Oval PG30D, Instruction Manual

Page: 2 / 12

T-518-9-E
SLIT DISC
WAVE-
SHAPING
& OUTPUT
L
1
L
2
① ② ③ ④
BLACK
DC24V
0V
RED
（B）
（A）
LOAD RESISTOR 510Ω
1
0
RECTI-
FIER
DETECTOR
PICKUP COIL OSC. COIL
H-F
OSCILLATOR
WAVEFORMS
δ
δ：HYSTERESIS WIDTH
a
b
φ
1
（D）
（D）
a
b
φ
2
（B）
（B）
a
b
φ
2
φ
1
（A）
（A） （A）
a
b
φ
1
φ
2
（C）
（C）
RECTIFIER
RECTIFIER OUTPUT
SLIT DISC
OSC. COIL
PICKUP COIL
1
0
TIME
Fig. 1
Fig. 2
■ OPERATING PRINCIPLE
1. Operation can best be understood by referring to Fig. 1. The oscillator coil L
1
in the H-F oscillator continuously
generates a 1 MHz frequency (waveform ① ). A disc, located between the oscillator coil L
1
and pickup coil L ,
has many slots arranged at regular intervals along its periphery. As the disc revolves, the magnetic field of
induction created by the former coil is interrupted on and off. The result is a signal induced in the pickup coil L
(waveform ② ), which is modulated by the slots along the slit disc. The signal is then rectified (waveform ③ ),
shaped, and processed for switching in the output circuit to control the current in the load. Part of its output
is fed back to change trigger levels at the rise and fall of the signal, thereby achieving improved hysteresis
characteristics.
. Figures (A) through (D) in Fig. show how the doubled pulse generation inherent to this pulse generator is
achieved. The oscillator coil L
1
is located perpendicular to the pickup coil L . Between these two coils is the
revolving disc which produces a single pulse signal at the leading edge in (B) and the trailing edge in (D) in the
course a slot in the slit disc moves past the magnetic field.
◎ Disc at position (A) …… Magnetic flux φ
1
and φ cancel out with each other in the oscillator coil; no
voltage is induced in the pickup coil across its terminals a and b.
◎ Disc at position (B) …… Magnetic flux φ
1
is interrupted by the disc and magnetic flux φ alone acts on the
pickup coil, inducing a voltage across its terminals a and b.
◎ Disc at position (C) …… Magnetic flux φ
1
and φ are interrupted by the slit disc; flux φ
1
and φ may reach
the pickup coil at the leading edge and at the trailing edge but being opposite to each other in direction, no
voltage is induced in the pickup coil across its terminals a and b.
◎ Disc at position (C) …… Magnetic flux φ is interrupted by the disc and magnetic flux φ
1
alone acts on
the pickup coil, inducing a voltage across its terminals a and b.