摘要:

The paper surveys the progress made in the design and manufacture of valves and cathode-ray tubes for television since the medium was first discovered. The survey is divided into three parts corresponding to three distinct stages in the development of valves, namely the pre-war period, the war-time standstill and the years since the war.In the earliest days most television valves were merely variations on existing types, but development of special valves soon began and was hastened by the adoption of our present transmitting system in 1937. Meanwhile, tube design had also progressed and 10–12-in magnetically focused tubes were used in 1937.During the war little work was done on television tubes and valves. Service demands speeded the production of miniature and all-glass valves, but cathode-ray-tube technique benefited only indirectly from war-time experience and a fresh start was necessary in 1945.The duty of the valve industry at this time was to help to make television receivers reliable, efficient and cheap. Some methods of performing this task are discussed and the consequent demands on valve designers considered. New types of valve and tube are described in some detail.Turning from development to production, the paper describes advances in the mechanization of valve production which have led to the attainment of production speeds rivalling those of any other country. Mass-production methods have also been introduced into tube manufacture since the end of the war, and an account of current methods closes the third part of the paper.After a statistical survey of valve and tube production between 1935 and 1951 has been given, views on future trends in both production and design are put forward. It is concluded that the valve industry is in a healthy condition now and that there is reason for optimism about its future.

DOI:10.1049/pi-3a.1952.0061

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper discusses the general trend in the size of directly viewed television tubes and considers the merits of both metal and all-glass types. The alternative method of producing large pictures—by projection—is considered, and the techniques by which the form of receiver might be improved are given.The various types of focusing employed for television tubes are discussed, and the reasons for the choice of electromagnetic deflection are given.The electron optics of the gun is considered in detail, the method by which the existing compromise has been obtained being indicated. The theory outlined refers to both directly viewed tubes and projection tubes. It is also shown that improvements in the performance of both types of tube could be achieved by the use of higher screen efficiencies and cathodes capable of withstanding higher loadings, and by a reduction in the spot-swelling characteristics of the electron gun.

DOI:10.1049/pi-3a.1952.0062

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The need to conserve stocks of scarce materials has prompted an investigation into the possibility of using an electrostatic focusing system for magnetically scanned television picture tubes. Such a lensfocusing system, requiring only a low voltage for focus, would be desirable; if the voltage is that of the cathode, the lens is termed a univoltage lens.The design considerations are discussed and a prototype gun is described. The characteristics of tubes using this type of gun are given and compared with those of standard magnetically focused tubes.The results at present available indicate that mass-production tubes operated with a final-anode potential below about 12 kV will require a low adjustable focusing-voltage supply. This is necessary for adequate resolution in all tubes. For final-anode voltages above 12 kV it is expected that good resolution can be maintained with the focus electrode connected to the cathode, notwithstanding the minor dimensional variations which will occur in bulk production.

DOI:10.1049/pi-3a.1952.0063

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper deals with the more important processes in the manufacture of aluminized television tubes, and describes a semi-automatic method of screen deposition which also incorporates film forming before screen drying. The design of the pipette which facilitates the continuous production of applied nitrocellulose films to fluorescent screens is dealt with in some detail, and mention is made of the special problems encountered with this important aspect of the screenaluminizing art.Stress is laid on the importance of achieving a satisfactory degree of vacuum during the exhausting process, and mechanized equipment for the continuous production of pumped tubes is described in detail. Similarly, the mechanization of aluminium evaporation and the final testing of tubes is described, with details of the processes and tests applied.The paper concludes with a mention of further improvements to manufacturing technique at present being investigated with the object of producing tubes which have a long life.

DOI:10.1049/pi-3a.1952.0064

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The use of an a.c./d.c. power supply is probably the most characteristic feature of British television-receiver design since the war. The paper examines those features of the design which are influenced by a.c./d.c. working, studies the valve requirements of each stage of the receiver and formulates the required types and characteristics of a suitable range of valves. Four receivers are described as examples of possible designs using this range.

DOI:10.1049/pi-3a.1952.0065

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The principal requirement of cathode-ray-tube life-testing equipment is that it shall give an accurate description of the life performance of any type of cathode-ray tube in the shortest possible time. This object is achieved only after due consideration of all the factors involved, which include the safety of personnel from electric shock and mechanical implosion, the flexibility and reliability of apparatus and methods of arriving at an estimate of life before failure actually occurs.The paper describes how the problem has been approached and concludes that the desired flexibility in the apparatus can best be achieved in an open-bench type of equipment. This entails the provision of electrical safeguards to protect the operator.

DOI:10.1049/pi-3a.1952.0066

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper reviews the development and present position of television tube phosphors and screens. The theoretical aspect of luminescent emission is discussed, and the limitations of the accepted theory are indicated. The preparation of the chief television phosphors is described, and their luminescent and other characteristics are mentioned. The more important methods of making the television screen are given, and the effect of voltage and current on the screen performance is discussed. Reference is made to a number of special matters, such as secondary emission, aluminized screens, screen colour and after-glow. A number of outstanding problems are indicated in a concluding Section.

DOI:10.1049/pi-3a.1952.0067

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The germanium rectifier is a non-linear resistor, and the essential differences between it and a diode are summarized. For this reason, circuits designed for a diode are not optimum for a germanium rectifier, and simple design procedure is outlined for each of the basic circuits where it may be used in a television receiver.The circuits covered include the high-level rectifier, low-level rectifier, mixer and interference suppressor. In addition to design procedure applicable to all types, the performance to be expected from some commercial types now available is indicated.Owing to the mechanism of conduction within the barrier layer, the performance of individual units which fall within a given group will vary from that of the average rectifier within the group. The nature of the variation to be expected is indicated, and data are given for assessing the expected variation of existing types now available.Circuit design procedure may be greatly simplified by adopting approximate formulae, and the derivation of such approximations is outlined in the Appendices.

DOI:10.1049/pi-3a.1952.0068

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper first describes recent developments in selenium rectifiers and examines the physical and electrical characteristics of modern highvoltage rectifier elements. A direct comparison with the thermionic rectifier is made, and it is shown that the metal rectifier offers advantages, and that it also has special characteristics which can be usefully employed in television receiver circuits. The importance of the correct choice of the working point on the characteristics, in order to obtain optimum rectifier performance in critical circuits or to produce special results, is discussed together with the associated questions of ventilation, thermal dissipation, rating and life. The latter part of the paper comprises a description of various applications of the metal rectifier in television circuits where its special electrical characteristics or flexibility are used to advantage.

DOI:10.1049/pi-3a.1952.0069

出版商:IEE    

年代:1952

数据来源: IET

摘要:

The paper gives an account of the typical British domestic television receiver of the present day. During the last two or three years, intensive development has resulted in a product which is basically simple yet capable of refined performance. The general arrangement of a receiver and its controls is described. Some of the background of circuit development is given with reference to the detailed technical aspects. Moreattention is paid to considerations involved in such matters as the video stage, vision- and sound-interference limiters, synchronizing-signal separation and radiation from line time-bases. An account of the steps that have to be taken to render a receiver safe is included. Where possible, design trends of the near future are indicated.

DOI:10.1049/pi-3a.1952.0072

出版商:IEE    

年代:1952

数据来源: IET