Microfilming camera

A microfilming camera for taking an microimage of a document on a film. The microfilming camera comprises a main mirror disposed beneath a transparent document support for the support thereon of a document to be microfilmed, which main mirror is used to deflect the optical path of a photo-taking system, a side mirror disposed on each side of the space delimited between the document support and the main mirror, and illuminating sources positioned exteriorly of the optical path and disposed in face-to-face relationship with the respective side mirrors.

BACKGROUND OF THE INVENTION 
1. Field of Technology 
The present invention generally relates to a microfilming camera assembly 
and, more particularly, to an illuminator used therein for illuminating a 
document to be microfilmed. 
2. Description of the Prior Art 
The microfilming camera assembly is now made available generally in two 
types. One is referred to as a "flatbed" type, or possibly an overhead 
type, wherein, while a photographic camera is mounted overhead the 
document support for the support thereon of a document to be microfilmed, 
an illuminator lamp is supported on each side of the document support for 
illuminating the document placed on the document support, such as 
disclosed in, for example, U.S. Pat. Nos. 3,649,120 and 3,669,534. The 
other is referred to as an "Inverted-flatbed" type, or possibly a built-in 
type, wherein the illuminator lamp is supported on each side of the main 
mirror disposed beneath the transparent document support for deflecting 
the imagewise light, such as disclosed in, for example, U.S. Pat. Nos. 
3,972,619 and 3,697,176. 
The "flatbed", or overhead, type renders the microfilming camera assembly 
as a whole to be bulky, whereas the "Inverted-flatbed", or built-in, type 
requires an optical path of increased distance for minimizing an irregular 
illumination, the increased distance of the optical path in turn rendering 
the camera assembly as a whole to be bulky. 
In any event, in both of these types, neither design nor device have 
hitherto been developed for maximizing the efficiency of use of light 
emanating from the illuminator lamps. Also, another problem arises that, 
if the illuminator optical path is shortened, the distribution of light 
used to illuminate the document to be microfilmed tends to become 
irregular. 
SUMMARY OF THE INVENTION 
The present invention has been developed with a view to eliminating the 
above discussed problems inherent in the prior art microfilming camera 
assemblies and has for its essential object to provide an improved 
illuminator built in the microfilming camera assembly, which is effective 
to make the camera assembly compact and wherein arrangement is made to 
increase the light collecting efficiency. 
In order to accomplish the above described object of the present invention, 
there is provided an illuminator built in a microfilming camera assembly 
comprising a main mirror disposed beneath a transparent document support 
for the support thereon of a document to be microfilmed, which main mirror 
is used to deflect the optical path of a phototaking system. The 
illuminator comprises a side mirror disposed on each side of the space 
delimited between the document support and the main mirror, and 
illuminating sources positioned exteriorly of the optical path and 
disposed in face-to-face relationship with the respective side mirrors. 
In this construction, rays of light emanating from the illuminating sources 
can be directed from the side mirrors towards the main mirror which in 
turn direct them towards the document support to illuminate the document 
placed on the document support. 
With this construction, the illuminating sources can be positioned 
frontwardly of the main mirror and inwardly of the side mirrors with no 
possibility of mirror-reflection of respective images of the illuminating 
sources, and therefore, a sufficient optical path for the illuminating 
light can be secured, making it possible to render the camera assembly as 
a whole to be compact. 
Preferably, each of the illuminating sources comprises an illuminating lamp 
having a built-in filament, and a light collecting reflector block. The 
light collecting reflector block includes an upper arcuate reflector 
arcuately curved about the filament of the illuminator lamp, a side 
arcuate reflector and a side Fresnel reflector both continued downward 
from the upper arcuate reflector, a side flat reflector positioned below 
the side Fresnel reflector, and a lower flat reflector continued from the 
side flat reflector towards a position below the illuminator lamp. 
With each of the illuminating sources preferably so constructed as 
hereinabove described, since the various reflectors of the light 
collecting reflector block having its inner surface formed into a light 
correcting mirror of a predetermined shape are used to reflect rays of 
light so as to converge them in readiness for the illumination of the 
document, the rays of light emitted from the respective illuminator lamp 
can be efficiently utilized as the illuminating light, and therefore, the 
light collecting efficiency can be increased. 
Also, since the sectional shape of the light collecting reflector block is 
fixed, the light collecting reflector block can be manufactured by the use 
of a drawn material, and therefore, not only can the productivity be 
increased, but also the optical adjustment can readily be accomplished. 
The distribution of light used to illuminate the document placed on the 
document support can be advantageously adjusted by adjusting the angle of 
the side flat reflector and/or the shape of serrations of the side Fresnel 
reflector.

DETAILED DESCRIPTION OF THE EMBODIMENT 
Referring first ot FIGS. 1 and 2, a microfilming camera assembly 1 shown 
therein is of the "Inverted-flatbed", or built-in, type and comprises a 
camera casing 2 of generally rectangular box-like configuration having a 
transparent document support 4 mounted on top of the camera casing 2. The 
document support 4 may be a glass plate and has a rectangular 
white-colored frame 3 formed on a peripheral edge portion thereof. 
The camera casing 2 has installed therein a main mirror 5 positioned below 
the document support 4 and inclined at a predetermined angle for bending 
the photo-taking optical path inwardly, a first auxiliary mirror 6 
positioned in face-to-face relationship with the main mirror 5 for bending 
the photo-taking optical path upwardly, a second auxiliary mirror 7 
positioned in face-to-face relationship with the first auxiliary mirror 6 
for bending the photo-taking optical path in a lateral direction, and a 
photo-taking structure 11 including a photo-taking lens assembly 8 
positioned in face-to-face relationship with the second auxiliary mirror 
7, said photo-taking structure being operable to take a photographic 
recording of an image of the document on an electrophotographic microfilm 
10 enclosed within a microfilm cassette 9. It is to be noted that, in the 
practice of the present invention, the photo-taking structure 11 may be a 
processing head such as disclosed, for example in U.S. Pat. No. 4,600,291, 
and the microfilm cassette 9 utilizeable in the present invention may be a 
film cassette disclosed in, for example, U.S. Pat. No. 4,572,649. 
The specific arrangement of the mirrors 5 to 7 as described above has made 
it possible to make the camera casing 2 in a generally flattened box-like 
configuration. 
Also, within the camera casing 2, a pair of side mirrors 12 are positioned 
on respective sides of the space between the document support 4 and the 
main mirror 5 and in face-to-face relationship with each other for bending 
an illuminating optical path. 
A pair of illuminators 13 are arranged frontwardly of the main mirror 5 so 
as to confront the respective side mirrors 12 and positioned inwardly 
between the side mirrors 12 and exteriorly of the photo-taking optical 
path. 
The illuminators 13 are of identical construction, and each comprises a 
tubular illuminator lamp 14 and a light shielding cover 15 exteriorly 
surrounding the illuminator lamp 14. The light shielding cover 15 for each 
illuminator 13 has its interior surface formed as a light collecting 
mirror and also has a light projecting slit defined at 16 for projecting 
rays of light from the lamp 14 towards the adjacent side mirror 12 
therethrough. 
The details of each of the illuminators 13 are best shown in FIGS. 5 and 6. 
As shown therein, each illuminator 13 comprises a light collecting 
reflector block 18 including an upper arcuate reflector 18a curved about a 
filament 14a of the tubular lamp 14, a side arcuate reflector 18b and a 
side Fresnel reflector 18c continued downwards from the upper arcuate 
reflector 18a, a side flat reflector 18d positioned below the side Fresnel 
reflector 18c, and a lower flat reflector 18e continued from the side flat 
reflector 18d so as to extend towards a position below the respective lamp 
14, said light collecting reflector block 18 being enclosed by the light 
shielding cover 15 which has the light projecting slit 16 defined therein. 
It is to be noted that the side flat reflector 18d is so supported that the 
angle of inclination thereof can be adjusted. 
Accordingly, a bundle of rays of light emanating from the lamp 14 between 
points C and D is reflected by the lower flat reflector 18e thereby to 
form a bundle of light rays within the range I--I which is used to 
illuminate the document placed on the document support 14. 
Similarly, a bundle of light rays between points B and C is reflected by 
the side flat reflector 18d thereby to form a bundle of light rays within 
the range of II--II, and a bundle of light rays between points A and B is 
guided by the side arcuate reflector 18d and the side Fresnel reflector 
18c towards the lower flat reflector 18e to form a bundle of light rays 
within the range III--III, both of said light bundles within the 
respective ranges II--II and III--III being also used to illuminate the 
document on the document support 4. 
A bundle of light rays between points A and E is reflected by the upper 
arcuate reflector 18a so as to join the above described illuminating 
light. 
With each of the illuminators 13 having been constructed as hereinbefore 
described, the light collecting efficiency of the light collecting block 
18 is high and, therefore, light emitted from the respective lamp 14 can 
be efficiently used as the illuminating light. 
Also, since the light collecting reflector block 18 has a fixed sectional 
shape, it can be made of a drawn material, and therefore, not only can the 
productivity be increased, but also the optical adjustment can readily be 
accomplished. 
Moreover, by the adjustment of the angle of inclination of the side flat 
reflector 18d and/or that of the shape of serrations of the side Fresnal 
reflector 18c, the distribution of illumination on the document support 
can be corrected. 
It is to be noted, if an auxiliary reflective plate 19 is fitted to one or 
a plurality of appropriate portions of the light collecting reflector 
block 18, the intensity of illumination at a specific portion of the 
document on the document support can be increased with no need to increase 
the number of the lamps 14 and that, if a diffuser 20 is provided on an 
appropriate portion of the lower flat reflector 18c of the light 
collecting reflector block 18, the peak value of the distribution of 
illumination can be suppressed to permit the intensity of light used to 
illuminate a peripheral area of the document to be increased. 
In the construction as hereinbefore decsribed, and referring now to FIGS. 3 
and 4, while the illuminators 13 are in reality positioned at respective 
locations I, the side mirrors 12 permit the illuminators 13 to act as if 
they were positioned at respective locations II, when rays of light are 
projected onto the side mirrors 12 through the respective slits 16. 
Similarly, the illuminators 13 are permitted by the main mirror 15 to act 
as if they were positioned at respective locations IV. 
Accordingly, by virture of these two phenomena, that is, since the 
illuminating light projected from the illuminators 13 are reflected by the 
side mirrors 12 and then by the main mirror 5, the illuminators 13 act as 
if they were positioned at respective locations III. 
The locations III are ideal positions for the respective illuminators 13 
where they would not bring about irregular illumination of the document 
placed on the document support. 
From the foregoing, it has now become clear that, since the illuminators 13 
are in reality located frontwardly of the main mirror 5 and inwardly 
between the side mirrors 12, the camera casing 2 can be made compact, and 
that, since by virtue of the mirrors 12 and 5 the illuminators 13 act as 
if they were placed at the respective locations III, the illuminating 
optical path can be sufficiently secured with no possibility of irregular 
illumination. 
It is also clear that, since the three mirrors 5 and 12 surround the 
document support 4, a plurality of illuminating optical paths are formed 
between the illuminators 13 and the document support 4, the intensity of 
illuminating light can be increased. 
Although the present invention has been fully described by way of example 
with reference to the accompanying drawings, it is to be noted here that 
various changes and modifications will be apparent to those skilled in the 
art. For example, although in the foregoing description reference has been 
made to the use of a film which is generally known as an 
electrophotographic microfilm, a silver haloid photographic film can be 
equally used in connection with the microfilming camera according to the 
present invention. 
Therefore, unless otherwise such changes and modifications depart from the 
scope of the present invention, they should be construed as being included 
therein.