US3793496A

US3793496A - Gear and clutch operating mechanism for multi-channel television tuner

Info

Publication number: US3793496A
Application number: US00279059A
Authority: US
Inventors: S Kimura; Y Aoki
Original assignee: Nidec Copal Corp
Current assignee: Nidec Precision Corp
Priority date: 1971-08-25
Filing date: 1972-08-09
Publication date: 1974-02-19
Anticipated expiration: 1991-02-19
Also published as: CA970845A; DE2240773C3; DE2240773B2; DE2240773A1; JPS4833202U

Abstract

A tuner for television broadcast receiver comprising a plurality of annular patterns made with a conductive material and arranged concentrically in groups, and grouped contact strips arranged to face said annular patterns and to be able to contact these annular patterns, respectively, and being operative so that either one of the grouped annular patterns and the grouped contact strips is rotated in accordance with the broadcast channel selecting operation and that all of said channels may be selected automatically in accordance with a binary code formed by the combinations of contact and non-contact state between the respective annular patterns and the respective contact strips. This tuner for television broadcast receiver is simple in structure and easy to construct.

Description

United States Patent [191 Kimura et al.

[4 Feb. 19, 1974 75 Inventors: Sachio Kimura; Yoshiaki Aoki, both of Tokyo, Japan [73] Assignee: Kabushiki Kaisha Koparu,

Tokyo-to, Japan [22] Filed: Aug. 9, 1972 [21] Appl. No.: 279,059

[30] Foreign Application Priority Data Aug. 25, 1971 Japan 46-76534 [52] U.S. Cl. 200/18, 200/11 R, 200/153 P, 200/5 R [51] Int. Cl. 01h 3/54 [58] Field of Search. ..200/l R, 5 R, 11 R, 11 D,

200/11 DA, 11 TW, 14,17 R, 18, 56 R, 200/56 A, 11 TC, 153 R, 153 P; 74/640 {56] References Cited UNITED STATES PATENTS 3,691,547 9/1972 Lipscomb 200/5 R X Duris et al 200/11 R X Gerhardt et al 200/11 DA X Primary Examiner-James R. Scott Attorney, Agent, or Firm-Cushman, Darby & Cushman 57 ABSTRACT A tuner for television broadcast receiver comprising a plurality of annular patterns made with a conductive material and arranged concentrically in groups, and grouped contact strips arranged to face said annular patterns and to be able to contact these annular patterns, respectively, and being operative so that either one of the grouped annular patterns and the grouped contact strips is rotated in accordance with the broadcast channel selecting operation and that all of said channels may be selected automatically in accordance with a binary code formed by the combinations of contact and non-contact state between the respective annular patterns and the respective contact strips. This tuner for television broadcast receiver is simple in structure and easy to construct.

2 Claims, 9 Drawing Figures PATENTED FEB 19 1924 SHEET 1 BF 5 wn wn on 2v oI wm an m w m W 8 8m PATENTEDFEB 19 m4 SHEU 2 1F 5 .PATENTEDFEBI 9 1974 saw am 5 PATENTEDFEBIQ I974 SHEET 5 0F 5 FlG. 8

CHANNEL l 'sr NO GROUP GROUP O O O O oo oo OOOO GEAR AND CLUTCH OPERATING MECHANISM FOR MULTI-CHANNEL TELEVISION TUNER BACKGROUND OF THE INVENTION 1. Field of the invention The present invention pertains to a tuner for television broadcast receiver, and more particularly, it relates to a tuner of the type described which is arranged so that all of the broadcast channels may be selected on the same tuning system for a range of bands from the VHF band to the UHF band.

2. Description of the Prior Art In order to enable the respective broadcast channels to be selected on the same tuning system for a range of bands from the VHF band to the UHF band, there have been proposed a tuner of the mechanical tuning type and a tuner of the electronic tuning type. However, these known tuners had the drawbacks and inconveniences such that a very high mechanical precision and a relatively large spece were required, and moreover, their structures tended to become quite complicated.

SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide a tuner for television broadcast receiver, which is simple in structure and easy to construct and permits all of therequired broadcast channels to be selected, as desired.

Another object of the present invention is to provide a tuner of the type described, which is arranged so that either one of the following groups, i.e., either a plurality of annular patterns made with a conductive material and arranged concentrically in groups, or grouped contact strips arranged to face said annular patterns and to be able to contact them respectively, is rotated by being coupled to a drive means intended for the channel selecting operation, and that the selection of channels may be performed in accordance with a binary code formed by the combinations of contact and non-contact state between said annular patterns and said contact strips.

Still another object of the present invention is to provide a tuner of the type described, which functions accurately and is-easy to make adjustments;

These and other objects as well as the advantages of the present invention will become apparent by reading the description of an embodiment of the invention when taken in conjunction with the accompanying drawings. b

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory illustration of a train of drive gears of the tuner of the present invention for use in a television broadcast receiver.

FIG. 2 is a fragmentary front elevation, on an enlarged scale, of the drive section shown in FIG. 1.

FIG. 3 is a top view of the drive section shown in FIG. 2.

FIG. 4a and FIG. 4b are explanatory illustrations of the channel number indicating section for use in FIG. 1.

FIG. 5 is an exploded perspective view of the intermittent feed mechanism associated with the second gear for operating contact strips for use in FIG. 1.

FIG. 6 is a front view of a group of contact strips which are attached to the first gear for operating contact strips in FIG. 1 and also to the clutch plate in FIG. 5, respectively.

FIG. 7 is a front view of the printed circuit carrying plate used in FIG. 1.

FIG. 8 is an explanatory illustration showing the manner in which the channels are selected by the combination of contact and non-contact state between the respective contact strips and the annular patterns.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, reference numeral 1 represents a drive member such as a drive gear rotatably mounted on a shaft 3 and having a ratchet gear 2 provided integrally and concentrically with this drive member. Numeral 4 represents a first intermediate gear rotatably mounted on a shaft 5 and being meshed with the drive gear 1. Numeral 6 represents a channel number indicating gear pivotably mounted on a shaft 8 and meshing with said first intermediate gear 4 and having, concentrically and integrally therewith, a supporting frame 35 for supporting a channel number indicating flap 36 which will be described later. Numeral 9 represents a second intermediate gear rotatably mounted on a shaft 10 and meshing with said first intermediate gear 4. Numeral l 1 represents a third intermediate gear rotatably mounted on a shaft 12 and meshing with said second intermediate gear 9. Numeral 13 represents a gear rotatably mounted on a shaft 14 and meshing with said third intermediate gear 11. Numeral 15 represents a first gear for operating contact strips rotatably mounted on a shaft 16 and meshing with the gear 13 and having a contact strip attachment plate 51 which will be'described later. Numeral 17 represents a second gear for operating contact strips rotatably mounted on a shaft 18 and meshing with the gear 13 and operating another contact strip attachment plate via an intermittent feed mechanism which will be described later. Numeral 19 represents a plate for supporting a printed circuit carrying plate, which will be described later, having two printed

circuit plates

20 and 21 in such a way that these two plates 20and 21 face said contact strip attachment plates, respectively. In this example, said ratchet gear 2 has 32 teeth. The gear ratio between the respective gears is arranged so that by the rotation of the drive gear 1 caused by the revolution of the ratchet gear 2 an amount corresponding to two teeth, the channel number indicating gear 6 will make a one sixtyfourth revolution to cause the channel number indication to proceed one step; and along therewith, the first gear 15 for operating contact strips will make a oneeighth revolution; and the second gear 17 for operating contact strips will make a one sixty-fourth revolution.

In FIGS. 2 and 3, reference numeral 22 represents a part of the plunger for a plunger solenoid. At one end of this plunger 22 is secured an operating member 23 which, in turn, receives a pin 24. Numeral 25 represents a pawl operating member which is rotatably mounted on a shaft 28. One arm 26 of this pawl operating member 25 has a slot 26a formed therethrough for receiving said pin 24. The other arm 27 has, rotatably mounted at one end thereof, a pawl lever 30 by means of a shaft 29. This pawl lever 30 is urged to rotate counter-clockwise by a spring not shown. One end 30a of this pawl lever 30 meshes with the ratchet gear 2. Numeral 31 represents a stopper for adjusting the operating stroke of said plunger 22. This stopper 31 is adapted to be adjustedof its sideways displacement by the pin-slot connection. Numeral 32 represents an adjusting member rotatably mounted on said shaft 3 for adjusting the meshing condition between said ratchet gear 2 and said pawl lever 30. This adjusting member 32 has a bent portion 32a facing the pawl lever and also has a forked portion 32b. Numeral 33 represents an eccentric member rotatably mounted on a shaft 34 and received in said forked portion 32b.

The aforesaid plunger solenoid employed in this example is of a special type which repeats the reciprocating movement that at the end of a certain short time after the plunger 22 has been pulled into the solenoid, the plunger again is caused to come out of the solenoid. This reciprocating movement of the plunger 22 is effected either by the use of a signal generating circuit or by the provision in the path of movement of the plunger for example, a switch means adapted to break or make a part of the power source circuit. This plunger solenoid is driven in two different ways depending on the purpose for which this solenoid is used. In one of these two different driving ways, the switch for operating the drive circuit of the plunger solenoid is kept closed to have the plunger 22 to continuously repeat the aforesaid reciprocating movement to thereby cause this plunger to perform its channelselecting action (which will be discussed later) successively one after another, so that when the desired channel number is indicated on the channel indicating section, the aforesaid operating switch is opened for the first time. The other of said two different driving ways is what is called the automatic channel selecting type which is operative such that, by closing the aforesaid operating switch, this state of the closed switch is selfsustained by the action of the plungersolenoid so that the action of the plunger is automatically repeated in succession and that, upon selection of the channel in which a broadcast is being performed, a signal representing this selection is generated from the known tuning circuit to the solenoid so that the action of the plunger solenoid is automatically brought to a halt.

FIGS. 4a and 4b show an example of the channel number indicating means. Reference numeral 35 represents a supporting frame having a shape of a bobbin which is attached integrally to the foresaid channel indicating gear 6. This supporting frame 35 has two

flanges

35a and 35a at both sides of the frame. Each of these two

flanges

35a and 35a has 64 holes 35b (see FIG. 1) formed on the outer peripheral region thereof. Numeral 36 generally represents flaps. Each of these flaps 36 has a projection 36a which is adapted to be received in one of the holes 35b of said supporting frame 35. These flaps 36 are arranged so that a single channel number is indicated by the front side and the reverse side of any two adjacent flaps 36. Numeral 37 represents a holding member adapted to engage the marginal edge of that flap 36 which has arrived at the indicating position and to thus hold this flap 36 in its vertical position. Those grouped flaps 36 which are positioned above the other group of flaps in FIG. 1 are disengaged one after another from the holding member 37 as the channel number indicating gear 6 rotates in accordance with the channel selecting action which will be described later, so that said upwardly positioned flap turns as it moves downwardly and indicates the channel number.

Next, in FIG. 5, reference numeral 38 represents a clutch drive gear which is coupled integrally to the gear 13 by a tubular member 39. As stated previously, the second gear 17 for operating contact strips is rotatably mounted on the shaft 18. This gear 17 has three arcuate slots 17a which are formed concentrically on this gear and arranged at equal intervals relative to each other. In this example, three pins 40 extend concyclicly at equal intervals from the second gear 17 for operating contact strips. Numeral 41 represents a clutch disk which is secured to the shaft 18. In this drawing, there are seen three pins 42 extending concyclicly at equal intervals from the clutch disk 41 and being received inv the slots 17a, respectively, of the second gear 17 for operating contact strips. Numeral 43 represents a spring which is shown only one in the drawing but the same springs are applied between the

respective pins

40 and 42. Numeral 44 represents a clutch gear rotatably mounted on the shaft 18 and meshing with the clutch drive gear 38. Numeral 45 represents a clutch cam having a cam portion 45a formed locally of its periphery and being integralwith said clutch gear 44. Numeral 46 represents a ratchet gear secured to the shaft 18 and is rotated integrally with the clutch disk 41. This ratchet gear 46 has eight teeth 46a formed at equal intervals on the periphery thereof. Numeral 47 represents a clutch lever which is secured to a shaft 49 and has a pawl 47a which, in turn, is brought into contact with the clutch cam 45. Numeral 48 representsa follower clutch lever which is also secured to the shaft 49 and has a pawl 48a of the ratchet gear 46. Numeral 50 represents a spring for urging the

clutch levers

47 and 48 to rotatecounter clockwise.

FIG. 6 shows one of the two contact mechanisms which are attached to the first gear 15 for operating contact strips and to the clutch. disk 41, respectively. These two contact mechanisms are altogether identical relative to each other, but there is shown only one of these two in the drawing. Numeral 51 represents a contact strip attachment plate which is secured to the first gear 15 for operating contact strips and another such plate is secured to the clutch disk 41. Numerals 52a, 52b, 52c and 52d represent contact strips which are attached onto the contact strip attachment plate 51 in such a way that they are electrically connected together via a short circuit pattern 53.

FIG. 7 shows the various patterns of the printed circuit plates which are arranged to face the contact strips of the respective groups. The first printed circuitplate 20 has four patterns corresponding to the grouped contact strips which, in turn, are attached to the first gear 15 for operating contact strips. Numeral 54 represents a first annular pattern which is made of a conductive material and which faces and always contacts the contact strip 52a to serve as a common terminal. Numeral 55 represents a second annular pattern which is made with a conductive material and faces said contact strip 52b and has an enlarged portion 55a which is brought into contact with said contact strip 52b at positions in the angle l-360 which is measured by setting the top (as viewed in the drawing) of the vertical line as 0, to control the first row representing one numerical unit in Group 1 of the previously mentioned bi nary code shown in FIG. 8. Numeral 56 represents a third annular pattern which is made with a conductive material and faces said contact strip 520 and has an enlarged portion 56a and another enlarged portion 56b which are brought into contact with the contact strip 52c at positions in the angles 90-l80 and 270-360 which are measured by setting the top (as viewed in the drawing) of the vertical line as to control the second row representing a single numerical unit in Group 1 of said binary code. Numeral 57 represents a fourth annular pattern which is made of a conductive material and faces said contact strip 52d and has enlarged

portions

57a, 57b, 57c and 57d which are brought into contact with said contact strip 52d at positions in the angles 45-90, l35-l80, 225-270 and 3 l5-360, to control the third row of a single numerical unit. The second printed circuit plate 21 is provided with four patterns to correspond to the grouped contact strips attached to said clutch disk 41. The

annular patterns

58, 59, 60 and 61 of the plate 21 face the contact strips 52a, 52b, 52c and 52d, respectively, and these annular patterns are of configurations identical with those of the

aforesaid patterns

54, 55, 56, and 57, respectively including

enlarg'ed portions

59a, 60a, 60b, and 61a-d. These patterns forming two groups are provided with

lead wires

62, 63, 64, 65 and 66, 67, 68, 69, respectively. In addition, the

annular patterns

56 and 61 serve as common terminals respectively. Accordingly, lead wires 62-63, 62-64, 62-65 and 66-67, 66-68, 66-69 form switching circuits, respectively. It should be understood that these switching circuits are arranged so that these circuits use, at one terminal thereof, the annular patterns 54 and 58 in common, respectively, and that therefore, in order to prevent interference from occurring between the respective switch circuits, there are connected arranged in the

same direction diodes

70, 71, 72 and 73, 74, 75 to these respective switch circuits, respectively. The changeover actions for the selection of channels caused by contact and non-contact between the annular patterns and the contact strips arranged to face these patterns, or in other words, caused by the combination of on-off actions of the switches, are controlled by, for example, a binary circuit not shown.

Description will hereunder be made on the functions of the tuner having the aforesaid arrangement.

Let us now assume that the respective contact strips are positioned on the one-dot chain lines shown in FIG. 7, facing the corresponding patterns. It will be understood that those contact strips 52b, 52c, 52d corresponding to the

annular patterns

55, 56, 57 and 59, 60, 61 are all in the non-contacting state. At this state, Channel No. l is being selected as shown in FIG. 8.

Explanation of the invention will hereunder be made based on the assumption that the driving of the plunger solenoid is of the automatic channel selection mode and that the television broadcast receiver is located in such an area as Tokyo wherein 62 channels are provided. Accordingly, let us assume that, in order to make changeover of channels starting at this state, there is repeated the operation of closing the operation-switch not shown of the plunger solenoid. Whereupon, the channels will be selected automatically in the order of from Channel No. 3, Channel No. 4 to Channel No. 6. More specifically, by the action of the plunger solenoid, its plunger 22will repeat its sideways reciprocating movement in FIGS. 2 and 3. During the forward movement, toward the left, of this plunger 22, the operating member 23 which is secured at the foremost end of the plunger 22 will travel toward the left 6 side, carrying with it the pin 24 which is received in said member 23 toward the left side also. As a consequence, the arm 26 of the pawl operating member 25 will make a counter-clockwise rotation about the shaft 28 owing to the engagement between this pin 24 and the slot 26a. Accordingly, the forward end portion 30a of the pawl lever 30 will disengage from the tooth 2a of the ratchet gear 2 via the arm 27 of this pawl lever 30, and it will rotate counter-clockwise about the shaft 29 as its fulcrum by virtue of the force of the spring not shown to thereby engage the next tooth 2b. Thereafter, during the returning movement of the plunger 22 toward the tight side, this portion of the mechanism, as a whole, returns to the position illustrated, so that the ratchet gear 2 is caused to proceed to an amount corresponding to one tooth by the pawl lever 30. As the foregoing actions are repeated, the drive gear 1 is rotated. This rotation is transmitted, via the first intermediate gear 4, the second intermediate gear 9, the third intermediate gear 11 and the gear 13, to the first gear 15 for operating contact strips and also to the second gear 17 for operating contact strips, and along with this, said rotation of the gear 1 is transmitted, via the first intermediate gear 4, also to the channel number indicating gear 6, whereby both the channel selecting action and the channel number indicating action are accomplished.

As shown in FIGS. 5 through 7, this channel selecting action is performed in such a way that the second gear 17 for operating contact strips makes one-eighth revolution during the one whole revolution of the first gear 15 for operating contact strips, and that the clutch disk 41 associated with the second gear 17 for operating contact strips is fed intermittently for one-eighth revolution at a time at the endof each one-eighth revolution of said gear 17 as will be discussed later. Both the first gear 15 for operating contact strips and the clutch disk 41 are provided with the contact mechanism shown in FIG. .6, respectively. The respective contact strips 52a-52d located on the contact strip attachment plate 51 face their corresponding patterns, respectively, of the printed

circuit plates

20 and 21 which are attached to the supporting plate 19 shown in FIG. 7.

As stated above, when the first gear 15 for operating contact strips and the second gear 17 for operating contact strips are rotated by the action of the plunger solenoid from the state in which Channel No. 1 has been selected, the contact strip attachment plate 51 located on the clutch disk 41 side will not be rotated because of the fact that the pin 42 moves in the slot 17a until the first gear 15 for operating contact strips coin pletes one whole revolution. Accordingly, those annu-.

patterns located on the printed circuit plate 21 side and the contact strips 52b, 52c and 52d which face these patterns are kept in non-contacting state, whereas only the enlarged portion 57a of the annular pattern 57 located on the printed circuit plate 20 side is in contact with the contact strip52d. By virtue of only this combination of contact, Channel No. 2 is selected. Then, by the combination of contact only between the enlarged portion 56a of the pattern 56 and the contact strip 520, Channel No. 3 is selected. When this Channel No. 3 is selected, this automatic channel selecting action is brought to a halt owing to the signal tuned in to the broadcast. Then, by closing the operation switch again, the previously stated channel selecting actions are repeated, so that next time, by the combination of contact between the enlarged portion 560 of the pattern 56 and and the contact strip 52c and between the enlarged portion 57b of the pattern 57 and the contact strip 52d, Channel No. 4 is selected. Thereafter, by the combinations of contact and non-contact modes between the respective patterns and contact strips, channels will be selected in succession.

In these channel selecting actions, the clutch disk 41 which supports the contact strip attachment plate 51 is caused to rotate intermittently by one-eighth revolution at a time at the end of each one whole revolution of the first gear .15 for operating contact strip, to thereby control the two numerical units of the binary code. More specifically, the second gear 17 for operating contact strips is caused to rotate counter-clockwise in FIG. via the train of gears in accordance with the rotation of the aforesaid drive gear 1, so that the spring 43 applied between the

pins

40 and 42 is energized. Also, the clutch cam 45 is rotated counter-clockwise via the gear 13,. the tubular member 39, the clutch drive gear 38 and the clutch gear 44. It should be understood that this clutch gear 44 is a arranged so that it will make one whole revolution during the one-eighth revolution of the second gear 17 for operating contact strips. As this clutch gear 44 has made a counterclockwise rotation through an angle of about 300, this clutch gear 44 pushes the pawl 47a upwardly by its cam portion 45a. On the other hand, the drive clutch lever 47 and the follower clutch lever 48 are caused by this clutch gear 44 to rotate counter-clockwise against the force of the spring 50 in such a way that the pawl 48a is detached away from the tooth 46a of the ratchet gear 46. When this pawl 48a has departed from the tooth 46a completely, the clutch disk 41 is instantaneously rotated counter-clockwise, via the pin 42, for an amount, i.e., one-eighth revolution, until this pin 42 is brought into contact with the other end portion of the slot 17a of the second gear 17 for operating contact strips, by virtue of the restoring force of the drive spring 43. In accordance with this movement, the contact strip attachment plate 51 is rotated. Also, as the pawl 48a has departed away from the tooth 46a completely, the cam portion 45a will disengage from the pawl 47a immediately after said departing of the pawl 480, so that the two

clutch levers

47 and 48 are caused by the force of the spring 50 to rotate counterclockwise. As a result, the pawl 48a is brought into engagement with the next tooth and thus a single intermittent feed completes. This intermittent feed is performed for each whole revolution of the first gear for operating contact strips. However, in accordance with thisfeed, the respective contact strips 52b-52d which are located on the printed circuit plate 21 side and which till then have been invariably in noncontact with their corresponding annular patterns 59-61 will be rendered successively to the following state such that the contact strip 52d will contact the enlarged portion 61a of the pattern 61, and then the contact strip 52c contacts the enlarged portion 60a of the pattern 60, and thereafter the contact strips 520 and 52d will contact the enlarged portion 60a of the. pattern 60 and the enlarged portion 61a of the pattern 6 1 in this order. Next, the contact strips 520 and 52d will contact the enlarged portion 60a of the pattern 60 and the enlarged portion 61b of the pattern 61, respectively, and the contact strip 52b contacts the enlarged portion 5% of the pattern 59. Then, the contact strips 52b and 52d will contact the enlarged portion 59a of the pattern 59 and the enlarged portion 610 of the pattern 61, respectively. Next, the contact strips 52b and 52c will contact the enlarged portion 59a of the pattern 59 and the enlarged portion 60b of the pattern 60, respectively. Thereafter, in the same way, the contact strips 52b, 52c and 52d will eventually contact the enlarged portion 59a of the pattern 59, the enlarged portion 60b of the pattern 60 and the enlarged portion 61d of the pattern 61, respectively. Thus, eight different kinds of combinations will be formed.

As stated above, according to the present invention, by virtue of the combinations of eight different kinds of contact and non-contact between the three

annular patterns

59, 60 and 61 and their corresponding contact strips 52b, 52c and 52d on the printed circuit plate 21 side, and of eight different kinds of contact andnoncontact between the three

annular patterns

55, 56 and 57 and their corresponding contact strips 52b, 52c and 52d on the printed circuit plate 20 side, there can be selected 64 channels in succession as shown in FIG. 8.

Also, in accordance with the aforesaid successive selection of channels, each of the channels selected is indicated by the flap-type indicating means shown in FIG. 4.

In the aforesaid embodiment, description has been made on an example wherein the contact strip attachment plate 51 is rotated by the first gear 15 for operating contact strips and also by the clutch disk 41. It should be understood, however, that conversely arrangement may be made so that the printed

circuit plates

20 and 21 are rotated. In order to attain this, it is only necessary to short-circuit the respective patterns of the printed circuit plates, respectively, and to attach lead wires to the respective contact strips, respectively.

Description has been made on an instance wherein all of the 64 channels can be selected. In case it is intended to be able to select more number of channels, for example 82 channels, it is only necessary to additionally provide another annular pattern on either one of the printed

circuit plates

20 and 21 and to provide additional contact strips accordingly.

We claim:

1. A tuner for television broadcast receivers comprising a first gear member rotatable intermittently in accordance with the broadcast channel selecting operation, a first plate member secured to said first gear member and having a plurality of first contact strips on its side face, a first printed circuit plate positioned against said first plate memberand having a plurality of conductive patterns contactable with said first contact strips, respectively, a second gear member interlocked with said first gear member, a clutch cam member interlocked with said second gear member and having at least a stepped cam portion thereon, a clutch disk member positioned adjacent to said second gear member and capable of being rotated by said second gear member and having a plurality of second'contact strips on its side face, a spring connected between said second gear member and said clutch disk, a second printed circuit plate positioned against said clutch disk member and having a plurality of conductive patterns contactable with said second contact strips, respectively, a ratchet gear coupled to said clutch disk, a clutch lever engageable with said stepped portion of said clutch cam member, and a follower clutch lever coupled to said clutch lever and engageable with said ratchet gear, said clutch disk being instantaneously turned to the roing to claim 1, in which said first and second printed circuit plates have a printed circuit comprising concentrically formed annular patterns to compose three bits binary code, respectively, and said first and second contact strips are arranged radially on said first gear member and clutch disk, respectively.

Claims

1. A tuner for television broadcast receivers comprising a first gear member rotatable intermittently in accordance with the broadcast channel selecting operation, a first plate member secured to said first gear member and having a plurality of first contact strips on its side face, a first printed circuit plate positioned against said first plate member and having a plurality of conductive patterns contactable with said first contact strips, respectively, a second gear member interlocked with said first gear member, a clutch cam member interlocked with said second gear member and having at least a stepped cam portion thereon, a clutch disk member positioned adjacent to said second gear member and capable of being rotated by said second gear member and having a plurality of second contact strips on its side face, a spring connected between said second gear member and said clutch disk, a second printed circuit plate positioned against said clutch disk member and having a plurality of conductive patterns contactable with said second contact strips, respectively, a ratchet gear coupled to said clutch disk, a clutch lever engageable with said stepped portion of said clutch cam member, and a follower clutch lever coupled to said clutch lever and engageable with said ratchet gear, said clutch disk being instantaneously turned to the rotational direction of said second gear member by action of said spring tensioned by disengaging said follower clutch lever from said ratchet gear by the rotation of said clutch cam member interlocked with said second gear member, thereby the connection between said contact strips and conductive patterns is changed over instantaneously.

2. A tuner for television broadcast receivers according to claim 1, in which said first and second printed circuit plates have a printed circuit comprising concentrically formed annular patterns to compose three bits binary code, respectively, and said first and second contact strips are arranged radially on said first gear member and clutch disk, respectively.