KR840002012B1 - Chrominance signal processing circuit - Google Patents

Abstract

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Description

Color signal processing circuit

1 is a schematic configuration diagram of a color signal system of a color television receiver to which the present invention is applied.

2 is a connection diagram of one embodiment of the present invention.

3 is a connection diagram of a phase control circuit that is part of the FIG.

4 is a registered circuit diagram for explaining the phase control circuit of FIG.

5 is a waveform diagram for explaining a phase control circuit.

The present invention relates to a color signal processing circuit of a color television receiver.

In the color signal processing circuit, ACC, image control and color control are performed. In the related art, since a separate gain control amplifier corresponding to each of these controls is connected in multiple stages, the circuit scale becomes large, and in the case of the integrated circuit, the number of leads derived from the integrated device increases. In addition, color control is performed by changing the phase of the continuous wave (insertion carrier wave) for color demodulation, and the phase shifting reactant element is provided outside the integrated circuit.

The object of the present invention is to individually gain for ACC, image control, color control, etc.

Hereinafter will be described an example of the present invention.

In FIG. 1, (1) shows a color signal processing circuit applied to the present invention. The carrier color signal is supplied to the input terminal 2. The carrier color signal appearing at the output terminal 3 of the color signal processing circuit 1 is supplied to the ACC detection circuit 5, and the carrier color signal appearing at the output terminal 4 is the color decoder 6 and the buster gate 7. Is supplied. The burst signal extracted from the burst gate 7 is supplied to the color synchronization circuit 8, and the insertion carrier formed in the color synchronization circuit 8 is supplied to the color decoder 6 and used for color demodulation. Three color difference signals R-Y, G-Y, and B-Y are obtained from the color decoder 6. The burst flag obtained by delaying the horizontal synchronizing signal is applied to the terminal 9 of the ACC detection circuit 5, the burst gate 7 and the color signal processing circuit 1. The color signal processing circuit 1 includes a terminal 10 to which an ACC signal from the detection circuit 5 is supplied, a terminal 11 to which an image control signal is supplied, a terminal 12 to which a color control signal is supplied, and color control. It has a terminal 13 to which a signal is supplied. These control signals are generated by volume or the like as DC voltage.

2 shows in detail the signal processing circuit 1 to which the present invention is applied. In Fig. 2, the output terminals 4 'and 4 "are connected to the phase control circuits 14' and 14" surrounded by a dotted line.

3 shows a phase control circuit.

In Fig. 3, reference numerals 14a and 14b denote input terminals to which an input signal whose level is differentially changed in phase is applied. The bases of the transistors 15a and 15b are connected to the input terminals 14a and 14b, respectively. The emitters of the transistors 15a and 15b are grounded through the resistors 16a and 16b, respectively, and the collectors of the transistors are connected to a power supply terminal [17: power supply voltage (+ VCC)]. It becomes a composition. A series circuit of a capacitor 18 and a resistor 19 is connected between the emitters of the transistors 15a and 15b, and output terminals 4 'and 4 "are derived from the connection points of both.

)로서 선정된다. 이제(

)로 하면, 저항 R 및 콘덴서 C에서 전체의 전류가 흘러서 출력단자(4)에서 취출되는 출력전압 V₃는(

)로 된다. 또한 (V₁=V)이고 (V₂=0)일때, 출력전압 V₃는When the capacitor 18 is set to C and the resistor 19 is set to R, the equivalent circuit of the phase control circuit is an input voltage source V ₁ , (15) by the emitter follower transistors 15a and 15b. the configuration is the four-degree containing V _2). When one input voltage V ₁ changes from 0 to V, the other input voltage V ₂ changes from V to 0. here (

) Is selected. now(

) As if, in the resistance R and the capacitor C is the total current flows through output terminal 4. The output voltage V ₃ which is taken out of the (

). Also, when (V ₁ = V) and (V ₂ = 0), the output voltage V ₃ is

늦는 출력전압 V₃를 얻을 수 있다. 또한 (V₁=0), (V₂=V)인 경우에는,Phase with respect to the input voltage

A late output voltage V ₃ can be obtained. In the case of (V ₁ = 0) and (V ₂ = V),

앞서는 출력전압 V₃를 얻게된다.Phase with respect to the input voltage

The preceding output voltage V ₃ is obtained.

로 변환된다. 신호 변환회로(20)는 다이오드(21),(22)의 직렬 접속과 다이오드(23) 및 트랜지스터(24)의 콜렉터-에미터 통로의 직렬접속이 2I₀의 정전류원(25)과 바이어스 전압원(26) 사이에 삽입되고, 다이오드(21) 및 (22)의 접속점은 트랜지스터(24)의 베이스에 접속되며, 이 접속점이 또한 저항(27)을 통하여 입력 단자(2)에 접속되는 구성으로서, 트랜지스터(24)의 베이스는 차동증폭기의 한쪽 트랜지스터(28)의 베이스에 접속되고, 트랜지스터(24)의 콜렉터는 상기 차동증폭기의 다른쪽 트랜지스터(29)의 베이스에 접속된다. 이런 트랜지스터(28),(29)의 에미터 공통접속점에는 2I₁의 정전류원(30)이 접속된다. 트랜지스터(28),(29)의 제각기 콜렉터는 트랜지스터(31),(32)의 제각기 에미터에 접속된다.In the configuration of FIG. 2, a carrier color signal including a burst signal is supplied to the input terminal 2 so that two signal currents differential in the signal conversion circuit 20 are provided.

Is converted to. The signal conversion circuit 20 has a series connection of diodes 21 and 22 and a series connection of collector-emitter passages of diodes 23 and 24 with a constant current source 25 and a bias voltage source of 2I ₀ . Interposed between 26, the connection points of diodes 21 and 22 are connected to the base of transistor 24, and this connection point is also connected to input terminal 2 via resistor 27, with the transistor The base of 24 is connected to the base of one transistor 28 of the differential amplifier, and the collector of transistor 24 is connected to the base of the other transistor 29 of the differential amplifier. A constant current source 30 of 2I ₁ is connected to the emitter common connection point of such transistors 28 and 29. Each collector of transistors 28 and 29 is connected to an emitter of transistors 31 and 32, respectively.

In addition, constant current sources 42a and 42b are connected to the collectors of the transistors 28 and 29, respectively. The constant current sources 42a and 42b flow equally the constant current I ₂ controlled by the image control signal, and are turned off by the switching signal (burst flag) from the terminal 9 in the burst section. It is image control to simultaneously change the amplitude of the luminance signal and the carrier color signal, and color control to change only the amplitude of the carrier color signal. As shown, an image control signal is applied to a gain control circuit provided in the luminance signal system. The output terminal 3 is also connected with an ACC detection circuit (see FIG. 1). The magnitude of the constant current 2I ₀ of the signal conversion circuit 20 is controlled by the ACC signal corresponding to the peak value of the burst signal generated from the ACC circuit 5. A gain control circuit (ACC circuit) is formed by a differential amplifier consisting of the signal conversion circuit 20 and the transistors 28 and 29, and its gain is proportional to (I ₂ / I ₀ ).

가 흐른다. 이제, 신호 전류 is에 의하여 트랜지스터(28),(29)의 콜렉터 전류가 도시된 바와 같이(I₁+ix),(I₁-ix)로 변화된다고 가정하자, 다이오드(34) 및 트랜지스터(35)로 되는 전류 밀러 회로에 있어서, 트랜지스터(35)의 에미터 전류는 (I₁+ix),(I₁-ix)로 되고, 출력회로(40)에 대해서는 2ix로 되는 출력 전류가 공급된다. 다이오드(21) 및 (23)의 베이스-에미터 간 전압강하 V_BE21및 V_BE23과 트랜지스터(28) 및 (29)의 베이스-에미터 간 전압강하 V_BE28및 V_BE29의 제각기는In the signal conversion circuit 20, the signal current is at the connection point of the diodes 21 and 22

Flows. Now, assume that the collector current of transistors 28 and 29 is changed by (I ₁ + ix) and (I ₁ -ix) as shown by the signal current is, diode 34 and transistor 35. In the current Miller circuit of (), the emitter currents of the transistor 35 are (I ₁ + ix) and (I ₁ -ix), and an output current of 2ix is supplied to the output circuit 40. Diodes 21 and 23 in the base-to-emitter voltage drop V _BE21 and V _BE23 of the transistor 28 and 29, the base-emitter voltage drops between each of the V _BE28 and V _BE29 is

It becomes Where Is is the reverse saturation current, q is the charge of the electron, K is the Boltzmann constant, and T is the absolute temperature. In addition, the relationship between V _B21 + V _BE28 = V _BE23 + V _BE29 is established.

In other words,

이므로 트랜지스터(28),(29)의 콜렉터에서 취출되어 출력회로(40)에 공급되는 신호성분은 I₁/I₀에 비례하게 된다.therefore

Therefore, the signal components taken out from the collectors of the transistors 28 and 29 and supplied to the output circuit 40 are proportional to I ₁ / I ₀ .

In addition, the emitters of the transistors 31 are connected to the bases of the transistors 44 and 45, and the collectors of these transistors 44 and 45 are connected to the power supply terminals through the resistors 48 and 49, respectively. 17 is connected to the input terminals 14a and 14b of the above-described phase control circuit (indicated by dotted lines). The emitter of the transistor 32 is connected to the base of the transistors 46 and 47, and the collectors of these transistors 46 and 47 are connected to the power supply terminal 17 through the resistors 51 and 52. At the same time as the connection is made, it is connected to the input terminals 14a and 14b of the above-described phase control circuit (shown in dashed lines). In-phase signals appear in the collectors of the transistors 44 and 45, and inverse signals appear in the collectors of the transistors 46 and 47. Therefore, the signals obtained at the output terminals 4 'and 4 "of the two phase control circuits are differential. The carrier color signals including the burst signals at the output terminals 4' and 4" are burst gates. And the color decoder 6 (see FIG. 1).

The emitters of the transistors 44 and 46 connected to the input terminal 14a of the phase control circuit are commonly connected, and the emitters of the transistors 45 and 47 connected to the input terminal 14b are common. Two differential amplifiers are connected. A gain control circuit is formed by the differential amplifiers by the transistors 28 and 29 and the two differential amplifiers. The emitter common connection points of the two differential amplifiers are connected to the collectors of the transistors 52 and 53, respectively, and to the collectors of the transistors 55 and 56, respectively. A common DC voltage source 54 is connected to the bases of the transistors 52 and 53, and a constant current source 57 of 2I ₃ is connected to both emitter common connection points. The constant current source 57 is ₃

In addition, a constant current source 58 of 2I ₄ is connected to the emitter common connection point of the transistors 55 and 56. The constant current source 58 is turned on in the burst section by the switching signal from the terminal 9 inverted as the inverter 59. The base of the transistor 55 is connected to the voltage source 54, and the base of the transistor 56 is connected to the variable voltage source 61 through the resistor 60. The voltage source 54 is connected to the constant current source 63 of 2I ₅ via the transistor 62 base-emitter junction, while the variable voltage source 61 passes through the resistor 60 and the diode 64 to the constant current of the diffuser. It is connected to the circle 63. The variable voltage source 61 is varied by the color control signal.

에 비례하게 된다. 그러므로 ACC신호에 의하여 정전류_{0 2 3} In the carrier color signal section, since the constant current source 58 is turned off and the constant current source 57 is turned on, the constant current 2I ₃ flows to the transistors 52 and 53 by I ₃ , and the constant current I ₃ causes the transistor to flow. A differential amplifier consisting of 45 and 47 and a differential amplifier consisting of transistors 44 and 46 operate. Therefore, the same color carrier color signals appear in the collectors of the transistors 44 and 45 as equiphases, and the same color carrier color signals appear in the collectors of the transistors 46 and 47 as reversed phases. Thus, two phase control circuits show carrier color signals in reverse phase with each other in phase with the original phase. This carrier color signal is supplied to the color demodulation circuit. In this carrier color signal period, the gain of the carrier color signal including the ACC is

Will be proportional to Therefore, constant current _{0 2 3} by ACC signal

에 비례한다.In the burst section, the constant current source 57 is turned off, and the constant current source 58 is turned on. The variable voltage source 61 is controlled by the color control signal, whereby the division ratio of the current flowing through the transistor 62 and the diode 64 is changed. As a result, the variable voltage source 61 flows through the transistors 44 and 46. The signal current and the level of the signal current flowing through the transistors 45 and 47 vary differentially. As described above, the output terminals 4 'and 4 "of the phase control circuit are provided with burst signals whose phase changes in response to signal levels supplied to the input terminals 14a and 14b, respectively. The signal is supplied with a gated color synchronizing circuit (see also Fig. 1), and in the color synchronizing circuit 8, an insertion carrier is generated with a phase corresponding to the phase of the burst signal. Color control is performed.

Proportional to

의 관계를 만족하면 되게 때문에, 콘덴서를 작은 용량의 것을 사용하여도 되므로 직접회로에 콘덴서를 내장시킬 수 있다. 또한 본 발명에서는 차동적으로 전체가 구성되어 있으므로, 전원 접지를 통한 잡음의 영향을 받지 않는다. 더우기, 이득 제어의 전체는 전류에 의하여 제어되어지므로 주파수특성이 양호하고 왜곡율이 낮게 된다.As will be understood in the description of one embodiment described above, a first differential amplifier comprising transistors 28 and 29 and a second differential amplifier as transistors 44 and 46 (or transistors 45 and 47) are provided. The gain control circuit is configured, and the amplitude of the carrier color signal is controlled by the gain control circuit. At the same time, the output side of the second differential amplifier

Since it is only necessary to use a small capacitor as a capacitor, the capacitor can be incorporated in an integrated circuit. In addition, in the present invention, since the whole is configured differentially, it is not affected by noise through the power supply ground. Moreover, since the entire gain control is controlled by the current, the frequency characteristic is good and the distortion rate is low.

Further, when performing the gain control by changing the constant current I ₃ transistors 44, 45, 46, the DC level of the output signal appearing on the collector of 47 Figure ₃ variation

Claims (1)

Primary copper amplifiers 28 and 29 to which the carrier color signal is supplied; first constant current source 30 connected to the primary copper amplifier; and phase control circuits 14 'and 14 " A color signal processing circuit having secondary differential amplifiers 44 and 46 (or 45 and 47) and second and third constant current sources 57 and 58 to time-divisionally control the phase and level of the carrier color signal. The second constant current source supplies an operating current to the second differential amplifier in a section in which a carrier color signal is present, and the third constant current source supplies an operating current to the second differential amplifier in a section in which a burst signal is present. The phase control circuit does not perform a phase shift in a state where the second differential amplifier is operated by the second constant current source, and performs a third constant current in a state where the second differential amplifier is operated by the third constant current source. The phase of the burst signal is shifted depending on the current caused by the source. And gain control for the carrier color signal by varying the level ratio of the constant current by the first and second constant current sources.

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