US 4,351,045 A · Tracking error measurement

Abstract

Method and apparatus for obtaining a measure of or relating to lateral tracking error at each of a plurality of predetermined radial distances from the spindle axis of phonographic turntable equipment that includes a spindle (13), a rotatable platter (14), and a pivotally mounted tonearm (11) to carry a cartridge-mounted stylus (12) via a separate or integral headshell (16). The apparatus comprises an alignment protractor (20, 120) placed on the platter for arcuate movement about the spindle axis, and a device (30, 130, 40) mounted on the tonearm in place of the cartridge or both the cartridge and headshell. The alignment protractor (20) is marked with a plurality of equi-angularly spaced radial lines indicative of differing tracking error values and a plurality of equi-spaced transverse straight lines crossing all the radial lines and intersecting at right angles the radial line indicative of zero tracking error. The device (30, 40) is marked with a distance scale comprising a main line (35, 45) directed at the offset angle with respect to the tonearm and intersected by equi-spaced distance marks corresponding to and/or defining different stylus points (whereby each distance mark defines a different value for the stylus overhang distance).

Claims14

Dependent claims

Apparatus for use in obtaining a measure of or relating to lateral tracking error at each of a plurality of predetermined radial distances from the spindle axis of turntable equipment that includes a spindle, a platter rotatable about the spindle axis, and a pivotally mounted tonearm, said apparatus comprising an alignment protractor in the form of a marked planar member apertured to fit on or over the spindle such as to overlie and/or rest on the platter, the member's markings defining a primary line to extend radially of the spindle axis and be indicative of zero value of said measure, a plurality of angularly spaced secondary lines to extend radially of the spindle axis to each side of the primary line and be indicative of different non-zero values of said measure respectively, and a plurality of mutually parallel transverse lines directed at right angles to said primary line for extension across the primary line and all said secondary lines, said transverse lines being indicative of said predetermined radial distances, and further comprising a device having mounting means whereby the device may be secured to the tonearm in place of the usual cartridge, said device incorporating a marked transparent planar surface to overlie and/or rest on the alignment protractor, the surface markings defining a scale comprising a main line which, when the device is secured to the tonearm as aforesaid, is directed to the tonearm at the offset angle for overyling colinear alignment with a selected one of the alignment protractor's transverse lines, the scale further comprising a plurality of equi-spaced distance marks directed transversely of said main line, said distance marks defining stylus points of which any one can be selected to correspond to the particular tip of the stylus of the cartridge that has been replaced by the device.

A method of obtaining a measure of or relating to lateral tracking error at a predetermined radial distance from the spindle axis of turntable equipment that includes a spindle, a platter rotatable about the spindle axis, and a pivotally mounted tonearm to which a cartridge is usually secured, wherein said method comprises the steps of:

(a) mounting on the tonearm, in place of the usual cartridge, a device incorporating a marked transparent planar surface to overlie said platter, said markings defining a scale comprising a main line to be directed to the tonearm at the offset angle and further comprising a plurality of equi-spaced distance marks directed transversely of said main line to define stylus points of which any one may be selected to correspond to the tip of the stylus of the cartridge replaced by the device,
(b) placing on the platter an alignment protractor in the form of a marked planar member having an aperture whereby the member is fitted on or over said spindle such as to overlie the platter and extend beneath the marked planar surface of said device, the member's markings defining a primary line to extend radially of the spindle axis and be indicative of zero value of said measure, a plurality of angularly spaced secondary lines to extend radially of the spindle axis to each side of the primary line and be indicative of different non-zero values of said measure respectively, and a plurality of mutually parallel transverse lines directed at right angles to said primary line for extension across the primary line and all said secondary lines, said transverse lines being indicative of said predetermined radial distances,
(c) pivoting the tonearm about its vertical pivot axis and arcuately moving the member about the spindle axis until the alignment protractor's particular transverse line corresponding to said predetermined radial distance is directed to the tonearm at the offset angle,
(d) determining which particular one of the alignment protractor's radial lines is coincident with the stylus point along said particular transverse line, and reading the value of the said measure indicated by that particular one of said radial lines.

1 more element

Dependencies are inferred from the claim text.

Tracking error measurement

Life of this patent

Tracking error measurement

Life of this patent

Abstract

Claims14