Device for supporting optical system of television camera and having two spring systems for reducing rattling in two different directions

A device for supporting an optical system of a television camera has a pair of positioning holes, formed in a bracket holding an image pickup element, which are fitted respectively on a pair of positioning pins formed on a rear side of an escutcheon holding a lens, thereby positioning the image pickup element in a horizontal and a vertical direction. Rattling of the bracket in a direction perpendicular to the optical axis of the optical system is absorbed by a pair of plate springs, and also rattling of the bracket in a direction of the optical axis is absorbed by a pair of coil springs, thereby enabling a high-precision adjustment.

BACKGROUND OF THE INVENTION 
This invention relates to a device for supporting an optical system of a 
television camera such as a CCTV camera. 
FIG. 6 shows a conventional optical system support device of the type 
described. In FIG. 6, reference numeral 1 denotes a lens seat, reference 
numeral 2 a FB adjusting ring, reference numeral 3 an escutcheon, 
reference numeral 4 a bracket, reference numeral 5 an element mounting 
seat, reference numeral 6 an image pickup element, reference numeral 7 an 
element holder plate, reference numeral 8 a front chassis, and reference 
numeral 9 a leaf spring. The image pickup element 6 is attached to the 
element mounting seat 5, and then the element holder plate 7 is fitted on 
the image pickup element 6, and is fixedly secured by screws 10A to the 
element mounting seat 5, with the image pickup element 6 held 
therebetween. Then, the element mounting seat 5 is secured to a rear 
surface of the bracket 4 by screws 10B. The two leaf springs 9 for 
absorbing the rattling of the bracket 4 in an axial direction 
(forward-backward direction) are secured to a front surface of the bracket 
4 by respective screws 10C. Projections 4a, formed on an outer peripheral 
surface of the bracket 4, are engaged respectively in recesses 1a formed 
in an outer peripheral portion of the lens seat 1, and then the lens seat 
1 is fixedly secured to the front chassis 8 by screws 10D. As a result, 
the center of the image pickup element 6 coincides with the center of the 
lens seat 1, that is, an optical axis OA of this optical system, and also 
the positioning of the image pickup element 6 in a horizontal and a 
vertical direction is achieved. Then, the FB adjusting ring 2 for 
adjusting the flange-back is passed through an opening 3a in the 
escutcheon 3, and a threaded portion 2a on an inner periphery of the FB 
adjusting ring 2 is threaded on a threaded portion 1b on an outer 
periphery of the lens seat 1. With this arrangement, by rotating the FB 
adjusting ring 2, the lens seat 1 and the image pickup element 6 are moved 
back and forth, thereby adjusting the flange-back, that is, the distance 
between the lens seat 1 and the image pickup position. 
In the above conventional optical system support device, however, the 
projections 4a are fitted respectively in the recesses 1a for positioning 
the bracket 4 (which holds the image pickup element 6) with respect to the 
lens seat 1, and therefore a gap inevitably develops between the mating 
projection 4a and recess 1a partly because of the provision of a draft. 
This has resulted in a problem that when the FB adjusting ring 2 is 
rotated, rattling develops in the peripheral (circumferential) direction 
or a direction perpendicular to the optical axis, so that the image on a 
picture screen moves during the adjustment of the flange-back. Moreover, 
because of this rattling, much time and labor are required for the optical 
adjustment, which has invited a problem that a high-precision adjustment 
can not be carried out easily. Particularly recently, the image pickup 
size has become smaller, and even a slight degree of rattling is amplified 
on the picture screen. To deal with this, if the precision of processing 
(machining) of the component parts is improved so as to enhance the 
optical precision, this has resulted in a problem that the cost is 
increased. 
SUMMARY OF THE INVENTION 
With the above problems of the prior art in view, it is an object of this 
invention to provide a device for supporting an optical system of a 
television camera, in which the rattling of a bracket holding an image 
pickup element is eliminated, thereby enabling a high-precision 
adjustment. 
According to the present invention, there is provided a device for 
supporting an optical system of a television camera, comprising: 
an escutcheon having at its rear side a first positioning portion serving 
as a reference of positioning in a horizontal and a vertical directions, 
the escutcheon having a lens holding portion; 
a flange-back adjusting ring rotatably mounted on a front side of the 
escutcheon; 
a bracket mounted on the rear side of the escutcheon, the bracket holding 
an image pickup element, and having a second positioning portion fitted 
relative to the first positioning portion of the escutcheon; 
first spring means for absorbing rattling of the bracket in a direction 
perpendicular to an optical axis of the optical system; and 
second spring means for absorbing rattling of the bracket in a direction of 
the optical axis thereof. 
With this construction of the present invention, by fitting the second 
positioning portion of the bracket relative to the first positioning 
portion of the escutcheon, the positioning of the image pickup element in 
the horizontal and vertical directions is effected, and also the rattling 
of the bracket in the peripheral and axial directions are absorbed by the 
first and second spring means, and therefore the adjustment can be carried 
out with high precision.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
One preferred embodiment of the present invention will now be described 
with reference to the drawings. In FIG. 1, reference numeral 11 denotes an 
escutcheon, reference numeral 12 a bracket, reference numeral 13 an image 
pickup element, reference numeral 14 an element mounting seat, reference 
numeral 15 a plate spring, reference numeral 16 a coil spring, reference 
numeral 17 an element-mounting circuit board, reference numeral 18 a 
mounting angle, reference numeral 19 an FB adjusting ring, and reference 
numerals 20 and 21 screws. The escutcheon 11 has a tubular portion formed 
at its central portion, and a threaded portion 111 for holding a lens is 
formed on an inner peripheral surface of this tubular portion. A threaded 
portion 112 for threaded connection to a threaded portion 191 formed on an 
inner peripheral surface of the FB adjusting ring 19 is formed on an outer 
peripheral surface of the tubular portion of the escutcheon 11. As shown 
in FIG. 2, two positioning pins 113, serving as a reference or basis of 
positioning in a horizontal and a vertical direction, are formed on and 
projected from the rear side or face of the escutcheon 11, and two stopper 
walls 114 for imparting reaction forces respectively to the plate springs 
15 are also formed on the rear side of the escutcheon 11. The bracket 12 
has an opening of a rectangular shape formed through a central portion 
thereof, the image pickup element 13 being inserted into this opening. A 
pair of tabs are formed respectively on opposite lateral sides of the 
bracket 12, and a positioning hole 121 for passing a respective one of the 
positioning pins 113 therethrough is formed through each of these tabs, 
and a mounting boss 122 is formed on each of the tabs adjacent to the 
positioning hole 121. 
An assembling sequence for this embodiment will now be described. In FIG. 
1, the image pickup element 13 is first secured in position to a front 
face of the element mounting seat 14 by an adhesive or the like, and then 
the element mounting seat 14 is fastened to the bracket 12 by the screws 
20. This fastening operation is effected using the positioning holes 121 
of the bracket 12 as a reference, and an optical axis OA and an 
inclination thereof are properly adjusted. Then, mounting holes 151 in the 
plate springs 15 are fitted respectively on the mounting bosses 122 on the 
rear face of the bracket 12, and then the bracket 12 is attached to the 
escutcheon 11. This attaching operation is effected by fitting the 
positioning holes 121 of the bracket 12 respectively on the positioning 
pins 113 of the escutcheon 11. As a result, the center of the 
lens-mounting threaded portion 111 of the escutcheon 11, that is, the 
optical axis OA, coincides with the center of the image pickup element 13, 
and also a projection 152 of each of the plate springs 15 is pressed 
against the associated stopper wall 114 of the escutcheon 11 to urge the 
bracket 12 in one peripheral (circumferential) direction with respect to 
the escutcheon 11 by its reaction force, thereby absorbing the rattling of 
the bracket 12 in the peripheral direction. Then, the coil springs 16 are 
inserted respectively into the mounting bosses 122 of the bracket 12, and 
then the mounting angle 18 is fixedly secured to the escutcheon 11 by the 
screws 21. As a result, the bracket 12 is pressed against the escutcheon 
11 by the coil springs 16, so that the rattling of the bracket 12 in the 
axial direction (forward-backward direction) is absorbed. Then, pins on 
the image pickup element 13 are fitted respectively in holes in the 
element-mounting circuit board 17, and the FB adjusting ring 19 is 
attached to the escutcheon 11 by threading its threaded portion 191 on the 
threaded portion 112 of the escutcheon 11. 
As described above, in this embodiment, by rotating the FB adjusting ring 
19, the escutcheon 11 can be moved back and forth together with the 
bracket 12 and the image pickup element 13 without rattling, thereby 
adjusting the flange-back distance D highly precisely. Since no backlash 
or play is present between the escutcheon 11 and the bracket 12, the 
optical axis OA and the inclination thereof can be adjusted with high 
precision. Moreover, since the associated parts can be attached to the 
escutcheon 11 from one direction, the time and labor required for the 
assembling operation can be reduced. 
In the above embodiment, although the positioning pins 113 are formed on 
the escutcheon 11 while the positioning holes 121 are formed in the 
bracket 12, such positioning holes may be formed in the escutcheon 11 
while such positioning pins may be formed on the bracket. Instead of such 
pin-hole engagement, the engagement between convex and concave portions of 
any other suitable shape may be used. 
In the present invention, as is clear from the above embodiment, the 
optical axis of the television camera, the inclination thereof and the 
flange-back can be adjusted with high precision, and therefore the 
movement of the image on the picture screen during the flange-back 
adjustment as previously experienced can be eliminated. The flange-back 
adjustment can be carried out easily. There have now been increasingly 
used television cameras of the type in which a focus adjusting mechanism 
is not provided on a lens, and instead the focus adjustment is effected at 
the camera side. In this type of television camera, the adjustment when 
setting the camera is quite easily effected as a result of eliminating the 
movement of the image on the picture screen. Furthermore, the optical 
precision can be enhanced without improving the precision of processing 
(machining) of the component parts, and therefore the reduction of the 
image pickup size can be satisfactorily dealt with without increasing the 
cost.