Патент USA US3162743код для вставки
Dec. 22, 1964 3,162,728 R. E. PFISTER _ STEREO-SOUND REPRODUCING DEVICE Filed Nov. 2, 1962 "In INVENTOR. J1 ?le/‘zigzag, United States Patent Office 1 3,162,728 STEREO-SOUND REPRODUCING DEVICE Robert E. Plister, 1170 Logan Ave., Elgin, Ill. 3,162,728 Patented Dec. 22, 1964 2 An audio frequency transducer 44 is connected by leads 22 to the secondary of transformer 20 whereas the second ary of transformer 18 has a pair of leads 23 connected to a 1.3 volt lamp 24 for a purpose to be explained Filed Nov. 2, 1962, Ser. No. 234,965 presently. Similarly, leads 25 connect a second audio 1 Claim. (Cl. 179-4) frequency transducer 26 to the secondary of transformer The present invention relates in general to improv 21, and leads 27 connect the secondary of transformer ments in sound reproducing equipment and is more spe 19 to a 1.3 volt lamp 28 for purposes also to be explained ci?cally concerned with improved stereo-type of sound presently. The inclusion of these low voltage lamps, one reproducing apparatus, such as a stereo-record player, in each channel circuit, results in no noticeable loss of having remote speaker means selectively connected with 10 gain. A pair of ganged switches 29 arranged in the one output channel and including novel means for elimi input circuits to the transformers affords means to effec nating channel interference and extraneous record surface tively make the lamps non-functioning in instances of noise. use when their function is not desired. In known stereo-type sound reproduction, the inactive 15 Leads 215 to audio frequency transducer 26 includes a output transducer or speaker has a tendency to emit jack switch 31 into which may be inserted a jack 32 sounds of channel interference and spurious record surface having ?exible leads 33 of any desired length connected to noises. This is particularly annoying when one considers an auxiliary audio frequency transducer 34- which pref that in a system intended for children’s use, the records erably is enclosed in the body of a doll or other character will accumulate a certain amount of surface noise over a 20 representation 35. Preferably, and for full effect, the short period of time. This surface noise, when present character representation 35 is in substantial conformance in the inactive audio frequency transducer would have a with the subject of the stereo recording. The effect of detracting effect upon the active audio frequency trans animation by use of the doll representation may be ducer were it allowed to exist. In order to eliminate such unwanted sound, applicant has provided novel means to decrease the input gain to the inactive audio frequency enhanced by providing the body of said representation with an opening 36 to permit the insertion of the oper ator’s hand or ?ngers for manipulating features of the ampli?er and it is one of the objects of the invention representation. to accomplish this result. In use, insofar as described, only one channel of the Another feature of this invention is the effective re stereo-record player is audible at any one time. For moval of so-called cross channel modulation. The novel 30 example, the channel connected with transducer 21 may means provided herein effectively removes this type of be utilized to emit background sounds or to be inaudible, unwanted sound and is one of the objects of this in whereas the channel including transducers 26 or 343 may vention. emit spoken words, vocal accompaniment or be silent. The invention also contemplates the provision of a When only one channel is active it is the purpose of this modi?ed stereo-record player ampli?er system having 35 invention to eliminate all channel interference such as therein means to separate the audio output of one of the extraneous record surface noises and cross channel modu two stereo channels and deliver it to a remotely placed lation normally emitted from the audio transducer that audio transducer connected into one channel. As one is not active. example of a use of this arrangement the remotely placed To accomplish this each lamp 24, 28 has associated audio transducer may be arranged in the body of a 40 with it so as to be in?uenced by the degree of light dummy representative of, for example, a doll or animal, emitted from the related lamp, a cadmium sulphide vari and of a type and character to match the story or sound able resistance type photocell 37, 38 respectively. These produced in the selected channel. The audio output of photocells have a dark resistance of approximately 10 the other channel is delivered to the usual audio fre megohms which lowers to about 200 ohms in strong light. quency transducer of the system and, if desired, the Preferably, a re?ector 39 is associated with each lamp and remote ampli?cation can be terminated at will and the each lamp-photocell assembly is enclosed in a light-tight audio output formerly fed to the remote transducer can case 41 for maximum light absorption by the photocell. be directed to the second- audio transducer in the player. The output of one photocell, for instance photocell 37, Another object of the invention is to provide such a is placed across the input circuit of audio frequency system. 50 ampli?er 17, through lead 4-2. The output of the other Another object is to provide a stereo-record player and photocell 38 is placed, by lead 43, across the input circuit remote audio transducer combination of the character re of audio frequency ampli?er 16. ferred to. Because each photocell perceives light only from the The structure by means of which the above noted and lamp with which it is associated, the resistance varies other objects and advantages of the invention are attained inversely with the light strength. Therefore, the stronger will be described in the following speci?cation, taken in the light the lower the resistance of the related photocell. conjunction with the accompanying drawings showing a Now, because the photocell 37, for example, is connected schematic representation of a stereo-record player and across the input to ampli?er 17, there is a decrease in representative illustration of electronic components and input gain to this ampli?er when the output of audio a character representation associated therewith for carry 60 frequency transducer 44 is active and visa versa. ince ing out the features of the inventionl , the dark resistance of the photocells is high, their con Referring to the exemplary disclosure of the invention nection with the input to the respective ampli?ers does not shown in the accompanying drawings, the stereo-system ‘ affect the signal so long as no modulation is present on includes any conventional type of stereo-record player in the opposite ampli?er. When audio is present in a given cluding a stereo pickup cartridge 11 and conventional 65 transducer and the resistance of the photocell is reduced, potentiometers i2, 13 arranged in input lines 14, 15 a reduction of gain in the other channel is noted. In to audio frequency ampli?ers 16, 17 respectively. The this manner any interference and spurious record surface output from said ampli?ers is connected to the series noise in either channel is completely eliminated while the hook up output audio frequency transformers 18 and 20, other channel is active, the exact degree of elimination 19 and 21 respectively. In the present instance each 70 being dependent upon the percent of modulation present transformer 18, 19, 20 and 21 has a secondary impedance in the opposite channel. Photocell saturation occurs at a of about 3.5 ohms. ' level just below normal room volume hence, as long as 3,162,728 4 3 each audio frequency ampli?er speakers, one connected the volume controls 12, 13 are in a normal listening posi tion, or above, the system will function satisfactorily. At any level less than normal, cross channel interference and to the output of one transformer of each pair of trans formers, a photo-cell connected to the input circuit to record surface noise is of no consequence the audio frequency ampli?er in one ampli?cation system, a light source for said photo-cell connected to the sec It might be noted also that due to the slightly delayed return response of the lamp and photocell at saturation, ondary of the other audio frequency transformer in the pair of transformers in the other ampli?cation system input to the opposite ampli?er is completely attenuated effective when the speaker in said other ampli?cation not only during modulation of the opposite ampli?er but system is active to attenuate signal input to the ?rst named also during short pauses between words and phrases. It will be apparent that when either audio frequency 10 audio frequency ampli?er, and switches in the circuits to said light sources operative to shunt the respective trans transducer is active, the opposite transducer is inactive and formers to render the respective light source ineffective. that substantially all unwanted noise normally emitted from the inactive transducer is eliminated and that for normal speech, audible in one channel, the opposite channel will remain silent. 15 Although applicant has disclosed herein a representa tive embodiment of the invention, it is to be understood that the disclosure is by way of illustration and not limita tion and that the invention is capable of embodying a variety of modi?cations. in detail structure and application 20 without departing from the spirit and scope of the appended claim‘ What I claim and desire to secure by Letters Patent of the United States is: In a stereo-record player of the type including a dual 25 audio frequency signal ampli?cation system, an audio frequency ampli?er in each system, a pair of‘ audio fre quency transformers connected in series to the output‘ of References Cited by the Examiner UNITED STATES‘ PATENTS 2,110,358 3/38 Dreisbach ____________ -_ 179-1 2,205,447 6/40 Wallace et a1 __________ __ 179—1 2,247,329 2,335,575 6/41 11/43 Deitz ________________ __ 179—-1 Bierwirth _____________ __ 179-1 2,379,768 7/45 Van Wynen ________ __ 179-—170.6 2,495,809 2,748,201 2,839,616 1/50 5/56, 6/58 Graham ______________ __ 179-1 McMillan ___________ __ 330—84 MacMillan __________ __ 330-59 3,020,488 2/62 De Miranda et al. ____ __ 330~59 3,047,670 3,079,463 7/62 2/63 Gardner ______________ __ 179-1 Feldman ____________ __ 179—1.5 ROBERT H. ROSE, Primary Examiner.