JPS60208188A - Signal generator - Google Patents

Abstract

PURPOSE:To give a stable offset to an input signal with a wide range by forming plural offset signals through the combination of plural reference signals and averaging the maximum pitch of the offset signals so as to use comparatively a few offset signals. CONSTITUTION:A light current flowing to a colorimetry sensor 4 comprising R and B sensors is fed selectively to a log amplifier section 5 via a decode section 1 and a switch section 3, the result is subject to logarithmic compression and amplified and outputted by a final amplifier 6. The relation between a reference voltage of an A/D converter 11 and the lightness of a light source is changed by using a system controller 13 so as to control a mode terminal 10 thereby changing a voltage Vout of the final amplifier section by several V. That is, when the Vout is out of the range of 0.3-3V being a permissible output of the A/D converter, the range is restored within 0.3-3V by giving an offset voltage to the Vout and a stable offset is given to the input signal with wide range.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a signal generator for outputting adjustment signals of multiple levels.

(Prior art) Conventionally, for example, a signal that uses a reference signal having a level ratio of i:2:4:a... to form an output signal with a uniform pitch such as 1:2:l15:6:... Generators are known.

However, in such devices, if the reference signal level fluctuates due to fluctuations in hot water temperature, etc., the maximum error between each output signal value fluctuates, and this can lead to extremely large error values. .

If such an error occurs, the reliability of the signal generator will be extremely low.

Furthermore, when offset adjustment is performed using the output of the signal generator, a large output error may occur due to an error in the offset value.

(Objective) It is an object of the present invention to provide a signal generating device that can overcome the drawbacks of the prior art as described above.

Another object of the present invention is to provide a 17Hij number generator with less variation in the maximum error value.

Another object of the present invention is to provide a signal generating device that can reduce the maximum error value.

/- (Example) The present invention will be explained below based on examples.

The first factor is the principle diagram of the colorimetric sensor device according to the present invention. Reference numeral 1 denotes a decoding section which controls what is output from the colorimetric sensor device CMS according to the input signal to the select input terminal 2. Reference numeral 3 denotes a Swiss/Sochi section which determines whether or not to send the photocurrent from the colorimetric sensor 4 to the log amplifier section 5 under the control of the decoding section 1. When not being sent, it is short-circuited and excess electron-hole pairs are removed. Note that the colorimetric sensor 4 includes an LR sensor that detects red color and a B sensor that detects blue color.

The log amplifier unit 5 logarithmically compresses the photocurrent of the colorimetric sensor 4 and converts it into voltage. It is the 6-digit final amplifier section and the log
The output of the amplifier section 5 is amplified to match the input level of the A/D converter 11 at the next stage. Reference numeral 7 denotes an Irmr control section which cancels the offset of the amplifier section 6 by adjusting the magnitude of the reference current (adjusted by an external resistor R0).

This is an eight current shunt section that generates a current used to cancel voltage temperature fluctuations in the log amplifier section 5.

Reference numeral 9 denotes an offset section serving as a signal source and offset adjusting means, which forms a current for applying an offset voltage to KVout so that the R signal and B signal can be used within the specified input signal range of the A/D converter.

Further, a mode set signal from the system controller 13 is inputted to a mode set input terminal for controlling the offset value of the 10-digit offset section 9. Furthermore, a select signal from the system controller 13 is also input to the select input terminal 2.

11 is an A/D converter for converting the output of the amplifier section 6 into a digital signal, and a memory for storing the output of the 12-digit converter.

This is an arithmetic circuit as an arithmetic means for forming color temperature information using the outputs of 14 memories. I5 is an image sensor that converts a subject image into an electrical signal. 16.17
is a gain control amplifier that adjusts the mutual gain of the R (red) signal, G (green) signal, and B (blue) signal, which are the color signals output from the image sensor 15; 1 and 2 are provided for each signal.

Further, the gain of each of the amplifiers 16 and 17 is controlled by the output of the arithmetic circuit 14, and the level of each color signal is adjusted according to the color temperature of the object.

A process encoder 18 forms a standard television signal such as an NTSC signal based on the color signal. Further, LM is a level detection circuit serving as a level detection means, which discriminates in which level range the level of the output Vout of the final amplifier section 6 falls, and inputs this discrimination signal to the system controller 13.

Next, the operation will be explained.

The photocurrent flowing through the colorimetric sensor 4 consisting of the R sensor and the B sensor is selectively sent to the log amplifier section or short-circuited by the decoder section and the switch section. The photocurrent sent to the log amplifier section is logarithmically compressed into voltage,
It is amplified by the final amplifier and output. The above flow is called signal acquisition mode. Additionally, under the control of the decoding section, no current flows from the sensor to the log amplifier, but a constant current flows from the current shunting section to the log amplifier, and the same goes for the rest. Since the ambient temperature is measured by this, andrL is set to temperature measurement mode. Furthermore, by controlling the mode terminal 10 by the system controller 13, the voltage of the final amplifier section is varied by several volts, thereby changing the relationship between the reference voltage of the A/D converter and the brightness of the light source.

In this way, the outputs of the R sensor, the B sensor, and the current shunt section 8 are converted into AID in time series via the log φ amplifier section 5 and the final amplifier section 6'f by the select signal of the system controller 13, and then stored in the memory 12. be remembered.

As a result, the memory 12 temporarily stores the outputs of the R sensor, B sensor, and current shunting section.

The calculation circuit 14 calculates the output ratio of the R sensor and the B sensor, excluding the thermal condensation coefficient, based on these stored values.

The details are disclosed in Japanese Patent Application No. 58-20340 filed by the applicant, so the explanation will be limited to the above.

Here, the output ratio of the R sensor and the B sensor corresponds to a one-to-one color temperature ratio.

FIG. 82 is a diagram showing an example of the configuration of the colorimetric sensor device tcMs, in which the same reference numerals as in FIG. 1 indicate the same elements.

19u is an R sensor as a color sensor, and 20 is a B sensor as a color sensor. Further, 21 is an operational amplifier.

In this embodiment, when each input terminal A, B of the select input terminal 2 is (o, n) according to the output from the sequence controller 13, the output of the B sensor is output from the log amplifier section 5 and the final amplifier section 6.
It is outputted from the output terminal Vout of the colorimetric sensor device via. Also, when (A, B) = (0, 1), the output of the R sensor is processed in the same way and outputted to V out, and (A, B
) = (1, 0), the constant current 1 from the current shunt section 8 is processed via the log amplifier section 5 and the final amplifier section 6, and V o
It is output from ut.

Also, when (A, B) = (1, 1), 1
61. A constant current of V is output, which is processed in the same way as V
Output can be completed from out. Since the outputs of each sensor and the footrest flow source are processed in a time-sharing manner in this way, the circuit configuration is simplified.

In this embodiment, offset adjustment is performed in multiple stages in the final amplifier section 6, so that the dynamic range can be greatly expanded.

That is, the final amplifier section is configured as shown in Figure 3 (!:
The potential at point A is the sum of the signal component v8 and the reference voltage V□ (Va+
When considering V□, ), IS = Vs / R1 and X
(7) f output Vout is y out = Va(R+R→
−+V**rR1.

Therefore, in the configuration shown in FIG. 3, when the A/D converter 11 performs, for example, LSB 13 mV, 8-bit A/D conversion, the input level range is 0 to 3.328 V, so considering the saturation of the amplifier, the V The effective level range of out is approximately 0.3 to 3V.

On the other hand, when the brightness of light is doubled, Vs is approximately 7 to 18 m.
If V increases and the amplifier gain is set to 14.6, V o
In ut, it will increase by 1.26V.

ff1l'F) In order to keep Vout within the input level range of the A/D converter, only a brightness range of about 10 steps is allowed.

However, this results in an extremely narrow dynamic range as a colorimetric sensor device.

As a practical matter, if it cannot process light in the range of Ev = O = 23, it is of little practical use.

Therefore, in the present invention, ■ When out is outside the range of 0.3 to 3 V, which is the allowable input of the A/D converter, V out
By applying IC offset voltage [), 3~3v
It is configured to return within

If 1+1 is configured as shown in Fig. 2 and 4.
−(V3+Vitr VB, )/R+=Vs/
R.

than on the other hand l5=Is'-I.

Because it can be expressed as Is’ = Vs / R, +I.

It can be expressed as

Therefore, a V out = Vs + Viz? +,” R2+ I
o ” R2H, + R.

= □ Vs + VIKF + IO” R21 It can be expressed as f-nafu.

Therefore■. It is also possible to adjust the offset of V out by changing the size of the black.

For example, as shown in Part 5, ■.・E in case of R120
It can only handle the light intensity at V5~Evloi, but Io” R
2 = 1.5 V and e is Ev2.5 - Ev7.5.1
When 0-R, = 3V, f of E v O-E V 5
You will be able to sing songs that use f.

That is, the offset part. Evll~ by ink adding cloud R7
You will be able to handle the scenery in EVlO1.

In addition, in order to provide such an offset, the offset section uses force 1/ant mirror circuits CMI to CIV as shown in the second diagram.
13 are provided, and the respective outputs L, It, and L are L:
It is configured to have a ratio of It:l3=4+2:1. Here, t and t are each equivalent to the reference signal.

Also, for the 1ttt style IC, the relationship I, =I(!) is set.

In addition, each terminal C, D, E of the mode terminal 10 is set to 1 or 0, respectively.
When the mode signal is input, ■1 to ■ are combined,
The value of 10 as the output value is 0, +1.5Ic.

lc, 1.5Ic, 2ic, ..., 3.5J
It can be changed to c.

Here, in the colorimetric sensor device of the present invention, it is sufficient to read the signals of the R sensor and the B sensor as V8 and calculate the ratio thereof.

In that case, the signals for the two glazes must both be in the same mode.

This is because otherwise, the above-mentioned error will have an effect.

In other words, if the offset is not redundant as shown in Fig. 6 (a), and the two signals are R and B, Fig. 6 (
It is fine if R and B are in the same mode, as in 22 in A), but in a certain mode, as in 23 in the same figure,
R is in, but B is in the mode below it, and in the mode below, B is in, but if it is in the mode above R, the ratio of R and B is If you calculate it, you will get a completely wrong value.

Therefore, in this embodiment, this drawback is prevented by providing an overlapping portion between each mode as shown in FIG. 6(b).

However, the difference between R and H is set to be smaller than the overlapping portion thereof.

In this way, for example, even in a situation where R is entered in mode ■ but R is lower than its lower limit, mode C4 can be used.
If you set it to 1, both will be included.

In addition, input and work on each terminal (C, D, E). The relationship is determined as shown in the table below.

Table 1 Further, specific mode setting is automatically performed by the system controller 13 and the level detection circuit ELM in the following procedure.

Without any hesitation, set the mode to mode ■, which is the reference mode, and check whether R is within that range.

If R is larger than the upper limit (-sV) of ■, go to mode ■. If it is smaller than the lower limit (-9V) of (2), it goes to mode (2).

If it goes further to ■, compare the upper limit and lower limit of that ■ with R, change the mode to ■ Amake mode, and move.

In this way, find the mode in which R is included.

Once the artificial mode of R is found, check whether B is included. If B is also in that mode, input the system controller code signal to the mode terminal 10 in order to give an offset corresponding to that mode.
Give a predetermined offset, and in this state R sensor output, B
The sensor output and the output of the military TJlt/Me section are subjected to first and third processing using a select signal, and stored in the memory 12 after being subjected to A/D conversion, and then mutually calculated to form color temperature information.

Here, 11 + force J of current mirror circuit CMI to CM3
If the current values of , ~■, have an error, the offset voltage will also contain the error, making it impossible to cover the target brightness range of 9.

It is assumed that the difference between R and B is EVfl, which is 5 steps.

At this time, two problems occur.

The first is that a sufficient margin must be provided for one error so that the target light brightness range can be covered at the lower limit (mode ■). That is, electrician, ~
Suppose that there is an error of ±10 in I. Ic=lO
If OpA is I, = 200μA → 220~180μ
A■, = lOOμA → 110 to 90 μA I, = 50 μA → 55 to 45 μA.

If the maximum error occurs due to the mode, 350 μA becomes 385 μA or 13J5 μA. In this case, the problem is 315μA, but the error is 35μA and R1
This problem can be solved by determining the lower limit EV value for mode (■) by taking into account the applied error voltage. (If the error voltage is 1■
If so, the lower limit of mode
If it's VI, I can guarantee it up to EV2, but I'm busy. ) The second problem arises in the following cases.

Suppose now that it is found that mode ■KR is set.

However, if B is smaller than the lower limit of mode ■, in this case, the mode jumps to mode ■. In mode (2), since the overlap is provided, both R and B are included. Now, at this time, if mode becomes too high by 0.5V due to an error and mode (2) becomes low by n, sv, that quintillion will disappear.

If the overlapping portion is not larger than the difference in RlB even after subtracting the shunting error, a problem will occur in which R and B are covered by the 1-mode.

In order to deal with this problem, this embodiment does the following. That is, when looking at the difference (pitch) between each mode, the worst case situation appears.

Table 2: Maximum error between each mode ■ and ■, ■ and ■, ■ and ■,
Between ■ and ■ it is 5 μA each, but between ■ and ■, between ■ and ■ it is 15 μA each, and further between ■ and ■ it is 35 μA.

Moreover, such errors are unevenly distributed.

It's too late, like this constant current for offset setting■1~■
, are set at equal intervals, the maximum error between the modes will vary, and there is a possibility that an extremely large maximum error will occur.

Therefore, the overlap between each mode has to be increased accordingly, resulting in ■. The configuration and control of the constant current source for forming the current source becomes 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 1:2:428 but 1+α:2+β:4+γ:...

The specific way to determine α, β, and γ is as follows.

I+ =X1+ L ”' Xt + Is ”' X
Let s be x, = 4x.

x, = 2
(1±y).

x'5-xx (1±y), and the difference from the next mode is xx (1+y
)-x+xy (between mode ■, 0) 2XX(++y)
-xx (1-y) = x + 3xy (between modes ■ and ■) 3xx (1 + y) 12xx (i + y) l = x + xy (between modes ■ and ■) 4X (1 + y) -3x (1-y) = x + 7xy (mode ■) , ■) The red line above is the error, and the maximum is between mode ■ and 0. Therefore, to compensate for this drawback, x, l Xt
+ Set X3 as shown below.

X+=4X-ZIXt=2X+(Z-Z')IXs=
x + Z', X) + Xz +X3 = 7
As for x, in the mode, the value considering the error is made to approach the specified value.

Now, assuming an error of ±y%, each X+=(4x
Z)X(1±y),X5=(2x+(Z-Z'))
×(1±y), X2=(X1z′)×(1±Y) (
! : The difference from the next mode is (x+Z')
-)')=x+3xy+Z-2Z'+Zy (between -T-1 do ■ and ■) (4x-Z)
-2') ten (x+Z'month ten,, (1-y)=x+7xy
-2Z (between modes ■ and ■) All you have to do is find 2°2' when all these errors are equal, so x y + Z' + Z'y = 3 x y + Z-2Z' + Zy
=7 x y-2Z:・2xy-3Z'10Z10Zy-
Z'y=0( 4xy-3Z+2Z'-Zy=0 Z(t+y)-Z'(3+y)+2xy=0(-(3+y)Z+2Z'+4xy=O-=411y)=
0 Putting this into equation (1), for example, when x=50, y=Q, l, Z'=7
．． 152, i.e. I, = 189 μA, I! =104μp,,l3=5
Even if there is an error in the current of 7 μA, I
,=189±10 coefficient=207.9~170.1i,=1
04±lOchi=114.4~93.6■,=57±
jO% = falls within the range of 62.7 to 51.3, and the difference between each mode is as follows even in the worst case. Therefore, the maximum error is 1 between modes ■ and ■ and between mode 00.
3.1, which is significantly reduced. Furthermore, according to this embodiment, the outputs of a plurality of color sensors are sequentially inputted to a common log amplifier section and final amplifier section to obtain colorimetric information, so that the log amplifier etc. can be inputted to each color sensor separately. Compared to the case where the system is provided, there is no variation in the characteristics of each system, so accurate color temperature information can be obtained, and the configuration can be simplified by sharing the system.

Further, by providing an offset, a relatively inexpensive A/D converter with a narrow dynamic range can be used, and digital processing for forming high fl'l color temperature information is possible with a simple configuration.

(Effects) As explained above, according to the present invention, a plurality of offset signals are formed from a combination K of a plurality of reference signals, and the level of the reference signal is set so as to average the maximum pitch between each offset signal. The maximum value of the pitch error between each offset signal is reduced, and a stable offset can be provided to a wide range of input signals with a relatively small number of offset signals.

[Brief explanation of drawings]

2 is a block diagram of an example of an imaging device using the colorimetric sensor device according to the present invention, FIG. 2 is a diagram showing an example of the configuration of the colorimetric sensor device, and FIG. 3 is a diagram showing an example of the configuration of the final amplifier section. 4 is a diagram showing an example of the configuration of the final amplifier section according to the present invention, FIG. 5 is a diagram showing the principle of offset 8A adjustment, FIG. 6 (a) is a diagram showing an example of the offset adjustment method, Figure 6 (
B) is a diagram showing an example of an offset adjustment method according to the present invention. 9...offset unit as signal source and offset adjustment means, CMS...colorimetric sensor device, ■, ~■,...current as reference signal, 19.20.
... R sensor and B sensor as color sensors, LM ... Level detection circuit as level detection means, 14 ... Arithmetic circuit as calculation means. Figure 3 VFEF Figure 4 REF

Claims (1)

[Claims] It has a signal source that forms a plurality of output values by combining a plurality of reference signals of different levels, and the maximum value of each pitch error between the output values based on the error pressure of the reference signal is the same.
A signal generating device characterized in that the reference signal level is set to be approximately equal to .