US2740061A - Apparatus for photographic printing - Google Patents

Description

March 27, A E REEVES APPARATUS FOR PHOTOGRAPHIC PRINTING 2 Sheets-Sheet 1 Filed Sept. 28, 1951 1 8 H 1 y 2 0 M w 0 3 J 2 m w a m 8 r o. 2 r OOK m n /\v 94 J 7 w. a a 2 J Aer/me E: REEVES,

IN VEN TOR.

March 27, 1956 A. E. REEVES 2,740,051

APPARATUS FOR PHOTOGRAPHIC PRINTING Filed Sept. 28, 1951 2 Sheets-Sheet 2 36 3 77'me De/ay L sysz em 25 P 30 31 Aen/ue E REEL Es,

INVENTOR.

BY I 5 ATTOQNEY.

United States Patent 2,740,061 APPARATUS FOR PHOTOGRAPHIC PRINTING Arthur E. Reeves, Los Angeles, Calif.; Robert Gordon Nichols, executor of Arthur E. Reeves, deceased Application September 28, 1951, Serial No. 248,847 2 Claims. (Cl. 313-34) This invention relates to photography, and particularly to a timer device for the testing of the density of negatives.

Such an apparatus in general is described in Patent No. 2,142,413, issued on January 3, 1939, in the name of Arthur E. Reeves. Another form of such apparatus is described and claimed in an application filed in the name of Arthur E. Reeves on September 21, 1946, under Serial Number 698,416, and entitled Continuous Film Printer With Automatic Control of Electromagnetically Actuated Shutter Operating Means, now Pat. No. 2,583,- 342. This application is a continuation in part of said co-pending application.

It is one of the objects of this invention to provide a simplified apparatus of this character.

It is another object of this invention to provide a device in which the source of illumination for the test printing is such thatsubstantially uniform light intensity is produced for the entire printing area. This is accomplished by the aid of a luminous or fluorescent tube.

When using luminescent or fluorescent tubes excited by a relatively low voltage, such as about forty volts, the tubes exhibit unpredictable vagaries. Thus, it may take an appreciable interval to initiate the discharge when the excitation is removed. Since the printing time of the apparatus must be accurately predetermined in order that the tests have significance, such vagaries are intolerable. Accordingly, it is another object of this invention to provide a tube of this character that can be accurately controlled.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a front elevation incorporating the invention;

Fig. 2 is an enlarged sectional view, taken along a plane corresponding to line 22 of Fig. 1; and

Fig. 3 is a wiring diagram of the system.

The film tester includes a frame 1. On opposite sides of this frame are disposed brackets 2 and 3. Upon these brackets are mounted the reel structures 4 and 5. A negative film 6 is adapted to be supplied to the testing apparatus by being unwound in intermediate steps from reel and wound onto reel 4. This arrangement, in general, is similar to that disclosed in the said prior patent and prior application.

An upper frame member 7 is disposed above the frame 1. This frame 7 serves to support a cellular structure 8, forming a series of vertical light wells 11 disposed underneath a transparent supporting plate 9. A portion of a testing apparatus of the negative film 6 is intended to rest upon this plate 9 during a test print operation. The negative film 6 may be appropriately guided in a light-tight manner through the upper frame 7, all as described in the said prior patent and prior application.

A ground glass plate 10 is mounted below the wells 11 in order to assist in diffusing illumination passing upwardly through the wells 11.

A plate 12, disposed below the wells 11, is laterally adjustable by the aid of a rod 45 in the horizontal guides 13. This plate has a series of rows of openings, the openings of each row being capable of alignment respectively with the wells 11. The apertures or openings in each row may have graduated areas, so as to pass different quantities of light to the wells. Such an arrangement is quite completely disclosed in said prior application.

A raw film supply mechanism 14 is mounted above the structure 8. It carries the raw film 15. The arrangement is similar to that described in said prior patent. This structure 14 is adapted to be moved downwardly so as to hold the raw film 15 against the negative film 6 above the wells 11 and plate 9, as described in the said prior patent. Mechanism is also provided for intermittently moving the raw film 15 so as to provide new sections of the film for each adjustment of the negative film 6 over the wells 11.

In order to provide a source of illumination beneath the wells 11, a fluorescent luminous tube 16 is provided. This tube extends longitudinally in a direction to lie beneath all of the wells 11. Since this tube 16 provides substantially uniform illumination throughout its entire length, the intensity of exposure on portions of the film 6 resting upon the plate 9 is capable of substantially accurate predetermination.

The tube 16 is mounted by having its downwardly directed ends accommodated in slots formed in a shelf or support 17. This shelf 17 may be made of asbestos, or other insulation material. It is supported by the aid of the angle iron brackets 18 and 19 on the wall 20 of the frame 1 (Fig. 2). The front edge of the support 17 may be slotted, as indicated at 21, in order to make it possible to remove and replace the tube 16. The wall 20 may be provided with a plurality of openings 25 in order to permit adjustment of the height of the support 17 with respect to the light wells 11. Thus, the supporting bolts 26 may be removed and replaced in any one of these apertures for raising and lowering the support 17.

The tube 16 is of the low voltage heated cathode type. The energizing voltage may be of the order of forty volts, supplied from a commercial source by the aid of the leads 22 and 23 (Fig. 3).

The downwardly directed ends of the tube are pro vided with the bulbous enlargements 24 and 27. At the lower ends of the tube are located the heated filaments or cathodes 28 and 29. These filaments are heated by the aid of secondary windings 30 and 31 (Fig. 3) of a transformer 32. The primary winding 33 of this transformer 32 is shown as energized from the leads 22 and 23.

The tube 16 has a low pressure filling of argon and mercury, and an electromotive force is impressed between the filaments 28 and 29 by the aid of an autotransformer 34 (Fig. 3). One filament 28 is connected, as by a lead 35, to one terminal of the auto-transformer 34. The other filament 29 is connected, as by lead 36, to an intermediate tap of the transformer winding 34.

The timing of the exposures is accomplished by manipulation of an adjustable resistance or impedance device 37, shown as mounted on top of the upper frame 7 and having an adjustable pointer 40. This device is included in a timing system 38 interposed between the leads 22, 23 and the auto-transformer winding 34. This timing system may employ the usual electronic circuits, including thermionic tubes and capacitors. It operates to energize the tube 16 upon closing of the circuit controller 39 interposed in the system 38.

Energization of the tube 16 continues only until some capacitors are charged toa definite value; and, thereafter, even with controller 39 closed, the tube 16 is deenergized.

Such timing systems being old, further description thereof is unnecessary.

Circuit controller 39 is closed when the mechanism 14 is moved downwardly to bring the raw film 15 into position above, the plate 9.

As soon as this occurs, the tube. 16 is energized and, at a predetermined time, as set by the pointer 40 of the timer device 37, the tube 16 is deenergized. When the mechanism 14 is moved upwardly, the circuit controller 39 is opened, andthe timing device is returned to inactive position.

The timer device 37 may be set for fractions of a second. The tube 16, as constructed, is capable of instantaneous encrgization and deenergization, even for minute time. increments of the order of a small fraction of a second.

This. is due, in large measure, to the provision of the bulbous enlargements 27, in combination with the use of the heated cathodes 2'8, 29 that remain energized even when no potential is impressed across these electrodes. The bulbous enlargements serve rapidly to cool and collect minute globules of mercury that may be condensed during the period. of deenergization of the tube 16. This cooling process ensures that the tube will be deenergized instantaneously after the timing system 38 is efiieetive to block the imposition of an energizing potential upon the auto-transformer winding 34.

In order to ensure against erratic operation of the tube due to static charges, a conducting layer 41 may be painted or otherwise attached to the exterior of the tube. This conducting layer 41 may be in the form of a stripe of silver paint or colloidal graphite, and extends downwardly to form the bands 42 below each of the bulbous portions 24 and 27. This conducting layer may be grounded, as indicated at 43.

The inventor claims:

1. A sealed transparent luminous discharge tube having a mercury content, said tube having an elongate central portion, and end portions both extending transversely of said central portion and in the same direction; and thermionic emission electrodes in the end portions respectively; said tube having bulbous enlargements in the ends, and located between the central portion and said elec' trodes respectively, the electrodes being located beyond said enlargements.

2. A sealed transparent luminous discharge tube having a mercury content, said tube having an elongate central portion, and end portions both extending transversely of said central portion and in the same direction; and thermionic emission electrodes in the end portions respectively; said tube having bulbous enlargements in the ends located between the central portion and said electrodes respectively; the electrodes being located beyond said enlargements and a continuous conducting layer external of the tube extending from one bulbous enlargement, along the central portion, to the. other bulbous enlargement.

References Cited in the file of this patent UNITED STATES PATENTS Ruff Feb. 22,

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