Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Clock or pulse waveform generating
Reexamination Certificate
1999-09-10
2001-03-13
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Clock or pulse waveform generating
C327S227000
Reexamination Certificate
active
06201426
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a pulse generation device and more particularly to a pulse generation device for newly generating a pulse based on a fly-back pulse generated in a television receiver.
FIG. 7
is a circuit diagram showing a conventional pulse generation device. A basic pulse which is used as the basis of a pulse to be created is input to an integrating circuit
22
via an input terminal
28
or a node N
15
. A comparing circuit
23
is supplied with a signal at the non-inverting input terminal or a node N
16
thereof from the integrating circuit
22
. Further, the inverting input terminal thereof is supplied with a reference voltage Vref9. The output of the comparing circuit
23
is connected to the input or an node N
17
of a buffer circuit
24
. The output of the buffer circuit
24
is connected to an output terminal
27
or a node N
20
of the pulse generating device via a resistor R
7
and further connected to the input of an integrating circuit
25
. A signal from the integrating circuit
25
is input to the non-inverting input terminal or a node N
18
of a comparing circuit
26
. The inverting input terminal thereof is supplied with a reference voltage Vref10. An output of the comparing circuit
26
is supplied to the node N
19
or the base of an NPN transistor Q
15
. The collector of the transistor Q
15
is connected to the output terminal
27
of the pulse generating device and the emitter thereof is connected to a ground potential node GND.
FIG. 8
is a waveform diagram showing signal waveforms of various node portions, for illustrating the operation of the pulse generating device of FIG.
7
. Slice levels by the reference voltages Vref9, Vref10 are shown together with the integrated waveforms at output nodes N
16
and N
18
of the respective integrating circuits
22
and
25
. A waveform at the output node N
17
of the comparing circuit
23
is a pulse waveform which is set at a high level in a period when the level of the integrated waveform is higher than the slice level of the reference voltage Vref9. A waveform at the output node N
18
of the integrating circuit
25
is obtained by integrating an output of the comparing circuit
23
by use of a resistor R
6
and capacitor C
5
of the integrating circuit
25
. A waveform at the output node N
19
of the comparing circuit
26
is a pulse waveform which is set at a high level in a period when the level of the integrated waveform is higher than the reference voltage Vref10.
By adding together the output of the comparing circuit
23
and an output obtained by inverting the output of the comparing circuit
26
by use of the transistor Q
15
, a waveform of the node N
20
can be obtained at the output terminal
27
of the pulse generating device. In the waveform of the node N
20
, a time width t9 ranging from the leading edge of the pulse input at the node N
15
to the leading edge of the pulse at the node N
20
can be determined by the reference voltage Vref9 and the time constant which is determined by a resistor R
5
and capacitor C
4
of the integrating circuit
22
, and a time width t10 corresponding to the pulse width at the node N
20
can be determined by the reference voltage Vref10 and the time constant which is determined by the resistor R
6
and capacitor C
5
of the integrating circuit
25
.
Thus, in the prior art case, a new and necessary pulse is created by shaping the integrated waveform obtained by integrating the reference pulse by the capacitor C and resistor R by use of the slice level. Therefore, if the value of the capacitor C or resistor R varies, the integration time constant varies and the delay time corresponding to the time width t9 until the slice level is reached varies so that the created pulse phase at the node
20
will vary.
Since the integration time constant is kept unchanged even if the horizontal period of the reference pulse varies twice as shown in
FIGS. 9A and 9B
, time widths corresponding to t9, t10 are kept unchanged (t11=t13, t12=t14 in FIGS.
9
A and
9
B). Therefore, the rate of the time widths with respect to one horizontal period (=1 or =2) will vary. Therefore, in order to keep constant the rate of the time widths of t11 and t12 with respect to one horizontal period=1 and time widths of t13 and t14 with respect to one horizontal period=2, it is required to change the values of the capacitor C and resistor R, but this is impossible in practice.
This invention has been made to solve the above problem and an object of this invention is to provide a pulse generating device which can significantly reduce a variation in the phase of a newly created pulse waveform and in which the rate of the pulse width of the newly created pulse waveform with respect to a reference pulse width and the rate of the time width corresponding to the time delay of the created pulse waveform with respect to the reference pulse are precisely correspond to the period of an input pulse.
BRIEF SUMMARY OF THE INVENTION
A pulse generating device of this invention comprises a monostable multivibrator circuit triggered by a rise or fall of an input pulse; an integrating circuit having substantially a constant charging/discharging ratio and including a first capacitor discharged or charged by an output of the monostable multivibrator circuit triggered; a triangular wave generating circuit for generating a triangular wave by triggering the monostable multivibrator circuit when an integrated voltage by the first capacitor of the integrating circuit has reached a first reference voltage and charging or discharging the first capacitor; an AGC circuit constituting a loop which is operated to set the waveform of the triangular wave to a substantially 0V AC potential at a second reference voltage by controlling a charging/discharging current of the integrating circuit according to the result of comparison between the integrated voltage by the first capacitor of the integrating circuit and the second reference voltage; and a pulse generating circuit for generating an output pulse based on of charging/discharging current or charging/discharging voltage of the integrating circuit controlled by the AGC circuit.
With the above construction, the rate of the rise phase of the newly created pulse waveform with respect to an input pulse and the rate of the pulse width thereof with respect to the period of an input pulse used as a reference can be precisely kept constant.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 5394020 (1995-02-01), Nienaber
patent: 5914591 (1999-06-01), Yasuda et al.
Namikawa Takeshi
Sumiyoshi Hajime
Kabushiki Kaisha Toshiba
Nguyen Linh
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Toan
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