JPH0618024B2 - Contact encoder encoder reading method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type encoder switch reader used when detecting a change in the state of a switch using a microcomputer.

Configuration of Conventional Example and Problems Thereof FIG. 1 shows an equivalent circuit of an encoder switch. The common terminal COM and the terminal A are connected by a resistor 1 and a contact point S ₁ and a resistor 2, and the common terminal COM and the terminal B are connected by a resistor 1 and a contact point S ₂ and a resistor 3. When the contacts S ₁ and S ₂ are mechanically interrupted, the intermittent waveform between the terminal COM and the terminals A and B becomes the second
As shown in the figure, the waveform includes chattering C.

In FIG. 2, in the case of clockwise rotation, the contact point S ₁ is _first contacted, then both contact points S ₁ and S ₂ are contacted, then only the contact point S ₂ is contacted, and finally both contact points S ₁ and S 2. _Two separate together. In the case of turning counterclockwise, first the S ₂ contacts come into contact, then both contacts S ₁ , S
₂ make contact, then only contact S ₁ makes contact, and finally both contacts S ₁ , S ₂ separate.

Chattering C occurs when this contact is intermittent, but this chattering time is not constant because there is a proportional relationship that it becomes shorter when the rotation speed of the switch becomes faster and becomes longer when the rotation speed becomes slow. However, in this chattering C, the two contacts are out of phase with each other, so that there is a time interval until one signal becomes stable and the other signal changes, as at t _C in FIG. Always has a characteristic that it is larger than 0 in terms of time.

Conventionally, a signal containing such chattering is
As shown, the switch 4 to the chattering removal circuit 5
The pulse discriminating circuit 6 detects the waveform after integration after the processing by the (integrating circuit using resistors and capacitors), and the phase detecting circuit 7 discriminates the rotation direction.

However, such a method has a drawback that it is difficult to guarantee a normal operation at low speed rotation and high speed rotation because the chattering time is not constant.

OBJECT OF THE INVENTION The present invention eliminates such drawbacks, and further, by performing processing by software,
It is an object of the present invention to provide a reading device with a contact-type encoder switch that has a wide range of applications with simple modification of hardware.

Configuration of the Invention In the present invention, four kinds of combination discrimination data of the open / closed states of the first and second contacts, which are sequentially supplied by comparing and detecting the current state of the switch with the state immediately before being read by software, are desired. It is converted to a status signal corresponding to the ordinal number, and it is determined whether it is clockwise or counterclockwise according to the discrimination data corresponding to the last number of the ordinal number, and there is an undesired input due to chattering or inversion of the switch. In the case of a right turn, it is configured such that neither right turn nor left turn is determined.

Description of Embodiments FIG. 4 shows a block diagram of an embodiment in which the present invention is equivalently configured by hardware. By the signal input to the input reading circuit 9 from the switch 8 having the configuration shown in FIG.
The input reading means (circuit) 9 sends the input information to the state determination means (circuit) 10. This state determination means (circuit) 10 determines four states at each time point and passes information to the processing means (circuits) 11 to 14 of each state. Then, the results of these processing means (circuits) 11 to 14 are passed to the discrimination result output means (circuit) 15 to output the clockwise / counterclockwise discrimination results.

Here, the four states are T = 0 when both contacts S ₁ and S ₂ are separated from each other in FIG. 5 (hereinafter, the state is abbreviated as T), and then either contact S ₁ , S ₂ are connected, T = 1, then both contacts S ₁ , S ₂ are connected, T = 2, and then the first connected contacts S ₁ , S ₂ are opposite. When the contact points S ₂ and S _{1 of the two} are separated, T = 3, and when the contact points S ₁ and S ₂ are separated again, the original T
= 0.

Here, the period T _{X in} which the chattering C is occurring is T _X = 0 or 1 when T = 0 immediately before and T = 1 immediately after, and when T = 1 immediately before and T = 2 immediately after. If T _X = 1 or 2, T = 2 immediately before and T = 3 immediately after, the chattering period is also T.
_{When X} = 3, T = 3 immediately before, and T = 0 immediately after, T _X =
It is 0 or 1.

Next, FIG. 6 shows a flowchart when this operation is carried out using a microcomputer. Input in Figure 6 =
(0,0) indicates that both contacts S ₁ and S ₂ are separated, and input = (1.0) indicates that contact S ₁ is connected and contact S ₂ is separated. = (0,1) indicates that the contact S ₂ is connected and the contact S ₁ is separated, and input = (1,1) indicates that both contacts S ₁ and S ₂ are connected. .

In FIG. 6, it is assumed that T = 0 when input = (0,0). Next, when input = (0,1) or input = (1,0) and the immediately preceding T is T = 0, T = 1 is set, and the input at that time is saved. Next, when input = (1,1), change to T = 2. Further input = (1,0) or input = (0,1)
When the previous T is T = 2, the stored input data and the current input are compared to see if they are the same. If they are the same, the switch rotation direction is changed from the state of T = 2. If the current data is different from the saved data, T = 3 is set. If the current input = (0,1), it is determined to be clockwise, and the current input = (1,0 If it is), it is judged to be counterclockwise.

Thus, since each state is discriminated and it is determined whether the state is clockwise or counterclockwise by comparing with the state immediately before that, the contact S
If there is chattering or the like in ₁ and S ₂ , the state signal corresponding to the determination data becomes an undesired input, the detection signal is not output, and neither chattering nor clockwise rotation is determined. Therefore, accurate determination can be performed without being affected by chattering or the like.

As described above, according to the present invention, the current state of the switch is read, and the current state of the switch is compared and detected with the state immediately before, so that the state processing means sequentially generates the state signals in response to changes in the discrimination data of the state discrimination means. Since it is decided whether to turn clockwise or counterclockwise based on the discrimination data corresponding to the final value of the state signal, the time is not constant depending on the way the switch is turned, or in an undesired order due to chattering or inversion of the switch midway. It is possible to configure a stable switch reader that does not malfunction even with respect to an input signal.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a contact encoder switch, and FIG.
1 is a block diagram of a switch of FIG. 1, FIG. 3 is a block diagram of a conventional contact type encoder switch reading circuit, and FIG. 4 is an equivalent view of a contact type encoder switch reading device according to an embodiment of the present invention. FIG. 5 is a block diagram shown in hardware, FIG. 5 is a timing diagram showing the state of the switch, and FIG. 6 is a flow chart for explaining the operation of the device. _{S 1,} S ₂ ...... contact, 9 ...... input reading circuit, 10 ...
... State discrimination circuit, 11, 12, 13, 14 ... Processing circuit, 15 ... Discrimination result output circuit.

Claims (1)

[Claims] 1. An open / closed state (ON, OFF) of a contact-type encoder switch including first and second contacts is defined as the first and second contacts.
Four combinations of open / closed states of (S1, S2) {(0,0),
(0,1), (1,1), (1,0)}, and the discrimination data is the discrimination data with the radix (0) when both the first and second switches are open. Or a desired ordinal number {T (S1,
S2) = i (i = 0,1,2,3)}, and the state signal {T (S1, S2) = i} is the last number (i =
In the case of 3), it is determined whether the switch is clockwise or counterclockwise by the discrimination data (S1, S2) corresponding to the last ordinal number (i = 3), and the clockwise flag is determined based on the result. Alternatively, a contact-type encoder switch reading method is characterized in that a counterclockwise flag is generated.