JPS5843327Y2 - Control voltage adjustment circuit - Google Patents

Description

[Detailed explanation of the invention] As is well known, color television receivers are equipped with various adjustment means such as color adjustment, brightness adjustment, and hue adjustment. It is preset to be in an image receiving state, and can be adjusted freely from the outside.

For convenience of explanation, such adjustment means will be collectively referred to as a control voltage adjustment circuit, and this circuit will generally be constructed as shown in FIG.

In the figure, 1 and 2 indicate fixed resistors, respectively, which are connected in series to the supply terminal 4 of a desired DC power source B as shown in the figure.

Then, a control voltage output terminal 5 is derived from a connection midpoint t between the resistor 1 and the semi-fixed resistor 3 on the power supply side.

The resistor 3 in the center is a variable resistor for resetting the product according to the manufacturer's rules before shipping the product, and after being adjusted to the best point,
It is fixed.

In other words, it is a semi-fixed resistor.

A preset-manual changeover switch SW is provided between the semi-fixed resistor 3 for presetting and the connection point t1, so that one fixed contact M and the other connection point t shown in the figure are connected to each other.
A variable resistor 6 for manual adjustment by the user is connected from the outside.

By the way, the above-mentioned variable resistor 6 for manual adjustment is generally used by 11 users without adjustment, and the switch SW is connected to the contact point M in order to manually adjust the collar, hue, etc.
In many cases, the state switched to the side does not match the best adjusted state (best point) before shipping.

In this case, when using a B-curve variable resistor 6 for manual adjustment, make sure that the button is placed at the center of its mechanical rotation range so that it matches the best point at the time of presetting. Desired tL<, it would be easier and more convenient for the user to perform manual adjustment around this position.

Here, a resistor of the same standard as the semi-fixed resistor 3 is used as the variable resistor 6, but since the resistance value usually varies by about ±20 degrees from the rated value, Even if you use resistors with the same rating display, there will probably be up to 40 yen variation.

Therefore, even if you switch the switch SW to the manual side and set around the rotational position of the variable resistor 6, the adjustment state obtained at this setting position will most likely not be the best point during presetting. I don't get it.

That is, it cannot be said that the configuration shown in FIG. 1 can sufficiently achieve the intended purpose.

To solve this problem, for example, as shown in FIG. 2, a variable resistor I for setting position adjustment is provided on the variable resistor 6 side, and a dummy resistor is placed on the semi-fixed resistor 3 side. 9, and the manufacturer makes fine adjustments using the newly added variable resistor 7 so that the movable center position of the variable resistor 6 described above matches the best point at the time of presetting.
The above objectives can be achieved.

However, this configuration has the disadvantage that not only the number of adjustment steps increases, but also the number of parts increases.

The present invention aims to eliminate such drawbacks by simplifying the structure, and the circuit of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is an example of the circuit of the present invention.

In this example, a semi-fixed resistor 3 for presetting and a variable resistor 6 for manual use are connected in parallel, and are connected to the power supply terminal 4 through the fixed resistor 1, and a variable resistor 6 located in the middle is connected in parallel. In parallel with this, there is a number l and a second fixed resistor 1.
A series circuit 11 consisting of 1A and 11B is connected.

The values of these resistors 11A and 11B are the same.

The values are designated as R1 and R2 for convenience.

Connection midpoint t of series circuit 11 and movable element 1 of variable resistor 6
2a is provided with a changeover switch SW for preset-manual switching.

A 1-circuit, 2-contact type switch is used as this switch, and as shown in the figure, its fixed contact M is connected to the movable element 12a of the variable resistor 6 mentioned above, and the other fixed contact P is connected to the connection midpoint t. and the output terminal 5 is connected to the movable contact.
is connected.

The resistors 3 and 6 may be connected in series.

The adjustment operation of the adjustment circuit 10 configured as described above will be described. With the changeover switch SW switched to the contact point PIIJ, the image receiver is adjusted, that is, preset, so that it is in the best condition.

When the changeover switch SW is switched to the contact M side, it becomes a manual switching state, but when the switch SW is switched to the contact M side, the resistor 6.11
The parallel circuit formed by A and 11B, in this example bridge 15, will now be considered.

Now, when the movable element 12a is in the position shown in the figure, the resistors divided by the movable element 12a are denoted by symbols 6A and 6B, and their respective resistance values are set as Ra t Rb, then the output terminal 51UK is connected. If the linear impedance of the circuit is sufficiently larger than the impedance of the adjustment circuit 10, the equilibrium condition of the bridge 15 is determined by the following equation.

Ra-R=Rb-R"-(1) Since the resistance values RR are selected equally as described above, if the movable element 12a is at the center position of its rotation angle range, it is inevitable that Ra =Rb=R/2 (R is the total resistance value of the variable resistor 6), so the equilibrium condition shown in equation (1) is established.

When this equilibrium condition is established, the control voltage obtained at the output terminal 5 becomes constant regardless of the switching state of the changeover switch SW.

This means that the control voltage at the time of presetting can be obtained even during manual adjustment, so as long as the movable element 12a is located at the center of rotation, exactly the same image reception state as at the time of presetting can be reproduced.

It should be noted that although the resistance value R8 of the variable resistor 6 also has some variation with respect to the rated value as mentioned at the beginning, this variation does not affect the equilibrium condition of the bridge 15 at all.

In other words, if the rated value is corrected and a variable resistor 6 with a value deviated by 20% is used, the divided resistance value Ra
, Rb also take the same value with a deviation of <20%.

In addition, in the variable resistor 6 described above, in order to easily determine the center of rotation of the movable element 12a, a means for indicating the mechanical center of the movable terminal of the variable resistor 6, that is, the center of rotation, such as a center By adding a click, or by displaying the center position on the plate surface on which the variable resistor 6 is mounted and fixed, and by attaching a mark corresponding to the eldest child of the movable element 12a,
The center of rotation can be easily determined.

By the way, in the bridge 15, if the resistance value R□ (-R2) of the series circuit 11 is set to be sufficiently larger than the value of the variable resistor 6, then if ML is selected such that R≧5Ro,
The control voltage obtained at the output terminal 5 becomes approximately dependent on the variable state of the variable resistor 6.

Therefore, when using the B-curve variable resistor 6 as described above, the control voltage with respect to the rotation angle θ of the movable element 12a changes linearly C as shown by the reference numeral 16 in FIG.

On the other hand, if the resistance value R is set to be equal to or less than the resistance value R/2, the influence of the series circuit 11 cannot be ignored, and the control voltage changes as shown by a curve 17, for example.

In this case, especially in the vicinity of the center of rotation f/l, the series circuit 1
The influence of the divided voltage of 1 is strong, and even if the variable resistor 6 is adjusted, the control voltage does not change at all.

Therefore, a control voltage such as curve 17 is suitable for use as a voltage for adjusting the hue, for example.

As explained above, according to the present invention, the manufacturer adjusts the variable resistor 3 for presetting with the movable element 12a of the variable resistor 6 for manual adjustment positioned at its center of rotation. By shipping after fixing the variable resistor 3 for presetting in the adjusted state, if the user does not know the best adjustment position during manual adjustment, the mover 12a of the variable resistor 6 for manual adjustment can be mechanically moved. The best adjustment state can be achieved by positioning it at the center of rotation based on the center instruction.

Therefore, the best adjustment position (standard position) for manual adjustment
can be found easily and reliably.

Also, when the changeover switch SW is operated to switch to the preset state, the movable element 12a of the variable resistor 6 for manual adjustment
A control voltage corresponding to the best adjustment state can be generated regardless of the position of the switch, and by setting the manual adjustment variable resistor to the desired adjustment state, the standard You can instantly select the state and the desired state.

Therefore, the present invention can significantly reduce the number of adjustment steps and the number of parts.

Further, according to the configuration of the present invention, even if the resistance value of the variable resistor 6 varies, the above-mentioned equilibrium condition will not be disturbed, so there is no strict requirement for the rated value.

Therefore, the yield of the adjustment circuit 10 is improved, and there is a practical effect that this type of circuit can be provided at low cost.

Therefore, it is extremely suitable for application to a color television receiver in which a large number of adjustment circuits 10 are used.

Of course, it can also be applied to other electronic devices that perform DC control.

In addition, if the side control voltage does not change directly in response to a change in the rotation angle of the movable element 12a, it is possible to correct the change to a linear change by appropriately selecting the resistance values of the resistors 2 and 19. can.

[Brief explanation of drawings]

1 and 2 are circuit connection diagrams for explaining the present invention, FIG. 3 is a connection diagram showing an example of the circuit of the present invention, and FIG. 4 is a diagram for explaining its operation. 3 is for presetting, 6 is each resistor for manual adjustment, 11
is a series circuit, 15 is a parallel circuit, and sw is a changeover switch.

Claims (1)

[Scope of utility model registration request] A variable resistor for manual adjustment, which has a first fixed terminal connected to the power supply side, a second fixed terminal connected to the ground side, and a movable terminal, and has means for indicating the mechanical center of the movable terminal. , a series connection consisting of two fixed resistors of equal value connected in series to each other, connected in parallel to the variable resistor between the first fixed terminal and the second fixed terminal of the variable resistor. A semi-fixed resistor for presetting connected in series or parallel to the parallel circuit of the circuit, the variable resistor for upward manual adjustment, and the above series circuit, and the midpoint of the connection between the above two fixed resistors. a 1-circuit, 2-contact changeover switch having a first fixed contact connected to it, a second fixed contact connected to a movable terminal of the variable resistor, and a movable contact; and a control connected to the movable contact of the changeover switch. It is an output terminal for taking out the voltage, and the movable contact of the changeover switch is connected to the first
The control voltage adjusting circuit is configured to switch the movable contact of the changeover switch to the second fixed contact side to set the preset state, and switch the movable contact of the changeover switch to the second fixed contact side to set the manual adjustment state.