+z-z')+
(x+z')l (1+y)=x+7xy-2z・
--(4) (between modes ■ and ■), and 2°2' can be determined so that these errors are equal, so from equations (2) and (3), 2xy-3z'
+z+zy-z' y=0...◆(5) From equations (3) and (4), 4xy-3z+2z' -zy=o* * m (6)
Solving equations (5) and (6) for Z and Z' gives z=11.06. z' = 7.152, and from this xl = 200-11.06 = 188.94x2 = 100
+(11,06-7,152)-zo-1=103.908.

Since x3=50+7.152=57.1'52,
If l1 = 189 A, I2 = 104 pA, and l3 = 57 A, even if there is an error of ±10% in each current, 11 = 189 ± 10% = 207.9 to 170. ll2=
1°04±10%=l14.4~93.6I3=5
7 ± 10% = 62.7 to 51.3 It falls within the range of each JLA, and the difference between each mode is as shown in Table 2 even in the worst case, and the maximum error is between modes ■ and ■ and between modes ■ and ■ This is significantly reduced to 13.1.

(Output level detection means of color sensor in embodiment of this invention) (FIG. 6) FIG. 6 shows the output level of the final amplifier unit 6 input to the A/D converter 11 of FIG. Part 4
a level detection circuit 14 that detects the output level of the color sensor;
In the figure, 31 and 32 are comparators, and the output of the final amplifier section 6 is input to the A/D converter 11, as well as the (-) input terminal of the comparator 2, the comparator 31, and the comparator 32. (+) Input to the input terminal. (+) input terminal of comparator 31 and comparator 32
The (-) input terminals of are connected to reference potential sources vH and vL corresponding to the upper and lower limits convertible by the A/D converter 11, respectively. The outputs of the comparators 31 and 32 are input to the AND gate 33, and the AND gate 33 and the comparator 31
The output of is input to the NOR gate 34, and the AND gate 33
The outputs of the AND gate 33 and the NOR gates 34, 35 are input to the system controller SC.

Therefore, if the output of the final amplifier section 6 is within the convertible range of the A/, 0 converter 11, the comparator 31.3
Both outputs of the AND gate 33 become high, and the output of the AND gate 33 also becomes high. On the other hand, the output of the final amplifier section 6 is A
If the level is higher than the convertible upper limit of the /D converter 11, the comparator 31, the comparator 32 and the AND gate 3
3 become low, high, and low, respectively, and the high output is supplied only from the NOR gate 34 to the system controller SC. Furthermore, if the output of the final amplifier section 6 is at a level lower than the lower limit of convertible output of the A/D converter 11,
Similarly, a high output is supplied only from the NOR gate 35 to the system controller SC. This determines whether the output of the final amplifier section 6 is within the convertible level range of the A/D converter 11, or whether it is higher or lower than this range.

(Specific information output means in the embodiment of this invention) (First
(Fig. 2, Fig. 7, Fig. 8) By performing the offset adjustment of the output of the color sensor by the above-mentioned means, the output of each color sensor can be kept within a predetermined level range. Highly accurate color temperature information can be obtained at low cost using an A/D converter, but even with the above method, the range of target light source light brightness is extremely wide. If the output signal of the color sensor is outside the range that can be converted from analog to digital, the purpose cannot be fully achieved as it is. Therefore, in this invention, when the output signal of the color sensor is outside the range that can be converted from analog to digital, it is specified as color temperature information. This information is output, and the specific procedure thereof will be mainly explained below.

In FIG. 7, first, the count value i of a setting counter (not shown) is set to i=1, the select signal input to the input terminal 2 of the decoder 1 is set to (0, l), and the output of the R sensor is read. is set to the R mode for inputting to the log amplifier section 5, and the offset is set to the mode (2) (step 101). In this state, the input signal (data) is taken in via the switch section 3 (step 102), and then the level detection circuit 14 checks whether the level of the input signal is higher than the A/D convertible range (step 103) or It is determined whether the data is lower than the range (step 104), and if the data is M a x > data > Min, step 1 is performed.
Proceed to 05.

In step 105, it is determined whether the select signal input is (0°1). In this case, the answer is YES, so the process proceeds to step 10B, and the data (R data in this case) is stored in the memory 12.

Next, the select signal input is set to (0, 0).

As a result, the B mode is set to read the output of the B sensor, and the process returns to step 102 (step 107). This time, the output of the B sensor is taken in via the switch section 3.
Similarly to the above, if M a x >Data > Min, the process advances to step 105 (steps 102 to 104).

In step 105, it is determined whether the select signal input is (0°1), but in this case, it is (0, 0), so the process advances to step 108, where the select signal input is (0, 1).
0).

Since the answer is YES, the process advances to step 109 and the BT'-data is stored in the memory 12 via the A/D converter 11.

Next, set the select signal input to (1, 0) and constant current il
etc. (step 110),
Here, in step 111, constant currents 11 and 161
A mode setting signal is input to the input terminal 10 so as to set an offset value that can be input to the A/D converter 11.
After that, the process returns to step 102 again, the constant current 11 is taken in through the switch section 3, and Max>i1 data>M
If i n, proceed to step 105;
．． Since both of the determination results of 108 are no, step 1
In step 112, it is determined whether the select signal input is (i, o), and since this is YES, the process proceeds to step 113, where data 11 is stored in memory 1.
2.

Next, the select signal input is set to (1, l), thereby setting the mode to read the constant current 16i1 (step 114), and then returning to step 102, reading the 1611 data via the switch unit 3, and setting the Max. >16i1
If data>Min, the process proceeds to step 105. Since all the determination results in steps 105, 108, and 112 are negative, the process proceeds to step 115, and the 1611 data is stored in the memory 12.

1? I+AJLlayIfI+IIhD! -go1frT
1 data is temporarily stored in the memory 12, and the ratio of the outputs of the R sensor and the B sensor is calculated from these data, excluding the influence of temperature fluctuations. That is, (nogR-j!ogB) is calculated on the calculation plane M14 (step 116).
), QogR-QogB=AogR/B=X, then for the change in X in Figure 8,
1〉x〉α2? (Step 117b) α2〉x〉α3
(Step 117C) x β1? (Step 118a) β1 x β2? (Step 118b)
β2 x β3 (step ttsc) is determined,
If all of them are negative, it is considered to be within the appropriate range of α3>x>β3, so the arithmetic circuit 13 derives color temperature information based on the value of X (step 121), outputs this color temperature information, and 16.17 gain is controlled (step 122).

On the other hand, if the determination is YES in step 117a;"117c or in any of steps 118a to 118C, the values stored in the memories M1-M3 or the memories M4 to M6 are output accordingly. (
Steps 119a to 119c, L20a to 120c)
That is, in the predetermined range α3 to β3, Y with respect to X
changes linearly, but in the region of X>α3 and x×β3, the change in Y with respect to X is set so as to gradually become smaller as shown in FIG. In other words, the predetermined α3~β
In both the upper region and the lower region other than 3, the change in Y gradually decreases step by step.

Therefore, if color temperature information is derived from this output Y as a control voltage and the amplifiers 16 and 17 are controlled using this, the color balance will gradually change and become bluish as the color temperature increases. Also, as the color temperature decreases, the color balance gradually changes and becomes reddish, making it possible to photograph dusk in a twilight manner, and even extremely bright subjects to be photographed with a sense of realism. In FIG. 8, Y is shown to change in three steps for both the larger and smaller X, but in reality it changes by α1. α2. α3. ...biβ1. β2. β
3. It is possible to have a larger number of stages.

Further, instead of the characteristics shown in FIG. 8, it is also possible to set the change in Y with respect to X to become gradually smaller continuously.

The flow up to step 122 described above is such that the outputs of the R sensor and B sensor are converted into A/D converter 11.
If the value is within the range where D conversion is possible, but if it is outside the range, in the embodiment of the present invention, specific information that can be set as color temperature information is output by the following operation. This corresponds to step 103 or 1° in FIG.
If the determination result of step 04 is YES, first, if the determination result of step 103 is yes, step 12
3, it is determined whether i=1, and since the answer is YES in this case, the process proceeds to step 124, where the offset mode is changed from the reference mode (■) to (2). This is to quickly find the optimal offset value.Next, set the count value i to i+1=2 and return to step 102 (step 125).As a result of the mode change, if a negative determination result is obtained in step 103, The above-mentioned operation continues, but if the determination result is still YES, the process goes to step 123 again, and since i=2 here, the process goes to step 126, where it is determined whether or not i=4. Therefore, the process proceeds to step 127, where the mode is changed from ■ to ■, and the count value i is set to i+1=3 (step 125), and the process returns to step 102. In this way, if the determination result in step 103 is YES, step 1
26, the offset mode is switched until i=4 is obtained. When i=4 is obtained in step 126, the process proceeds to step 120a, and the value stored in the memory M4 is output from the arithmetic circuit 13 as color temperature information.

This means that even after offset adjustment, the A/D converter 1
This is a case where the output of the R sensor or the B sensor is so small that it does not fall within the A/D convertible range according to 1, and the color temperature is determined to be extremely low. In this case, the value stored in the memory M4 is used as the color temperature information to simplify the explanation. Suppose we want to output it as . Note that the values stored in the memory M4 can be variably set depending on the brightness of the subject and the like. This also applies to the values stored in the memory M1, which will be described later.

Next, a case where the determination result in step 104 is YES will be described. If a yes determination result is obtained in step 104, the process proceeds to step 128, where it is determined whether or not i=1, and if yes, the offset mode is changed from the reference mode ■ to ■ (step 129), and the count value i After setting 1+1=2, the process returns to step 102 (step 125), and if a negative determination result is obtained in step 104, the above-mentioned normal operation proceeds, but if a positive determination result is still obtained, Stella 7' The process proceeds to step 128, where i=2, so the process proceeds to step 130, and since a yes determination result is obtained, the process proceeds to step 131, where the offset mode is changed from ■ to ◎, and the count value i1i+1=3. as (step 1
25) Return to step 102. If the result in step 104 is not negative, the result in steps 128 and 130 is negative, so the process proceeds to step 119a, where the value stored in the memory M1 is output as color temperature information.

This is a case where the output of the R sensor or B sensor is so large that even if the offset mode is set to ◎, it does not fall within the A/D convertible range by the A/D converter 11, and the color temperature is judged to be extremely high. . In this case, as in the case where the color temperature is extremely low, for the sake of simplicity, it is assumed that the value stored in the memory Ml is output as the color temperature information.

As mentioned above, the output of the color sensor is transferred to the A/D converter 11.
When the color temperature is outside the range where A/D conversion is possible, specific information (Ml or M4 in the above example) is output as color temperature information, so there is no risk of color measurement being impossible, and it is easy to use as a control and calculation means. It eliminates the calculation time of the microcomputer and the time required to switch the photocurrent of the color sensor and the current for temperature correction, allowing virtually instantaneous photography.For example, the output difference between the R sensor and the B sensor is very large. If the color temperature is too large to fall within the input range of the A/D converter 11 with the same offset value, the color temperature has already reached α1 in FIG.
Otherwise, it is determined that the level corresponding to β1 has been exceeded, and the specific information described above is output.

In addition, in addition to the case where a filter for R and 82 colors is used as a colorimetric sensor, the value of (jlogR-AogB) is determined and the same method as described above can be performed when a filter for three colors R, G, and B is used. The same effect can be achieved by performing the operation.

(Effects of the Invention) As described above, according to the colorimetric sensor device of the present invention, if the output level of the color sensor is within the convertible range of the analog-to-digital conversion means, the output of the analog-to-digital conversion means is The color temperature information used to adjust the color balance of the video signal is output by calculating the color temperature information, but if this is outside the range that can be converted above, specific information is output as color temperature information, so it is targeted. Even when the brightness range of the light source is very wide and exceeds the range that can be converted by the analog-to-digital conversion means, it is possible to output appropriate color temperature information as a control voltage. By omitting the calculation time of the microcomputer and the time required for switching the photocurrent of the color sensor and the current for temperature correction, it is possible to obtain an imaging device capable of substantially instantaneous photographing.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of the colorimetric sensor device of the present invention.
FIG. 2 is a block diagram showing the overall configuration of one embodiment of the colorimetric sensor device of the present invention, FIG. 3 is a circuit diagram showing an example of the final amplifier section and offset section in FIG. 2, and FIG. An explanatory diagram showing the principle of offset adjustment in an embodiment of the invention, FIG. 5(A) is an explanatory diagram showing a comparative example of an offset adjustment method, and FIG. 6 is a circuit diagram showing an example of the level detection circuit in the embodiment of FIG. 2, FIG. 7 is a flowchart explaining the operation of the embodiment of FIG. 2, and FIG. 8 is a circuit diagram showing an example of the level detection circuit in the embodiment of FIG. FIG. 3 is a diagram illustrating an example of output characteristics of color temperature information in an example. Explanation of symbols 1: Decode section, 2: Select input terminal, 3: Switch section, 4: Colorimetric sensor, 5: Log amplifier section, 6: Final amplifier section, 8: Current shunt section, 9: Offset section, lO: Mode setting input terminal, 11: A/D converter, 12: memory,
13: Arithmetic circuit, 14 two-level detection circuit, 16.17:
Gain control amplifier, Ml to M6: memory, sc system controller. rVL in Figure 4 and Figure 6.

Claims (2)

[Claims] (1) A plurality of color sensors that respectively detect different color signals, means for converting the output signals of the color sensors from analog to digital, and calculating the output of the analog-to-digital conversion means to achieve color balance of the video signal. A colorimetric sensor device comprising: means for outputting color temperature information for adjustment; and detecting whether the output level of the color sensor is within a convertible range of the analog-to-digital conversion means. and means for outputting specific information as the color temperature information when it is detected that the output level of the color sensor is outside a range that allows analog-to-digital conversion. (2) The colorimetric sensor device according to claim (1), wherein the specific information can be variably set.