JP3077152B2 - Electronic timer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic timer used to control the operation time of various types of industrial equipment or to set the operation start time, and particularly to a time setting unit. And an electronic timer using a variable resistor.

<Prior Art and its Problems> FIG. 4 is a configuration diagram of a conventional electronic timer. In FIG. 4, VR1 is a variable resistor for time setting, C is a charging capacitor, and these constitute the time setting unit 1. Have been.

Reference numeral 2 denotes a comparator, and Tr1 denotes a discharging transistor. When the potential at the time constant X of the variable resistor VR1 and the capacitor C rises to the level of the comparator 2, the discharging transistor Tr1 is turned on to turn on the capacitor C. Discharge the charge.

A counter 3 counts the number of times the capacitor C is charged and discharged, that is, the oscillation frequency of the time setting unit 1. Reference numeral 4 denotes a relay which switches the switching transistor Tr2 when the count value of the counter 3 reaches a predetermined value.
Is turned on to perform an exciting operation.

The comparator 2, the counter 3, and the discharging transistor Tr1 are integrated into an IC.

According to the electronic timer having the above-described configuration, by arbitrarily setting the resistance value of the variable resistor VR1 in the time limit setting unit 1, based on the time constant determined by the set resistance value and the capacitance of the capacitor C. And the potential at the point X is a in FIG.
Rise in a curve like. The potential at the point X is equal to
The transistor Tr1 is turned on, the charge of the capacitor C is discharged, and the potential at the point X becomes the fifth level.
The voltage drops as indicated by b in the figure, and the state shifts to recharging, and the potential at point X similarly increases.

The number of times of such charge / discharge, that is, the oscillation frequency of the time setting unit 1 is counted by the counter 3, and when the count value reaches a predetermined value, the switching transistor Tr
2 is turned on to excite the relay 4.

In the above-described conventional electronic timer, the time limit is set by the variable resistor VR1 and the capacitor C1.
, The time constant varies depending on the performance and quality of components such as the variable resistor VR1 and the capacitor C in each product (timer), and the setting time varies between products. .

In order to correct such a variation between products, as shown in FIG.
It is necessary to supplementally adjust the variation of the time constant by interposing 2.

In addition, in order to omit the intervention and auxiliary adjustment work of the auxiliary variable resistor VR2, a very high-performance, high-quality variable resistor
Only the VR1 and the capacitor C need to be selected and used, and in any case, there is a disadvantage that cost disadvantage cannot be avoided.

Furthermore, it is inevitable that the time constants of the variable resistor VR1 and the capacitor C fluctuate due to a temperature change or the like. Therefore, it is necessary to use the auxiliary variable resistor VR2 or to use only high-performance and high-quality parts. Even if you use it by selecting it,
As a result, there was a problem that the set time limit was changed. This has substantially the same problem with the timer device disclosed in Japanese Patent Laid-Open No. 59-63631.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and does not use an auxiliary variable resistor, and uses a component of relatively low performance and quality, but has a set time limit. It is an object of the present invention to provide an electronic timer capable of exhibiting a high timer accuracy by eliminating a change in the electronic timer.

<Structure and Effect of the Invention> An electronic timer according to the present invention includes a time setting unit including a time constant circuit having a variable resistor and a capacitor, and a relay that is operated when the time set by the time setting unit is reached. An electronic timer comprising: a means for detecting a time period determined by the total resistance value of the variable resistor and the capacitance of the capacitor in the time setting unit; and a variable resistor set by the time setting unit. Means for detecting a time period determined by the resistance value of the capacitor and the capacitance of the capacitor, storage means for sequentially and individually storing both time periods detected by the two detection means, and charging of the capacitor after storage by each of the storage means. Discharging means for sequentially and individually discharging charges; means for calculating a set time period by multiplying a ratio of the two time periods stored by the storage means to a maximum time period; and a setting calculated by the calculating means. Output means for operating the relay in a fixed time period.

According to the above configuration, when using the timer, the time period determined by the total resistance value of the variable resistor and the capacitance of the capacitor, and the time period determined by the resistance value of the variable resistor and the capacitance of the capacitor that are set. Is stored in the microcomputer, and then the ratio of the calculated time periods is multiplied by the maximum time period to calculate the set time period.The relay is operated at the calculated set time period. Even if there is a variation in the resistance value of the container, the variation can be eliminated in terms of a circuit. This eliminates the need for an auxiliary variable resistor for auxiliary adjustment of resistance value variations, and allows the use of a variable resistor whose performance and quality are relatively low, thereby reducing product cost. It is easy to plan.

Further, even if the resistance value of the variable resistor fluctuates due to a temperature change or the like, the ratio between the total resistance value and the set resistance value is calculated as described above each time the timer is used. can do.

Therefore, according to the present invention, it is possible to achieve an improvement in timer accuracy while being inexpensive. In particular, as disclosed in Japanese Patent Application Laid-Open No. 63-157519, even if the divided piezoelectric voltage is reduced to 0 V due to poor contact of the variable resistor or the like, a capacitor is interposed in the time limit setting unit, It is possible to effectively prevent an unexpected accident from occurring due to the instantaneous operation of the timer.

<Description of Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an electronic timer according to the present invention. In FIG. 1, reference numeral 1 denotes a time limit setting unit, which comprises a variable resistor VR and a charging capacitor C.

2 is a comparator, Tr1 is a discharge transistor, and when the potential at the point X rises to the level of the comparator 2 by the time constant of the variable resistor VR and the capacitor C, the discharge transistor
Tr1 is turned on to discharge the electric charge of the capacitor C. Reference numeral 4 denotes a relay which is excited when the switching transistor Tr2 is turned on.

5 is a microcomputer (hereinafter referred to as a microcomputer)
ROM5A for storing programs, RAM for storing data
5B and a CPU 5C that performs an arithmetic function are provided. 6 is I / O
A port and an A terminal and a B terminal for outputting a signal for applying a voltage to the input terminal and the movable contact of the variable resistor VR through the operational amplifiers OP1 and CP2, respectively, and a discharge signal to the discharge transistor Tr1. D terminal and switching transistor Tr2 for relay operation
And a C terminal for inputting an output signal of the comparator 2.

The comparator 2, the I / O port 6, the microcomputer 5, the operational amplifiers OP1 and OP2, and the discharging transistor Tr1 are integrated into an IC.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG. 2 and the timing chart of FIG.

According to the program stored in the ROM 5A of the microcomputer 5, first, after initialization (step S11), the output of the A terminal of the I / O port 6 is turned on (step S12), and the input of the variable resistor VR is input. A voltage is applied to the end through the on-amplifier OP1. Along with this, the potential at the point X rises along a curve like a1 in FIG. 3 based on a time constant determined by the total resistance value of the variable resistor VR and the capacitance of the capacitor C, and the rising potential becomes When the level of the comparator 2 is reached, this comparator 2
Is output to the C terminal of the I / O port 6 (step S13), and the output of the A terminal is turned off (step S13).
S15) At the same time, the output of the D terminal is turned on (step S1).
5) After the charge of the capacitor C is discharged via the transistor Tr1 and the potential at the point X drops as indicated by b1 in FIG. 3, the output of the d terminal is turned off (step S16).

Here, from step S12 when the output of the A terminal is turned on, C
The count value K1 divided until the step S13 in which the input is provided to the terminal is stored in the first memory area of the RAM 5B in the microcomputer 5 (step S14). This value K1 corresponds to the total resistance value of the variable resistor VR, and steps S12 to S17 are steps for detecting the total resistance value.

Next, the output of the B terminal of the I / O port 6 is turned on (step S18), and the operational amplifier O is connected to the movable contact of the variable resistor VR.
Voltage is applied through P2. Along with this, the potential at the point X changes based on a resistance value set by the current position of the movable contact in the variable resistor VR and a time constant determined by the capacitance of the capacitor C as shown by a curve a2 in FIG. When the rising potential reaches the level of the comparator 2, the output signal of the comparator 2 is input to the C terminal of the I / C port 6 (step S19), and the output of the B terminal is turned off. (Step S21) At the same time, the output of the D terminal is turned on (Step S22). After the charge of the capacitor C is discharged via the transistor Tr1, the potential at the point X drops as indicated by b2 in FIG. , D terminal output is turned off (step S
twenty three).

Here, steps S18 to C in which the output of the B terminal is turned on
The count value K2 divided until the step S19 in which an input is made to the terminal is stored in the second memory area of the RAM 5B (step S20). This value K2 corresponds to the set resistance value of the variable resistor VR, and steps S18 to S23 are detection steps of the set resistance value.

Next, the values K1 and K2 stored in the RAM 5B are read out. When the maximum time limit of the electronic timer is T _max and the set time limit is T _s , T _s = T _max × (K2 / K1) It is calculated (step S24).

For example, if K1 = 200, K2 = 100, T max = 10 ( min) Setting time period T _{s is, T s = 10 × (100/200} ) = 5 a (minute).

Then, the set time period calculated in step S24 is T _s
Is reached, the switching transistor Tr2 is turned on by the output from the terminal E to excite the relay 4 (step S25).

With the above operation flow, even if the resistance value of the variable resistor VR varies, or even if the resistance value varies due to a temperature change or the like, it is possible to eliminate such variation and variation in a circuit. Thus, a predetermined timed operation can always be performed with high accuracy.

In particular, according to the above configuration, even if the divided voltage of the variable resistor drops to 0 V due to poor contact of the variable resistor or the like, the timer operates instantaneously due to the interposition of the capacitor in the time setting unit. It is possible to effectively prevent unexpected accidents from occurring.

In place of the I / O port 6 shown in the above embodiment, an A / D
A converter may be used, and the same effect as in the above embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic timer according to the present invention, FIG. 2 is a flowchart showing the operation, FIG. 3 is a timing chart, FIG. 4 is a block diagram of a conventional electronic timer, and FIG. It is a waveform diagram of the charge / discharge operation in an electronic timer. 1 ... time limit setting unit, 2 ... comparator, 4 ... relay, 5 ...
... microcomputer, 6 ... I / O port, VR ... variable resistor, C ...
... capacitors.

Continuation of the front page (72) Inventor Kenichi Miyamoto 2075 Kaiyoshi, Okayama-shi, Okayama Omron Okayama Co., Ltd. (56) References JP-A-59-63631 (JP, A) JP-A-63-157519 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 43/04 H03K 17/28 G06F 9/06 G04F 3/00

Claims (1)

(57) [Claims] 1. An electronic timer comprising: a time setting unit including a time constant circuit having a variable resistor and a capacitor; and a relay that is activated when the time set by the time setting unit is reached. Means for detecting a time period determined by the total resistance value of the variable resistor and the capacitance of the capacitor in the time setting unit, and a time period determined by the resistance value of the variable resistor and the capacitance of the capacitor set in the time setting unit. Means for detecting a time period, storage means for sequentially and individually storing both time periods detected by these detection means, and discharge means for sequentially and individually discharging the charge of the capacitor after storage by each of the storage means. Means for calculating the set time period by multiplying the maximum time period by the ratio of the two time periods stored by the storage means, and outputting the set time period to operate the relay at the set time period calculated by the calculation means. Electronic timer, characterized in that a means for.