Zenith Radio Corporation

Zenith Electronics Corporation

Stanley E Lehnert

Donald Ankeny

A saturable reactor has a center control winding electromagnetically coupled to a pair of outer windings which, in turn, are each coupled in circuit with a respective toroidal shunt winding. The reactor provides side pincushion correction and eliminates center pinch in a raster scanned video display such as a cathode ray tube (CRT). The high inductance-to-resistance ratios of the toroidal windings as well as the shunt current paths permit increased deflection current to be provided to the horizontal deflection coils without saturating the reactor or requiring an increase in its size.

Saturable reactor with toroidal shunt paths

An electronic image framing circuit is described for eliminating the visible effects of pincushion distortion at the edges of a television image. Toward this end, portions of video lines which extend beyond a selected straight line image boundary are blanked by a pulse processor. The pulse processor responds to conventional horizontal rate and vertical rate pulses for developing blanking pulses whose widths are varied at a vertical rate. The modified blanking pulses are applied to a conventional blanking circuit for blanking the portions of video lines which extend beyond the desired image area. A parabola generator is also described for use in developing the modified blanking pulses.

Pulse wave to parabola wave converter

Electronic television picture framing circuit

A method is disclosed for the optical alignment of a projection television system having a bank of three light projection means for projecting into coincidence red, green and blue images to form a composite color image in space. The light projection means which are located off the projection screen axis project purposely distorted off-axis images effective to substantially compensate, upon projection, for the non-linear magnification distortion of the image resulting from the off-axis location. The method of optical alignment comprises replacing the cathode ray tubes of the light projection means with lamp means. A graticular geometrical analog of each of the projected images is interposed between the lamp means and a projection lens means. The analogs are projected consecutively and concurrently on the projection screen and the images are superimposed by manipulating adjustment means which adjust the light projection means in azimuth and elevation; whereby the images projected by the light projection means will be in substantial optical alignment each with the other and with the screen.

Method for optical alignment of a projection television system

A system for correcting for vertical off-axis optical projection distortions in a projection television is disclosed. In a projection television wherein the image projection axis is obliquely disposed in the vertical direction relative to the projection screen axis, a system for correcting for video image distortion caused by this configuration involving modulating the vertical size input is disclosed. A vertical rate correction signal is developed from the vertical output circuit and provided in a feedback arrangement to a sawtooth wave signal generating circuit for regulating electron beam vertical sweep in a projection television CRT, or CRT's. By decreasing CRT electron beam vertical sweep rate across that portion of the projection screen where the video image is vertically stretched and increasing the vertical sweep rate for the vertically compressed portion of the video image, a linear, distortion-free image is presented on the projection screen.

Vertical image correction for projection TV

An article of manufacture is disclosed for use in a projection televison system. A cathode ray picture tube has a face panel with a rearwardly extending skirt and a window for receiving a cathodoluminescent imaging screen. The tube has a seal land which defines a plane whose normal makes a non-zero acute angle with respect to the axis of said window. The article is for use in a system having a cathode ray picture tube whose projection optical axis is on the axis of a remotely located viewing screen, and at least one displaced axis cathode ray picture tube; that is, a tube whose projection optical axis is displaced from the axis of the viewing screen by a non-zero acute angle. The method according to the invention provides for compensating for the non-linear magnification distortion of the projected image caused by the displacement of the tube off the viewing screen axis.

Method of manufacture for projection television system

An article of manufacture is disclosed for use in a projection television system. A cathode ray picture tube has a face panel with a rearwardly extending skirt and a window for receiving a cathodoluminescent imaging screen. The tube has a seal land which defines a plane whose normal makes a non-zero acute angle with respect to the axis of said window. The article is for use in a system having a cathode ray picture tube whose projection optical axis is on the axis of a remotely located viewing screen, and at least one displaced axis cathode ray picture tube; that is, a tube whose projection optical axis is displaced from the axis of the viewing screen by a non-zero acute angle.

Article of manufacture for projection television system

A method and network are described for correcting vertical non-linearity and mis-convergence in a color television projection system. The correction method includes adjusting the height of the projected image so that proper convergence is attained at either the top or at the bottom of the image, and so that the opposite end of the image is stretched. The stretched end of the image is compressed to proper size and proper convergence by shunting current away from each of three vertical deflection yokes included in the projection system.

Network and method for correcting vertical non-linearity and

Means and method are disclosed for compensating for non-linear magnification distortion in projection television systems. The projection television system has a projection screen for displaying a light image cast thereon. The screen is spaced apart from at least one light projection means whose projection optical axis lies at a non-zero, acute-angle A with respect to the screen axis. The light projection means comprises cathode ray tube means having a cathodoluminescent screen on the inside surface of a face panel thereof whose axis is substantially parallel to the projection optical axis. Electron-beam generating means are disposed on the cathode ray tube electron-optical axis for forming an electron image on the cathodoluminescent screen which is converted to a visible image by the cathodoluminescent screen. Lens means on the projection optical axis provide for projecting on the projection screen the light image of the electron-formed visible image. The light image inherently has non-linear magnification distortion attributable to the location of the projection means off the projection screen axis. The system is characterized according to one embodiment of the invention by the cathode ray tube electron-optical axis defining a non-zero, acute-angle B with respect to the axis of the cathodoluminescent screen. The value of the angle B and the orientation of the electron optical axis is selected according to the invention to cause the electron-formed visible image to have an orientation and a non-linear magnification distortion effective to substantially compensate for the off-axis-induced non-linear magnification distortion of the projected light image.

Projection television system

A television receiver includes circuitry for processing a received signal and displaying video information therein upon the viewing screen of a cathode ray tube. Conventional horizontal and vertical deflection circuitry provide the required scanning signals. A center tapped winding on the receiver's horizontal output transformer is coupled to a pair of oppositely oriented diodes which are coupled to a common load. A vertical trace or scan signal is applied to both diodes, alternately switching them on during the vertical scan interval. The respective portions of vertical scan signal coupled by each diode are serrated in response to the applied horizontal retrace pulses and when combined in the common load form a train of horizontal frequency pulses having first and second portions at opposite polarities and an envelope corresponding to the vertical scan signal. An amplifier, having a collector load tuned to the horizontal scan frequency, is coupled to the common load and produces a 'bow-tie' signal which is applied to the receiver's vertical deflection amplifier for top and bottom pincushion correction.

Low level pincushion correction circuit

A television receiver includes conventional circuitry for detecting the information components of a received television signal. A cathode ray tube viewing screen is scanned by horizontal and vertical scanning circuitry. Low level pincushion correction circuitry imposes a bow-tie signal upon the vertical scan signal forming a composite signal. A series connected vertical yoke has a first terminal coupled to a vertical deflection amplifier and a second terminal connected to ground. The composite signal applied produces vertical scan and pincushion correction currents in the yoke. A tank circuit, resonant at the horizontal scan frequency, is interposed between the vertical yoke windings and a pair of shunting capacitors are connected in parallel with each of the yoke windings and the tank circuit to reduce yoke impedance to the pincushion correction components of the composite signal.

Growing community of inventors

Addison, IL, United States of America

Stanley E Lehnert