US2248815A

US2248815A - Television receiver

Info

Publication number: US2248815A
Application number: US285836A
Authority: US
Inventors: Deserno Peter
Original assignee: Standard Elektrik Lorenz AG
Current assignee: Alcatel Lucent Deutschland AG; C Lorenz AG
Priority date: 1938-08-04
Filing date: 1939-07-22
Publication date: 1941-07-08
Anticipated expiration: 1958-07-08

Description

July 8, 1941. DESERNQ 2,248,815

TELEVISION RECEIVER Filed July 22, 1939 [n yen for 6 fer Peder/70 by Z Patented July 8, 1941 2,248,815 I TELEVISION RECEIVER Peter Deserno, Berlin, Germany, assignor to C. Lorenz Aktiengesellschaft,- Berlin-Tempelhof, Lorenzweg, Germany, a company Application July 22, 1939, Serial No. 285,836 In Germany August 4, 1938 6 Claims. (0,1.250-27) This invention relates to television receivers, and more particularly to new and useful means for eliminating certain troubles heretofore observed in such devices.

It is a fact known to everyone skilled in theart that individual instrumentalities, such as the image amplifier, the time base circuits and the like, forming part of a television receiver fed from the mains supply, demand a certain building-up time from the moment at which thereceiver is switched in circuit with such current source to the moment at which the receiver is ready to operate. This delay in operation thus introduced by the above mentioned building-up time is disadvantageous in several respects. For instance, in cases that the full anode voltage" is applied across the cathode ray tube during such built-up time, the life of this tube will be considerably reduced. Furthermore the fluorescent screen of the cathode ray or Braun tube will be subject to damage if the cathode ray prior to the operation of the time base circuits continually remains on the same spot of the fluorescent screen. Moreover, the appearance of an indefinite image on the fluorescent screen before the receiver has actually acquired perfect synchronism is very annoying. All these troubles in coaction with one another will undoubtedly give the observer the impression that the receiver is out of order. These difliculties are also noticed when the operator disconnects the receiver from the mains supply.

According to one object of this invention, the above mentioned difficulties are eliminated by the provision of means which during a predetermined period of time immediately after the receiver has been connected to the power circuit prevents that a cathode ray becomes produced by the cathode ray tube, and which upon opening this circuit will immediately extinguish the cathode ray.

It is a further object of my invention to prevent the formation of the cathode ray by decreasing the normal potential of the auxiliary anode or of the focusing lens of the cathode ray tube. The delay for this period of time is determined by thermostatic means, while the cathode ray is extinguished by a contact which is mechanically coupled with the power switch of the receiver.

My invention will be more readily understood from the following description taken in conjunction with the accompanying drawing, the single figure schematically illustrates one embodiment according to this invention.

' in this drawing, reference letter B indicates the throat portion of the cathode ray tube illustrative for this invention, the remaining parts of which have been omitted for the sake of simplicity since immaterial for the scope of this invention. Reference letter K denotes the cathode, S the auxiliary anode, L the focusing electrode and A the anode of this tube. ous electrodes normally receive their proper'con- The varitrol potentials from a potentiometer device connected across any suitable potential source Q;

the negative pole of this source is connected to the cathode K and also to ground.

For carrying out the indicated operation of this device, a particular operating circuit is branched off from the power supply with the object'to operate a thermostatic relay T, which inturn controls a contact t with a predetermined time delay. This contact is disposed between the ground pole of the source Q and either of the electrodes L or S of the cathode ray tube B. A switch A mechanically coupled with the main switch C of the receiver D is interposed in series with the operating circuit. A further contact 1', mechanically coupled with the switch A,

is interposed in a path shunted across the contact t.

It will now be assumed that the receiver has just been switched in, which condition is shown in the drawing. Since either of the electrodes S or L is directly connected to ground over the closed contact t, the tube B is unable to produce a cathode ray. The switch A is closed so that the thermostatic relay T is energized from the mains supply. After the elapse of a predetermined period of time which corresponds to the building-up time of the various circuits of the receiver, this relay operates to open the contact if. Because of the fact that the contact 1' was opened when the switch A was closed, ground is removed from the electrode S or L which now acquires its proper control voltage from the poteniometer with the result that the cathode ray is immediately produced.

Upon disconnecting the receiver, the switch A is opened and the contact r in turn closed, thereby bringing the electrode mentioned above to the earths potential thus immediately extinguishing the cathode ray. In response to this disconnection, the thermostatic relay T is allowed to cool and to restore its contact t to normal in order to maintain the electrode S or L at ground potential when contact r again becomes opened when the receiver is again switched in.

In order to immediately extinguish the cathode ray also in cases when the plug connector is involuntarily removed or when line faults occur, a special relay G may be provided which is normally operated from the mains supply and which in a de-energized condition connects either of the electrodes S or L directly to ground.

What is claimed is:

1. In a television receiver, means for closing and opening a feed circuit between the said receiver and a mains supply for rendering said receiver eifective and inefiective, a cathode ray tube normally adapted to produce a cathode ray during the effectiveness of the said receiver, relay means for grounding one of the electrodes of said tube responsive to the closing of the said circuit for preventing during a predetermined period of time the said cathode ray tube from producing a cathode ray, and. means responsive to the opening of the said circuit for grounding said one of said electrodes for immediately extinguishing the cathode ray which is produced by the said cathode ray tube after the lapse of the said period of time.

2. In a television receiver, means for closing and opening a feed circuit between the said receiver and a mains supply for rendering the said receiver effective and inefiective, a cathode ray tube comprising at least a cathode and an auxiliary anode, a potential source normally maintaining the said auxiliary anode at a proper control potential for causing the said cathode ray tube to produce a cathode ray during the efiectiveness of the said receiver, means responsive to the closing of the said circuit for changing the potential of the said auxiliary anode in order to prevent during a predetermined period of time that the cathode ray tube forms a cathode ray, and means responsive to the opening of the said circuit for grounding said auxiliary anode and immediately extinguishing the cathode ray which is produced by the said cathode ray tube after the elapse of the said period of time.

3. The invention according to claim 2, characterized in that the said means responsive to the closing of the said circuit is a slow operating thermostatic relay having its back contact interposed between the said cathode and the said auxiliary anode for interrupting this path after a predetermined period of time.

4. The invention according to claim 2, characterized in that the said means responsive to the opening of the said circuit is a contact interposed in a path between the said cathode and the said anode for closing this path when the said circuit is opened and said means last mentioned is mechanically interconnected with a switch means which serves to open said circuit.

5. The invention according to claim 2, characterized in that the said means responsive to the opening of said circuit is a contact interposed in a path between the said cathode and the said anode and that a further relay normally operated from the mains supply is used in order to immediately extinguish the said cathode ray when line fault-s occur.

6. In a television receiver means for closing and opening a feed circuit between said receiver, a mains supply for rendering said receiver effective and ineffective, a cathode ray tube normally adapted to produce a cathode ray during the efiectiveness of the said receiver, a switch for controlling said mains supply and contact means mechanically connected to said switch for grounding a control electrode of said tube and immediately extinguishing said cathode ray, responsive to the opening of said switch.

PETER DESERNO.