Apple Inc.

Peter Krause

Aik Keong Ong

Douglas Lea Heirich

David V Hoenig

Robert Norman Olson

Larry Forsblad

Brian Girvin

Brian H Berkeley

Steve Cabral

Phuan Boon Chong

A power supply circuit for a digital processing system. A first stage of the power supply circuit is used to generate power for a first component of the digital processing system and to drive a second stage of the power supply circuit. The second stage of the power supply circuit supports a second component of the digital processing system. The first and second stages of the power supply circuit are electrically connected to each other.

Two stage power supply circuit for independently supplying power to first and second components of a digital processing system

A computer system is provided comprising a support frame, a logic board mounted to the support frame, a processor on the logic board, a cathode ray tube mounted to the support frame above a plane of the logic board, and a transparent housing located over the cathode ray tube.

Computer assembly having a common housing for a cathode ray tube and a logic board

The present invention, generally speaking, provides for automatic cutoff control in a DC coupled CRT video drive using a low DC supply voltage and circuitry that is lower in power consumption than conventional circuitry for the comparable video performance. A simple, easy to implement solution is achieved with an extremely low component count. Cutoff control response is fast, allowing discontinuous operation of auto cutoff control. In one embodiment of the invention, a cutoff control signal is applied to individual CRT G1 terminals. Fast response cutoff control drive is realized using an IC current source and a single transistor current-to-voltage (CTV) converter. Supply voltage variations on the video driver are clamped via a clamping device to the negative supply voltage of the G1 CTV converter.

Automatic cutoff control for a DC coupled CRT video drive

Dramatically lower power consumption of a video display to is achieved during standby mode. Using relatively simple sync-energy converting circuitry, the power supply can be switched on/off electronically, without the need to have the main power supply running and without an auxiliary supply. Power consumption of 0 W may thereby be achieved. In accordance with one embodiment of the invention, sync-signal energy is stored in a storage capacitor. During charging, the capacitor is decoupled from any load such that capacitor voltage will reach a peak voltage of the unloaded source signal. Charge and discharge cycles repeat continuously for so long as the power switch is turned off. This charging and discharging allows the display to be turned on using the power switch, even without the momentary presence of AC line voltage. A possible non-retriggable state is avoided using an RC time constant.

Method and apparatus for power supply startup in video monitors

Protection of EHT and/or scan output stages in multiscan displays is provided without the use of additional components within the power supply other than those required to perform the power supply function itself. Operation is non-dissipative, conserving power. A drive control signal is AC coupled. The switch is on during retrace of the flyback pulse. The drive control signal is varied in accordance with the load, becoming active longer and longer periods of time with increasing load until the control signal vanishes (becomes continuously asserted), turning off the switch. In accordance with a further feature of the invention, feedback to a controlling integrated circuit concerning an overload condition may be achieved without dedicating a line or pin to a separate feedback signal.

Method and apparatus for protection of EHT and/or scan output stages in

A technique is provided for very efficiently injecting DC current into a horizontal deflection yoke to achieve raster shifting. The DC current (which is bi-directional) is used to unbalance the scan current, thereby providing a means to shift the horizontal scan raster to the left and right. This ability makes it is possible to offset symmetry problems in the yoke and CRT gun system. The amount of current and the direction of the current is both user adjustable and system adjustable, and is controlled through a microcontroller. Preferably, the microcontroller uses an H-synchronized clock generated by an on-screen display (OSD) controller, thereby avoiding the need to separately generate a high frequency clock. Using a current switching approach, low power losses are achieved in a circuit that is low cost and requires few components.

Method and apparatus for digital control of raster shift in CRT displays

The present invention, generally speaking, provides an improved base drive arrangement for scan and/or EHT output stages in a television or video display monitor. In accordance with one aspect of the invention, by adding just a few components to an existing main base drive circuit, two power transistors may be driven, e.g. a scan output transistor and an EHT output transistor. The two power transistors are switched at the same time, allowing pulse width modulators of the scan and EHT circuits to operate on a common time base. Switching of two power transistors at the same time would usually require a quite complicated design to offset the different storage times of the two devices, thereby achieving high performance but at a considerable cost premium. The base drive circuit of the invention achieve substantial synchronization of the two transistors at minimal cost. In accordance with another aspect of the invention, a base drive circuit uses a low DC supply voltage and a resistive element in series with the main current path in order to produce a more constant maximum base current over frequency.

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Singapore, Singapore

Peter Krause