JPS6349906A - Position detecting circuit for injection molding machine - Google Patents

Abstract

PURPOSE:To improve the accuracy of positional detection by extracting the initial pulse of a pulse generator at the time of turning a clear pulse to low (high) to clear a counter. CONSTITUTION:A position detecting circuit is constituted of a synchronizing shaping circuit A, a reset condition detecting circuit B, a clear pulse forming circuit C, and an up/down counter IC 7. A count up/down pulse or the like is inputted from an incremental encoder to the detecting circuit. The circuit B selects an up/down count pulse based on an up/down selecting signal and execute logic operation based upon the selected signal and a counter reset pulse. The circuit C shapes a counter clear pulser to a pulse with one clock width synchronizing with a master lock and inputs the shaped pulse to a clear terminal of the counter IC 7. Consequently, a count error to be generated due to the width of a reset pulse can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position detection circuit for detecting the position of a movable side portion of an injection molding machine.

(Prior Art) In an injection molding machine, in addition to temperature control, position control of a movable part with respect to a stationary mold is an important control parameter, and various position detection means are provided.

(Problems to be Solved by the Invention) Among these position detection means, from the point of view of cost, there is an incremental encoder that makes contact with the movable side part and outputs up/down forces and runt pulses, and an incremental encoder that outputs up/down forces and runt pulses. A circuit is often used in which a limit switch or the like that is provided and outputs a clear pulse is connected to an up/down counter to perform position detection.

However, when a mechanical detection contact such as a limit switch is used to detect the origin position, the pulse width of the clear pulse becomes long due to installation accuracy and mechanical problems.
As shown in Figure (b), in the normal mask/slave method, the time during which no counting is performed is long, and the output value in the section where the pulse is input is always zero and no counting is performed. Therefore, the output value of the position detection circuit had an error equal to the length of the reset pulse.

Therefore, the present invention provides a position detection circuit for an injection molding machine that can solve the disadvantages of the conventional position detection circuit as described above, eliminate errors associated with resetting at the measurement origin, and improve the accuracy of position detection. − The purpose is to

(Structure of the Invention) The 0 position detection circuit for the forming machine according to the present invention inputs the count pulse and master clock from the 4-tessellation generator and outputs the count pulse shaped into the width of 1 master clock. The count pulse from the pulse generator, the master clock, and an externally set up/down selection signal are input to the synchronous shaping circuit to perform the up/down of the first note immediately after the reset pulse reaches LO%4. “/down” A reset condition detection circuit that outputs a set condition signal and a reset condition detection circuit that operates with either count pulse and a reset condition detection circuit that inputs the circuit reset condition signal and master clock to generate a counter clear pulse synchronized with the master clock. A clear pulse generation circuit that generates a clear pulse, and an up/down counter that inputs a count pulse of a synchronous shaping circuit to count up/down, and clears the count value with a clear pulse output from the clear pulse generation circuit. One feature is that the pulse is LOW (or old GH) and the first pulse of the pulse generator is extracted, and that pulse is used to complete the click.

(Embodiment) The present invention will be explained below using the illustrated embodiment. 1st
The figure shows a circuit block diagram of an embodiment of the position detection circuit according to the present invention. ``This detection circuit is composed of a synchronous shaping circuit A, a reset condition detection circuit B, a clear pulse generation circuit C1, and an up/down counter IC. A count-up or count-down pulse from an incremental encoder (not shown) that contacts the side part, and a limit switch (not shown) provided at the measurement origin.
Not shown.

) is input.

In addition, the detection circuit has a master clock 7 that operates the entire circuit, a mask reset that resets it, an up/down selection that selects whether to reset with the up/down count pulse, and a reset enable. Each pulse can be set or generated. Here, the synchronous shaping circuit A is composed of a D-flip ICI, 2, and a NANO C6, into which the count-up pulse is input, and the count-up pulse or count-down pulse in each line is generated by the master clock with a width of one master clock. It becomes a shaped count pulse and is input to the υP and DOWNfi terminals of the up/down counter IC7.

Reset condition detection circuit B is for countdown (7) NO
RIC9, inverter ICl0. D7 lip IC8 and count-up inverter 1c14. N0RI
C12, 47 Her 11C13, D 7') Tube I
CII (7) Consists of two systems, both outputs are N
It is output to the next stage through ORICl3. In this reset condition detection circuit B, an up/down count pulse is selected by the up/down selection signal, and the selected word and counter reset pulse calculation are performed. In other words, when the counter set pulse is input, D flip IC8 or ICII
is cleared, and the up or down pulse input at that time is latched into the D-flip IC8 or ICII.

Clear pulse generation circuit C is JK flip T C 16
.

D flip IC17, IC1B, EOR IC1
9, NOR IC20.

It is composed of NAND IC21 and shapes the counter clear pulse into a one-crotter width pulse synchronized with the master lock. This pulse is NANDed only if the reset enable signal allows the counter to be reset.
It passes through IC21 and is input to the clear terminal of up/down counter IC7. At this time, as shown by O in Fig. 2 (a), the reset occurs at any selected part of the up/down count pulse of the first note of the count pulse immediately after the reset pulse becomes LOW. In the subsequent pulses, counting is performed even if the reset pulse is at a LOW level.

This eliminates counting errors caused by the width of the reset pulse, and improves the counting accuracy of the incremental encoder.

(Effects of the Invention) The embodiment of the position detection circuit for an injection molding machine according to the present invention is as described above, and can provide the following effects.

Counting errors caused by the width of the reset pulse are eliminated, improving the accuracy of position detection.

[Brief explanation of the drawing]

Figure 1 is a circuit block diagram showing an embodiment of the present invention, Figure 2 is a circuit block diagram showing an embodiment of the present invention.
Figure (a) is a timing chart of the embodiment, Figure 2 (b)
is a timing chart of a conventional example. A: Synchronous shaping circuit, B: Reset condition detection circuit, C
・・Clear pulse generation circuit, IC7 ・・Up/down counter.

Claims (1)

[Scope of Claims] Position detection comprising a pulse generator that physically contacts the movable part of the injection molding machine and outputs up/down count pulses, and an origin position detector that outputs a reset pulse at the measurement origin position. a synchronous shaping circuit that inputs count pulses from the pulse generator and a master clock and outputs count pulses shaped to a width of one master clock; and a synchronous shaping circuit that receives count pulses from the pulse generator and a master clock; , a reset condition detection circuit which inputs an externally set up/down selection signal and determines whether to operate at either the first up/down count pulse immediately after the reset pulse becomes LOW; A clear pulse generation circuit inputs the reset condition signal of the condition detection circuit and the master clock to generate a clear pulse for the counter synchronized with the master clock;
A position detection circuit for an injection molding machine, comprising an up/down counter that counts down and clears the count value with a clear pulse output from the clear pulse generation circuit.