In earlier U.S. Pat. No. 4,751,583 and U.S. Pat. No. 4,745,040, there is provided apparatus for electronic development of photographic films, of types using light sensitive crystals, or other chemical compounds, that absorb light energy when exposed to a light image, to change chemical composition. The disclosed electronic development processes involve applying light energy of constant time-energy integral to incremental portions of the film to drive the light sensitive crvstals, or other compounds, into saturation, and electronically detect at each such incremental area the quanta of light that is not absorbed by the film. At each portion of the film storing a latent image from a previous exposure, the light energy being absorbed until reaching saturation varies according to the extent of prior exposure, whereby the latent image is detected and electronically reproduced from the variations in the interrogating light energy that are not absorbed by the film at the different positions.
SUMMARY OF THE INVENTION
According to the present invention, a similar process is employed for electronically developing, or reading out, a multi-color latent image that has been stored in an exposed conventional color photographic film. Briefly according to the invention, the film is scanned by a series of different color interrogating light beams, with each different color light beam being of a different frequency color closely corresponding to the different light frequency sensitively of a different color sensitive chemical compound in the film, and with each such different color interrogating light beam having only a sufficient time -energy integral sufficient to bring its color sensitive chemical compound in the film into a condition of saturation. The light energy from each different color interrogating beams, that is not absorbed by the film, as that beam scans the film frame, is electronically detected and electrically recorded. Therefore, each different color latent image in the color film is separately detected and recorded.
According to the invention, a preferred apparatus to perform this electronic development of the exposed film, is provided in the form of a small, portable, light tight, battery operated unit, that is similar in size and configuration to the audio portable playback units, presently in widespread use for playing audible recordings on compact discs. Within the unit is provided a light scanning mechanism, an electronic light detector, electrical signal recorders, and different color light filters, as required; all being in miniature size and low power capacity to be driven by a portable battery power source.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view illustrating a process and apparatus for electronic development of a conventional photographic film;
FIG. 2 is a schematic chart illustrating the variable light absorption in the photo film of the interrogating beam, according to the stored latent image from a previous exposure;
FIG. 3 is a schematic illustration showing the process applied to an exposed photographic color film; and FIG. 4 is a perspective view illustrating a battery powered portable electronic developing apparatus, according to the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 illustrates an electro-optical method and apparatus for destructively reading out the latent images in an exposed but undeveloped photographic film, without the need for chemically processing the film, all as disclosed in earlier U.S. Pat. No. 4,745,040. As shown, a low intensity fine interrrogating laser beam 90, having light frequencies within the visible sensitive band of the film 32, is rapidly scanned in a series of lines forming a rectangular raster across the film 32, as the film 32 is advanced longitudinally. The intensity of the interrogating beam 90 taken with the speed of scanning the lines is adjusted to apply only sufficient light energy to each incremental area of the film 32 so as to expose the light sensitive silver halide crystals, or other light sensitive chemical compound, into a condition of saturation. However, the time-intensity integral of exposure is carefully controlled to be sufficiently low so as not to greatly exceed this saturation level. A lens system 93 and mirror 94 is properly located to receive the scanning light beam after its passage through the film 32, and collect and apply the received light to an electronic light sensor or detector 87, where the received light is converted into an electric signal and amplified at 96. After a sufficient level of amplification, the received signal is recorded by recorder 97 to provide a recorded elecrtrical image corresponding to the original latent image on the exposed but undeveloped photo film.
As each incremental position of the film frame 32 is scanned by the fine beam of interrogating light 90, a different quanta of energy is absorbed by the light sensitive silver halide crystals, or other light sensitive chemical compound, at that position of the film 32, adding to the previous exposure (by the original light image exposure), and driving the light sensitive crystals at that position into a condition of saturation. Where the previous exposure by the light image has been at a low level (dim), a greater quanta of light energy from the interrogating beam 90 is absorbed; whereas where the latent image at that position results from a greater exposure of light from the image, a lesser quanta of light energy is absorbed from the interrogating beam 90, to drive the crystals into saturation. Therefore the quantity of the interrogating light that passes through the film 32 to energize the detector 87 varies, as the beam is scanned over the film frame as the inverse (or positive) of the latent image, and the electrical signal being recorded in recorder 97 correspondingly varies according to the stored latent image in the film 32. It will be appreciated that the laser scanning speed is normally quite fast to provide an extremely short interrogating exposure of the film 32; and a highly sensitive light detector system 87, high gain amplifier 96 are required to reproduce the very low level variations in the scanning interrogating light beam 90, after its passage through the film 32.
The high speed scanning mechanism for very rapidly sweeping the laser beam 90 in a series of displaced lines 91 across the film 32 may comprise a multifaceted prism 88 driven by a high speed motor 89, as are now commonly used in high speed laser printers. After passing through the film 32, the reduced intensity laser beam 32 is collected by a lens system 93, parabolic mirror (not shown), or other optical collector, and focused onto a suitably disposed mirror 94 to be directed to the light sensitive electronic detector 87, as earlier described.
It will be appreciated that changes may be made in the scanning system for the interrogating light beam 90. The beam itself may be generated by a different source of light, other than a laser, and be controlled to generate light at constant intensity, and, by the use of suitable color filters, produce light energy at the light sensitive wavelenth of the light sensitive crystals, or other compound, in the film 32. The light beam 90 can be finally focused by the use of lenses or collectors or reflectors (not shown); and be scanned across the film frame 32 in a spiral pattern, or other pattern, other than the rectangular raster, as shown in FIG. 1. It will be appreciated that the finer the interrogating light beam 90, and the more sensitive the detector 87, the greater the number of pixels of the latent image that can be recovered from the film frame 32, and elecrically recorded by the recorder 97.
FIG. 2 is a simplified illustration showing the varying degree of absorption of the interrogating light beam 90 by the film frame 32, as the scanning interrogating beam 90 scans the series of different lines in the film frame 32. At a first incremental area of the film frame, shown at the left in FIG. 2, the quanta of light energy previously absorbed in forming the latent light image is represented by the region numbered 98. The remaining area above region 98, and indicated by the number 102, represents the additional quanta of energy that is absorbed by the light sensitive chemical compound at that area, that is necessary to drive the compound at that area into a condition of complete saturation. At the next position on the chart of FIG. 2, corresponding to the next adjacent area on the film frame 32, the initial light energy absorbed from the original light image, and stored as a latent image, is shown at region 99. This differs from the energy stored at 98, according to the variations in the original light image exposing the film 32. Consequently, a lesser quanta of light energy is absorbed from the interrogating light beam 90, in order to drive the light sensitive chemical compound at this position into a fully saturated condition; as illustrated by the region 103.
In a similar manner, each of the next two incrementally small areas on the film frame have absorbed different quantas of energy from the original exposure of the light image, as represented by the regions 100 and 101, shown in FIG. 2. Therefore as the interrogating light beam 90 passes each of these next two areas or regions, the quanta of light being absorbed by the film crystals at these two areas also varies inversely to that of the latent image, as represented in FIG. 2 by the areas numbered 104 and 105, respectively. Thus the quantity of light energy received by the light detector 87 as the film frame is progressively scanned by the interrogating light beam 90 varies in inverse proportion (positive) to that of the latent image previously stored in the film, and the recording of this varying signal of the complete film frame corresponds to the positive of the original latent image stored in the film.
It will be appreciated that this electronic optical readout of the latent image in the film frame 32 is destructive, in that the light sensitive chemical compounds in the film 32 are driven into a fully saturated condition by the interrogating light beam, thereby erasing the latent image in the film frame. The reading out of the film frame by the scanning interrogating beam is , of course, performed in a dark environment to prevent spurious exposure of the light sensitive film 32, or performed in an illuminated environment that is outside of the light sensitive frequency band of the film 32. For film of different light sensitivety (higher or lower ASA ratings), the scanning speed of the interrogating light beam 90 is correspondingly varied as is the longitudinal speed of driving the film 32, both to correspondingly change the time of exposure of the film to the interrogating light beam 90.