US3515050A

US3515050A - Automatic film processing device

Info

Publication number: US3515050A
Application number: US657558A
Authority: US
Inventors: Curtis C Attridge; Malor Wright
Original assignee: CURTIS C ATTRIDGE
Current assignee: CURTIS C ATTRIDGE
Priority date: 1967-08-01
Filing date: 1967-08-01
Publication date: 1970-06-02
Anticipated expiration: 1987-06-02

Description

June 1970 c. c. ATTRIDGE ETAL 3,515,050

AUTOMATIC FILM PROCESSING DEVICE Filed Aug. 1, 1967 PRE-DEVELOPMENT 0' L REVIEW OF f FREE-DEVELOPMENT FILM v l8 CONTROL MEANS f FINAL M16 DEVELOPMENT 58 DELAY CONTROL MA Z 0/? WR/GH 7' INVENTORS.

United States Patent 01 fice 3,515,050 Patented June 2, 1970 AUTOMATIC FILM PROCESSING DEVICE Curtis C. Attridge, 12 Devon Drive, Endicott, N.Y. 13670, and Malor Wright, Bedford Road, Lincoln, Mass. 01773 Continuation-impart of application Ser. No. 285,290, June 4, 1963. This application Aug. 1, 1967, Ser. No. 657,558

Int. Cl. G03d 13/ US. Cl. 95-89 6 Claims ABSTRACT OF THE DISCLOSURE Apparatus for accurately controlling the development of a film strip. The film strip is partially developed in a developing bath and then passes into a density measuring station having a light source on one side of the film strip and a photodetector on the other side of the film strip. When the film passes out of the first developing bath, it carries with it a certain amount of developing solution. The measured density is used to control the output of a cathode ray tube. Electron bombardment of the faceplate of the cathode ray tube causes emission of heat which in turn acts on the developing solution which is carried by the film strip to accurately control the development of the film. After passing by the cathode ray tube, the film proceeds to a final developing bath where developing is completed. In a second embodiment, the density measurement is made at the cathode ray tube.

CROSS-REFERENCE This application is a continuation-in-part of application Ser. No. 285,290, now abandoned, filed June 4, 1963, for Automatic Film Processing Device and Method, and is related to application Ser. No. 638,163, filed Mar. 10, 19,67, for Automatic Film Processing Device and Method which is a continuing application of Ser. No. 285,421, now abandoned, filed June 4, 1963.

SUMMARY OF THE INVENTION This invention relates to film processing devices and more particularly to an automatic and accurately controlled developing device.

While the following description will be directed to the processing of aerial reconnaissance film, it is not intended that the broad concept be so limited since it will become obvious to those skilled in the art that what is herein disclosed is applicable to processing of any type of film.

Resolution of fine detail, a factor of paramount importance in photographic reconnaissance, severely restricts the choice of exposure latitude of reconnaissance film principally because the degree of detailrecorded (resolution) is at least partially dependent upon obtaining an optimum negative density for the scene recorded on the film. Controlled processing, which in effect has the capability of extending the range of exposure for a given level of resolution, is therefore an extremely important and critical means of increasing the amount of information that can be extracted from a given photographic exposure.

The prior art discloses many techniques to vary the contrast and/or density of the image, during the course of processing and retrieving the latent image placed on the film. One of these techniques is to vary the temperature of the developing solution. This has rather obvious defects in that, when one portion of a negative is being developed at a given solution temperature and a given time, these parameters may not be applicable to the next succeeding portion of the film. As a result, a compromise had to be achieved and it became possible for the parameters so compfiomised to be unsatisfactory for major portions of the Still another method available to the prior art was one which involved increasing the agitation or activity of the solution over various parts of the film. This, too, had obvious disadvantages in that the increased activity could only be viewed at a considerably later period of time and it was possible to increase the activity at an area where, for example, decreased activity was desirable.

Our invention overcomes the difficulties of the prior art by providing increased solution activity at selectable portions on a film strip automatically where the amount and the duration of activity can be accurately controlled over smaller portions of the film than has previously been possible or practical.

DESCRIPTION OF THE DRAWING The features of" our invention which we believe to be novel are set forth with particularity in the appended claims. Our invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram in flow chart form of our processing device;

FIG. 2 is one embodiment of our invention utilizing an electron beam tube as a source of energy to control the temperature of development at discrete areas of the film;

and

FIG. 3 is another embodiment of the invention utilizing an electron beam tube as a source of energy for both controlling the temperature of the development process and for making density measurements.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS Although the particular embodiments of the invention discussed hereinafter disclose the use of conventional developing fluids for use with particular silver halide films, it is to be fully understood that the invention is not so limited. Such embodiments merely are illustrative of par ticular manners of practicing the invention and as such should in no way be read as limiting the inventive concept beyond the limitations expressly set forth in the appended claims. For example, infrared radiation is disclosed as the source of scanning the film for density measurements. If other forms of radiation are developed which will not expose areas of the film, such radiation may be used to measure the sensitivity of the silver halide film. The invention is in no way limited to the use of silver halide film but is broad enough to encompass any chemically processed photosensitive material that may be scanned for density measurement without further exposing the material.

Referring now to FIG. 1 there is depicted the basic concept of our invention in flow chart form, showing a film predevelopment stage 10, stage 14 previewing the predevelopment film and a final development stage 16. At the previewing stage 14 signals are developed which are transmitted to a control means 18. These signals are developed by scanning incremental portions of the film to determine the density of these incremental portions. Control signals from control means 18 are transmitted to the final development stage 16 to produce the desired development activity which in turn produces a film with an image of uniform developed density regardless of inconsistencies in the image as it is placed on the film and an inconsistency in the predevelopment and in the development chemistry and transport means. In addition, there is shown a stop bath 12 between the predevelopment stage 10 and the review of predeveloped film or preview stage 14. The stop stage 12 may be necessary in some instances and has been shown to include a dotted line extending between predevelopment stage and preview stage 14. The optional stop stage 12 is necessary in those instances where sufficient time elapses between predevelopment stage 10 and preview stage 14 to cause excessive development and merely serves to inhibit such development. However, when very little, if any, time elapses between stages 10 and 14, stop stage 12 may be unnecessary.

Application Ser. No. 638,163 discloses and claims a number of methods and apparatus for practicing the inventive concept described above by utilizing various sources of heat energy to control the rate of development of the film. Exemplary of the energy sources disclosed are R.F. coils and dielectric heating means. The embodiments illustrative of the inventive concepts disclosed and claimed as part of this invention are shown in FIGS. 2 and 3 herein.

Referring now to FIG. 2 there is shown an embodiment of our invention wherein a raster producing cathode ray tube is utilized to control the development process. In this embodiment, film is brought into tank 22 containing developer solution 24 and drum 26. This is the predevelopment stage. Film 20 upon leaving tank 22 may, if the path length is great, he required to have a stop bath 12 interposed between tank 22 and detector 50. It is obvious that some developing solution will remain on the film 74. As previously stated, this latter mentioned tank may include a further development process or may be utilized to appropriately stop any further action on the development of the film.

In another embodiment of the invention the infrared generator 48 is not utilized. In this embodiment, shown in FIG. 3, the beam of cathode ray tube 68 may either be deflected in the same manner as a flying spot scanner or, may be made to scan along a single line. Detector 50 is placed on the under side of film 20 to detect the energy emanating from faceplate 69 that passes through film 20. This also obviates the need for scan synchronization stage 60 since the detector will always know the instantaneous of this film appears on pages 50 and 51 of the Seventh while traveling from tank 22 to detector 50 and development will occur over this path length.

As film 20 progresses to detector 50, the level of predevelopment is detected by means of infrared generator 48 and photoelectric cell 50. Infrared generator 48 emits 'rays of infrared energy which are collected and detected 'by infrared sensitive photoelectric cell 50. At this point,

there will be an appreciable amount of metallic silver due to the predevelopment. Silver halide, the material in the undeveloped emulsion, is a whitish-looking material having a degree of transparency of about 40 to 60 percent and a reflectance of about 60 to 40 percent depending upon the condition and type of film. Such factors as the degree of wetness, amount of predevelopment and the like, govern the relative reflectance and transmissiveness of the film to infrared radiation. Metallic silver is a blackish material and hence substantially nontransmissive; Hence as the density level of the image on the film increases with increased development less infrared radiation is transmitted by any discrete area of the film and less radiation is received by photosensor 50. A decreased current output from the photoelectn'c cell 50 will be applied to control means 58 to decrease the output level of energy from the CRT 68.

Immediately after passing detector 50, the film 20 is placed in close proximity with the faceplate of the cathode ray tube 68. In this embodiment, a thin film of metal, such as columbium, is deposited on the inside of the infrared transparent cathode ray tube faceplate 69 of cathode ray tube 68 and the metal film is bombarded with electrons. Bombarding the metal film with electrons produces a moving spot of infrared energy which is radiated onto the film. The water embedded with the emulsion will absorb the energy thereby increasing development activity. This heated emulsion will now produce increased activity in the developer solution embedded in the emulsion. The amount of heat necessary is determined by the development detector 50, the output of which is applied to delay/ control means 58 and to a scanning synchronizer 60. Here, too, it is necessary for the infrared and detecting radiating

device

50 and 48 respectively to scan across the film and the appropriate scan information is applied to deflecting plates 66. Simultaneously the detector output information is applied to the delay/ control means 58 the output of which is applied to grid 64 of the cathode ray tube to appropriately modulate the electrode beam emanating from cathode 62. Thereafter the film proceeds to tank 72 in which is contained an appropriate developer Edition, first 1956 printing of Kodak Films available from Eastman-Kodak Company, Rochester, NY. A de' veloping bath that may be used is Kodak Developer D-76, the chemical constituents of which are set forth on page 42 of the Fifth Edition (1954) first 1959 printing of Processing Chemicals and Formulas available from Eastman-Kodak Company, Rochester, NY. Typical treatment of the film may be a predeveloped time period of three minutes, that is, any one point on the film would travel from entry into bath 24 to a point the CRT 68 in a period of three minutes. Radiation treatment of the film is instantaneous. The final development time, for example, may be five minutes, that is, the period it takes for any one point on the film to travel from roller 38 to stop bath solution not shown. A typical stop is Kodak SB-la, the formulation of which is found on pages 44 and 45 of the Fifth Edition of Processing Chemicals and Formulas. The CRT may be activated by a current suitable to raise the temperature of the developing solution D-76, from 68 F. to F., increasing the density of the discrete area of the film so treated from 1.2 to 1.5 and increasing gamma from 0.85 to 1.00.

. It is to be fully appreciated that the times quoted hereinabove for development are limited only to the use of the particular developing solution D-76 and that high speed developers would work as well as the D-76 developer with the added feature of more rapid total time of development. For example, rather than the 12 minutes disclosed with respect to D-76 developers are marketed with developing times of a magnitude of the order of 10 seconds. It is fully understood that the in vention is in no way limited by the use of D-76 developing solution but it is within the concept of the invention to use available developing solutions and solutions which may become part of the art as advances are made.

Final development time may be approximately seven minutes. That is a total time of 8 minutes for a point on the film to run through bath 74 which may also be D-76 solution. It is obvious that a more concentrated solution might be used in bath 74 to decrease the time that any point on the film takes in the final development bath or a solution with more rapid'development properties might be used.

Thus, an automatic film processing device and method which overcomes the difficulties of the prior art by providing increased solution activity at selectable incremental portions of the film step automatically has been fully and completely disclosed. While we have described what is presently considered a preferred embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the inventive concept,

and it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What is claimed is:

1. Chemical processing apparatus for developing a photographic material comprising:

(a) means to partially develop said photographic material;

(b) means to measure the density of the partially developed material; and

(e) means to control further development of said photographic material in response to said density measurement said means including a cathode ray tube means to control the further development by the application of heat to the photographic material, said cathode ray tube means having a faceplate which generates heat upon electron bombardment.

2. Apparatus as. set forth in claim 1 wherein said density measuring means includes a separate density measuring station which is distinct from said controlling means.

3. Apparatus as set forth in claim 1 wherein said density measuring means directs infrared radiation at the photographic material to measure its density.

4. Apparatus as set forth in claim 2 including a synchronizing means to synchronize operations of said density measuring means and said controlling means.

5. Apparatus as set forth in claim 1 wherein said density measuring means utilizes the output of said cathode ray tube.

6. Apparatus as set forth in claim 1 wherein the chemical processing apparatus includes a final developing bath for the photographic material after it is treated by said controlling means.

References Cited UNITED STATES PATENTS 1,762,936 6/1930 Seymour 95--94 XR 1,895,760 1/1933 Hunt 95-89 2,989,909 6/ 1961 Reed 355---20 XR NORTON ANSH-ER, Primary Examiner F. L. BRAUN, Assistant Examiner