Eastman-kodak Company

Gte Products Corporation

John M Kresock

David M Orlicki

Jasper S Chandler

Sanwal P Sarraf

Bruce E Koppe

Timothy E Neale

In a highly accurate linear scan control for a CRT image display system useful for reproducing photographic images, distortion effects produced by system transients resulting from deflection drive amplifier circuits, are eliminated by introducing a step incremental increase in the input drive waveform at the start of the trace (scan) interval following the end of the retrace interval.

Linear scan control for a CRT display system

A high bandwidth video output amplifier circuit suitable for driving a cathode ray tube for printing high resolution images on photographic stock with good tonal reproduction includes a high voltage amplifier comprising an emitter follower amplifier with a constant current collector load circuit inputing to an emitter follower buffer current amplifier circuit which drives an output load device such as a cathode ray tube. The constant current collector load provides desired high amplifier gain. A negative feedback path is coupled from the buffer output to the input of the high voltage emitter follower amplifier circuit via an intermediate emitter follower buffer at the input to the voltage amplifier transistor. The feedback provides stable, controlled overall voltage gain and the intermediate buffer amplifier isolates the video input and feedback path from the collector-base Miller capacitance of the voltage amplifier transistor thereby providing a significant extension of the amplifier bandwidth. The voltage amplifier transistors are mechanically mounted on a common dual heat sink to enhance dc operating stability of the overall circuit. The constant current circuit is provided with supplemental base drive during power down operation to maintain a high positive bias voltage on the CRT load device so as to avoid CRT spot burn during collapse of the CRT raster during system turn off.

High bandwidth video output amplifier circuit for high resolution

A beam scanning galvanometer is disclosed which oscillates a mirror in a non-resonant mode. The moving parts of the galvanometer are made with as small a moment of inertia as possible because the mirror is oscillated in a non-resonant mode. The galvanometer uses two sets of crossed leaf-springs to support the mirror instead of bearings which are usually used in non-resonant galvanometers. Each of the sets of leaf-springs is formed of a single strip of cold rolled stainless steel. The springs are embedded in uniquely shaped cavities in a permanent magnet that supports the mirror at a distance very close to an axis of rotation of the mirror. The mirror is specially shaped with beveled edges so that its moment of inertia is low and so that it can oscillate in very close proximity to a driving current coil which surrounds the mirror supporting magnet. A magnetic position sensor is used to detect an angular position of the mirror during operation of the galvanometer. A compensating system eliminates distorting magnetic field effects from a magnetic driving system from adversely influencing the magnetic position sensor. Signals from the magnetic position sensor are usable to provide accurate feedback information to a galvanometer driving system.

Beam scanning galvanometer with spring supported mirror

An improved method of, and electrical circuit for driving with precision and accuracy an electro-mechanical device such as a galvanometer is disclosed. The method precisely controls high speed linear scanning of the device in a forward scan segment of each cycle of operation, and further provides very fast re-set of the device without position overshoot during a re-trace segment of a cycle. The electrical circuit includes memory means for generating an electrical command waveform for controlling the device during each cycle of operation, and drive servo means for applying electrical power to the device. The servoing action of this circuit substantially eliminates any difference between an actual position of the device and the position directed by the command waveform during each forward scan segment of a cycle of operation, with the result that each forward scan segment is highly accurate and repeatable. During each re-trace segment of a cycle the circuit re-sets the device at high speed in a way that limits accuracy destroying effects of device overshoot and oscillation.

Method and circuit for driving an electromechanical device rapidly with

There are disclosed an apparatus and a method for thermal printing by dye transfer of a high definition image on a receiver element such as a full color slide transparency. This new thermal printing apparatus includes a laser, means to scan a finely focused spot of light from the laser along a line, means to position a dye donor element and a closely adjacent receiver element (side transparency) to be scanned by the laser light spot, and laser drive and control logic (LDCL) means for turning the laser full-on to an optimum power level for a time determined by high speed print data in the form of data words. The method according to the invention includes the step of applying to a dye donor element thermal energy from a laser at a power level at which the dye ablates rather than sublimes. The laser is driven at an optimum power-on level and the length of time the laser is on determines the amount of dye transferred to a receiver element as a dye pixel. This substantially improves the linearity of tone scale of the dye pixels printed on the receiver element over a wide range of exposures and densities. A slide transparency image made in this way nearly equals and, in some cases, may exceed the visual quality of an image made by photography.

Apparatus and method for thermal printing of finely detailed images of

A method and apparatus for generating a dynamic focus correction voltage signal for a cathode ray tube which comprises the steps of: generating horizontal and vertical scan counter signals, and inputting the counter signals to a dynamic output voltage generating means which produces an output voltage that is proportional to the distance the scan is from the center of the image on the CRT in both the vertical and the horizontal directions.

CRT scan system dynamic focus circuit

Beam scanning galvanometer with low inertia mirror and magnet

A beam scanning galvanometer is disclosed which oscillates a mirror in a non-resonant mode. The moving parts of the galvanometer are made with as small a moment of inertia as possible because the mirror is oscillated in a non-resonant mode. The galvanometer uses two sets of crossed leaf-springs to support the mirror instead of bearings which are usually used in non-resonant galvanometers. Each of the sets of leaf-springs is formed of a single strip of cold rolled stainless steel. The springs are embedded in uniquely shaped cavities in a permanent magnet that supports the mirror at a distance very close to an axis of rotation of the mirror. The mirror is specially shaped with beveled edges so that its moment of inertia is low and so that it can oscillate in very close proximity to a driving current coil which surrounds the mirror supporting magnet. A magnetic position sensor is used to detect as angular position of the mirror during operation of the galvanometer. A compensating system eliminates distorting magnetic field effects from a magnetic driving system from adversely influencing the magnetic position sensor. Signals from the magnetic position sensor are usable to provide accurate feedback information to a galvanometer driving system.

Magnetic position sensor

An efficient, precisely controlled apparatus for and method of heat fusing an image onto a receiver element, such as a slide transparency. The apparatus includes a light chamber which integrates and directs to an open end of the chamber light from an area light source which emits black body radiation at a given color temperature. A receiver element with an image to be fused is positioned adjacent to the open end of the chamber and the light source is turned and off by an electric timing and control circuit. The electric circuit precisely controls the color temperature of the light source. The circuit also electronically measures the temperature rise during fusing of the image to the receiver element then immediately turns off the light the instant complete fusing is accomplished. The method includes the steps of controlling the color temperature of the light source in accordance with optimum energy absorption by the image and by the surface of the receiver element, applying the light energy with a controlled intensity pattern to obtain highly uniform temperature rise over the area of the image including its edges, and measuring the rise in temperature produced by the light and turning the light source off as soon as a desired image fusing temperature at the surface of the receiver element is reached such that uniform fusing of the image without distortion of the receiver element is obtained.

Apparatus and method for fusing an image onto a receiver element

Electronic flash apparatus produces a variable amount of flash illumination corresponding to pre-flash photographic conditions, i.e. subject distance, film speed, ambient light intensity, etc. Circuitry, which has a threshold adjustable in response to a pre-flash signal relating to the flash illumination required for the photographic conditions, monitors energy as it is delivered to a flash tube to produce flash illumination, for activating quenching circuitry to limit the discharging of a flash capacitor to an amount of energy corresponding to the pre-flash signal.

Electronic flash apparatus

A circuit and method for effecting automatic brightness control for a television receiver CRT. The video signal is AC coupled to a signal input of a comparator. The comparator also has a reference input to which is applied a viewer-adjusted reference signal. A DC output voltage is developed in response to the difference in voltages present at the signal and reference inputs. The comparator is rendered sensitive, via a Video Blanking pulse to only the luminance component and a portion of the horizontal sync component of the video signal. The Video Blanking pulse can be synthesized by phase shifting and clipping the horizontal retrace pulses.

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Elba, NY, United States of America

John M Kresock