JPH01143520A - Numeric value setting device - Google Patents

Abstract

PURPOSE:To obtain a numeric value setting device with high reliability and a long service life by turning an operating knob in interlocking with a slider type variable resistor and outputting a numeric value in response to the quality of turning as a digital code so as to allow the use of one contact only thereby reducing the fault occurrence rate. CONSTITUTION:A slider type variable resistor 15 generates a voltage V in response to a voltage VCC fed between stator terminals and the position of the slider slided in interlocking with the operating knob 14. With the number (n) of numerals to be set, the voltage V and stepwise reference voltages V0, V1-Vn-2 generated by dividing the voltage VCC by resistors 12 into (n-1) voltage equally are given respectively to (n-1)-set of comparators 13, they are compared and a level '1' is outputted when voltage V is larger than each reference voltage. An encoder 17 based on the output gives a digital code corresponding to the numeric value, a buffer 19 stores it once and gives the result to an output terminal 11. A decoder/driver 18 is provided with an input function to select kinds of the code, converts the inputted digital code and outputs a BCD code and the numeral is displayed on a display device 16.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a numerical value setter that reduces the number of contacts and reduces failures.

(Summary of the Invention) The present invention is configured such that a numerical value setter has only one mechanical contact point.

(Prior Art and its Problems) A digital switch has been known as this type of numerical setting device. As shown in Figs. 5 and 6, for example, there are four mechanical contacts 3 between the four output terminals 1 for outputting the BCD code and the common terminal 2.
When pusher 804.5 is pressed to rotate the rotor 7, which also serves as the dial 6, each contact 3 opens and closes in accordance with the number to be set, and a BCD code is output from the output terminal l. be.

However, during use, the contact resistance of these digital switches increases due to wear on the contact surfaces.

(2) Similarly, due to wear, the positions of the opposing contacts shift, resulting in an open failure.

(3) Contact surfaces corrode and contact resistance increases.

Factors such as failure may occur.

In particular, a digital switch for BCD code output has 4 contacts, and a decimal code output has 10 contacts, so the problem is that the more contacts there are, the higher the failure rate. was.

(Object of the invention) The present invention has been proposed in view of the above points, and its object is to:
It is an object of the present invention to provide a highly reliable numerical value setter with few failures.

(Structure and Effects of the Invention) In order to achieve the above object, the present invention includes an operator, a sliding variable resistor interlocked with the operator, and a variable resistor generated based on the sliding variable resistor. A plurality of comparators that discriminate analog voltages step by step, an encoder that converts the output of these comparators into digital codes equivalent to numerical values and outputs them to the outside, and a display that displays the numerical value corresponding to the output code of this encoder. It features a numerical value setter with .

With this configuration, the numerical value setter of the present invention has one contact point, which has the effect of reducing the incidence of failure and providing a highly reliable numerical value setter with a long life.

(Description of Embodiments) FIG. 1 is an external perspective view of a numerical value setter according to an embodiment of the present invention.

In the figure, on the front side, a display 16 consisting of a 7-segment 1-LED and an operator 14 consisting of a rotatable roller are provided. Output terminal 11 on the protruding board at the rear
Terminal patterns such as the following are formed.

FIG. 2 is a circuit diagram showing the internal electrical configuration, and the configuration and operation will be explained with reference to the operation explanatory diagram of FIG. 3.

In FIG. 2, a sliding variable resistor 15 generates a voltage VCC applied between fixed terminals and a voltage V depending on the position of the variable terminal which moves in conjunction with the operator 14. Voltage V
changes linearly as the variable terminal moves, as shown in FIG. 3a.

If the number to be set is n, then (n-1) comparators 13 are provided, and the comparators 13 are connected to the voltage V generated by the sliding variable resistor 15 and the voltage VCC. is divided equally into J+(n-1) parts by the resistor 12 to generate stepwise voltages V, , V, , V, .
...V, , V, □ are respectively input as reference voltages. When these two voltages are input, the comparator 13 compares the levels of both, and outputs "l" if the voltage (2) is large. FIG. 3 shows this change in output value, and "l" is outputted from the comparator step by step in accordance with the change in voltage (2) in FIG. 3a.

The encoder 17 outputs a digital code corresponding to a numerical value based on the output from the comparator 13. FIG. 3C shows this digital code as a BCD code.

The buffer 19 temporarily stores the digital code output from the encoder 17 and then outputs it to the output terminal 1! send to.

The decoder/driver 1B converts the digital code output from the encoder 17 and sends an operation signal to the display 16, which is made up of 7-segment LEDs, to display the set number. Figure 3d shows the numbers displayed corresponding to the digital code.

The encoder 17 is also provided with a select input for selecting the type of digital code to be output, and can select and output BCD code, decimal code, and other various codes.

With this configuration, the sliding variable resistor 15
When the operating element 14 interlocked with is rotated, a numerical value corresponding to the amount of rotation of the operating element 14 is set and outputted to the output terminal 11 as a digital code. The numerical values set at the same time are displayed on the display 16.

FIG. 4 shows a circuit diagram of a numerical value setter according to another embodiment, and the difference from the previous embodiment is that the buffer 22
A chip selector terminal 21 is provided at the terminal. Since the other parts are the same as those in FIG. 2, the same numbers are given to the common parts and the explanation will be omitted.

In this embodiment, the chip selector terminal 21 is connected to the buffer 22.
By providing this, a digital code is output from the output terminal 11 only when there is human power on the chip selector terminal 21. When there is no input to the chip selector terminal 21, the output terminal 11 is in a high impedance state.

In this embodiment, when used in connection with another host, the output line is made common to each other, and by controlling the input to the chip selector terminal 21, it is possible to scan each digit and capture the digital code. It becomes possible.

In the second embodiment of the numerical value setter shown above, the following effects can be obtained.

(1) The number of mechanical contacts is reduced from multiple to one, which reduces the occurrence of failures and improves reliability.

(2) Since the input impedance of the comparator is very high (106 ohms or more), even if the contact resistance of the sliding variable resistor increases, it will operate normally without being affected by the increase, and the numerical setting device will have a long life. can be significantly extended.

(3) By using a 7-segment LED display, the set value can be checked even in a dark place.

(4) A resistor is used as the means for generating the reference voltage of the comparator,
Furthermore, since it is composed of a comparator, a decoder/driver, an encoder, etc., the numerical value setter can be easily integrated into an IC.

(5) By setting the numerical value to the resistance value of a mechanical sliding variable resistor, there is no need to hold the set value in the event of a power outage, and a backup power source or the like is not required.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a first embodiment of a numerical value setter according to the present invention, FIG. 2 is a circuit diagram showing its internal configuration, FIG. 3 is an explanatory diagram of its operation, and FIG. A circuit diagram showing the internal configuration of the second embodiment, FIG. 5 is an external perspective view of a conventional digital switch, and FIG. 6 is a circuit diagram thereof. 13... Comparator 14... Operator 15... Sliding variable resistor 16... Display 17... Encoder

Claims (1)

[Claims] (1) An operator, a sliding variable resistor linked to this operator, multiple comparators that discriminate in stages the analog voltages generated based on this sliding variable resistor, and these A numerical value setter that includes an encoder that converts the output of a comparator into a digital code equivalent to a numerical value and outputs it to the outside, and a display that displays a numerical value corresponding to the output code of the encoder.