JPH0656387B2 - Rotation direction discrimination method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational direction discriminating method of a rotating body, and more particularly to a rotational direction discriminating method suitable for optical scanning system drive control of a copying machine or the like and having a simple circuit configuration. .

2. Description of the Related Art In the conventional rotation direction determination method, the output of a rotation encoder is connected to an input port of a microcomputer via a logic circuit such as a flip-flop, and the rotation direction of a rotating body is determined by the logical value of the input port. Was there.

Hereinafter, a specific example of the conventionally used rotation direction determination method will be described with reference to FIGS.

FIG. 3 is a configuration diagram showing an example of a conventional rotation direction determination method,
FIG. 4 is a timing chart thereof, and FIG. 5 is a flow chart of the rotation direction discrimination processing.

In the figure, 1 is a microcomputer, 2 is a D type negative edge trigger flip-flop (hereinafter,
It is simply referred to as a "flip-flop"), and a and b indicate two-phase outputs of the rotary encoder.

FIG. 4 shows the timing when the rotation direction of the rotating body shifts from the forward rotation (CW) to the reverse rotation (CCW) in the above rotation direction determination method.

The A and B phase outputs a and b of the rotary encoder are processed by a waveform shaping inverter circuit composed of a resistor, a capacitor and an inverter to obtain the waveforms of signals c and d. The signals c and d are respectively connected to the clock input and D input of the flip-flop 2.

With the above configuration, triggered by the falling edge of the signal c, the logical value of the signal d appears at the Q output and becomes the signal e.

The signal e is the input port P of the microcomputer 1.
It is connected to A1. As a result, the rotation direction of the rotating body can be determined by reading the logical value of the input port PA1 as shown in the flowchart of FIG.

As described above, the conventional rotation direction determination method has a problem that a logic circuit element such as the flip-flop 2 is required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems in the conventional rotation direction determination method and not to use a logic circuit element such as the flip-flop. An object of the present invention is to provide a method for discriminating the rotational direction of a rotating body, which has a simple circuit configuration.

Configuration The above object of the present invention is a rotation direction determination method in which a microcomputer determines the rotation direction of the rotating body by the output signal of a rotary encoder that is connected to the rotating body and generates two-phase waveform outputs having different phases. In, the one phase of the rotary encoder is connected to the non-maskable interrupt input of the microcomputer, the other one phase is connected to the input port of the microcomputer, and the rotation direction of the rotating body is determined by the logical value of the input port. This is achieved by the rotation direction discrimination method characterized by the above.

Hereinafter, the configuration of the present invention will be described in more detail based on examples.

FIG. 2 is a block diagram of a rotation direction discriminating apparatus showing an embodiment of the present invention. In the figure, 1 is a microcomputer,
Reference characters a and b indicate two-phase outputs of the rotary encoder. Further, the signals c and d are obtained by subjecting the signals a and b to waveform shaping inversion. The above points are the same as in the conventional example shown in FIG.

The difference between the present embodiment and the conventional system shown in FIG. 3 is that the signal c is connected to the non-maskable interrupt input (hereinafter referred to as “NMI”) of the microcomputer 1 and the signal d is connected to the same port PA1. That is the point.

The operation of this embodiment will be described below with reference to FIGS. 1 (A) to (D).

FIG. 1 (A) shows the NM of the microcomputer 1.
It is a flowchart of I interrupt processing. When the falling edge of the NMI input is detected, the microcomputer 1 enters the NMI interrupt processing routine after completion of the instruction currently being executed, regardless of the EI / DI (interrupt enable / interrupt disable) state.

Among them, the microcomputer 1 reads the logical value of the port PAI, and the flag (CWFLG) indicating the rotation direction set in the internal memory (random access memory, hereinafter referred to as “RAM”) of the microcomputer.
Is set to "1" or "0".

As shown in FIG. 1 (B), the direction of rotation is determined by the above flag C.
It is determined whether the WLG is “1” or “0”, and the forward rotation (CWFLG = 1) and the reverse rotation (CWFLG = 0) are determined.

As described above, the NMI interrupt does not depend on the EI / DI state and enters the interrupt process. Therefore, at the end of the NMI interrupt, it is necessary to judge whether or not to execute the EI instruction. This is automatically set to DI when interrupt processing starts.
This is because the DI state is maintained unless the EI instruction is executed.

Therefore, as shown in FIG. 1 (C), when the interrupt processing other than the NMI interrupt is entered, and as shown in FIG. 1 (D), before the DI is executed, it is set in the internal RAM of the microcomputer 1. The EIFLG that is present to "0", and EI
Set to "1" before executing the instruction.

As shown in FIG. 1 (A), before the NMI interrupt processing is completed, it is determined whether or not the EI instruction is executed according to the value of this EIFLG.

In the present invention, the reason why the signal c is an NMI instead of another maskable interrupt is as follows. That is, since the normal maskable interrupt does not execute the interrupt processing unless it is in the EI state, when the signal c is connected to another maskable interrupt, the signal c is output in the DI state.
When the interrupt input of is input, the interrupt process is not executed immediately and the signal d cannot be checked. After that, even if the interrupt process is executed at the time when the EI state is entered, the signal d
This is because there is no guarantee that the state of (1) is the same as the state at the time when the interrupt input is input, and therefore an error will occur in the checking of the rotation direction.

As described above, according to the present embodiment, the rotation direction can be determined by the program without the need for the conventional logic circuit element.

As described in the above description of the rotating body in general, the present invention is a rotation direction determination method that uses a two-phase rotary encoder connected to the rotating body, and is applicable to all control of the rotating body. In particular, it is effective in controlling the optical scanning system of a copying machine, that is, in controlling the precise reciprocating motion of a scanning system such as a scanner and a slider (a document table moving type copying machine).

Effect As described above, according to the present invention, it is possible to determine the rotation direction of the rotating body with a simple circuit configuration.

[Brief description of drawings]

1 (A) to (D) are flow charts of processing in one embodiment of the present invention, FIG. 2 is a configuration diagram of one embodiment of the present invention, and FIG.
FIG. 4 is a block diagram showing an example of a conventional rotation direction determination method,
FIG. 5 is a timing chart thereof, and FIG. 5 is a flowchart of the rotation direction discrimination processing. 1: microcomputer, a, b: output of rotary encoder, c, d: the above output after waveform shaping.

Claims (1)

[Claims] 1. A rotating direction discriminating method in which a microcomputer discriminates a rotating direction of the rotating body by an output signal of a rotary encoder which is connected to the rotating body and generates two-phase waveform outputs having different phases. One phase of the encoder is connected to the non-maskable interrupt input of the microcomputer, the other phase is connected to the input port of the microcomputer, and the logical direction of the input port is used to determine the rotation direction of the rotating body. Rotation direction determination method.