Pleyel Patent - 1924
Patent Specification
Convention Date (France): Nov. 29, 1922.
Application Date (in United Kingdom): Nov. 8, 1923   No. 28.185/23.
Complete Accepted: Nov. 27, 1924.

Complete Specification

Improvements in Syncrhonizing Systems.
[Note: this explanatory page should be read in connection with this illustrated Webpage on our site:
 Illustration of Pleyel Patent for Synchronizing instruments]


    We have posted the original English Patent text below, complete with all the strange punctucation and odd terminology, just as it appears on the original documents at The Patent Office in South Wales. Generally speaking, the fuzzy monologue can be simplified by calling the "master" a "master" and the "synchronouus member" a "slave unit". The cycle of 3 perforations — called G (Guide or Govern, perhaps?), A (Accelerate) and R (Ritard) — cause the "master" and the "slave unit(s)" to operate the roll, or other devices, at the same speed.

    If all is working together, properly, nothing happens. If the "master" and "slave" are out of synchronization, then the G perforation activates a series of commands which cause the system to accelerate or ritard the other music roll. A or R perforations must "overlap" the G before these tempo adjustments will take place. Also, all the rolls must be equipped with these 3 perforations in sequence for the Pleyel system to function; the "master" and "slave" rolls have to be perforated in advance for these automatic tempo adjustments.

    Part of the text which follows concerns the operation of what most Pianola owners would easily recognize as a standard style of a music roll "tracking device" ... only it has been adapted to operate the sliding "tempo control" found on typical pneumatic player actions.

    Insofar as American companies experimented earlier with multiple organ rolls, phonographs synchronized with player rolls and automatic tempo adjustment "control" perforations, there might be some question about the validity of this patent, were to it be challenged in the States and abroad, in 1924. (With the Vitaphone on the horizon and radio in many homes, probably few companies cared to question the originality of these Pleyel claims.)

    It takes a dedicated person to read through the Patent text which follows, primarily due to the poor sentence construction and the muddled descriptions of what seem to be rather simple concepts, at least for those familiar with Player-Piano actions..

    [At this time, the Drawings on the companion page can be viewed with great detail in Netscape Communicator and Navigator, as well is Internet Explorer. (For some reason, Opera 5.02 reproduces that illustration in a distorted fashion, but we hope to correct this, possibly by rephotographing the Patent Drawing in the near future.)]

    Finally, even if you don't wish to read the original text below, we suggestion that you scroll down to the ADDENDA ... or use this Link. There are some important theories about this Pleyel device, which might be of interest to you.

Jump to the ADDENDA
Click Here

    We, Société Pleyel Société Anonyme, of 22, rue Rochechouart, Paris, France, a French company, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement: —

    This invention relates to a synchronizing system, available for various applications, to automatic instrument or mechanical apparatus, amongst which may be mentioned by way of example, automatic musical instrument, kinematographs, phonographs, these several apparatus being naturally in any number.

    The general principle is the following: As illustrated in the accompanying drawings Figs. 1 to 4 and apparatus called "master" adjusts the movement. One or more other apparatus is to be controlled in such manner as to move in synchronism with the master. These are the apparatus called synchronized or to be synchronized. The movement of the master produces periodically a phenomenon G. The movement of each of the synchronized apparatus produces periodically two phenomena; one called accelerating, noted by A, which can only react thereon, the other called retarding, denoted by R, which also can only react thereon. The three phenomena follow each other in the order R, G, A, R, G, A, R, etc. Each of the phenomena is adjusted so that in case of synchronism the end of R coincides with the beginning of G, and the end of G coincides with the beginning of A.

    On the other hand, the arrangement is such that each of the phenomena A or R only really operates by accelerating or retarding the synchronous member, if it overlaps the phenomenon G, that is to say, if at a given moment the two phenomena, G of the master and A of the synchronous member, or G or the master and R of the synchronous member are coincident. From this point if the synchronous apparatus is slow with respect to the master the phenomenon A lagging over G, comes into operation and accelerates the synchronous member.

    If on the contrary the synchronous apparatus is fast with respect to the master, the phenonmenon overtaking G comes into operation and retards the synchronous member.

    The essential principle of the apparatus consists therefore, as above stated, in the slowing down of the synchronized apparatus which are fast, and the acceleration of the synchronized apparatus which are slow by actions controlled simulteneously by the "master" and by each synchronized member.

    With the assistance of any arrangement which should not introduce any retardation, and is suitable for the kind of apparatus in view, the proper movement of the master apparatus causes with known aperiodicity the working of a mechanical, electrical or pneumatical control during a fixed time, whilst the synchronized member or members also each of them cause with corresponding aperiodicity the alternative working of two similar controls.

    It is easy by means of the graph No. 1 to represent the time during which these controls operate; it comprises three horizontal parallel lines, equally divided by vertical lines. The controls are shown by thick lines and the periods of rest by thin lines, successive times are shown by the numerals 1,2, 3 etc.

    The series of controls marked G relate to the "master" apparatus, the two others A and R relate to one of the synchronized members. If t is the duration of each control, it will be observed that the period of rest is twice t, the cycle being equal to three times t, so that each line of control consists of a period of action t and of a period of rest 2t. When the apparatus are running normally, ie. when there is perfect synchronism, the two series A and R register with the series G, in other words the three series of controls A, G, R, follow each other at the times

    o        t    2t       3t        4t        5t       etc.
    G       A      R        G        A         R    etc.

    A is displaced with respect to G by one period and R by two periods: thus they never coincide two by two.

    It follows that there are three cases to be considered, starting from an initial condition assumed to be normal:

    Firstly, the speeds of the master and of the synchronized members remain equal; this is the case in the graph, Fig. 1. The operation of the speed governor should then naturally be nil, it follows that the controls A and R should have no effect; the arrangement according to the invention must fulfil this condition.

    Secondly, the synchronized member gains, which means that owing to some external cause, its speed increases, generally slightly. This case is shown in the graph, Fig. 2, and the hatched rectangles S show the time during which the two controls coincide.

    In accordance with the invention the two controls then working simultaneously during a portion of their period, operate in a retarding direction the speed governor of the synchronized member, these operations are repeated and continue until there is coincidence, only stopping when R is correctly displaced with respect to G, as shown at S1. At this instance the speeds have become equal again and synchronism is re-established.

    Thirdly, the synchronized member loses; in this case the coincidences will naturally then be manifested between G and A and the change produced according to the invention will be one of acceleration. The small graph, Fig. 4, shows the relative positions of G, A and R in the three casees; the first column on the left relates to the normal running, the second to the case when the synchronized member is slow and the third to that when it is fast.

    From what has been said it follows clearly that it is necessary to have a member such as the controls A and R of the graph, causing respectively the acceleration and the retardation of the apparatus to be synchronized as soon as the said controls operate at the same time as the master control G, i.e. until the displacements of A or of R with respect to G disappear.

    In the graphs which have served to illustrate the principle which is the basis of the system, the controls are shown as being of equal duration; this condition the object of which was merely to simplfy the explanation of the system, is in no way essential and controls of unequal duration, such as shown in the graph, Fig. 3, may also be included; it will suffice merely to arrange them in such way as to ensure the necessary corrections for bringing about synchromism, i.e.  that in the case of synchronism the end of R should coincide with the beginning of G, and the end of G wih the beginning of A.

    It is clear that the system explained is capable of being carried out in various ways: including electrical, mechanical or pneumatic means.

    By way of example of carrying out the invention, there will be described apparatus intended to insure the synchronous operation with the automatic master piano or one or more other automatic pianos; in this case as pneumatic controls can be used simply, these latter have been retained.

    The apparatus will be described with reference to Fig. 5 of the accompanying drawings which is a diagram of the aggregate of the arrangement.

    A partial vacuum practically constant is maintained in a wind-chest 1 of a pneumatic piano of usual construction; this wind-chest is connected by a pipe 2 to the "master" control member. The wind-chest is provided with a diaphragm 4, on which rests the rod of a valve 3, which when it rises, as will be explained subsequently, can put the said wind-chest into communication through the pipe 5 with a box provided with two valves 6 and 7, similar to the valve 3; the rods of the said valves resting on diaphragms 61 and 71, respectively. The compartments in which valve 3, 6 and 7 are located normally communicate with the atmosphere by suitable openings, clearly shown above them in the diagram. The valve-box is connected at the bottom below the diaphragms 61 and 71 to the pipes 8 and 9 respectively. The pipe 8 communicates with the control which has been called A and the pipe 9 with the control R: their capillary tubes as is customary in pneumatically operated pianos communicate with the vacuum wind-box.

    The compartment which serves as seat for the valve 6 communicates through a suitable pipe with the left-hand side 10 of a double bellows 12, whilst the compartment of the valve 7 communicates through another pipe with the right-hand side 11 of the bellows 12. The two faces of this double bellows are moveable and connected together by a tie-rod 18, so that when the partial vacuum is greater in 11 than 10, the aggregate of the two movable faces oscillates towards the left and vice versa.

    The side 10 of the bellows 12 is provided with a pivoted screwed rod 14 on which is a double nut 13 to which is attached a pointer 15 which moves in front of a scale 16 when the bellows is in operation, as will be explained later.

    The operation takes place as follows: —

    In normal working the bellows 10 and 11 are in communication with the atmosphere, as also is that portion of the wind-chest in which the valve 3 is located. The partial vacuum which exists in the wind-chest 1, of course also exists in the pipe 2, when its end is closed. The control of the master will only make itself felt when pipe 2 is opened.

    As soon as this control operates the valve 3 rises, the atmospheric pressure acting on the diaphragm 4, which in urn acts on the rod of the valve. The effect of this rising is to place the lower portion of the valve box in communication through the pipe 5 with the wind-chest 1 in which there is a partial vacuum.

    The valves 6 and 7 operate similarly. These two valves serve as interrupters and the initial partial vacuum extends to the compartment 10 or 11 of the double bellows 12, only when the valves 3 and 6 or 3 and 7 respectively operate simultaneously.

    At starting the compartments 10 and 11 are at atmospheric pressure. The speed of the synchronous member has been previously adjusted by means of a suitable device shown diagrammatically at 17 in such way that this speed is practically equal to that of the master. Having obtained this equality, the double bellows is adjusted to the mid-position by means of the nut 13 on the screwed rod 14, to correspond practically with the equality of speeds.

    The oscillations of the double bellows 12 caused by alterations of pressure in the compartments 10 and 11 control the accelerations or retardations of the synchronous member by means of the governor 17. In the drawing if the compartment 10 empties partially, the double bellows oscillates towards the right. In this event the governor 17 ought to cause the gaining of the synchronous member.

    In the case of an automatic piano the governor is constituted by the tempo box. It may also be constituted by a member independent of the motor governor, increasing or decreasing a supplementary passage for exhaust air which starts up the motor. For any other apparatus, this governor would be a box or speed changer suitable to the nature of the apparatus.

    For the operation itself of the apparatus the alternations introduced into the speed of the synchronous member may be observed continuously by means of the movements of the indicating pointer 15 over the scale 16.

    If the corrections introduced by the apparatus in the speed of the synchronous member take a systematic course, it will be necessary to alter the initial rate of the syncrhonous member, as well as the adjustment of the nut 13, making the use of the readings of the pointer.

    If for example the compartment 10 is constantly collapsed, the rate of the synchronous member would be too slow: suppose that the mean normal reading on the scale 16 is 100; it would be necessary to stop the apparatus, change the speed in an accelerating direction by operating on the governor 17, bring back the bellows 12 into equilibrium and adjust the nut 13 so that the mean position of the bellows 12 may correspond to the position marked 100 by the pointer on the scale.

    As has been stated previously, the carrying out in practice of the controls G, A and R consists for example, in the case of two automatic pianos in the opening to the atmosphere of the pipe 2 on the one hand, 8 and 9 on the other. It will now be explained how this communication with the atmosphere is effected.

    In a general way it will be done by the passage over the two tracker ducts of the two automatic pianos of paper having in it a series of special perforations, made for this purpose in the two perforated rolls which make the two pianos play.

    There is a series G of perforations on the roll which passes over the tracker duct of the apparatus G. These perforations are made beforehand on the perforated roll in such way as to produce the series of controls G, under the conditions which have already been laid down in the theoretical part of the description.

    In a similar way there is the double series A and R of perforations on the roll which passes over the tracker duct of the synchronous piano and similarly these perforations are made beforehand on the perforated roll of the synchronous member so as to produce the double series of controls A and R under the conditions specified above.

    Before starting the two rolls of the master and of the synchronous member are put in position under conditions such that on the simultaneous starting up of the two apparatus, i.e. from the simultaneous start of the unrolling of the two rolls the theoretical conditions explained above of the overlapping of the series of controls G by the two series of controls A and R might immediately be brought about.

    Several synchronous members may be adjusted simultaneously by the master, the wind-chest 1 is then common to all, and the pipe 2 single, but there are as many pipes 5 and apparatus (8, 9,12, 13 and 17) as there are synchronous members to be adjusted.

    The capacity of the compartments 10 and 11, the length of the lever-arm 13-14, the sensitiveness of the governor 17 have to be settled in a way suitable to each category of synchronous apparatus considered.

    For certain apparatus it may be desirable to modify the duration of the controls 8 and 9 of the synchronous members once the duration of the controls 2 has been judiciously chosen, in such manner as to suit all the synchronous members in use. Periodicity itself is not essential, as has been clearly explained at the commencement for the case iillustrated by the diagram Fig. 3.

    It has been stated above that the controls may include electrical, pneumatic or mechanical means, which is obvious; but it may be useful to point out summarily in what way they may be carried out in these cases. For any other apparatus than an automatic piano, the controls G, A and R may be carried out as follows:

    A cam of suitable shape attached to a shaft driven with a rotary movement the speed of which is proportional to the speed of the master apparatus or synchronized member operates the periodical closing of an electric circuit.

    The periodic currents thus set up actuate an electro-magnet. This electro-magnet opens and closes periodically the pipes 2 (or 8 and 9) to the atmosphere accordingly as it is a question of a master or of a synchronized member.

    For example to carry out the series of controls G of Fig. 1 there may be provided a cam closing the circuit during a period equal to one-third of the period of rotation of the shaft carrying the cam, and opening the circuit the other two-thirds.

    The electro-magnet above mentioned will then open the pipe 2 to the atmosphere during the fixed period equal to one third of the period of rotation of the shaft, and will close this pipe during double this period; or the cams may control the pipes 2, 8, 9 directly.

    Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:—

    1. An improved synchronizing system, applicable to automatic instruments or mechanical apparatus generally and particularly to automatic pianos, comprising a master apparatus controlling the synchronism of the other apparatus in the system each of the latter being provided with two similar mechanisms, one for accelerating and the other for retarding and the control operating only when there is a concurrence of one or other of the latter mechanisms with a mechanism operated by the master apparatus.

    2. In a synchronizing system as claimed in Claim 1, the arrangement of the master apparatus in such a way that at intervals generally equal it acts to vary the speed of the apparatus to be synchronized only when they are out of synchronism but does not act thereon when they are working normally.

    3. A synchronizing system as claimed in Claim 1, which is operated pneumatically and wherein the master apparatus and the apparatus to be synchronized therewith are each provided with a suitably perforated band, the perforations being arranged in such manner that adjustment of apparatus out of synchronism only takes place when a perforation of the band of such apparatus is in position simultaneously with a perforation of the band of the master apparatus, and such adjustment will continue so long as this coincidence exists.

    4. A synchronizing system as claimed in Claim 1, which is operated electro-pneumatically and wherein a cam in the master apparatus effects the periodic closing of an electric circuit, the period currents thus set up controlling the adjustment of the apparatus to be synchronized.

    5. A synchronizing system as claimed in Claim l which is operated mechanico-pneumatically and wherein a cam in the master apparatus effects the adjustment of the ap-aratus to be synchronized.

    5. The improved synchronizing system substantially as described with reference to the drawings.
Dated the 8th day of November 1923
A. S. CACHEMAILLE - Chartered Patent Agent
2, Norfolk Street, Strand, London W. C., Agent for the Applicants

Redhill: Printed for His Majesty's Stationery Office, by Love & Malcomson, Ltd. — 1924


    It turns out that the Pleyel Company did construct at least one player  which synchronized music with another instrument, and that was in the year 1929.  This machine still exists and is scheduled to be rebuilt in Europe, within the very near future.

    While we are not at liberty — at this time — to go into detail about the surviving Pleyel instrument ... we can state 2 definite things about the design:

1.) The invention had NOTHING TO DO with George Antheil's "BALLET MECANIQUE" and was in development before he came to Paris, while the existing instrument was built after he went on to other pursuits. It was not designed for "synchronizing" 16 pneumatic Player-Pianos as has been stated by those connected with the modern presentations using erratic solenoid players ... which were, in essence, performing a score that was written for 4 standard pianos, at most.

    The Pleyel patent probably had to do with "synchronizing" music rolls with silent movies — as well as being used to accompany a separate solo instrument, as in the 1929 model which exists today, complete with 1 roll featuring the 3 control holes: "G", "R" and "A".

    A Fotoplayer™ featured 2 music rolls (which "BALLET MECANIQUE" was originally composed for) and this, given the tympani and sound effects inherent in the silent movie accompaniment instrument, could have been used as follows: a Pianolist could operate 'everything' as a SOLIST with the Pleyel equipment "synchronizing" with the Fernand Léger motion picture ... the projector's variable speed electric motor and the music rolls being equipped with the "G/R/A" control perforations, as explained in the patent text and drawings, above.

  2.) The Pleyel synchronization patent was used for a mechanical piano performance in tandem with a second instrument ... and this was probably the original concept, especially after talking pictures destroyed the Fotoplayer™ market, by the late 'Twenties.

    We will update this ADDENDA, which pertains to the Pleyel patent, as more information comes to light. For our time, the best way to enjoy the experimental and exciting Antheil music is via the traditional SOLO Pianola ... using our 1991 Interpretive Arrangements which completed the musical ideas that eluded the talented composer in his own day.

L. Douglas Henderson - ARTCRAFT Music Rolls
Wiscasset, Maine 04578 USA
March 30, 2001

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