JP3043242B2 - Control device for analog circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an analog circuit, and more particularly, to a control voltage applied in a time-sharing manner from the outside of the device to a plurality of control voltages inside the device. An improved controller for individually supplying a plurality of analog circuits.

[0002]

2. Description of the Related Art In recent years, as microcomputers have become widespread as control elements for various consumer devices, television receivers and audio devices have been increasingly equipped with such microcomputers. In such a device, various analog circuits are controlled by a microcomputer and an analog IC operating under instructions from the microcomputer. Recently, there are many analog ICs that include analog circuits to be controlled.

For example, in the case of a television receiver, when a user issues a command to change the taint or color of a television signal, the command is temporarily taken into the microcomputer, and control corresponding to the command is performed by the microcomputer. The analog circuit is applied to the analog IC, and an analog circuit built in the analog IC operates.

Here, the operation of such an analog IC will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the connection between a conventional microcomputer and an analog IC.

In the figure, a plurality of PWM (pulse wave modulation) circuits 2 to 4 are arranged inside a microcomputer 1, and pulse signals modulated in pulse width by the PWM circuits 2 to 4 are integrated into desired voltages by integrating circuits 5 to 7. It becomes an analog signal that is smoothed to a level and transmitted at a voltage level. Thereafter, these signals are applied to analog circuits 9 to 11 which are controlled circuits in the analog IC 8.

However, the method of FIG. 1 requires a separate control signal line for each control, and has the problem that the number of pins of the microcomputer and the IC increases and the wiring becomes complicated.

Therefore, a method of using a digital signal for transmitting a control signal is well known. In this method, a digital signal is time-divided, and a signal is transmitted using a clock signal line and a data signal line. An example of the configuration shown in FIG. 2 can be given.

In FIG. 2, digital data synchronized with a clock signal from the microcomputer 1 is transmitted to an analog IC 8.
Has been applied. The address control circuit 12 in the analog IC 8 decodes the incoming digital data, determines to which controlled circuit data should be transmitted, and distributes the digital data to the controlled circuits according to the determination result. . The digital data is stored in a D / A conversion circuit 1
After being converted into an analog signal by 3 to 15, it is applied to analog circuits 9 to 11.

Therefore, according to the method shown in FIG.
It is possible to perform a plurality of controls with this signal line.

[0011]

However, when a recent television receiver is taken as an example, the number of controls to be realized has been greatly increased in accordance with the increase in the number of functions of the device. Certainly, according to the method of FIG. 2 described above, a plurality of controls can be performed by providing a plurality of D / A conversion circuits 13 to 15 inside the analog IC 8, but D / A conversion is performed according to the number of controls.
The number of A conversion circuits also increases.

The problem here is that the analog I
In C, having a large number of D / A conversion circuits with a large number of elements is directly linked to an increase in chip area. That is, by incorporating a large number of such D / A conversion circuits,
Undesirable situations such as an increase in the unit cost of the analog IC, an increase in the size of the component, and a decrease in the production yield rate are caused. For example, even with basic user controls alone, control of brightness, contrast, sharpness, color, taint, and volume is almost essential. As these extended functions, AV switches, video switches, and audio switches can be set from inside / outside. Switching to select • The functions to be implemented, such as switching between video inputs 1 and 2, are increasing. In addition, regarding the control of hidden functions that are invisible to the user, there is a strong demand for realizing the following control as adjustment at the time of factory shipment.

[0013] Since the required clock frequencies are different between the NTSC system and the PAL system, selection of a crystal oscillator corresponding to these is necessary. • RGB of a CRT for white balance adjustment
Cutoff and RGB drive adjustment ・ IF VCO oscillation control ・ Screen distortion correction To cover all these demands, many analog D / A conversion circuits are provided in the analog IC, and product competitiveness is maintained, that is, parts There is a limit to reducing the unit price.

On the other hand, what should be noted here is that the microcomputer 1 is made of MOSIC. In other words, with respect to the microcomputer 1, the increase in the number of elements does not cause any problem. Even if a large number of D / A conversion circuits are incorporated, it is rare that the product cost is affected. The upper limit of the number of D / A conversion circuits may be determined within the same range.

From the background described above, the signal lines remain small as shown in FIG.
A transmission method for performing A conversion processing has been desired.

[0016]

In order to solve the above-mentioned problems, a control device for an analog circuit according to the present invention separates a control voltage given from an external device in a time-division manner into a plurality of control voltages inside the device, and controls the plurality of control voltages. A control device that individually supplies a control voltage to a plurality of corresponding analog circuits, wherein a control voltage is input in a time-division manner, and a control voltage input unit arrives in synchronization with a time-division timing of the control voltage, A designation input unit for receiving a designation signal for designating an analog circuit to be supplied with the control voltage; a reference voltage input unit for receiving a reference voltage for determining a voltage of the inputted designation signal; Voltage dividing means for dividing a voltage into a plurality of voltage sections; and
Determining means for determining a section to which the voltage of the designated signal belongs, and specifying an analog circuit assigned to the section as a supply target of the control voltage; and an analog circuit provided one-to-one with the analog circuit and forming a pair with the analog circuit Has a DC hold circuit that captures and outputs the control voltage when the control voltage is specified as a supply target of the control voltage, and the control voltage output from the DC hold circuit is individually supplied to a corresponding analog circuit. Things.

Further, a control device for an analog circuit according to the present invention comprises:
The reference voltage is a power supply voltage of a circuit that generates the designation signal.

[0018]

According to the present invention having the above-described structure, first, a control voltage having a meaning unique to each analog circuit is applied to the device in a time division manner. At this time, the designation signal is also input in synchronization with the control voltage. Here, in order to accurately determine the voltage of the designation signal, the control device inputs a reference voltage. This reference voltage is divided into a plurality of voltage divisions inside the device, and these divisions are assigned one-to-one with each analog circuit. Therefore, it is determined to which category the voltage of the designation signal belongs, and an analog circuit to which the control voltage is to be applied is specified.

On the other hand, the control voltage in which the analog circuit to be supplied is specified is captured by the DC hold circuit and output. As a result of applying this output voltage to each analog circuit, transmission of a large number of control voltages through a limited number of signal lines becomes possible.

Further, according to the present invention, since the reference voltage is a power supply voltage of a circuit for generating the designation signal, a relative voltage between the power supply voltage of the circuit and the power supply voltage of the control device according to the present invention is provided. Even when an error or the like occurs, the section to which the voltage of the designated signal belongs can be correctly determined.

[0021]

【Example】

Embodiment 1 FIG. Here, an embodiment of the present invention will be described. The purpose and configuration of the present invention are partially the same as those of Japanese Patent Application No. 5-288247 filed earlier by the present applicant. Therefore, the common configuration will be outlined first, and the configuration having a difference will be described later. Add.

In this embodiment, as described above, the microcomputer performs the D / A conversion processing. Based on this assumption, the present embodiment converts two signal lines transmitted as digital signals in FIG. 2, ie, clock and data, into analog signals and transmits them.

That is, one of the two signal lines is the control voltage itself to be applied to any one of a plurality of analog circuits built in the analog IC. The other is a designation signal for designating a circuit to which a control voltage is to be applied from a plurality of analog circuits.

A feature of the designation signal is that the voltage of this signal indicates an analog IC to be designated. In other words, in the case of a digital signal, a target is specified by a plurality of address bits, but the present specification signal is characterized in that the target is specified by a voltage.

As described above, the control voltage is transmitted to the desired analog circuit by the set of the control voltage and the designation signal. Since the transmission is performed every time in a time-division manner, the control voltage is captured inside the analog IC. A DC hold circuit for holding is provided one-to-one with the analog circuit. And this D
The output of the C hold circuit is provided to the analog circuit.

The above is an outline of the configuration of the invention disclosed in Japanese Patent Application No. 5-288247.

The prior application can solve the conventional problem, but according to the present invention, the following configuration is added in order to more surely specify the analog circuit.

That is, the control device of the present invention is supplied with a reference voltage for determination in order to accurately determine the voltage of the designated signal. As described later, when a relative variation occurs in a power supply voltage between a microcomputer having a designating signal generation circuit and an analog IC incorporating a control device according to the present invention, an analog circuit to which a control voltage is to be transmitted is used. This takes into account that a discrepancy may occur between the two in the specification. That is, the present invention is characterized in that such a discrepancy is eliminated by using a reference voltage common to both.

In the present invention, the reference voltage is divided into a plurality of voltage sections in the control device, and each section is assigned to an analog circuit on a one-to-one basis. That is, when the designated voltage is in a certain section, a configuration is adopted in which the analog circuit assigned to that section is specified as a target to which the control voltage is to be applied.

The above is the outline of the present embodiment.

Here, the details of this embodiment will be described with reference to the drawings.

FIG. 3 is a conceptual diagram showing a configuration of a television signal processing analog IC incorporating a microcomputer and a control device according to the present embodiment. Note that members corresponding to the configuration in FIG. 2 are given the same reference numerals. In the figure, reference numeral 16 denotes a first D / A for generating a control voltage which varies in a time-division manner depending on an analog circuit to be applied.
The converter 17 is a second D / A converter that changes in synchronization with the time-division timing of the control voltage and generates a designation signal for instructing an analog circuit to which the control voltage is applied, as described later, based on the voltage.

Control signals 18 to 20 are applied with a control voltage, and capture and hold the control voltage when the object to which the control voltage is to be applied is an analog circuit forming a pair with the control circuit.
In the C-hold circuit, output voltages of these three circuits are applied to first to third analog circuits 9 to 11, respectively.

On the other hand, reference numeral 21 denotes a hold control circuit which comprises a plurality of comparators, determines a voltage section to which the voltage of the designated signal belongs, and permits a capture operation of a desired DC hold circuit among the plurality of DC hold circuits. . Also,
38 is a control voltage input terminal to which a control voltage is applied, and 39 is a designation input terminal to which a designation signal is inputted. Here, a feature of the present embodiment is that a reference voltage input terminal 41 for inputting a reference voltage of the hold control circuit 21 is provided.

FIGS. 4 and 5 are waveform diagrams for explaining the combination of the designation signal and the control voltage in this embodiment. FIG. 4 shows the voltage of the designation signal and FIG. 5 shows the control voltage at that time. In these figures, the horizontal axis represents time, and the taint, color, and contrast of the television receiver are controlled with the elapse of time. That is, in these figures, it can be considered that circuits corresponding to the respective functions of taint, color, and contrast are adopted as the first to third analog circuits.

Here, control of each of these functions will be described. In the present embodiment, it is assumed that the rules of the correspondence between the voltage division of the designation signal generated from the second D / A converter 17 and the control are between the microcomputer 1 and the analog IC 8 as follows.

First section (4 V to 4.5 V): Control of taint Second section (3.5 V to 4 V): Control of color Third section (3 V to 3.5 V): Control of contrast However, As will be described, in consideration of the transition period of the designation signal, it is assumed that none of the above-mentioned control is designated at 4 V and 3.5 V, which are the boundaries of each section, and at the voltages in the vicinity thereof. The setting of such a designated prohibited area is disclosed in Japanese Patent Application No. 5-288247.

First, in controlling the taint, the second D / A converter 17 is used to realize the designation signal of the first section.
Outputs a signal of 4.25 V from t1 to t2. At this time, it is assumed that a control voltage of 2 V is generated from the first D / A converter 16, and this control voltage is analog I
It is applied to the first to third DC hold circuits 18 to 20 in C8.

On the other hand, the hold control circuit 21
It is determined that the control voltage should be applied to the analog circuit for taint control based on the V designation signal, and the first DC hold circuit 1 of the first to third DC hold circuits 18 to 20 is determined.
Only 8 performs the capturing operation. As a result, the first DC hold circuit 18 captures and holds the control voltage of 2 V, and applies the control voltage to the first analog circuit 9. Thus, the first analog circuit 9
As a result, the desired control can be performed on the taint.

Next, color control will be described.

Assuming that the control voltage of the color is 3 V,
Since it is necessary to boost the voltage from 2V, the period t2 to t3
This boosting is performed. During this time, the voltage of the designation signal is reduced to 4 V, and no analog circuit is designated (designation prohibited state). Then, the time when the boosting is finished is estimated, and the designated signal is set to 3.75 V in the period t3 to t4.
As a result, only the second DC hold circuit 19 performs the capturing operation, and the control of the second analog circuit 10, that is, the color can be performed.

Similarly, regarding the contrast, the designation signal is held at 3.5 V for a certain period of time t4 to t5 to disable the designation, and is set to 3.25 V at t5 to t6. The control of the analog circuit 11 is performed.

Here, in the hold control circuit 21,
The manner in which the reference voltage is divided into a plurality of voltage sections will be described.

FIG. 6 is a circuit diagram showing details of the hold control circuit 21 of FIG. In the figure, a microcomputer 1 for generating a designation signal is connected to a reference voltage input terminal 41.
5V is input from the same power supply as the power supply of the first embodiment, and this reference voltage is divided into a plurality of voltage sections by dividing resistors 50 to 54. Specifically, the first to fourth comparators 25 to 25
The values of the 28 reference voltages 29 to 32 are 4.5V,
It is set to 4.0V, 3.5V and 3V. Further, these comparators are provided with AND gates and OR gates necessary for generating logic for voltage determination. However, here, for the sake of simplicity, 4V, 3.
A comparator for providing a designated prohibition area near 5 V or the like is not shown. For the following description, the existence of this area is neglected.

First, consider a case where a designation signal of 4.25 V is applied to the designation input terminal 39 in the taint period of FIGS. At this time, the output of the first comparator 25: "L"level; the output of the second comparator 26: "H"level; the output of the third comparator 27: "H"level; the output of the fourth comparator 28: "H". As a result, the output terminal 33 becomes “H” level, the output terminal 34 becomes “L” level, and the output terminal 35 becomes “L” level. Therefore, it is determined that the first DC hold circuit 18 of FIG. 3 performs the capturing operation only during the period when the output terminals 33 to 35 are in this combination.

Next, in the color control period, 3.7.
When the designation signal of 5V is applied to the designation input terminal 39, the output of the first comparator 25: "L"level; the output of the second comparator 26: "L"level; the output of the third comparator 27: "H". Level • The output of the fourth comparator 28 is “H” level, and as a result, the output terminal 33 is “L” level • The output terminal 34 is “H” level • The output terminal 35 is “L” level Therefore, it is assumed that the second DC hold circuit 19 performs the capturing operation only during the period when the output terminals 33 to 35 are in this combination.

Consider the same for the contrast.
In response to the application of the 25V designation signal, the output of the first comparator 25: "L"level; the output of the second comparator 26: "L"level; the output of the third comparator 27: "L"level; The output of the signal 28 becomes the “H” level, the output terminal 33 is the “L” level, the output terminal 34 is the “L” level, and the output terminal 35 is the “H” level. Shall be performed.

As can be seen from the configuration of the present embodiment, the reference voltage required to generate the voltage division can theoretically be generated in the analog IC. For example, if the power supply voltage of the analog IC is 9 V, it is possible to calculate the division resistances 50 to 54 from the voltage and generate the same voltage division as described above. This case is advantageous in that the reference voltage input terminal 41 is not required in FIG. 6, but when the power supply voltages of the microcomputer 1 and the analog IC 8 vary relatively, the following problems may occur.

That is, when the power supply voltage of the analog IC 8 is 9
V ± 5%, that of microcomputer 1 is 5
In the case of a general specification of V ± 5%, the former has a lower voltage of 8.55V (9V × 95%),
Consider the case where a higher voltage of 5.25 V (5 V × 105 percent) is applied to the latter.

At this time, if 3.75 V is to be output from the microcomputer 1 as a designation signal in order to perform color control, this value is 3.93 V (3.75 V).
V x 105 percent). However, one analog IC
8, the voltage division for color control is 3.5V to 4V.
Although V is prepared, this division is 3.32V to 3.8V
(3.5 V and 4 V × 95 percent).

That is, in this case, the microcomputer 1
Although the color control is scheduled to be performed, the voltage 3.93 V of the designation signal does not enter the color control section but enters the taint section which is the voltage section above it.
As a result, when the user performs a button operation or the like so as to change the color, a problem occurs that the taint changes.

Such a problem can be suppressed by improving the design accuracy of the power supply system. For example, analog IC8
By using a constant voltage such as a Zener voltage for generating the voltage division on the side, the problem caused by at least an error in the power supply voltage on the side of the analog IC 8 is solved. However, even in that case, the problem caused by the power supply voltage error on the microcomputer 1 side is not solved. In addition, a circuit element for generating a Zener voltage is required, which is not advantageous in terms of product cost. Therefore, in determining the voltage, both generally use their own power supply voltages. At this time, the voltage error of the power supply system (such as a regulator) often reaches about ± 5%, and the above-mentioned problem is not completely eliminated.

In this embodiment, only three voltage divisions have been described. However, in practice, the same number of divisions as the number of types of control are required. Therefore, the voltage range of 0 to 5 V is subdivided according to the number of controls. Will be transformed. For example, when 20 kinds of control are performed, the width of each voltage section is less than 0.25 V, and the design margin is smaller than in this embodiment.

In view of such circumstances, the present embodiment is provided with a reference voltage input terminal 41 for inputting a reference voltage of the hold control circuit 21. That is, by using the power supply voltage itself of the microcomputer 1 as a reference voltage,
Even if there is a relative variation in the power supply voltage of the microcomputer 1 or the analog IC 8, as long as both reference voltages match, the above-described problem does not occur at all. Normally, the power supply voltage is generated by a regulator or the like, and thus exhibits a constant variation. However, the configuration of the present embodiment is also effective against instantaneous voltage fluctuations such as ripple noise.

Embodiment 2 FIG. Next, another embodiment will be described. The second embodiment also has a configuration substantially similar to that of the first embodiment, and therefore, corresponding components are denoted by the same reference numerals and description thereof will be omitted.

Although the control device of the first embodiment is provided with the reference voltage input terminal 41, the second embodiment is characterized in that the reference voltage is obtained by another configuration.

FIG. 7 shows a microcomputer and a second embodiment.
1 is a conceptual diagram showing a configuration of a television signal processing analog IC incorporating a control device according to the first embodiment. In the figure, the difference from the first embodiment is that the second embodiment does not have the reference voltage input terminal 41, while the designated input terminal 39 is newly input to the peak hold circuit 60 inside the analog IC 8. The peak hold circuit 60 uses the maximum value of the voltage sent from the microcomputer 1 to the analog IC 8 via the designated signal at a predetermined time interval as a reference voltage in order to match the voltage reference between the microcomputer 1 and the analog IC 8. It is a circuit to hold.

FIG. 8 shows a hold control circuit 21 according to the second embodiment.
FIG. 3 is a circuit diagram showing details of the embodiment. This hold control circuit 21
Then, the reference voltages 29 to 29 of the plurality of comparators 25 to 28
32 is generated not from the voltage of the reference voltage input terminal 41 but from the voltage held by the peak hold circuit 60.

The sample interval in the peak hold circuit 60 may be determined from the time that is shorter than the maximum time during which the circuit can hold the voltage. In the case of the television signal processing IC, the vertical interval of the television receiver is used as the sample timing. There is a method to adopt a ranking period. This is because no image is displayed during this period, so that noise that may be generated by transmitting the reference voltage does not appear on the screen.

When this method is employed, the voltage holding time required for the peak hold circuit 60 can be obtained from the vertical blanking interval. That is, in the case of the NTSC system, since 60 fields are transmitted per second, vertical blanking occurs once every 1/60 second. Therefore, any circuit that can stably hold the voltage for 1/60 second may be used. Further, in this case, if the transmission of a plurality of control voltages is also performed collectively in the vertical blanking period, the period of the vertical blanking period 21H (1H corresponds to one scanning line), that is, (1/1) 60) $ 262.5 x 2
It is only necessary to be able to hold the voltage for 1 second = about 64 microseconds, and the required circuit scale is very small.

[0061]

As described above in detail, according to the control device of the present invention, it is possible to transmit a large number of control voltages via very few signal lines. For this reason, the transmission of the control voltage through two signal lines, which was conventionally realized only with digital signals, can be performed with analog signals. Further, since the control device of the present invention can input the reference voltage, it is possible to accurately specify the analog circuit to which the control voltage is applied.

As a result, more control voltages can be transmitted through a smaller number of signal lines, and it is possible to cope with multifunctional television receivers and the like while suppressing the unit price of analog ICs and increasing the size of parts. Further, it is possible to facilitate the inspection in the shipping process.

Further, according to the present invention, since the power supply voltage of the circuit for generating the designation signal is adopted as the reference voltage, even if a relative error or the like occurs between a plurality of power supply voltages, the voltage of the designation signal can be reduced. It is possible to correctly determine which section belongs.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the connection between a microcomputer and an analog IC, which are the most common in the past.

FIG. 2 is a diagram showing a configuration for realizing a known method using a digital signal for transmission of a control signal.

FIG. 3 is a conceptual diagram showing a configuration of a television signal processing analog IC incorporating a microcomputer and a control device according to the present embodiment.

FIG. 4 is a diagram illustrating a voltage of a designation signal in a waveform diagram illustrating a combination of a designation signal and a control voltage in the first embodiment.

FIG. 5 is a diagram illustrating a control voltage in a waveform diagram illustrating a combination of a designation signal and a control voltage in the first embodiment.

FIG. 6 is a circuit diagram showing details of a hold control circuit 21 of FIG. 3;

FIG. 7 is a conceptual diagram showing a configuration of a television signal processing analog IC incorporating a microcomputer and a control device according to a second embodiment.

FIG. 8 is a circuit diagram illustrating details of a hold control circuit 21 according to a second embodiment.

[Explanation of symbols]

 Reference Signs List 1 microcomputer 8 analog IC 9-11 analog circuit 16 first D / A converter 17 second D / A converter 18 first DC hold circuit 19 second DC hold circuit 20 third DC hold circuit 21 hold control circuit 38 control voltage input terminal 39 designated input Terminal 41 Reference voltage input terminal 50-54 Divided resistor 60 Peak hold circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 5/38-5/63 G11C 27/00 H03M 1/66 WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A control device which separates a control voltage given from an external device in a time-division manner into a plurality of control voltages inside the device and individually supplies the plurality of control voltages to a plurality of analog circuits respectively corresponding to the control voltage. Control voltage input means for receiving a control voltage in a time-division manner, and a designation input for receiving a designation signal for arriving in synchronization with the time-division timing of the control voltage and for designating an analog circuit to be supplied with the control voltage Means, a reference voltage input means to which a reference voltage for determining the voltage of the input designation signal is inputted, voltage dividing means for dividing the reference voltage into a plurality of voltage sections, and Determining means for determining a section to which the voltage of the designation signal belongs, and specifying an analog circuit assigned to the section as a supply target of the control voltage; A DC hold circuit that is provided in one-to-one correspondence, and captures and outputs the control voltage when an analog circuit forming a pair with itself is specified as the control voltage supply target, and is output from the DC hold circuit. A control device for an analog circuit, wherein each control voltage is individually supplied to a corresponding analog circuit. 2. The analog circuit control device according to claim 1, wherein the reference voltage is a power supply voltage of a circuit that generates the designation signal.