Abstract:
In a high prrecision PLL circuit arrangement, a phase detecting circuit produces a detecting signal which is directly proportional to a phase difference between a horizontal synchronizing signal and a voltage-controlled oscillating signal. A loop filter circuit produces a delay signal for delaying a frequency control at a predetermined time constant in response to the detecting signal derived from the phase detecting circuit. A voltage-controlled oscillating circuit produces an oscillating signal having a frequency directly proportional to a voltage of the delay signal from the loop filter circuit. A non-linear circuit includes a non-linear element for changing at least one of an AC gain and a DC gain of the loop filter circuit, and prevents an erroneous capture phenomenon of the PLL circuit arrangement in response to the detecting signal from the phase detecting circuit.
Abstract:
A vertical deflection circuit used in a cathode ray tube display device for shortening a vertical blanking period is disclosed which includes back-flow blocking diode means for preventing an oscillating current from flowing backward to a vertical push-pull output amplifier circuit in the vertical blanking period, resonating capacitor means, and electrostatic energy supplying means for energizing a fly-back pulse. The resonating capacitor means is provided to generate resonance due to the capacitance of the capacitor means and the inductance of a vertical deflection coil, on the basis of the electro-magnetic energy of the vertical deflection coil at a time immediately before a retrace line starts from the bottom of display screen, thereby producing a fly-back pulse. The back-flow blocking diode means prevents the fly-back pulse from flowing backward to the vertical output circuit, that is, prevents the fly-back pulse from de-energizing the output of the vertical output circuit. According to the above vertical deflection circuit, the power consumption in a vertical retrace operation is reduced, and a ratio of the vertical blanking period to a vertical scanning period can be made small. Accordingly, an effective scanning time is increased, and it becomes possible to display information precisely.
Abstract:
A cathode ray tube display in which a signal for detection of a cathode current is inserted into a part of the vertical blanking period of the video signal to be displayed, a cathode current corresponding to the signal for detection is detected, and a cathode voltage or a grid voltage is negative feedback controlled so that the detected cathode current becomes constant, thereby stabilizing the cathode current. The display has a local overscan circuit for executing a vertical scan on the screen with a width larger than a predetermined scan width only at a timing of the cathode current detecting signal inserted for a vertical blanking period, and even in the case where an underscan system to scan by a width smaller than a predetermined display screen width is used as a scan system of the screen display. The invention prevents a harmful visible display image by the cathode current detecting signal appears on the screen.
Abstract:
A vertical deflection circuit for a CRT display device comprises a first negative feedback circuit for detecting a vertical deflection current flowing through a vertical deflection coil feeding it back to a ramp wave generator to thereby stabilize a vertical size of the display image on the CRT screen, second negative feedback circuit connected between the deflection coil to an input of the output circuit for detecting a mean vertical deflection current which is fedback to an output circuit to thereby stabilize a vertical position of the display image on the CRT screen and a controlling circuit for controlling feedback amount of the first and second negative feedback circuits to thereby regulate a vertical size and a vertical position of the display image on the CRT screen variably.
Abstract:
A video output circuit for driving a CRT of a grid-cathode differential drive type is disclosed, in which a collector potential of an output transistor in a horizontal blanking interval is detected by a diode arrangement; the potential thus detected is smoothed by a smoothing filtering arrangement output current of the output transistor is controlled by an output obtained by the smoothing filtering arrangement; and negative feedback control is effected so that the collector potential of the output transistor is made constant. In this way, a bias adjusting power supply, which was required heretofore, is made unnecessary.
Abstract:
A CRT display including a horizontal deflection circuit. The horizontal deflection coil supplied with a horizontal deflection signal, with inductance L, has an energy-dissipating coil resistance connected in series and hence a second-order distortion expanding the left-hand side of the picture screen of the display and contracting the right-hand side thereof is produced. In the preset invention, to correct for the second-order distortion, the current flowing through the deflection coil means is detected, the deflection distortion component is extracted from the current, and a deflection distortion correcting current corresponding to the deflection distortion is supplied to an auxiliary coil for correcting the horizontal deflection of the electron beam.
Abstract:
An adaptive crosshatch signal generator includes a frequency detector for detecting a horizontal scanning frequency, a square calculator supplied with the detected output of the frequency detector, and a variable pulse width multivibrator controlled to have an output pulse width substantially in inverse proportion to the squared output. Longitudinal lines of a crosshatch signal are formed by the output pulses of the multivibrator. The crosshatch signal has a longitudinal line width which is always substantially equivalent to the distance between adjacent scanning lines and is generated by using a simplified configuration irrespective of input signal format.
Abstract:
A focus adjusting device for projection display, comprising at least one set of 4-pole magnetic field generating means, and adjustment means for adjusting the magnetic field strength of the 4-pole magnetic field generating means so as to eliminate astigmatism caused by fabrication error and attachment error of an electron gun and a focus coil.
Abstract:
A convergence correction circuit according to the present invention has a phased locked loop including a programmable counter. The programmable counter has programmable count start and end points. The output of the programmable counter is supplied to a memory storing convergence distortion correcting data therein. As the horizontal screen size is increased, a value closer to the lower limit 0 of the start point as compared with that taken when the horizontal size is small is set as the count start point of the programmable counter, and a value closer to the upper limit (2.sup.7 -1) of the end point as compared with that taken when the horizontal size is small is set as the count end point. In accordance with the horizontal screen size, the count start and end points of the programmable counter are changed. Correct convergence correction is performed even if the horizontal screen size is changed.
Abstract:
A video output circuit of a wide bandwidth comprises a bridged-T-type circuit, a first inductor connected in series to the bridged-T-type circuit, and a shunt circuit connected in series to the bridged-T-type circuit and including a second inductor and a first resistor connected in parallel with each other. The bridged-T-type circuit, the first inductor and the shunt circuit cooperate to constitute together with a plurality of stray capacitors a low-pass filter whose order is at least 4 and whose merit index is at least 3.