Variable resistance

The control part of the slide member in contact with electrodes of a variable resistance with resistance members and a plural number of electrodes is made larger than the insulation part between two adjacent electrodes so as to secure the conductivity between the electrodes and the slide member. The form of the slide member and the space provided between each electrode part with respect to other such parts satisfy a predetermined mathematical relationship.

BACKGROUND OF THE INVENTION 
In the case of the conventional variable resistance, a slide member 
connected to a terminal moves slidingly over the resistance between 
adjacent terminals connected to the circuit so as to set a resistance 
value proportional to the distance between terminals. When the slide 
member moves slidingly directly over the resistance body, the 
characteristics of the resistance body covered with metal varies due to 
the wear and the friction in such a manner that the set resistance value 
often deviates. Further, there exists the semi-fixed variable resistance 
which is an improvement of the above mentioned variable resistance, which 
is so designed that the electrode parts are led out of the resistance 
body, whereby there is a difficulty that when the semi-fixed variable 
resistance is arranged in the circuit and set for adjusting the resistance 
value, the slide member often drops on the insulation part between the 
electrodes in such a manner that the slide member is insulated from the 
electrodes. Hereby, even if the slide member is set on the electrode, it 
often moves and drops on the insulation part due to the vibration, the 
shocks and so on. 
SUMMARY OF THE INVENTION 
The first purpose of the present invention is to offer a variable 
resistance so designed that a resistance part and a plural number of 
electrode parts are provided in such a manner that the conductivity 
between the slide member and the electrodes of the variable resistance on 
which electrodes the slide member moves slidingly. 
Another purpose of the present invention is to secure the conductivity 
between the electrode parts and the slide member of a variable resistance 
whose resistance part and the electrode parts consist of a printed circuit 
material plate on which the resistance layer, the conductive layer and the 
support layer are laid. 
Further another purpose of the present invention is to offer a variable 
resistance which can be used either as a resistance capable for setting on 
optional resistance value within the range built in the circuit or as a 
semi-fixed output voltage (current) adjusting resistance of the circuit. 
Further another purpose of the present invention is to offer a means for 
realizing the compactness, the light weight and the high efficiency of a 
camera by applying the above mentioned variable resistance to the member 
of the electronic circuit of the camera. 
Further, other features and advantages of the present invention will be 
disclosed from the explanation to be made below in accordance with the 
accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
In FIG. 1, 1 is the insulation base plate, 2 the resistance body provided 
on the base plate 1, a - n the comb-tooth shaped electrode projecting from 
the resistance body 2. 3 is the slide member movable sliding over the 
electrode part (a - n). 3a is the rotary shaft rotatably holding the slide 
member 3, presenting the slide position ajdusting groove at the upper end. 
4, 4' are the terminals of the variable resistance. 5 is the conductive 
piece between the electrode part n and the terminal 4. 5' is the 
conductive piece between the electrode part a and the terminal 4'. The 
slide member 3 is electrically connected to the electrode a. The 
resistance body 2 consists of resistance material printed or metallized on 
the insulation base plate 1 in a conventional way. The electrode part (a - 
n) consists of conductive material printed and metallized on the upper 
part of the resistance body 2 in a conventional way. Further, the 
electrode parts and the resistance parts are alternatively provided, being 
overlapped partially. The connecting terminals 4, 4' are soldered on the 
pattern on the other printed plate (not shown in the drawing) so as to 
obtain an electrical conductivity. Other printed plates can be cemented 
auxiliarily. 6 is an almost semi-circular shaped projection in contact 
with the electrode part provided on the slide member for production of a 
click effect to be explained later. 
FIG. 2 and FIG. 3 respectively show the relation between the position of 
the semi-circular shaped projection 6 and that of the electrode parts 
shown in FIG. 1, when as is shown in FIG. 2, the slide member is set on 
the electrode part b the value of the variable resistance is represented 
by the set resistance 2 between the terminal 4 and the electrode part b. 
The value of this resistance is obtained between the terminals 4 and 4'. 
It often happens that the slide member 3 is in contact with the insulation 
base plate 1 as is shown in FIG. 3, the contact position of the slide 
member 3 with the electrode part b being disturbed due to the external 
strength such as inferior adjustment, vibrations or shocks. In this case, 
the conductivity between the slide member 3 and the electrode h or i and g 
is interrupted so that no resistance value is obtained between 4 and 4', 
losing the efficiency as resistance. 
FIG. 4 shows the important members of the embodiment shown in FIG. 1 in 
sectional view. In the drawing, 2 and 3 correspond to the insulation base 
plate 1 and the slide member 3 in FIG. 1. In the present embodiment, the 
electrode part (a - n) are provided on the resistance body 2. 6.sub.1 is 
the thickness of the slide member 3, while t.sub.2 is the thickness of the 
electrode parts (a - n) fixed on the resistance body 2. R represents the 
radius of the almost semi-circular shaped projection provided at the 
position at which the slide member is in contact with the electrode. 2S is 
the width of the insulation part between the adjacent electrodes (h, i). 
In accordance with the present invention, the contact part of the slide 
member 3 with the electrode is choosen larger than the insulation part 
between the electrodes. In this way, the conductivity between the 
electrode and the slide member can be secured, preventing the contact part 
of the slide member 3 with the electrode from dropping between the 
electrodes. Namely, it is sufficient to choose the value of the width 2S 
of the insulation part so as to satisfy the following relation: 
EQU .sqroot.(R + t.sub.1).sup.2 - S.sup.2 + t.sub.2 .gtoreq. R + t.sub.1 (1) 
By choosing the value of the width 2S of the insulation part so as to 
satisfy the relation (1) the conductivity between the slide member and the 
electrode part is secured in such a manner that the set resistance value 
can be obtained at the output terminals of the resistance because the 
circular projection is in contact with the electrode parts h-i even when 
the slide member drops on the insulation part between the electrodes. 
In accordance with the present invention, the click effect takes place on 
the slide member by choosing the relation between the contact part of the 
slide member with the electrode part and the insulation part between the 
electrodes so as to satisfy the relation (1). Namely, a click is produced 
every time the projection 6 of the slide member 3 drops between the 
electrodes at the time of setting and regulating the resistance by 
rotating the rotary shaft 3a by means of a driver and so on. In 
consequence, the man who regulates the resistance can confirm from the 
click feeling that the slide member drops between the electrodes. This, he 
can confirm whether the slide member is at the desired position. 
FIG. 5 shows the variation of the set resistance value in accordance with 
the set position of the slide member. In the drawing, 3 is the slide 
member, whereby 3.sub.1 is the member set on an electrode part, 3.sub.2 
the member set between the electrodes b and c and 3.sub.3 the member set 
between the electrodes c and d. R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are 
the values of the resistances between the electrodes a and b, b and c, c 
and d and d and e. 4 and 4' are the terminals for taking out the 
resistance value. The resistance value between the terminals 4 and 4' when 
the slide member is set on the electrode part c is R.sub.1 + R.sub.2. The 
resistance value between the terminals 4 and 4' when the slide member is 
set between the electrodes b and c is R.sub.1. The resistance value 
between the terminals 4 and 4' when the slide member is set between the 
electrodes c and d. The value of the resistance is R.sub.1 + R.sub.2 when 
the slide member is set on the electrode c or when it is set between the 
electrodes c and d, whereby when it is on the electrode c there is a 
possibility that the slide member should drop between the electrodes b and 
c due to the external strength such as vibration of shock, when the 
resistance value is R.sub.1, quite different from the set value. By 
chosing the dimentional relation between the members of the variable 
resistance so as to satisfy the relation (1) it is possible to produce the 
click effect in such a manner that the slide member can easily be set 
between the electrodes so as to prevent the deviation of the resistance 
value from the set value due to the external strength. Further the 
resistance body between the electrodes a and b in FIG. 1 can be of 
conductive material. 
Below the variable resistance composed on the print circuit plate 
consisting of resistance layer, the electrode layer and support layer will 
be explained. The present embodiment is constituted with the circuit base 
plate of the printed circuit plate material so designed that the 
resistance layer and the conductive layer laid on the insulation base 
plate are processed by etching or the like so as to constitute the 
resistance members in the resistance layer and the wiring, the terminals 
and so on in the conductive layer. 
The present embodiment will be explained in accordance with the camera in 
which the subject of the present invention is applied. 
Quite recently the automatization of the camera has made a great progress 
which the built-in electrical circuit has become more and more 
complicated. Further the realization of the compact and light camera is 
remarkablly desired. Thus, a large restriction is put on the space to be 
occupied with the electrical circuit members to be built in the camera. 
Hereby the conventional technics of the constitution and the arrangement 
of the electrical circuit can not meat the above requirement sufficiently, 
whereby it is difficult to solve the problem even by means of integrating 
the electrical circuit members (IC, LSI). The present embodiment 
represents an automatic exposure control single reflex camera in which the 
electrical circuit consisting of the above mentioned printed circuit plate 
is applied. 
FIG. 6 shows the basic structure of the printed circuit plate to be used in 
the present embodiment. In the drawing, 101 is the insulation base plate 
forming the support layer, consisting for example of glass, epoxy resin 
and so on. 102 is the resistance layer composed on the base plate 101, 
consisting of resistance material such as nickel, phosphur and so on. 103 
is the conductive layer composed on the resistance layer 102, consisting 
of cupper film. For the above printed circuit plate, the material sold by 
the Mica Corporation, U.S.A. under the trade name "MICA PL1 OMEGA" and so 
on is used. FIG. 5b shows the layer construction shown in FIG. 6a 
processed by means of selective etching in such a manner that the upper 
conductive layer is partially removed so as to constitute the resistance 
part and the conductive part, whereby 102' represent the resistance layer. 
Namely the resistance layer at there spots represent the resistance 
elements with the remaining conductive layer parts 103 and 103' as 
terminals. The value of the resistance can be determined as desired by 
closing the length, the width and so on of the resistance layer as is 
shown in FIG. 6c. Further the parts 103, 103' of the conductive layer are 
used as the wiring, the terminals and so on. In this way the circuit base 
plate of the desired pattern can be manufactured. 
FIG. 7 shows the important members of an embodiment of the camera, in which 
the variable resistance in accordance with the present invention is used, 
in perspective view, whereby the upper cover 200 of the camera body is 
removed. In the drawing, 201 is the camera body, whereby a TTL-AE-single 
reflex camera with priority on shutter time is shown. 202 is the winding 
up lever, whereby the shutter dial 203 and the film sensitivity setting 
mechanism are of coaxial construction. 206 is a flexible wiring base plate 
for connecting the sub-circuit base plate 205 with the main circuit base 
plate 207. 207 and 207' are the main circuit base plates, respectively 
presenting an integrated circuit IC1 and IC2, consisting of the afore 
mentioned printed circuit plate material and arranged along the roof plane 
of the pentagonal prism 208. Further, beside IC, such external member as 
condensers, transistors and so on are arranged accordingly on the main 
circuit base plates 207 and 207'. 204 is the sub-circuit base plate of the 
light measuring circuit including the light sensing element such as SPC, 
being connected to the main circuit base plate by means of the flexible 
wiring base plate 220. TC is provided in the hole in the main circuit base 
plate, being connected to the terminals, whereby the insulation plate 209 
is arranged between the main circuit base plates 207, 207' and the roof 
plane of the prism. 210 is the winding back shaft, coaxially to which the 
film sensitivity setting variable resistance 211 is provided, whereby the 
slide member 211' is connected by means of a not shown cable to the film 
sensitivity setting mechanism coaxial with the shutter dial in such a 
manner that when the slide member is rotated in the pulled up state of the 
shutter dial the slide member rotates sliding over the contacts of the 
afore mentioned film sensitivity setting variable resistance so as to set 
the film sensitivity. 213 is the flexible wiring base plate for connecting 
the subcircuit base plate presenting the afore mentioned film sensitivity 
setting variable resistance to the main circuit base plate 207, whereby 
other not shown sub-circuit base plates and so on are connected to the one 
end 213' of this base plate. Hereby 214 is the display meter, 215 the lens 
mount and 216 the movable mirror. 
FIG. 8 shows an embodiment of the electrical circuit to be used to the 
camera. This circuit is provided in a space in the camera. The preferable 
position for the space is between the roof plane of the pentagonal prism 
and the upper cover in case of the single reflex camera. In FIG. 8, 206 is 
the flexible wiring base plate for connecting the sub-circuit base plate 
(not shown in the drawing) to the main circuit base plate 207. 207 and 
207' are the main circuit base plates, consisting of the afore mentioned 
printed circuit plate material. As the sub-circuit base plate, the circuit 
base plate constituting the input circuit for the photographic information 
of the camera is suited. The main circuit base plates 207 and 207' 
respectively present IC1 and IC2, being accordingly provided with the 
external members such as condensers, transistors and so on. 220 is the 
light measuring circuit base plate, on which IC3 of the light measuring 
circuit including light sensing element (for example silicon photo cell) 
is mounted and which is connected to the main circuit base plate 207 by 
means of the flexible wiring base plate. This light measuring circuit base 
plate is provided near the view finder. 209, 210, 211 and 212 are the 
variable resistances in accordance with the present invention, to be 
arranged on the back side of the main circuit base plates 207 and 207'. 
213, 214, 215 and 216 are the grooved rotary shafts of the variable 
resistances. These shafts are pivoted on the base plate so as to be 
rotated as one body with the slide members of the variable resistances 
209, 210, 211 and 212. The variable resistances can be regulated, by means 
of rotating the grooved rotary shafts with the driver from the upper side 
of the base plate. 
FIG. 9 shows the upper plane (FIG. 9a) and the lower plane (FIG. 9b) of the 
main circuit base plate 207 shown in FIG. 8. The main circuit base plate 
207 is provided on the right roof plane of the pentagonal prism. FIG. 9a 
shows the pattern on the upper plane of the base plate whereby the black 
parts are the conductive parts consisting of the conductive layer while 
other parts are the surface of the insulation base plate. The central 
square part 501 in the drawing is the hole for mounting IC, whereby IC is 
inserted in this hole while the input and the output terminal are 
soldered, leading to the conductor terminals 502. 503 shown as block rings 
are the terminals with holes, by means of which holes the circuit in the 
pattern on the lower plane shown in FIG. 9b is connected to the circuit on 
the upper plane. Further the external members are mounted on the base 
plate by means of the holes. 504 is the terminals for connecting the 
circuit to other main circuits base plates, whereby on this part the 
flexible wiring plate or the comb-tooth shaped wiring plate is mounted in 
such a manner that by means of this wiring plate the first and the second 
main circuit base plate are connected. The part 505 shown as white circle 
in the drawing in the hole for mounting the flexible wiring base plate on 
the main circuit base plate, whereby the wiring terminals of the wiring 
base plate are soldered on the terminals 506. FIG. 9b shows the pattern on 
the lower plane of the first main circuit base plate shown in FIG. 9a, 
whereby the patterns shown in FIG. 9a and FIG. 9b consist of printed 
circuit plate material with resistance layer, conductive layer and support 
layer on both plane of one insulation base plate. The parts in black in 
the drawing are the wirings, the terminals and the connecting points of 
the variable resistances consisting of conductive layer. The part A in 
circle in a dotted line is the variable resistance. The part A shows the 
state before the slide member of the variable resistance and the grooved 
shaft have been mounted. The black radial parts in A constitute the 
electrodes with which the not shown slide member is in contact. The 
hatched parts are the resistance elements consisting of the resistance 
layer. 517 a and 517b are the terminals. The terminal 517a is connected to 
the circuit through the wiring part 521. 522 is the hole for mounting the 
grooved rotary shaft (not shown in the drawing). The variable resistance 
in the present embodiment is constituted with the electrode parts (in 
black) and the resistance elements (hatched parts) as is shown in FIG. 9, 
whereby the grooved rotary shaft and the slide member are in seated into 
the hole 522 in such a manner that the shaft and the slide member are 
pivoted so as to be in contact with the terminals. The value of the 
variable resistance is determined with the length and the thickness of the 
resistance element between the terminal 517a and the slide member when the 
slide member is set at a certain position of the electrode parts. The 
output terminal of the resistance is between the terminal 517a and the 
terminal 517c of the upper base plate plane of the rotary shaft. The 
terminal 517c is connected to the circuit through the wiring part. The end 
507' of the trimming part 507 shown in a comparatively thick line is 
partially removed by means of the laser light so as to adjust the 
resistance value, whereby the value of the resistance element 508 can be 
finely adjusted at somewhat higher value. The hatched parts of the ladder 
shaped pattern 509 is partially removed by means of the laser light so as 
to alter the resistance value of the element 509. Hereby the resistance 
element 510 presents the trimming pattern consisting of two ladder shaped 
parts and one part in a thick line. By accordingly trimming these parts by 
means of the laser light the resistance value can be adjusted finely. 
Other resistance elements 512, 513 and so on present the trimming parts in 
a same way in such a manner that the value of each resistance element can 
be adjusted after the base plate has been built in the circuit, whereby 
the number of the resistances can be reduced by means of this trimming. 
Hereby the low resistance elements 514 and 515 have no trimming parts. The 
resistance element 516 and the electrode part 517 constitute a variable 
resistance, whereby the central circle is the hole for mounting the shaft 
of the slide member. The pointed end of the slide member mounted on the 
base plate through this hole moves sliding over the electrode parts 517 so 
as to operate as variable resistance. The resistance is adjusted by 
rotating the shaft by means of a driver and so on from the surface of the 
base plate after the resistance has been built in the circuit. 518 and 519 
in while circle are the holes for mounting the flexible wiring base plate, 
while the wiring terminals of the wiring base plate are soldered on the 
terminals 520. The variable resistance shown in FIG. 9 serves to adjust 
the input and the output of the control circuit and so on, and can be used 
as semi-fixed resistance for fine adjustment or as variable resistance for 
setting the resistance value. 
FIG. 10a shows a pattern on the surface of the main circuit base plate, 
being constituted in the same way as the first main circuit base plate 
shown in FIG. 9a, whereby the black parts are the conductive parts 
consisting of conductive layer. The central square part 521 is the hole 
for IC, whereby the terminals at the side are connected to the wirings of 
the main circuit base plate through the printed wiring plate or the 
comb-tooth shaped wiring plate. 523 is the hole for mounting the printed 
circuit plate, whereby the terminals of the wiring base plate are soldered 
on the terminals 524. FIG. 10b shows the pattern of the resistance 
elements, the wirings, the terminals and the variable resistance 
consisting of the printed circuit plate material on the lower side of the 
pattern shown in FIG. 10a, on which plate material the resistance layer, 
the conductive layer and the support layer are laid, whereby the pattern 
in conductor is connected to the pattern on the upper side through the 
holes 503. 525, 526 and 527 are the variable resistances, 528 and 529 the 
low resistance elements and 530 to 535 the resistance elements, whereby 
they are constituted as is explained in accordance with FIG. 9. Hereby the 
central square part 521 is the hole for mounting IC. 527 is the variable 
resistance with 1/x characteristics, whereby the adjacent electrodes are 
respectively connected to each other by means of resistance elements of 
different length (resistance). 525 and 526 are the variable resistance 
with 1/x characteristics, whereby every three electrodes are connected 
with two resistance elements. Hereby the distance between each adjacent 
electrodes is choosen so small that as many electrodes as possible might 
be mounted in such a manner that the space occupied with the pattern can 
be made use of efficiently. Further there is a hole for mounting the 
rotary shaft of the slide member at the center of these resistances, 
whereby the slide member can be adjusted by means of a driver or the like 
from the side of the surface of the base plate (FIG. 10a). Each resistance 
element presents the trimming part as is explained in accordance with FIG. 
9 in such a manner that the resistance value can be adjusted finely by 
means of the laser light after the base plate has been mounted. 
The slide members and the rotary shafts of the variable resistances 525, 
526 and 527 shown in FIG. 10 are mounted in the same way as in case shown 
in FIG. 9. The value of the variable resistance 527 is taken out between 
the terminal 527a on the lower side and the terminal 527b on the upper 
side. The value of the variable resistances 525 and 526 is taken out in 
the same way as in case of 527. The variable resistance shown in FIG. 10 
serves to adjust the input and the output of the control circuit of the 
camera and can be used either as semi-fixed resistance for fine adjustment 
or variable resistance for setting resistance value. 
FIG. 11 shows the main circuit base plate of the camera in which the 
variable resistance in accordance with the present invention is used, in 
section, whereby the base plate is provided on the roof plane of the 
pentagonal prism. In the drawing, 601 is the pentagonal prism, 602 the 
insulation plate provided on the roof plane of the prism and 603 the hole 
for the variable condenser. 604 is the main circuit base plate consisting 
of the afore mentioned printed circuit plate, on whose upper surface the 
conductor pattern as is shown in FIG. 9a is formed and on whose lower 
surface the resistance bodies and the conductor pattern as is shown in 
FIG. 9b are formed. 605 is the rotary shaft for adjusting the variable 
resistance, presenting a head with a groove on the upper surface, and the 
slide member 608 on the lower surface, whereby the slide member 608 moves 
sliding over the electrodes of the variable resistance. Hereby 607 and 
607' are the spring washer. 609 is the integrated circuit construction, 
being inserted in the hole 610 in the base plate as is shown in the 
drawing, whereby the terminals 611 and 611' are soldered on the conductor 
terminals on the upper surface. 612 is the external member such as 
condenser soldered at the terminal on the upper surface of the base plate. 
Further the pattern on the upper surface is electrically connected to the 
pattern on the lower surface of the base plate with the hole not shown in 
the drawing, so as to constitute an electrical circuit construction. 
FIG. 12 shows an embodiment of the variable resistance in accordance with 
the present invention, which is used as the input setting means of the 
shutter time of a camera. 
700 shown in a dotted line in FIG. 12a and FIG. 12b is the base plate on 
which the resistances are fixed, whereby the resistance parts 701 and the 
electrode parts 702 are fixed as is shown in FIG. 1. 703 is the shutter 
dial 203 shown in FIG. 7. The variable resistance is constituted coaxially 
with the shutter dial 703. The slide member 704 functionally engaged with 
the shutter dial moves sliding over the electrode parts (a - n) so as to 
produce the set resistance value between the terminals 705-706 in 
accordance with the set position of the slide member, whereby the shutter 
time in accordance with the resistance value can be produced. 
In the case of the present embodiment, by means of providing a plural 
number of the electrode parts at a position on the shutter time scale 
provided on the shutter dial, for example at the position on the variable 
resistance corresponding to the time between 1/125 sec. and 1/250 sec., it 
is possible to set the shutter time information between 1/125 sec. and 
1/250 sec., whereby the slide member can be set with sure by means of the 
afore mentioned click effect, whereby the displacement due to vibration or 
shock can be avoided in such a manner that the intermediary value or an 
optical value of the shutter time use for the conventional camera can be 
set. 
FIG. 13 shows an embodiment of the above mentioned shutter time input 
setting variable resistance consisting of the printed circuit plate 
material on which the resistance layer, the conductive layer constituting 
the electrodes and the support layer are laid. FIG. 13 shows the pattern 
of the circuit base plate of the above mentioned shutter time input 
setting resistance. In the drawing, the black parts 912 are the electrode 
parts while the hatched parts 911 the resistance parts consisting of 
resistance layer. 913 and 913' are the terminals of the variable 
resistance, on which the conductor parts of the flexible wiring base plate 
are wired. The central circle 916 is the hole in which the rotary shaft of 
the slide member is mounted. 917 and 917' are the holes for mounting the 
base plate. 
The variable resistance in accordance with the present invention is quite 
suited as other photographic information input means of the camera and can 
be used either as film sensitivity information input means or as aperture 
value information input means. The variable resistance for the film 
sensitivity setting can be constituted together with the slide member 
being capable of being provided coaxially with the shaft of the winding 
back lever 202 shown in FIG. 7 and driven by means of the film sensitivity 
setting dial at the shutter dial. 
The aperture value setting variable resistance can be realized by arranging 
the variable resistance shown in FIG. 12 and FIG. 13 coaxially with the 
winding up shaft shown in FIG. 7. 
FIG. 14 shows the variable resistance in accordance with the present 
invention used as the film sensitivity setting variable resistance in a 
camera, being arranged coaxially with the winding back shaft shown in FIG. 
4, so as to constitute the film sensitivity setting variable resistance 
together with the slide member driven by the film sensitivity dial at the 
shutter dial. The black parts in the drawing are the conductor parts 
consisting of conductive layer, while the hatched parts are the resistance 
elements consisting of resistance layer. The central circle 921 is the 
hole in which the winding back shaft and the slide member are inserted as 
is shown in FIG. 7. 922 are the electrode parts of the variable 
resistance, over which the not shown slide member moves sliding so as to 
set the film sensitivity. 923 are the terminals, on which the conductors 
of the flexible wiring base plates are soldered. 924 is the resistance 
element of the variable resistance, the parts 924' in each of which one 
resistance element is connected between the adjacent electrodes are 
arranged outside as well as inside of the electrodes and the parts 924' in 
each of which two resistance elements are connected between the adjacent 
electrodes are arranged outside as well as inside of the electrodes. In 
this way the number of the electrodes can be increased. Hereby the 
variable resistances present the 1/x characteristics. The part shown in a 
thick semi-circle 925 in the drawing shows the non-operative range for the 
automatic exposure. The terminals 926 and 926' are the electrodes for 
detecting the position at the time of mounting the slide member, whereby 
927 are in marks. 
FIG. 15 shows the pattern of another embodiment of the sub-circuit base 
plate presenting the film sensitivity setting variable resistance shown in 
FIG. 14, whereby in the present embodiment the number of the electrodes 
are smaller than that of the electrodes shown in FIG. 14. The same member 
in the drawing as those in FIG. 14 have the same figures. Hereby 932, 
932', 933 and 933' are the electrodes for detecting the position at the 
time of mounting the slide member, whereby between these electrodes the 
low resistance elements 934 and 935 are provided in parallel. Other 
members are similar to those in the embodiment shown in FIG. 14, so that 
their explanation is omitted here. Further the embodiment in which the 
afore mentioned parallel resistance elements 934 and 935 is realizable. 
Hereby the value of the parallel resistance has to be selected so as not 
to become an error for the value of the variable resistance. The position 
detecting terminals 932 and 932' (or 933 and 933') are short circuited by 
means of the slide member, when a short circuit signal is produced so as 
to detect the slide member. 
As explained in detail above in case of the variable resistance in 
accordance with the present invention, the conductivity between the slide 
member and the electrodes are secured by means of the slide member while 
the resistance value never alters after the resistance has been set and 
adjusted at a certain determined value so that it can be used as variable 
resistance to be set in an optical range and further as superior 
semi-fixed variable resistance for adjusting the input and the output of 
the electronic circuit. 
The variable resistance in accordance with the present invention is quite 
suited as that for the electronic circuit of the precision instrument such 
as camera for which the compactness, the light weight and the high 
integrated efficiency are requested whereby by constituting the electrode 
parts and the resistance member as one body on the circuit base plate 
consisting of the afore mentioned printed circuit plate material on which 
the resistance layer, the conductor layer and the support layer are laid 
the superior arrangement efficiency of the members of the electronic 
circuit can be obtained. 
Further the variable resistance in accordance with the present invention 
can substitute the conventional variable resistance as photographic 
information input setting means (shutter time information, the film 
sensitivity information and the aperture value information) of the camera, 
whereby by properly selecting the number of the electrodes and the 
material of the resistances so as to optionally designing the resistance 
coefficient the intermediary value of the set information value 
conventionally used and other information values can be obtained.