Interpolation method and apparatus for improving registration adjustment in a projection television

• US 5,537,159 A
• Filed: 05/19/1994
• Issued: 07/16/1996
• Est. Priority Date: 05/27/1993
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kondo, Makoto, Hamamatsu, Toshihiko, Suematsu, Masayuki
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): Burgess, Glenton B.
• Application Number:
  US08/246,131
• Time in Patent Office: 789 Days
• Field of Search: 348/730, 348/731, 348/734, 348/86, 348/87, 348/180, 348/189, 348/190, 348/572, 348/571, 348/678, 348/686, 348/687, 348/744, 348/747, 348/745, 348/806
• US Class Current: 348/745
• CPC Class Codes: H04N 3/2335 with calculating means
• CPC Class Codes: H04N 9/28 Arrangements for convergence or focusing

Abstract

The nonlinear, deflection waveform used improve registration in a three picture tube projection television system is produced using interpolation of stored data setting points by first performing a reduced number of high-order interpolation calculations using the setting points and then performing low-order interpolation calculations either between two calculated high-order interpolated data points or between one of the calculated high-order interpolated data points and one of the setting points. This results in reducing the work load on the central processing unit in the registration system. In addition, a reduced bit-size requirement for the interpolation portion of the registration is obtained by storing registration data of a first bit size and then adding bits below the original LSB for the interpolation calculation prior to performing the digital to analog conversion.

Claims

1. A projection television apparatus comprising:

a video signal processing circuit receiving an input video signal for processing a red component signal, a green component signal and a blue component signal of the input video signal;

three cathode ray tubes for displaying output signals from said video signal processing circuit, respectively;

a registration correction waveform generation circuit for producing correction signals for the three cathode ray tubes using setting data represented as data points on a waveform, including high-order interpolating means for performing a high order interpolating calculation to the setting data allocated to each data point for interpolating first interpolation data calculated by said high-order interpolating means among the respective data points, and low-order interpolating means for interpolating second interpolation data calculated by a low-order interpolating calculation between either said setting data and said first interpolation data or two pieces of said first interpolation data; and

converting means for sequentially sampling the setting data corresponding to the respective data points and said first and second interpolation data interpolated among said data points, and converting the sampled data into a registration correction waveform signal.

2. The projection television apparatus according to claim 1, further comprising storage means, wherein said high-order interpolating means causes said setting data corresponding to the respective data points and said first interpolation data interpolated among said data points to be temporarily stored in said storage means.

3. The projection television apparatus according to claim 1, wherein said high order interpolating means and said low order interpolating means each include storage means, respectively, each for temporarily storing the setting data corresponding to the respective data points, and said first and second interpolation data interpolated among said data points.

4. A color television projecting apparatus having three projection tubes, comprising:

a non-volatile memory having a first bit number for each data word stored therein for storing data used to correct registration of overlapped images formed by said three projection tubes;

an interpolation calculating circuit for interpolating the data read out from said non-volatile memory;

a D/A converter having a second bit number for data fed thereto for converting an output of said interpolation calculating circuit into an analog signal; and

an output circuit for supplying the output of said D/A converter to a respective deflecting coil in said three projection tubes,

wherein said first bit number for data stored into said non-volatile memory is smaller than said second bit number of said D/A converter.

5. The color television projecting apparatus according to claim 4,

wherein said first bit number of the registration setting data stored said non-volatile memory is m bits, and said second bit number the of said D/A converter is set to m+n bits.

6. A registration interpolating method for correction registration of a plurality of images on a screen of a projection television monitor having three primary color picture tubes, comprising the steps of:

setting a bit number of registration adjusting data for primary color picture signals fed to said three primary color picture tubes to n;

adding m-bit data to data smaller than LSB of said data having the bit number of n, thereby converting said data into (n+m)-bit data;

performing an interpolation with the value of said (n+m)-bit data;

performing a first outputting step for outputting (n+m)-bit interpolation data;

a converting said interpolation data using a D/A converter into an analog signal; and

performing a second outputting step for outputting an analog deflection correction signal to each projection tube.