US2431051A

US2431051A - Power supply system

Info

Publication number: US2431051A
Application number: US486199A
Authority: US
Inventors: Henry N Kozanowski
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1943-05-08
Filing date: 1943-05-08
Publication date: 1947-11-18
Anticipated expiration: 1964-11-18
Also published as: GB606371A

Description

Nov. 18, 1947. H. N. KozANowsKl POWER 4SUPPLY SYSTEM Filed May 8, 1943 Hiob INVENTOR. Jnry )1L Ifzanow/ii/ Patented Nov. 18, 1947 POWER SUPPLY SYSTEM Henry N. Kozanowski, Collingswood, N. J., assgnor to Radio Corporation of America, a corporation of Delaware Application May 8, 1943, Serial No. 486,199

(Cl. Z50-27) Claims.

This invention is related to television apparatus and is particularly concerned with the power supply systems for use therewith.

In its more specific applications, the invention is related to a form of power supply system which is particularly useful in connection with mobile television equipment where it is desirable to provide a relatively Wide operating voltage range,

`both negative and positive, relative to a predetermined reference potential, such as ground, with an extremely simplified supply source.

It has been found in the use of certain forms of television apparatus, such as that type known as the Image Orthicon which incorporates a photo-sensitive electrode element, a resistance mosaic element which receives an electro-optical image thereof and is then suitably scanned, and also an electron multiplier unit which intensies the output signal resulting from scanning the photo-sensitive electrode, that it is usually desirable, and in fact substantially necessary, to provide operating voltages with predetermined ranges in both the negative and positive sense with respect to some element of the tube, such as the electron emitting cathode element, which is held at a fixed potential, such as ground. With such operation, a proper voltage gradient may be maintained in the tube when the photo-sensitive cathode upon which the light image is directed is operated negatively, relative to ground (e. g., at about -500 volts), and the electron multiplier unit is operated at a positive voltage relative to the cathode and to ground (e. g., at about +500 volts). Within the assumed voltage range, other intermediate positive (or negative) values may be used to provide proper focusing and operation of the tube.

When the system of the foregoing type is to be used in connection with mobile equipment, it is important to provide the foregoing voltage range by means of equipment which is both compact and free from hum, and yet which will provide both the positive and negative voltages from a single power supply unit.

In television apparatus, as now customarily used. the light image is cast upon the photosensitive target element of the scanning or camera tube and is then scanned by a cathode ray beam to produce the television or Video signal. Where high denition ilickerless scanning is to be produced, the scanning pattern usually divides the image into more than ve hundred lateral scanning traces or lines and each of these complete scannings is repeated at about thirty times per second, With the pattern scanned interlaced f Where desired. The result is that the cathode ray beam Which is to scan the light sensitive photo-cathode or mosaic must be deflected in a suitable manner to scan in excess of fifteen thousand picture lines per second, although in the direction normal thereto the scanning is only at a rate of about thirty picture fields in the same time period.

The above suggested scanning sequence is merely one of many. In some uses of the system, it is of course apparent that the number of picture lines may be reduced and the number of picture frames per unit of time increased, and the scanning may even be Sequential rather than interlaced. Such changes are usually made at times mainly in the interest of the simplicity of circuit and operation and relative freedom from dicker.

The line deilection is usually accomplished by energizing suitable line deection coils with an electrical energy wave of such form as to cause this deflection to occur along a saw-tooth pattern, that is, the deliection for each scanning line takes place at a substantially uniform rate and, when accomplished, the scanning beam snaps back abruptly to scan the next succeeding line. To this end, the current flowing through the deflection coils for deflecting the scanning beam is of saw-tooth wave formation with the saw-tooth frequency coinciding with the line deection frequency.

In this connection it Will be appreciated that the return-period (also known as the backkick) offers a wave shape of energy of such steepness and energy content that suggestions have already been made in the art to utilize such portion of the deflection energy wave to energize a rectifier element whose output would be a direct current which could be suitably smoothed and freed from ripple eiects to provide the tube operating voltages. However, all such arrangements of the prior art were of such type that the D. C. and the A. C. circuits could not readily be separated one from the other, and it was not possible to provide any convenient means Whereby the rectier arrangement could provide suitable voltages for operating the system in such a Way that one portion could be operated negatively relative to a xed reference potential point, or ground, and another portion could be operated positively relative to the established reference point, or ground.

To this end, the present invention is so constituted as to include a suitable relay tube to which the defiection energy is applied for transfer through any appropriate inductive coupling means, such as the deection output transformer7 to drive electron beam cleliecting coils of the scanning or camera tube. The invention also provides a suitable rectifier element to which the so-called back-kick energy of the beam deflection Wave is supplied by way of a, capacitive coupling element. To provide the voltage division, a voltage divider is connected across the rectifier to provide a direct current path and,

.ikewise, the cathode element of the rectifier is :onnected capacitively to the Xed reference point, such as ground, so that it operates at ground A. C. potential. By making a connection from the ground point to a suitable intermediate point on the voltage divider, a symmetrical voltage division both positive and negative relative to ground may be made by the voltage divider. With the connection to ground made at other points, an unequal voltage division in both the positive and negative sense, relative to ground, may be had. Also, intermediate voltages may be readily obtained by intermediate connections between the ground connection point and the outer terminals of the voltage divider unit.

In accordance with the foregoing brief description and explanation of the invention, it becomes an object of the invention to provide a television system wherein operating voltages of both positive and negative sign, relative to a ground or fixed potential, may be delivered from a single rectifier unit which is energized under the control of the energy supplied to the electron beam deiiecting coils of the television camera or scanning tube. Y

A further object of the invention is that of providing a circuit whereby the relatively high operating voltages required for controlling cathode ray types of television apparatus may be obtained from the energy applied to suitable deecting coils for controlling the electron beam motion within that apparatus.

Other objects of the invention are those oi providing a power supply system for cathode ray apparatus wherein regulation, due to the high resistance voltage dividers which inherently form part of the power supply unit, is not a great problem since the current drain is usually of the order of micro-amperes.

Still other objects of the invention are those of developing a power supply system for cathode ray apparatus which eliminates hum difficulties by means oi" simplified filtering units and, at the same time, provides a definite lock-in between any resulting hum conditions and the scanning action with the cathode ray apparatus to nullify thereby the possible eiects of such ihmnj Other and further objects of the invention are those of developing a power supply system particularly useful in connection with cathode ray apparatus where eioient separation between A. C. and D. C. circuits is obtained.

Other objects of the invention are those of providing a power supply system for television apparatus which overcomes one or more defects of prior art systems and, at the same time, provides a compact, eflicient and well-stabilized operating device.

Still other and further objects and advantages of the invention will become apparent to those skilled in the art to which it is directed when the following specications of one of the preferred forms of the described device are considered in connection with the single figure of the drawing illustrative thereof.

Making reference now to the drawings, electrical energy of substantially saw-tooth wave formation (as shown) is supplied from any convenient and well known deection energy source (not shown) to the input terminal il from which it is supplied by way of the coupling condenser I3 to the input or control electrode of a 4suitable thermionic ampliiier or relay tube l5. While this tube is shown as a triode. it is apparent that 4 other tube types, such as 6L6, may readily be used. The tube l5 is suitably biased by the leak resistor Il, in well known manner. Operating voltage is applied from a suitable energy source (not shown) which is connected to the terminal i9, as indicated.

The energy output from the tube l5 is supplied by way of the primary Winding 2| of the output transformer 23, whose secondary winding 25 connects to the load terminals 2l to energize the lateral or horizontal electron beam deecting coils (not shown) for deflecting the cathode ray beam generated within a cathode ray tube, such as the 'Orthicon type above suggested, or any other type such as the well known image reproducing tube types. While the energy appearing at the output terminals 2l is supplied to the deflecting coils of a cathode ray tube device, it will be appreciated that this invention is concerned primarily with a power supply arrangement and hence neither the coils themselvesy nor the auxiliary units, such as the well known damping tube circuits, are shown. Suitable ground connections for the tube elements and the A. C. connected output circuit of the tube l5are indicated at 29.

A condenser element Si connects by way of conductor 33 to the upper terminal point 35 of the transformer primary winding 2| to apply the back-kick energy Wave (of the general waveform shown) to a diode or other suitable rectifier unit 3l which has its anode or plate element Se connected to receive energy from condenser Si, and a connection to ground 29 for A. C. is provided through the tube cathode 4l by way of the condenser t3. The filter condenser Ll5, connected to one terminal of the load resistor l1 and to ground 29, has a low impedance to the frequency of the horizontal deflection energy, as compared to the capacity 3l, so that the cathode il may be maintained at ground potential as far as A. C. is concerned.

The voltage divider resistance i9 has one terminal directly connected to the cathode M of the reotiiier diode 9i' and its other terminal connects to the resistor @1, so that a return D. C. circuit for the tube 3l is provided which permits the connection oi an intermediate point on the voltage divider 49, such as point 5l, to ground 29. If the tapping point 5l on the voltage divider 49 is centrally located thereon, it will be apparent that voltages of equal value, but opposite polarity, may be obtained at the output terminals 53 and 55, with the polarity of the voltage as indicated by the drawings, and the desired positive and negative voltages are from a single deflection energy wave and a single rectifier unit, since the cathode element 4l of the rectiiier remains fixed relative to ground 29 at A. C, values, although it may differ from ground by any desired D. C. potential.

To this end, if it be assumed, for purposes oi illustration, that a voltage drop of 1000 volts occurs across the voltage divider i9 and the point 5l is at the mid-point oi the voltage divider, the voltages derived at the output terminals 53 and 55 will be -500 volts relative to ground 29 and +509 volts relative to ground 29, respectively. However, if the voltage divider resistor is uniform and the ground connection point 5| is located 10% of the distance between the negative and the positive end terminals 53 and 55 thereof, it will be evident that the output terminal 53 will then be at a voltage of volts relative to ground 29, while the positive output terminal 55 (that is,

derived simultaneously the cathode D. C. potential) will be at +900 volts relative to ground 29. Depending upon the location of the point 5|, various intermediate voltages relative to ground 29 may be derived at the auxiliary output terminals represented at points 51 and 59, for instance.

It accordingly becomes evident that suitable negative and positive voltages for the purposes above defined, for instance, may be derived across the voltage divider 49 and, for instance, where the power supply is to be used in connection with Orthicon apparatus (which devices have, per se, already been described in the literature) adequate voltages yfor providing for electron beam focusing, acceleration, and other tube operations are readily attained, as well as the voltages for extreme operating conditions. Still further, with the frequency of the back-kick impulses at the terminal 33 of the transfo-rmer 23 being relatively high, as aforementioned, filtering is simplified and, at the same time, any hum frequency resulting occurs at the deflection frequency and is not troublesome.

Having now described the invention, what is claimed is I 1. A power supply system for cathode ray television apparatus comprising a source of substantially saw-tooth wave formation electrical energy for energizing the cathode ray beam dew fiecting means of said apparatus, inductive means for supplying the said saw-tooth wave en ergy to the said cathode ray beam deflecting means, a thermionic rectifier element having at least a cathode and an anode, means to supply an impulse component of the energy in said in ductve means to the rectier to cause current flow therethrough, a resistive means connected between the anode and cathode of the rectifier, capacitive means for connecting the rectier cathode to a point of fixed potential, and means for connecting an intermediate point on the voltage divider to the point of fixed potential. whereby the outer terminals of the voltage divider are at potentials of predetermined opposite polarity relative to the said fixed point.

2. A power supply system for cathode ray television apparatus comprising a source of substantially saw-tooth wave formation electrical energy for energizing the cathode ray beam defiecting means of said apparatus, inductive means for supplying the said saw-tooth wave energy to the said cathode ray beam deflecting means, a therm- `ionic rectifier element having at least a cathode and an anode, means to supply an impulse component of the energy in said inductive means to the rectifier to cause a current flow therethrough, a resistive means connected between the anode and cathode of the rectifier, capactive means for connecting the rectifier cathode to a point of fixed potential, and a connection from a central point on the voltage divider to the point of xed potential, whereby the outer terminals of the voltage divider are at potentials of equal and opposite polarity relative to the said fixed point.

3. A power supply system for cathode ray television apparatus comprising a source of substantially saw-tooth wave formation electrical energy ,for energizing the cathode ray beam deflecting means of said apparatus, transformer means for supplying the said saw-tooth wave energy to the said cathode ray beam defiecting means, a thermionic rectifier element having at least a cathode and an anode, capacitive means to supply an impulse component of the energy in said transformer means to the rectifier to cause a uni-directional current flow therethrough, a resistive` means connected between the anode and cathode of the rectifier, capacitive coupling means forl connecting the rectifier cathode to a point of Xed potential, capacitive filter means connecting the rectifier anode to the said point of fixed potential to smooth ripple in the output thereof, and means for connecting an intermediate point on the voltage divider to the point of fixed potential, whereby the outer terminals of the voltage divider are at potentials of opposite polarity relative to the said fixed point.

4. A power supply system for cathode ray television apparatus comprising a source of substantially saw-tooth wave formation electrical energy for energizing the cathode ray beam deiiecting means of said apparatus, transformer means for supplying the said saw-tooth wave energy to the said cathode ray beam deflecting means, a thermionic rectifier element having at least a cathode and an anode, capacitive means to supply an impulse component of the sawtooth wave energy from said transformer to the rectifier to cause a uni-directional current flow therethrough, a resistive means connected between the anode and cathode of the rectifier, capacitive coupling means for connecting the rectifier cathode to a point of fixed potential, capacitive filter means having a. low impedance to the saw-tooth frequency relative to the capacitive coupling means connecting the rectifier anode to the point of fixed potential to smooth ripple in the output thereof, and a connection from an intermediate point on the voltage divider to the point of fixed potential to derive output voltage of predetermined opposite polarity relative to the said fixed point at the terminals of the said voltage divider.

5. A power supply system for cathode ray television apparatus comprising a source of substantially saw-tooth wave formation electrical energy for energizing the cathode ray beam deflecting means of said apparatus, transformer means for supplying the said saw-tooth wave energy to the said cathode ray beam deflecting means, a thermionic rectifier element having at least a cathode and an anode, capacitive means to supply an impulse component of the energy in said transformer means to the rectifier to cause a unidirectional current fiow therethrough, resistive means connected between the anode and cathode of the rectifier to provide a. direct current path between said elements, capacitive coupling means for connecting the rectifier cathode to a predetermined point of fixed potential to maintain the said cathode at a fixed alternating current potential, and e, connection from an intermediate point on the voltage divider to the point of fixed potential to establish the cathode direct current potential and to provide predetermined voltages relative to the said predetermined point at the outer terminals of the said resistor means.

HENRY N. KOZANOWSKL REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA I LN TS Number Name Date 2,074,495V Vance Mar. 23, 1937 2,188,647 Busse Jan. 30, 1940 2,297,925 Usselman Oct. 6, 1942 2,157,534 George et al. May 9, 1939 2,302,876 Malling Nov. 24, 1942 2,051,372 Farnsworth Aug. 18, 1936