JPH03117092A - Color signal controller - Google Patents

Abstract

PURPOSE:To scarcely cause a killer malfunction at the time of black-and-white receiving in a strong electric field and a killer malfunction at the time of color receiving in a weak electric field by varying a ratio of a killer operating current and a killer offset current by an ACC detecting current, at the time of switching the sensitivity of a killer detector to the electric field strength. CONSTITUTION:A killer detecting circuit is provided with a killer detecting sensitivity correcting circuit 412 to which an output of an ACC detector 34 being an automatic color control circuit is supplied, and which obtains a correcting current varied in accordance with whether the detecting output is large or small, and a killer detector 411 in which the correcting current from the circuit 412 is added or subtracted to or from at least one of an operating current for detection or an offset current, and which has a hysteresis characteristic in its mode signal output characteristic in each of the case of shifting from a black-and-white receiving state to a mode signal for showing a color receiving state, and the case of shifting the color receiving state to a mode signal for showing the black-and-white receiving state. In such a way, it does not occur that an erroneous decision of a color mode is obtained in the black- and-white receiving state, and it does not occur that color disappearance is generated at the time of a weak electric field in the color receiving state.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) This invention relates to a color signal control device used in color television receivers, video tape recorders (VTRs), etc. This is an improved circuit.

(Prior Art) A color television signal processing circuit is provided with a color killer circuit. FIG. 3 shows a conventional color signal control device, in which a chroma signal is supplied to an input terminal 31 and introduced into a chroma amplifier 32.

The output of the chroma amplifier 32 is input to the burst amplifier 33 and also to the second chroma amplifier 41.

Burst amplifier 33 extracts the burst signal and supplies it to automatic color control (ACC) detector 34 .

The ACC detector 34 performs amplitude detection on the burst signal, and controls the gain of the chroma amplifier 32 using its output.

Thereby, the burst signal output from the chroma amplifier 32 is always maintained at a constant level.

Furthermore, the output of the burst amplifier 33 is transmitted to the killer detector 4
0 and is supplied to an automatic phase control (APC) detector 35. A
The PC detector 35 is an APC carrier (APC-CW)
The phase comparison between the output signal and the burst signal is performed, and the error voltage is supplied to the control terminal of the voltage controlled oscillator (VC0) 36.

The output of VC03B is phase-shifted by a 906 phase shifter 37 and input to an APC/Kl carrier amplifier 39 via an amplifier 38.

The APC/killer amplifier 39 is a carrier APC for APC.
-CW and the gear rear K I -CW for the killer are being created.

APC loop includes APC detector 35, VC03B, 90
It is formed by a phase shifter 37, an amplifier 38, and an APC/Kl carrier amplifier 39. This causes V C03B
The oscillation output of will be phase-locked to the burst signal.

The APC/KI carrier amplifier 39 also creates a carrier K I -CW for killer detection, and this carrier K I -CW for killer detection is input to the killer detector 40 . The killer detector 40 multiplies the carrier Kl-CW and the burst signal, and when the bust signal is present, the system is placed in color signal processing mode, and the burst signal is absent or at a very low level (weak electric field). If so, set it to Kara Killer mode. Output of killer detector 40 (
Although not shown, the mode signal) is supplied to the demodulator 42, chroma amplifier 41, etc.

The output of chroma amplifier 41 is supplied to demodulator 42 .

The demodulator 42 is supplied with a carrier (RY) CW for demodulating the (RY) signal and a carrier (B-Y) CW for demodulating the (B-Y) signal from the carrier amplifier 43. .

The carrier amplifier 43 also creates a carrier (RY) CW and a carrier (B-Y) CWC using the output of VC03B.

FIG. 4 shows a specific circuit of the killer detector 40.

When a burst gate signal indicating a burst period is supplied to the base of transistor Q13, transistor Q13 is turned off, and the entire detector becomes operational. Transistors Q14 and Q15 constitute a constant current source.

A burst signal is supplied between the bases of transistors Q9 and QIO forming a differential pair. Also, transistor Q
A carrier Kl-CW for killer detection is supplied between the common base of transistors Q6 and Q7 and the common base of transistors Q5 and Q8. Transistors Q5 to QlO form a double-balanced differential amplifier, and the detected output (current) is taken out from the common collector of transistors Q5 and Q7, and is connected to terminal P1.
The filter is charged via the

The transistor Ql-04 is a current mirror circuit section that converts the differential output into voltage and current. Transistor Qll~
Q14 is a circuit that flows an offset current during the burst gate period.

The killer operation level of the killer detector is determined by the ratio of the collector current of the transistor Q15, which is the operating current IO of the detector, and the offset current Iof'f' (collector current of the transistor Q12).

When the detection output is large, a mode signal indicating a color reception state is obtained from the killer determination circuit 401, and when the detection output is small, a mode signal indicating a monochrome reception state is obtained from the killer determination circuit 401.

It is now assumed that black and white reception is in progress. At this time, the detection output is small (zero), and the killer judgment circuit 401 outputs
A mode signal indicating the monochrome reception state is obtained. However, this circuit uses carrier KI-C for killer detection.
W easily leaks into the burst signal line, and if the phase of this leaked carrier happens to coincide with the phase axis of the detection carrier, a detected voltage is applied to the filter.

In response to this, the killer determination circuit 401 outputs a mode signal indicating a color reception state even though it is a monochrome reception state. In other words, it will malfunction.

To reduce such malfunction, transistor Q12
This can be countered by inserting a high resistance between the collector and the filter to increase the killer offset current 1off'. In other words, by increasing the offset current Io1'f', the filter is set so that even if leakage carriers exist, the filter is unlikely to be charged with a current due to the detected output.

However, with this method, there is a problem that normal operation cannot be obtained when the detection output is small when receiving a weak electric field. Furthermore, in a color reception state, it is very difficult to select a high resistance value to obtain a normal detection output. This is because when the electric field becomes weak, the detection output also becomes small, and depending on the selection of the resistance value, it may become impossible to maintain the mode signal indicating the color reception state.

FIG. 5 shows a circuit designed to solve the problems of the color signal control device described above.

The same parts as in FIG. 3 are given the same reference numerals as in FIG. 3.

The difference is that the output of the ACC circuit 34 is further input to a killer discrimination circuit 401, and that the killer discrimination circuit 401 and the killer detector 40 are associated with each other.

FIG. 6 shows a specific circuit example of the killer detector 41 and the killer discrimination circuit 45.

The burst signal is differentially input between the bases of transistors Q3LQ32. Transistor Q30 constitutes a constant current source. Between the common base of transistors Q35 and 038 and the common base of transistors Q34 and 037,
A killer detection carrier Kl-CW is supplied. Transistors Q30-Q37 form a double-balanced differential amplifier, and the common collector output of transistors Q3B and Q37 is converted into a current by a current mirror circuit made up of transistors Q38-Q40. Also, transistor Q
The common collector output of 34 and Q35 is the transistor Q4.
The current is converted by a current mirror circuit consisting of Q1 to Q43.

This converted current is further supplied to the filter through a current mirror circuit consisting of transistors Q44 to Q4B. Resistance R1 is a load resistance.

During the burst gate period, the detection current is smoothed by the load resistor RL and the capacitor of the filter, and charge is accumulated in the capacitor. During the non-gate period, the charge on the capacitor is transferred to the switch circuit formed by the transistor Q45.04B and the gate formed by the transistors Q47 and Q48. There is a natural discharge through the circuit, but there is almost no voltage drop.

Assume that you are currently in a color reception state, and that you have changed from this state to a monochrome reception state. Then, since there is no burst signal, the filter output becomes the emitter potential of the transistor Q52, assuming that the detected output has no DC offset of the transistors Q45 and Q4B. transistor Q
5LQ52, Q5 (is a bias circuit.

The above detector is associated with the output of the ACC detector 34 via a killer discrimination circuit 401.

That is, the output of the ACC detector 34 is the output of the transistor Q61.
, QB2. Transistor QBI
A power supply current is supplied to the common emitter of SQ62 through a transistor Q63. Transistor Q[f4
, QB5 form a current mirror circuit. The collector output of transistor Q82 is provided to the base of transistor 06B. At this base is a transistor Q51
A current path is formed from the emitter of , via a resistor RB.

Transistors Q6 [i, Q87, QB8, QB9 and Q70 form a comparison circuit between the filter output and the collector output of transistor Q62, and also output a mode signal indicating the color reception state, black and white, through a current mirror circuit consisting of transistors Q7LQ72. This is a circuit that obtains a mode signal indicating the reception state.

Assume that ACC detection is now at maximum sensitivity (ACC open loop). This state is obtained in a monochrome reception state or in a color reception state when the reception level is very low and there is a weak electric field. At this time, the output of the ACC detector 34 is the transistor Q81
Assume that the potential is higher on the base side.

Then, when the base potential of transistor Q61 is high, transistor Q132 operates, and the base potential of transistor Q8B rises due to the voltage drop across resistor RB. on the other hand,
The filter output is low level.

This increases the difference between the base potential of transistor Q67 (filter output) and the base potential of transistor QBft (large DC offset).

This means that the output of the transistor 068 cannot stop the collector output of the transistor Q68 unless the base potential of the transistor Q69 (the base potential of the transistor QB7) becomes considerably large. In other words, when an ACC open loop is formed, the base potential of transistor Q6B increases, increasing the DC offset with respect to the filter output.

This allows the AC-C
By monitoring the detection output, false 1 operation can be prevented.

Next, in the color reception state, among the outputs of the ACC detector 34, the output potential on the transistor QB2 side is high, and the output potential on the transistor QGI side is low. For this purpose, transistor Q[il operates, and transistors QB4, Q8
Through the current mirror circuit of 5, the transistor Q[i
This will lower the base potential of 8.

As a result, the base potential of transistor Q68 changes to the resistance RB.
It decreases due to the voltage drop of , reducing the difference with the filter output (small DC offset).

Therefore, at this time, even if the base potential of the transistor Q87 changes greatly, a color killer output is not immediately obtained (the transistor Q69 remains on), and the color mode is maintained in both strong and weak electric fields. Able to maintain signal. Therefore, color fading in a weak electric field can be prevented.

However, the circuit shown in FIG. 6 has the following problems.

(a) It is configured to give a DC offset to the killer discrimination circuit 4012 by the ACC detection output, making it difficult to select the current input and output from the ACC detector (especially the collector current of transistor Q85, the base current of transistor Q6B, and the resistor RB). accompanies.

(b) The load of the killer detector is given by the resistor RL, but since the effects of DC offset, offset current, and input signal offset always appear on this, the killer malfunction can be improved by using the ACC detection output, and when the electric field is weak. It is extremely difficult to design a device that can sufficiently improve killer performance.

(C) Furthermore, it is difficult to obtain the desired performance because the sensitivity and offset of the killer detector appear at the same time.

(Problem to be Solved by the Invention) As mentioned above, conventionally, because there is no sensitivity switching of the killer detector depending on the electric field strength, for example, in a monochrome reception state with a strong electric field, if there is carrier leakage, the color reception state is changed. You may get a false positive result.

In order to improve this, it was considered to connect a high resistance to the filter, but this resulted in the problem of 3. When the electric field is weak in the color reception state, it is immediately judged as black and white, which deteriorates the performance. .

In addition, as in the circuit shown in Figure 6, if the ACC detection output is converted into current depending on the strong or weak electric field and the killer detection sensitivity is switched (increasing the DC offset), the killer detector itself can be improved. Because of the existence of the offset and the offset of the ACC detection output, it is difficult to design a desired killer characteristic.

Therefore, this invention uses the ACC detection current to switch the sensitivity of the killer detector to the electric field strength.
By changing the ratio of the operating current and the killer offset current, it is possible to prevent killer malfunctions (color fading) when receiving black and white reception in a strong electric field, and to prevent killer malfunctions (color fading) when receiving color in a weak electric field. The purpose of the present invention is to provide a color signal processing device that can perform the following steps.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a killer detection circuit that: 4. An ACC detection output that is an output of the automatic color control circuit is supplied, and changes depending on the magnitude of this detection output. a killer detection sensitivity correction circuit that obtains a correction current; the correction current from the killer sensitivity correction circuit is added to or subtracted from at least one of the detection operating current or the offset current;
A killer that has hysteresis characteristics in the mode signal output characteristics when transitioning from a monochrome reception state to a mode signal indicating a color reception state, and when transitioning from a color reception state to a mode signal indicating a monochrome reception state. It is equipped with a wave detector.

(Function) With the above means, the correction current from the killer detection sensitivity correction circuit is directly added to or subtracted from the detection current or offset current of the killer detector, so that the mode signal output characteristics have hysteresis characteristics. Therefore, an erroneous determination of the color mode will not be obtained in a monochrome reception state, and color fading will not occur in a weak electric field in a color reception state.

5 (Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. Since the overall system block is almost the same as the configuration shown in Figure 6,
The same parts as in FIG. 6 are given the same reference numerals. The difference from the circuit in FIG. 6 is that a killer detector 411 and a killer detection sensitivity correction circuit 412 are provided. The killer detection sensitivity correction circuit 412 receives AC from the ACC detector 34.
C detection output is input.

The ACC detection output can be used as information indicating whether the mode is monochrome reception mode or color reception mode, as well as information indicating whether it is a strong electric field state or a weak electric field state.

If the ACC detection output is, for example, a predetermined level or higher, it can be determined that the reception state is black and white, or even if the reception state is color, there is a weak electric field and a very small input signal.

If the ACC detection output is lower than a predetermined level, for example, 6 If it is small, it can be determined that color reception is in progress.

The killer detection sensitivity correction circuit 412 is an ACC
The information from the detector 34 is determined and the killer detector 411
The detection sensitivity of can be corrected.

Here, in the monochrome reception state, it is necessary to prevent carriers from leaking into the burst input section and causing erroneous determination (color mode determination).

For this purpose, the killer detection sensitivity correction circuit 412 needs to prevent the color killer output outputted from the killer detector 411 from changing easily, and makes the detection sensitivity of the killer detector 411 dull.

Next, in the color reception state, the AC of a predetermined level or higher is
If a C detection output is obtained and the electric field gradually becomes weaker from this state, if the erroneous determination that the mode is monochrome reception mode is made immediately, color loss will occur.

Therefore, in such a case, as long as the ACC detection output is obtained at a predetermined level or higher, the killer detection output changes from the color signal reception state (color mode) to the monochrome reception state (B
/W mode) It is preferable not to change the content immediately. For this purpose, the killer detection sensitivity correction circuit 412 makes the sensitivity of the killer detector 411 dull.

In other words, the killer detection sensitivity correction circuit 412 provides a hysteresis characteristic to the mode determination output of the killer detection 411.

FIG. 2 shows a specific configuration example of the killer detector 411 and the killer detection sensitivity correction circuit 412 described above.

In FIG. 2, a burst signal is supplied between the bases of transistors Q81 and Q82. This transistor Q
The common emitters of 81 and 082 are connected to the collector of a transistor Q91 forming a constant current source, and also to the collector of a transistor Q91 which is an output of a current mirror circuit to be described later.
112 collectors.

The collector of transistor Q81 is connected to the common emitter of transistors Q83 and Q84, and the collector of transistor Q82
The collector of is connected to the common emitter of transistors Q85 and Q8B. A carrier K ICW for killer detection is supplied between the common bases of the transistors Q84 and 085 and the common bases of the transistors Q83 and Q8[i. The common collectors of transistors Q83 and Q85 are supplied to killer discrimination circuit 413, and are connected to the collectors of transistor Q87, collectors of transistor Q95, and filter F for smoothing the detected output.

The emitter of transistor Q87 is connected to the common base of transistors Q89 and Q90 and the collector of transistor Q89. Transistor QB7~090
is the transistor 08 that constitutes a double-balanced differential amplifier.
A current mirror circuit for extracting the output of the detector consisting of Q1 to Q8g is formed.

Transistor Q95 can provide a DC offset to the filter F output. The base of transistor Q95 and the base of transistor Q94 are connected to a 10B power supply, and the common emitter of transistors Q94 and Q95 is connected to the collector of transistor Q92 constituting a constant current source.

Transistor Q93 is a switch transistor that turns on or off the power supply line VC and the ground type 9-value circuit.

The killer detector 411 described above obtains a detection output of the burst signal and the killer detection carrier Kl-TCW,
This output is smoothed by filter F and supplied to killer discrimination circuit 413. When a burst signal is present,
When a detection current is obtained, the output potential of filter F becomes high, and when there is no burst signal in the monochrome reception state, no detection output is obtained and the output potential of filter F becomes low.

On the other hand, in the killer detection sensitivity correction circuit 412, the ACC detection output is supplied between the bases of transistors Q103 and Q104. The ACC detection output is the result of amplitude detection of the burst signal, and when the burst signal is at a sufficient level (in the color reception state), the transistor Q1
The base potential of transistor Q103 is low and the base potential of transistor Q04 is high. Be0 Obtains output with low blackout.

The common emitter of transistors Q103 and Q104 is
It is connected to the collector of transistor Q102 that constitutes a constant current source. Transistor Q101 is a switch transistor connected between the power supply and ground, and is turned on during the burst signal period.

The collector output of transistor Q103 is further connected to transistors Q109 and Q110 via a current mirror circuit constituted by transistor Q105.010B.
It is connected to filter F through a current mirror circuit configured by ``.

Further, the collector output of transistor Q104 is further connected to transistors Q111 and 01 through a current mirror circuit constituted by transistors Q107 and Q108.
The signal is supplied to the common emitters of transistors Q81 and Q82 through a current mirror circuit configured by transistors Q81 and Q82.

Therefore, the detection output of the ACC detector 34 is related to the killer detector 411 through the killer detection sensitivity correction circuit 412.

1 In this case, transistors Q 104 , Q 1.07Q
The path of I08, Qllll 5Q112 is associated with the operating current IO of the killer detector 411, and the path of transistors Q103, Q105, Q106, Q109, QllO is associated with the offset current 1off of the killer detector 411.
associated with. Here, the operating level of the killer detector 411 is determined by the ratio of the operating current 0 and the offset current 1orf'. The killer discrimination circuit 413 consists of transistors Q112 to Q117, including a pair of transistors Q113 and Q115, and a transistor Q11.
2 and Q114 form a differential amplifier, a 10B power supply is connected to the base of the transistor Q114, and a filter F is connected to the base of the transistor Q115. The output of this differential amplifier is taken out through current mirror transistors Q11B, Q1, and 17, and is used as a mode discrimination signal. In addition, the transistor Q11
8 and Q119 form a VBE clamp circuit, these transistors 0118 and Q119 are connected in series between the power supply voltage Vc and the reference potential point, both bases are connected to a 10B power supply, and both emitters are connected to a filter. Connected to F.

If the detected output of the ACC detector 34 indicates a monochrome reception state, the base potential of the transistor Q103 will be high and the base potential of the transistor Q104 will be low. Then, the filter F is passed through the collector output of transistor Q103 or the current mirror circuit (Q105 to QIIO).
is supplied to the terminal. In other words, the offset current Ioff is increased. An increase in the offset current 1 off means that the difference from the operating current IO of the killer detector 411 decreases, and the terminal potential of the filter F decreases.

As a result, in the black-and-white reception state, the potential of the output of the filter F becomes low, but since the offset current is further increased by the ACC detection output, the determination output in the black-and-white (B/W) mode is more strongly maintained.

In other words, even if a small amount of detection output appears due to carrier leakage into the burst input section in a monochrome reception state, the output will not be erroneously switched to the color mode determination output.

3 Next, in the color reception state, the transistor Q10
The base potential of transistor Q104 is low, and the base potential of transistor Q104 is high. Then, transistor Q104 operates, and its collector output becomes a current mirror circuit (Q10
7 to Q122) to the emitter of the transistor Q8LQ82 of the Kira detector 411. As a result, the operating current 0 of the killer detector 411 increases. This means that the detection current becomes larger, and the ratio with the offset current is increased, and the terminal voltage of the fill F is forcibly shifted to a higher direction (to obtain color mode determination). Therefore, even in a reception state of a weak electric field, the color killer does not work immediately, the color does not disappear or appear, and the killer detection performance can be improved.

In a weak electric field, if the terminal voltage of filter F is increased to maintain the color mode, it is thought that the color mode will be maintained even when black and white reception occurs, but in this case, the bust Since there is no signal and the detection efficiency of the killer detector decreases, the voltage at the filter F terminal drops sufficiently and a color killer output (B/W mode) can be obtained, so there is no need to worry.

Although the correction currents given to the offset current and operating current described above are explained at a ratio of 1:1, the ratio may be changed.

According to this embodiment described above, since the configuration is such that the ratio of the operating current or offset current of the killer detector is controlled, an interface between the ACC detector and the killer detector can be easily obtained. In the conventional circuit, the ACC detection output was associated with the killer detector in the form of bias control, which caused design difficulties. According to this embodiment, coupling with the killer detector can be facilitated by selecting the current ratio of transistors Q103 and Q104 and the number of transistors to be added.

Furthermore, according to this killer signal generation method, when switching from B/W mode to color mode and from color mode to B/W mode in the killer discrimination circuit 413, mode switching can be performed reliably and quickly. .

Time to change from B/W mode to color mode Potential difference VB where the collector potential of transistor Q83 changes to color mode
Requires E. If the charging voltage per gate at this time is ΔV1 and the discharging voltage is ΔV2, 67.7 mV during charging (rise) X 3.5XIO = 45.4 mV during discharging (falling) ΔI...
Killer correction current 0. bIIA SI O... Killer operating current 0.24 mA, I off... Offset current 0.028 mA SC-filter capacitor 0
．． ,018μAStl...Gate width 3.5m,
VBE...0,7■, 6t...63.5μ From the above two values, the time to reach the potential difference ΔV (=VBE) from B/W mode to color mode is t c - (VBE/ ( ΔVI −ΔV2 ) )
t=0.71m5ec Therefore, approximately 0.7m5ec is the time to change from B/W mode to color mode.

Next, the time to change from color mode to B/W mode is the time until the collector potential difference of transistor 083 reaches VBH, and the discharge time Δv2 per gate is 24.9+nV (decrease) 7 Therefore, color Potential difference Δ from mode to B/W mode
The time to reach V (=VBE) is X 63.5X 1
O-b master 1.8m5ec, so from color mode B/
The color fading time to reach the W mode state is 1.8 m5ec.

To summarize the above points, in the case of B/W mode, the killer detector has good sensitivity because there is no burst signal during strong electric field.
A B/W mode determination output is obtained. In addition, when the electric field is weak,
Coloration tends to occur when noise is included and detected, but since there is no burst signal and the detection efficiency decreases when the electric field is weak, a B/W mode determination output is obtained.

In addition, when there is leakage of carriers, the offset current 1 off increases in the case of a strong electric field, lowering the sensitivity of the killer detector and obtaining a B/W mode determination output. When the electric field is weak,
Noise is included in addition to carrier leakage, and the operating current IO of the killer detector increases, but the ratio of the amount of carrier leakage to noise is 8. The sensitivity of the killer detector decreases isometrically, and B/W mode The judgment output is obtained.

On the other hand, in the case of color mode, a color mode determination output can be reliably obtained in the case of a strong electric field. In addition, when the electric field is weak, noise is included in addition to the signal, but the operating current of the killer detector 411 is 1o.
It acts to increase the detection sensitivity, lowers the detection sensitivity, obtains a color mode judgment output, and eliminates color fading.

[Effects of the Invention] As explained above, according to the present invention, when switching the sensitivity of the killer detector to the electric field strength, the ratio of the killer operating current to the killer offset current is changed by the ACC detection current, and black and white is detected in a strong electric field. In contrast, a weak electric field can prevent killer malfunctions (color fading) during color reception.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing essential parts of the invention, FIG. 3 is a block diagram showing a conventional color signal control device, and FIG. FIG. 5 is also a block diagram showing a conventional color signal control device. FIG. 6 is a circuit diagram showing a part of the blocks in FIG. 5 in detail. 32... Chroma amplifier, 33... Burst amplifier,
34...ACC detector, 35...APC detector, 3
B...VCo, 37...90'' phase shifter, 38.39
．． 4143...Amplifier, 42...Demodulator, 411...
... Killer detector, 412 ... Killer detection sensitivity correction circuit, 413 ... Killer discrimination circuit.

Claims (1)

[Claims] Extracting a burst signal from the output of a chroma signal amplifier,
Compare the phase of the burst signal and the carrier for phase control,
An automatic phase control loop circuit configured to control the oscillation output phase of the voltage controlled oscillator that generates the carrier for phase control according to the error voltage, and an automatic phase control loop circuit that performs amplitude detection of the burst signal and outputs its gain detection. an automatic color control circuit that controls the gain of the chroma amplifier to maintain the burst signal at a constant level, and a carrier for color killer control created using the burst signal and the output of the voltage controlled oscillator. A color signal control device comprising a killer detection circuit that performs a comparison and obtains a killer detection output as a result of the comparison, wherein the killer detection circuit is supplied with a detection output that is an output of the automatic color control circuit;
A killer detection sensitivity correction circuit obtains a correction current that changes depending on the magnitude of the detection output, and the correction current from this killer sensitivity correction circuit is added to or subtracted from at least one of the detection current or offset current, and the black-and-white reception state is A killer detector having a hysteresis characteristic in the output characteristic of the mode signal is used in the case of transitioning from the color reception state to the mode signal indicating the color reception state, and in the case of transitioning from the color reception state to the mode signal indicating the monochrome reception state. A color signal control device characterized by comprising: