JPH02260708A - Electronic variable resistor - Google Patents

Abstract

PURPOSE:To easily perform adjustment by controlling >=2 kinds of resistor ladders whose resistance values in one step change differently with use of the output of an up/down counter, and performing the fine adjustment of the resistance value. CONSTITUTION:In a first resistor ladder 1, for example, by setting R1=R2=R3= R4=R5, R6=R7=R8, and R1:R8=1:0.5, and turning on the switches S1-S4 of a first switch circuit 2 sequentially, the resistance value between (a) and (b) changes linearly between 0.5R1-2.5R1 in stepwise. Similarly, in a second resistance ladder 5, by setting 1/8R1=R9=R10=R11=R12=R13, R14=R15=R16, and R9:R16=1:0.5 and setting the resistance value so that the stage of one step can be set finer than the that of the first resistor ladder 1, and turning on the switches S5-S8 of a second switch circuit 6 sequentially, the resistance value between (b) and (c) changes linearly between 0.0625R1-0.3125R1 in stepwise. When a fine adjusting signal is inputted, the resistor ladder with few change of resistance value of one step is controlled by the pulse of a clock signal. In such a way, the fine adjustment can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic variable resistor whose resistance value can be varied in response to the number of pulses of a clock signal.

[Conventional technology]

Conventional variable resistors are designed to move the conductive brush that is in contact with the resistive film mechanically from one end of the resistive film to the other end, thereby creating a connection between the conductive brush and one end of the resistive film or the other end. By making the resistance value variable, a variable resistor was formed.

[Problem to be solved by the invention]

The problem is that in order to set the resistance value of the variable resistor to a certain value, the brush must be moved mechanically, so there is a possibility that the set position may shift due to vibration or the like. Further, when automatically adjusting the variable resistor, a device for mechanically moving the brush is required, which causes problems in that the device is expensive and takes a lot of time for adjustment.

[Means to solve the problem]

In this invention, two or more types of resistance ladders having different changes in resistance value per step are controlled by the output of an up/down counter to finely adjust the resistance value.

[Function] When a fine adjustment signal is input, the resistance ladder with a smaller change in resistance value per step is controlled by the number of pulses of the clock signal to perform fine adjustment.

〔Example〕

This invention will be explained based on the drawings.

In FIG. 1, the first resistance ladder 1 is, for example, R1=
R2=R3=R4=R5, R6・R7・R8, R1:R
8・1:0.5, first switch circuit 2 31~S
As shown in Fig. 2, when the switches 4 are turned on sequentially, the resistance 4 between a and b changes stepwise and linearly between 0.5R1 and 2.5R1. For example, 1/8R1・+29=R10=R1
1・R12=R13, R14=R15=R16, R9:
When the resistance value is set so that each step is finer than the first resistance ladder 1, such as R16=1:0.5, and the switches 35 to S8 of the second switch circuit 6 are turned ON in sequence, The resistance value between b and c is as shown in Figure 3.
It changes linearly in steps between 0.0625R1 and 0.3125+11. The first non-volatile memory 3 is for storing signals for turning ON/OFF the switch of the first switch circuit 2, and stores signal information even when the power is turned off. When the power is turned on again, a signal in the same state as before the power was turned off is output to the first switch circuit, thereby reproducing the resistance value before the power was turned off. The first UP/DOWN counter 4 is in the state where the fine adjustment signal is not input.
When the /D signal input is in the UP state, the count increases at the rising edge of the clock signal, and the U/D signal input is in the DOWN state.
The UP/DCVN counter counts down at the rising edge of the clock signal in the state of , and the count value of the UP/DOWN counter changes in accordance with the number of pulses of the clock signal. When the fine adjustment signal is being input, the count enable C of the first UP/DOWN counter 4 is activated.
Even if E is enabled and a clock signal is input, the first UP/DOWN counter 4 is IIP/DOW.
The fine adjustment signal that does not carry out the N count is inverted by the inverter 9, passes through the count enable CE of the second UP/DOWN counter 8, the preset P, and the OR circuit 10, and becomes the storage signal input of the second nonvolatile memory 7. Terminal M2
is input.

When the fine adjustment signal is not input, the second [IP
/DOWN The preset P of the counter 8 is in the preset state, for example, 1■・0.2■・0.4I=0.8
■・Preset the signal of 1. Further, the input of the storage signal input terminal M2 of the second non-volatile memory 7 becomes a write state, and the preset value of the second UP/DOWN counter is stored. Since the second switch circuit 6 is driven by the stored signal, S8. S? , S6 is OFF.

S5 turns ON and the resistance value between b and c is 0.125R1
becomes. In other words, when the fine adjustment signal is not input, the resistance value between b and c is the preset value of 0.125.
It is fixed at R1. This fixed resistance value is added to the resistance value between a and b, so the resistance value between a and C is 0.5R.
1+0.125R1~2.51111 +0.125R
It changes linearly in steps between 10 and 10. When the fine adjustment signal is input, the count enable CB of the first UP/DOWN counter 4 becomes enabled, and the first UP/DOWN counter 4 becomes enabled.
/DOWN counter is in a stopped state. Therefore, a
, b is the resistance value when the first UP/DOWN counter stops.

Since the fine adjustment signal passes through the inverter 9 and is inverted, the count enable CE of the second UP/DOWN counter 8 becomes a countable state and at the same time becomes a preset disabled state. If a clock signal is input in this state, the second UP/DOWN counter 8 will indicate that the input of the U/D signal is UP.
In the state of , the count increases at the rising edge of the clock signal.
When the input of the L and U/D signals is in the DOWN state, the count is DOWN at the rising edge of the clock signal. The clock signal is also input to the storage signal input terminal M2 of the second non-volatile memory 7 via the OR circuit 10, and at the falling edge of the clock signal, the count value of the second tlP/DOWN counter 8 is input to the second non-volatile memory. Memorize to 7. Since the second switch circuit 6 is driven by the signal stored in the second nonvolatile memory 7, the resistance value between b and c changes as shown in FIG. 3(a). - as an example Sl of the first switch circuit 2;
S2. When the fine adjustment signal is input when S3 is OFF and S4 is ON, the resistance value between 85 is 2R1 plus b
, the resistance value between c is < 2R as shown in Figure 3 (b)
1+ 0.0625R1 and 2R1+ 0.3125R1
You can make each step finer between the steps. In other words, fine adjustment becomes possible.

Note that the first and second UP/DOW operations can be performed without using the first and second non-volatile memories 3.7 shown in the embodiment of FIG.
A similar effect can be obtained by backing up the N counter 4.8 with a battery or the like.

Further, in the embodiment, the first resistance ladder 1 and the second resistance ladder 5 are connected in series, but the same effect can be obtained even if they are connected in parallel by selecting the resistance value. .

〔Effect of the invention〕

As explained above, the present invention stores in a nonvolatile memory a count value that is counted up or down in response to the number of input clock signals depending on the state of the U/D signal, and uses this stored signal to operate a switch circuit. ON/O
In addition to changing the resistance value of the resistance ladder by using FF, by switching the fine adjustment signal, I made a rough adjustment with a coarse resistance ladder with 1 step of steps, and made a fine adjustment with a fine resistance ladder of 1 step, so - The set resistance value will not deviate due to vibration, and a highly reliable variable resistor can be provided.

In addition, the resistance value can be finely adjusted by inputting the fine adjustment signal, U/D signal, and clock signal from the outside, which eliminates the need for a conventional mechanical brush movement device, making automatic adjustment easy. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing changes in resistance value depending on the state of the switch. In Figure 1, 1.5 is the first and second resistance ladder, 2.6 is the first and second switch circuit, 3.7 is the first,
The second non-volatile memory 4.8 is the first and second UP/DO
A WN counter, 9 an inverter, and 10 an OR circuit. Patent applicant: Anritsu Corporation Representative: Patent attorney: Ryutabe Koike

Claims (1)

[Claims] a first resistance ladder, a first switch circuit that electrically connects the input of the first resistance ladder, and a first switch circuit that stores a signal for turning ON/OFF a switch of the first switch circuit. a non-volatile memory; a first UP/DOWN counter that performs an UP or DOWN count when a fine adjustment signal is not input corresponding to the number of pulses of the clock signal and supplies the count value to the first non-volatile memory; , a second resistance ladder connected in series with the first resistance ladder and having a step change of one step smaller than a one step change of the first resistance ladder; and an input of the second resistance ladder. a second switch circuit that electrically connects the second switch circuit, a second nonvolatile memory that stores a signal for turning the second switch circuit ON/OFF, and a fine adjustment signal that corresponds to the number of pulses of the clock signal. UP when is input
A second UP/DOW that performs a count or a DOWN count and provides the count value to a second non-volatile memory.
Electronic variable resistor with N counter.