Patent Publication Number: US-3876897-A

Title: Mounting of electrode targets in storage tubes

Description:
United States Patent [1 1 Geyer 1 Apr. 8, 1975 1 MOUNTING OF ELECTRODE TARGETS IN STORAGE TUBES [75] Inventor: Hans Geyer, Baldham, both of Germany [73] Assignees: Paul Kahl, Munich; Siemens Aktiengesellschat&#39;t, Berlin &amp; Munich, Germany [22] Filed: Apr. 23, 1973 [2]] Appl. N0.: 353,750  
 Related US. Application Data [63] Continuation-impart of Ser. No. 157,096, June 28,  
 [30] Foreign Application Priority Data [51] Int. Cl. H0lj 29/02; HOlj 29/45; HOlj 29/82 [58] Field of Search. 313/65 R, 65 A, 65 T, 65 AB, 313/66, 285, 292, 67, 68 R, 68 D [56] References Cited UNITED STATES PATENTS 2,917,574 12/1959 Toulon 313/65 R X 3.030536 4/1962 Hackett et al. 313/85 R 3,073,981 1/1963 Miller et a1. 313/390 3,271,608 9/1966 Rome et a1. 313/388 3,303,373 2/1967 Alting-Mees 313/65 R 3,325,672 6/1967 Funahashi et al..... 313/65 A X 3,437,860 4/1969 Ney 313/65 T 3,704,387 11/1972 Carpenter et a1. 313/67 3,725,711 4/1973 Sadler r 313/66 Primary E.raminer-Robert Segal Attorney, Agent, or Firml-lill, Gross, Simpson, Van Santen, Steadman, Chiara &amp; Simpson [57] ABSTRACT Electrode target disks are mounted in storage tubes in spaced relation behind window panels within an annular centering groove in a metal frame signal ring and held in firm contact with bearing pressure by a retaining ring centered in the groove and held under bearing pressure by locking means which may take various forms, i.e., an expansible locking ring or locking lugs upset from the frame ring. The diameter of the groove, target disk and locking ring are differentially smaller than the inside diameter of the storage tube to permit easy access for ready replacement of the target disk through the inside of the tube.  
 15 Claims, 2 Drawing Figures 5a 5 3 I I I MOUNTING OF ELECTRODE TARGETS llN STORAGE TUBES The present application is a continuation in-part of our pending application Ser. No. 157,096 filed June 28,,  
 1971 with respect to which priority claim was established in regard to German Patent Application No. P 37 981 filed July 30, 1970.  
  This invention relates to mounting of storage elec&#39; trode target disks in picture-recording or electric signal-storage tubes, and is more particularly concerned with mounting of such target disks separate and spaced from glass front window panels or plates on the tubes.  
  Heretofore, a photo-sensitive layer has commonly been vapor deposited on an electrically conductive glass plate. However, where the photo-sensitive layer is in the form of a semi-conductor storage electrode target on which, for example, 600,000 photo diodes/cm are applied according to the integrated circuit technique, a different arrangement must be used. Such targets are employed in video camera tubes and may also be employed in electric signal storer and/or intermediate storer tubes. Prior attempts to solve the mounting of such targets have not been satisfactory due to high cost caused in production by, among other things, re quirement for several working cycles. For example, in prior arrangements it has been impossible to remove or exchange the electrode target where that becomes desirable for any reason as where testing shows the target to be defective, without opening and reworking the window end of the tube.  
  An important object of the present invention is to overcome the foregoing and other disadvantages, deficiencies, inefficiencies, shortcomings, and problems in prior methods and structures, and to attain important advantages and improvements as will hereinafter become apparent.  
  Another object of the invention is to provide a simple and efficient improved, new apparatus for mounting electrode targets in tubes of the character indicated.  
  A further object of the invention is to mount elec trode targets readily replaceably in tubes of the character indicated.  
  Still another object of the invention is to provide a low cost, efficient, rugged, simple mounting of electrode target disks in storage tubes.  
  Yet another object of the invention is to provide an arrangement such that a standard form of tube can be equipped with either a photo-sensitive or a storagesensitive target.  
  Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawing, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:  
  FIG. 1 is a fragmentary longitudinal sectional view through the forward end portion of a tube such as a video recording tube embodying features of the invention; and  
  FIG. 2 is an enlarged fragmentary vertical sectional view similar to FIG. 1 but showing a modification.  
  Having reference to FIG. 1, a calibrated glass tube 1 is provided at its forward end with a flared, generally conical end portion 2 across which is mounted a glass window plate or panel 3 carried by a metal frame ring 4 which functions as a signal ring. As will be observed, the outside diameter of the ring 4 is greater than the maximum diameter of the flared enlargement 2 so that the ring perimeter is freely accessible.  
  A hermetically sealed relation of the tube 1 and window 3 to the ring 4 is attained by simultaneously bonding the glass members to the metal ring 4, which is of a compatible coefficient of expansion, as by means of high frequency heating. In preparation for such bonding, the terminus of the flared tube portion 2 is uniformly ground flat to receive the frame ring 4 flat thereagainst. Of course the window panel 3 being desirably flat will fit marginally close against the outer face of the ring 4. In the example shown, the diameter of the window panel 3 is smaller than the outside diameter of the ring 4. By thus assembling and bonding the glass members 1 and 3 to the metal ring 4, the assembly can be heated without difficulty for several hours to, for example, 450C which is especially advantageous during production. For its principal function of mounting a storage electrode target disk 6, the frame ring 4 is of an inside diameter to extend a limited distance inwardly relative to the inside diameter of the tube 1.  
  According to the present invention new and improved means are provided for mounting the target disk 6 on the axially inner side of the ring 4 in a manner to enable free mounting and exchange of the disk 6 through the inside of the tube 1. To this end the ring 4 is provided with an annular centering, rabbet groove 5 in the axially inner side of its radially inner margin, within which a margin of the scanning target disk 6 (shown schematically) is engaged and clamped by means of a clamping ring 7 held in place by an expansible and contractile retaining split spring ring 8. To accommodate this relationship, it will be observed that the clamping ring 7 is of a thickness slightly greater than the depth of the groove 5, and the outside diameter of the ring 7 is sufficiently less than the progressively flaring diameter of the inner surface of the tube portion 2 to accommodate the expanded locking ring 8 on a diameter which enables the locking ring to thrust against the adjacent outside margin of the clamping ring with sufficient but not excessive pressure so as to effect firm electrical contact but to avoid crushing the clamped margin of the target disk 6 which may comprise a thin glass wafer or any other suitable and possibly relatively fragile material.  
  Locking thrust force is generated in the ring 8 by the combined action of its expansibility acting to return with substantial uniformity to a slightly larger normal diameter than the diameter to which it is held in the locking relationship by a cam surface and thrust shoulder 2a provided by the inside flaring surface of the tube head end portion 2. An advantage of the firm but not excessive clamping pressure applied by the locking ring 8 against the clamping ring 7 resides in that assurance is afforded of good contact between the margin of the target member 6 and the metal frame ring 4 through which video signals are transmitted. As will be observed, the length of the cam surface 2a is sufficient radially and axially inwardly relative to the line on which the locking ring 8 shoulders thereagainst, to extend radially inwardly to juncture with an inner cylindrical surface la of the wall of the tube 1 on a diameter on the order of half of the cross sectional diameter of the locking ring. This assures thorough locking retention of ring 8 in its operative locking position against the cam surface 2a serving as a thrust shoulder and the clamping ring 7, while minimizing the amount of expansion and contraction range required in the locking ring 8 to enable manipulation of the same into and, out of the locking position.  
  As will be observed in FIG. 1, the outside diameter of the target disk 6 and the clamping ring 7 as well as the diameter of the groove 5 which holds these elements centered is less than the diameter of the tube insidewall surface axially inwardly from the flared tube head end enlargement tube. An important advantage of this arrangement is that the target 6 can not only be preformed and then inserted and mounted with the rings 7 and 8 in place on the ring 4 through and from within the tube 1 after the head end of the tube assembly has been completed, but the target 6 can also be exchanged at any time together with the individual components 7 and 8 of the mounting structure if replacement is required after quality tests, through the inside of the tube 1 without necessitating discarding of the entire tube assembly or opening and reworking the window or head end of the tube. It may also be noted that while the target mounting assembly affords numerous advantages in a physical sense as will be evident and as already pointed out, such as ease of assembly, centered retention of parts, and ready replaceability, quite adequate effective target area is freely exposed within the inside perimeter diameter of the rings 4 and 7, consistent with the tube envelope diameter.  
  Interference with operational access to the exposed scanning target area is avoided by having the locking ring 8 so related to the clamping ring 7 as to be well spaced at the inside perimeter of the ring 8 from the inside perimeter of the clamping ring 7, as shown. Further, the thickness of the inner target-carrying margin of the frame ring 4 is at a minimum consistent with structural stress resistance requirements so that access to the marginal portion of the target area is as free as possible under the circumstances. To this end, for example, the axially outer side of the radially inner margin of the frame ring 4 is desirably provided with an annular groove 50 in its outer face, opposite to the groove 5 whereby not only is such inner margin of the frame ring reduced in thickness, but an offset spaced relation is provided from the window panel 3 affording a wider angle of access for incoming image to the target 6. In addition, the offsetting groove 5a provides a convenient diametrical enlargement of the clearance space between the window 3 and the target 6 for communication of one or more bypass passages 9 through the ring 4 between the clearance space and the interior of the tube 1 into the annular enlargement groove adjacent to the extremity of the generally conical widening 2 of the tube head portion. Thereby when the tube 1 is interiorly evacuated as is necessary for proper functioning of this type of tube, the clearance area between the window 3 and the target 6 is likewise evacuated. The passages 9 may be slots or borings, as preferred.  
  In FIG. 2 another desirable arrangement is disclosed for attaining the same results as in the form of FIG. 1. To this end, the glass tube 1&#39; having a generally cylindrical inner diameter surface In and a generally flaring end portion 2&#39; on its head end carries a window disk 3 through the medium of the metal signal frame ring 4 all secured together as a pre-assembly in the manner already described. In this form of the invention, also, the frame ring 4 has an inside diameter greater than the diameter of the inside wall surface la of the tube and is provided with a rabbet groove 5&#39; on the axially inner side of the radially inner margin of the ring 4 within which the margin of the storage electrode disk member 6 is secured in electrically sound engagement with the ring 4 within the groove 5 by means of the clamping ring 7&#39;, the outside diameter of the groove 5&#39;, of the disk 6, and the ring 7&#39; being sufficiently smaller than the diameter of the tube inside wall la to enable mounting of the target disk 6&#39; and the ring 7&#39; within the groove 5&#39; through and from within the tube 1&#39; after the head structure of the tube 1&#39; including the window 3&#39; and the ring 4 has been completed as a sub-assembly. It will also be noted that the offsetting groove 5a has one or more bypass passages 9 communicating through the ring 4&#39; with the inside of the tube 1 past the groove 5 and the clamped target disk margin for the same purpose and to the same effect as described for the corresponding groove 5a and bypass passage 9 in FIG. 1.  
  Means are provided for releasably securing the ring 7 in clamping relation to the margin of the disk 6&#39;, but in this instance comprising utilizing material of the ring 4 itself for the purpose. To this end, a radially and axially inner edge 10 of the metal frame ring 4&#39; has malleably upset from a plurality such as three or four equidistantly spaced limited areas therein respective retaining or locking tabs 12 which extend generally radially inwardly and are bent toward and into engagement with the axially inner side of the ring 7 to thrust it toward the margin of the target disk 6&#39;. To facilitate this, the depth of the groove 5 is at least slightly greater than the combined thickness of the target disk 6 and the clamping ring 7. In addition, resilient, spring pressure is advantageously provided for between the clamping disk 7&#39; and the margin of the disks 6 not only to assure increased electrical contact pressure of the target disk 6 against the ring 4, but also to absorb or damp pressure or force generated during formation of the locking tabs 12. Advantageously, an annular transversely concave convex relief spring ring 13 of the same diameter as the ring 7&#39; is provided for this purpose having its convex face in engagement with the margin of the disk 6 under compression of the clamping ring 7 thrusting thereagainst and held under such compressing thrust by the locking tabs 12. By reason of its resilient flexibility, the spring 13 compensates relief or temperature differentials so that there is never any looseness in the electrical contact of the target disk with the ring 4&#39;, and in addition shocks or vibrations are readily absorbed thereby protecting the target disks 6&#39;.  
  Should it become necessary after the assembly has been completed including locking the clamping ring 7 by means of the tabs 12, to remove the target disk 6&#39; as for replacing the same, that can be readily done by bending the tabs 12 out of the way, or even removing the same altogether since they are of relatively small mass of the malleable material of the ring 4&#39;. Thereby the clamping ring 7 and the spring ring 13 as well as the disk 6 can be easily removed through the interior of the tube 1. After the disk 6 or a replacement therefore has been inserted through the tube 1 into the groove 5, the spring ring 13 and the clamping ring 7&#39; are replaced, and the same locking tabs 12, or new locking tabs 12 are bent into thrusting locking engagement with the clamping ring 7.  
  Among thenumerous advantages of the present invention, it may againbe emphasized that the particular target mounting disclosed enables the same basic discharge tube structure to be employed both for photosensitive and for storage-sensitive targets. Thus the schematically illustrated target 6, 6 may be equipped for either of these purposes, as desired, while the remaining components of the assembly, as standardized, remain the same.  
  It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.  
 We claim as our invention:  
  1. Mounting of a target disk on the end of a tube of the character described which includes a window panel across said end, both said tube and said window pane] being formed from glass, comprising:  
 said tube end being on a flared head portion of the tube;  
 said end being a planar receiving surface on the flared head;  
 a metal frame ring of at least as large diameter as said end having an axially inner side bonded to said planar surface;  
 said glass window panel having a margin engaging the axially outer side of said frame ring and bonded thereto;  
 said frame ring having on its axially inner side a radially inner margin facing axially inwardly relative to the tube;  
 the target disk having a margin engaging said frame ring margin;  
 a clamping ring engaging against the axially inner side of said target disk margin;  
 a locking ring engaging said tube head and said clamping ring and thrusting the clamping ring into clamping relation to the disk margin;  
 said disk and said clamping ring being of smaller outside diameter than the inside diameter of said tube; and  
 said locking ring comprising a split expansile spring ring which is expansible to larger diameter than the inside diameter of the tube so as to effect engagement with said flared head, but which is of smaller inside diameter than the inside diameter of the tube so as to engage in thrusting relation with said clamping ring.  
  2. A target disk mounting according to claim 1, said frame ring substantially spacing said window panel and said target disk apart, and a bypass passage through said frame ring communicating with the space between the panel and the disk and with the interior of the tube.  
  3. A target disk mounting according to claim 1, wherein said margin of the clamping ring has a groove within which the margin of the target disk is engaged and within which said clamping ring fits, said clamping ring being of a greater thickness than the depth of the groove so as to project axially inwardly relative to said axially inner side of the frame ring and to facilitate the engagement of the locking ring with the clamping ring. V  
  4. Mounting of a target disk in a storage tube having permanently secured to an end thereof a metal signal frame ring of at least as large outside diameter as said tube and with a window panel permanently mounted on said ring in closing relation to the tube end, comprising:  
 said frame ring being of substantially smaller inside diameter than an inside wall of said tube;  
 an annular rabbet type groove in a radially inner margin of a face which faces axially inwardly away from said window panel on said frame ring;  
 a target disk having a margin releasably engaged in said groove;  
 a clamping ring received in said groove and clamping said target disk margin against the frame ring within the groove;  
 said clamping ring having its outside diameter and said disk having its diameter smaller than the diameter of said inside wall of the tube so that both the disk and the clamping ring can be assembled through the tube within said inside wall and into mounted position within said groove;  
 said inside wall of the tube having a flare at said end and thereby providing a groove between said frame ring and said flare; and  
 an expansible ring member engaging said flare and releasably engaging the clamping ring at its axially inner side and locking the clamping ring in place, said ring member being adapted to be manipulated into and out of the locking engagement with the clamping ring, within the tube.  
  5. A mounting according to claim 4, including passage means in said frame ring bypassing the margin of said target disk and the clamping ring for equalizing the atmosphere between said window pane] and said target disk and the interior of the tube axially inwardly from the target disk,  
  6. A mounting according to claim 5, wherein said frame ring has on its axially outer side a groove communicating with the area between the window panel and the target disk, and said passage means communicates with said groove.  
  7. A mounting according to claim 4, wherein said expansible ring member is in the form of a resilient split locking ring.  
  8. A mounting according to claim 4, wherein said expansible ring member comprises a split spring locking ring which is retractable to a substantially smaller diameter than said inside wall facilitating movement thereof into and out of the locking relation to the clamping ring and is expansible to larger diameter than the inside wall so as to effect engagement with said flare and is then of smaller inside diameter than the inside diameter of the clamping ring but of larger inside diameter than the outside diameter of the clamping ring so as to assure engagement with the clamping ring when the expansible ring member is expanded into engagement with said flare.  
  9. Mounting of a target disk in a storage tube having permanently secured to an end thereof a metal signal frame ring of at least as large outside diameter as said tube and with a window panel permanently mounted on said ring in closing relation to the tube end, comprising:  
 said frame ring being of substantially smaller inside diameter than an inside wall of said tube;  
 an annular rabbet type groove in a radially inner margin of a face which faces axially inwardly away from said window panel on said frame ring;  
 a target disk having a margin releasably engaged in said groove;  
 a clamping ring received in said groove and clamping said target disk margin against the frame ring within the groove;  
 said clamping ring having its outside diameter and said disk having its diameter smaller than the diameter of said inside wall of the tube so that both the disk and the clamping ring can be assembled through the tube within said inside wall and into mounted position within said groove; and  
 locking means comprising locking tabs carried by said frame ring and extending into locking engage ment with said clamping ring.  
  10. A mounting according to claim 9, including passage means in said frame ring bypassing the margin of said target disk and the clamping ring for equalizing the atmosphere between said window panel and said target disk and the interior of the tube axially inwardly from the target disk.  
  11. A mounting according to claim 9, wherein said groove is deeper than the combined thickness of said disk and clamping ring, and said tabs are formed from material of said mounting ring malleably upset therefrom into said locking engagement with the clamping ring.  
  12. A mounting according to claim 9, wherein said clamping ring comprises a rigid ring member, and a resilient pressure spring ring disposed between said rigid ring member and the margin of said disk and compressed by the rigid ring member toward and into engagement with the disk margin.  
  13. A mounting according to claim 12, said pressure ring comprising a concave convex cross section resilient metal ring having a convex face engaging the disk margin.  
  14. Mounting of a target disk within the end of a storage tube which includes a window panel across said end and a metal signal frame ring permanently secured between said window and said tube end and having an inside diameter which is smaller than an inside wall diameter of the tube, comprising:  
 a target disk;  
 said frame ring having a groove inset in its radially inner axially inwardly facing margin within which the margin of said disk is seated;  
 compressible means thrusting against said disk margin;  
 a clamping ring fitting in said groove and pressing against said compressible means; and  
 means comprising locking tabs carried by said frame ring and thrusting said clamping ring toward said disk margin in said groove to maintain the compressible means under compression against the disk margin.  
  15. A mounting according to claim 14, wherein said resilient compressible means comprise a concave convex spring ring having a convex face in engagement with said disk margin.  
 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 76, 897 DATED April 8, 1975 INVENTOR(S) Geyer It is certified that error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:  
 On the front page of the patent, column 1, [75], should read:  
 Column 1, [73] should read:  
 &#34;[7 Assignee: Siemens Aktiengesellschaft of Berlin 81 Munich, Germany-- Signed and gealed&#39;this eleventh 0f N0vemberl975 [SEAL] Arrest:  
 RUTH C. MASON C. MA-RSHALL DANN .-1t!es1ing Officer Commissioner (if Ialenrs um! Trudcmurkx