US3135237A

US3135237A - Indicating device

Info

Publication number: US3135237A
Application number: US180094A
Authority: US
Inventors: Robert F Huntley
Original assignee: Zenith Radio Corp
Current assignee: Zenith Electronics LLC
Priority date: 1962-03-16
Filing date: 1962-03-16
Publication date: 1964-06-02
Anticipated expiration: 1981-06-02

Description

R. F. HUNTLEY INDICATING DEVICE Filed March 16, 1962 INVENTOR.

BY da,

Hunieg United States Patent O Delaware Filed Mai'. 16, 1962, Ser. No. 180,094 3 Claims. (Cl. 116-124.1)

This invention is directed to indicating devices and more specifically, to an indicating device for a wave-signal receiver tuning mechanism.

In the past, pocket size transistorized radios have largely provided inadequate indicating means for the tuner of the radio. The legend or numbers indicating station frequencies have usually been spaced on the periphery of the tuning knob which normally has a rotational limitation of 180. Therefore, the station numbers have to be spaced quite closely which makes tuning very critical and difficult for the average user. The use of a Venier type of tuning knob reduces the criticality of tuning but is an added expense and, in any event, the close spacing ofthe frequency indicating numbers still makes visual tuning difficult. Slide rule dial scales are in general use on larger size radios but have heretofore been impractical for the pocket size transistorized radios because of cost and the large amount of space required.

Accordingly, it is a yprincipal object of this invention to provide an improved tuning indicator.

It is a more specific object of this invention to provide a tuning indicator having a slide rule dial scale for a radio of the pocket size transistor type.

It is yet another object of this invention to provide an indicating device of the above type which is economical in construction and requires a minimum amount of space.

In accordance with the above objects an indicating device for a wave-signal receiver tuning mechanism is provided comprising a rotatable shaft movable with actuation of the tuning mechanism over a rangev which is less than 360. A first lever is disposed transversely of the shaft and has one end affixed to the shaft and a second end which traces a circular arc upon rotation of the shaft over said range. A scale is provided having a straight edge which constitutes a chord of the arc. A movable indicator is mounted in camming engagement with this straight edge. A second lever has one end coupled to the indicator and another end pivotally coupled to the second end of the first lever. Spring means are provided which bias the indicator against the straight edge.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE l is an elevational view of a pocket size transistorized radio embodying the present invention;

' FIGURE 2 shows an enlarged portion of FIGURE 1 partially cut away and partially in section showing in detail the indicating device of the subject invention; and

FIGURE 3 is a partial sectional view taken along line 3-3 of FIGURE 2.

The pocket radio of FIGURE 1 includes a cabinet 10 having a front panel 11 composed of a lower portion 12 which serves as a speaker grille and an upper portion 15 which accommodates a slide rule dial scale assembly 16. A speaker 13, shown in dashed outline, is positioned within cabinet 10 behind grille 12.

Extending from the top of cabinet 10 are serratededges of two

disks

17 and 18 which may be actuated by the user of the radio. Disk 17 is coupled to the on-oif volume Patented June 2, 1964 control and disk 18 is coupled to the tuning mechanism and the remaining components and circuitry of the receiver, except for its tuning indicator, are entirely standard and will not be discussed in detail.

Referring now to FIGURE 3, which shows a portion of the tuning mechanism of the radio, disk 18 is fixed at its center to a rotatable tuning shaft 20. Shaft 20, in turn, is coupled to movable tuning plates 21 which in conjunction with fixed plates 22 constitute a capacitor whose capacitance varies with the rotation of shaft 20 to tune the radio to a selected frequency in a manner well `known in the art. The capacitor plates are arranged to limit the rotational range of shaft'20 to 180.

Dial scale 16 includes a straight edge 23 as shown in FIGURES 1-3 along which a circular indicator 24 is mounted for sliding movement. The lower portion of panel 11 forms an off-set 25 at its top, as best shown in FIGURE 3, to conceal all but a small sector of indicator 24, as best shown in FIGURE 1. The position of this sector of the circular indicator indicates the frequency to which the radio is tuned. In other words, indicator 24 may travel along scale 16 and its position may berread in terms of frequency by reference to scale 16.

Indicator 24 is coupled to tuning shaft 20 by means of a two lever linkage. The first lever may be considered as that portion of disk 18 which, as best shown in FIG- URE 2, extends between shaft 20 and a stud 26 fixed to an off-center point of the disk. In essence, one end of the lever is fixed to the tuning shaft and the second end constitutes the off-center point. Stud 26 traces a circular arc of determined by the limits of rotation of shaft 20, from a starting position indicated by the full construction lines in FIGURE 2 where the tuning capacitor is tuned to a high frequency corresponding to "16 on the dial scale and a finishing position shown by the dashed outline in which the tuning capacitor is in its low frequency condition corresponding to 5.5 on the radio dial. Broken line 28 indicates the rotational range of stud 26 between its starting and finishing positions.

Straight edge 23 of scale 16 is a chord of the arc through which stud 26 travels and for an ideal mode of operation has a point 27 which substantially coincides with the location of stud 26 in its finishing position as shown in FIGURES 1 and 2.

Indicator 24 is coupled to stud 26 by a second lever 30 which has one end 31 coupled to indicator 24 and another end 32 pivotally coupled to stud 26. FIGURE 2 showsY the two extreme positions of lever 30 corresponding to the starting and finishing positions of stud 26.

Spring means are provided for biasing indicator 24- against straight edge 23 and include a spring 33 coiled around and fulcrumed on stud 26. Spring 33 includes two

ends

34 and 35 which are held apart against the bias of the spring coils. More specifically, end 34 abuts against a hub 36 on disk 18 and end 35 is hooked around an edge of lever 30 to bias the lever and indicater 24 against straight edge 23. This bias is maintained throughout the 180 rotation of disk 18. i

Operation Rotation of disk 18 by the user rotates tuning shaft 20 and at the same time, through lever linkages 30 and the portion of disk 18 connecting shaft 20 and stud 26, moves indicator 24 along straight edge 23 to indicate the selected operating frequency of the receiver. Optimum length of slide rule dial 16 is achieved by providing that the straight edge 23 has a point along its edge which coincides with the finishing position of stud 26. If straight edge 23 were to be placed close to the axis of rotation of shaft 20, lever 30 would have to be reduced in length and this would greatly reduce the useful length of dial 16 thereby impairing its effectiveness. On the other hand,

if straight edge 23 were placed further away from shaft 20 so as not to constitute itself a chord of the are traced by the path of stud 26, indicator 24 would approach a reversal of motion before reaching its finishing position which would bring the indicator back toward the right end of the scale and make visual tuning at the left end of the dial impossible. The specific point of reversal occurs when shaft 20, stud 26 and indicator 24 all fall in the same line.

Therefore, the present invention provides an improved tuning indicator which gives the user the advantages of an adequate slide rule dial scale and at the same time is an inexpensive indicating device requiring a minimum amount of space.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made Without departing from the invention in its-broader aspects, and, therefore, the aim in the appended claims is to cover all suchchanges and modifications as fall within the true spirit and scope of the invention.

I claim:

1. An indicating device' for a Wave-signal receiver tuning mechanism comprising: Y

a rotatable shaft movable with actuationY of said tuning mechanism over a range which is less than 360;

a first lever disposed transversely of said shaft having one end fixed to said shaft and a secondend which traces a circular arc upon rotation of said shaft over said range;

a scale having a straight edge which constitutes a chord of said arc;

a movable indicator mounted in camming engagement with said straight edge;

a second lever having one end coupled to said indicator and another end pivotally coupled to said second end of said first lever;

and spring means biasing said indicator against said straight edge.

2. An indicating device for a wave-signal receiver tuning mechanism comprising: y

a rotatable shaft movable with actuation of said tuning mechanism over alrange of approximately 180;

a rst fixed-length lever disposed transversely of said shaft having one end fixed to said shaft and a second end which traces a circular arc upon rotation of said shaft from a starting position to a finishing position at opposed points in said range;

a scale having a straight edge including a point which substantially coincides with the location of said second end of said first lever in said finishing position;

a movable indicator mounted in camming engagement with said straight edge;

a second fixed-length lever having one end coupled to said indicator and the second end pivotally coupled to said second end of said first lever;

and spring means biasing said indicator against said straight edge.

3. An indicating device for a Wave-signal receiver tuning mechanism comprising:

a rotatable tuning shaft for actuating said tuning mechanisrn having a rotational range of approximately a disk coaxially mounted on said shaft for rotation therewith and having a-predetermined olf-center point which traces a circular arc upon rotation of the shaft from a starting position toa finishing position at opposed ends of said range;

a scale having a straight edge which constitutes a chord of said arc and including a point which substantially coincides with the location of said off-center point of said disk in said finishing position;

a movable indicator mounted in camming engagement with said straight edge;

a stud secured at said off-center point of said disk;

a fixed-lengthV lever having one end coupled to said indicator and a second end rotatably journalled on said stud;

and a spring fulcrumed onv said stud for biasing said indicator against said straight edge.

References Cited in the file of this patent UNITED STATES PATENTS 2,190,059 Edwards Feb. 13, 1940

Claims

1. AN INDICATING DEVICE FOR A WAVE-SIGNAL RECEIVER TUNING MECHANISM COMPRISING: A ROTATABLE SHAFT MOVABLE WITH ACTUATION OF SAID TUNING MECHANISM OVER A RANGE WHICH IS LESS THAN 360*; A FIRST LEVER DISPOSED TRANSVERSELY OF SAID SHAFT HAVING ONE END FIXED TO SAID SHAFT AND A SECOND END WHICH TRACES A CIRCULAR ARC UPON ROTATION OF SAID SHAFT OVER SAID RANGE; A SCALE HAVING A STRAIGHT EDGE WHICH CONSTITUTES A CHORD OF SAID ARC; A MOVABLE INDICATOR MOUNTED IN CAMMING ENGAGEMENT WITH SAID STRAIGHT EDGE; A SECOND LEVER HAVING ONE END COUPLED TO SAID INDICATOR AND ANOTHER END PIVOTALLY COUPLED TO SAID SECOND END OF SAID FIRST LEVER; AND SPRING MEANS BIASING SAID INDICATOR AGAINST SAID STRAIGHT EDGE.