Camera capable of winding and rewinding film by revolution of motor

The present invention provides a camera having a film feed mechanism comprising a microphone for sensing the surrounding noise around the camera, a noise level measuring portion for measuring the sensed noise (sound pressure), a noise level discriminator for comparing the measured noise level with a predetermined level to discriminate whether the measured noise level is higher or lower than the predetermined level, a feed mode change-over portion for changing the film feed speed to a silent mode or a normal film feed by selecting the normal film feed or the film feed whose generated noise level is low in response to the discriminated noise level, and a film feed mechanism for feeding a film in both winding and rewinding.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a camera being capable of winding and 
rewinding a film by a revolution of a motor, and having a silent film feed 
mode for reducing film feed noise in response to the surrounding noise 
level. 
2. Description of the Related Art 
Conventionally, in a camera having an automatic film feed mechanism by a 
motor, it has been well known that winding and rewinding of a loaded film 
(film feeding) should be done as fast as possible in order to prepare the 
following shot or to load the following roll of film when winding the film 
before taking a photo or rewinding the film after taking a photo. 
Due to this, a small and powerful DC motor has been mounted in the camera 
to improve a film feeding speed. 
However, in accordance with the higher film feeding speed, the noise level 
generated in feeding the film becomes much higher than the conventional 
case, and there occur troubles at a place where silence is required or 
time when silence is required. There is a case that such noise is produced 
by the fact that noise, which is generated when the feed mechanism is 
operated at a high speed, is added to noise, which is generated from the 
motor. 
In order to solve such troubles, for example, Japanese Patent Application 
KOKAI Publication No. 2-191925 discloses a camera having a change-over 
mode for changing the rewinding speed to change the mode in response to 
the state of the surroundings, thereby making it possible to select either 
a silent mode in which generating noise is reduced by decreasing a 
rewinding speed thereby rewinding the film or a high speed mode in which 
the film is rewound with a high noise level. 
However, in the above publication, since a photographer manually operates a 
changing switch, there will occur a case in which noise is erroneously 
given off if the photographer forgets to change the mode. Also, generally, 
when the rewind of the film is started, such an operation cannot be 
temporarily stopped and the mode cannot be changed so as to change the 
film winding speed until the rewind of the film is finished. Due to this, 
in the case of the erroneous operation, there is a case in which the film 
is rewound in the silent mode even when the photographer may rewind the 
film in the normal mode. 
Moreover, if a photographer cannot judge the mode selection with regard to 
the surrounding noise level, and winds or rewinds the film beyond 
necessity in the silent mode in which the feeding speed is low, rewinding 
time is made longer or a chance for releasing the shutter may be lost. 
SUMMARY OF THE INVENTION 
Therefore, an object of the present invention is to provide a camera which 
can feed a film in a silent mode in response to a noise level of the 
surroundings at the time of feeding the film. 
According to the present invention, first, there is provided a camera being 
capable of winding and rewinding a film by a revolution of a motor, 
comprising noise level measuring means for measuring a noise level of the 
surroundings of the camera; noise level discriminating means for 
discriminating whether the noise level measured by the noise level 
measuring means is higher or lower than a predetermined value; and control 
means for controlling a revolution speed of a motor for feeding a film 
based on the result of the level discriminated by the noise level 
discriminating means. 
Secondly, according to the present invention, there is provided a camera 
being capable of winding and rewinding a film by a revolution of a motor, 
comprising noise level measuring means for measuring a noise level of the 
surroundings of the camera; noise level discriminating means for 
discriminating whether the noise level measured by the noise level 
measuring means is higher or lower than a predetermined value; film 
feeding means for rewinding a film after exposure and/or a film after 
rewinding a film after taking a predetermined number of photos; and 
changing means for changing a film feeding mode to a normal mode for 
feeding the film at a predetermined normal speed or a silent mode for 
feeding the film at a higher speed than the normal speed based on the 
result of the level discriminated by the noise level discriminating means. 
Additional objects and advantages of the invention will be set forth in the 
description which follows, and in part will be obvious from the 
description, or may be learned by practice of the invention. The objects 
and advantages of the invention may be realized and obtained by means of 
the instrumentalities and combinations particularly pointed out in the 
appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The embodiments of the present invention will be explained in detail with 
reference to the drawings. 
The outline of the camera of the present invention can be explained as 
follows. 
The surrounding noise level is measured in accordance with the input of a 
film feed start signal. The measured level is compared with a 
predetermined level. It is selected whether a normal film feed is 
performed or a film feed with a low level of a feed noise (silent mode) is 
performed based on the compared result. Thereby, either the film winding 
or the film rewinding is performed. In this embodiment, in the case that 
the silent mode is selected, the film feed speed (the revolution of the 
motor) is lower than the film fed speed in the normal mode. 
FIG. 1 is a block diagram showing the outline of a film feed mechanism, 
which is a feature of a camera of the present invention. 
The film feed mechanism comprises a microphone 1 for sensing the 
surrounding noise around the camera, a noise level measuring portion 2 for 
measuring the sensed noise (sound pressure), a noise level discriminator 3 
for comparing the measured boise level with a predetermined level to 
discriminate whether the measured noise level is higher or lower than the 
predetermined level, a feed mode change-over portion 4 for changing the 
film feed speed to a silent mode or a normal film feed by selecting the 
normal film feed or the film feed whose generated noise level is low in 
response to the discriminated noise level, and a film feed mechanism 5 for 
feeding a film in both winding and rewinding. 
FIG. 2 shows the structure in which the film feed mechanism is mounted on 
the camera. 
In a camera shown in FIG. 2, a film 13 is delivered from a film cassette 12 
loaded on the camera 11, and is wound around a take-up spool 14 of the 
camera. A photo-interrupter 15 is provided to detect the movement of 
perfolations on the film 13. A film counter 16 is provided to identify the 
position of the film as much as one frame by counting one frame of the 
film by a signal generated from the photo-interrupter 15. 
Also, there are provided a shutter drive circuit 17 for detecting a finish 
timing of a shutter (not shown), a microphone 18 stored in the camera 11, 
a noise level measuring circuit 19 for measuring the surrounding noise 
level captured by the microphone 18, a film winding mechanism 20, 
connected to the spool 14, for winding the film 13 by reduction gears (not 
shown), a film rewinding mechanism 21, connected to the film cassette 12, 
for rewinding the film 13 by reduction gears (not shown), a motor 22 for 
driving the winding mechanism 20 and the rewinding mechanism 21, a motor 
drive circuit 23 for driving the motor 22, a film end detection mechanism 
24 for detecting the end of the film 13, and a central processing unit 
(CPU) 25 for controlling each of the above components. 
An operating procedure of winding and rewinding the film of the 
above-structured camera will be explained with reference to a flow chart 
shown in FIG. 3. 
When the load of the film 13 on the camera is finished, the camera is set 
in a state that a photo can be taken, and a film counter K is set to "1" 
(step S1). A photo taking sequence begins by pressing a release button 
(not shown) (step S2). When the shutter drive is ended, a shutter drive 
end signal is inputted to the CPU 25 from the shutter drive circuit 17 
(step S3). 
A film end detection is carried out by the film end detection mechanism 24. 
If it is detected that the film is not ended (NO), the surrounding noise 
level is measured to prepare a next photo taking (step S6). Then, the 
measured surrounding noise level is compared with a predetermined 
reference noise level (step S6). 
As a result of the comparison, if the measured surrounding noise level is 
lower than the reference noise level, a low voltage is applied to the 
motor 22 to be driven (step S7), the film counter K is advanced by one 
(step S8), and the motor 22 is stopped (step S11). 
If the measured surrounding noise level is lower than the reference noise 
level in the comparison in step S6, a high voltage is applied to the motor 
22 to be driven (step S9), the film counter K is advanced by one (step 
S10), and the motor 22 is stopped (step S11). After the motor 22 is 
stopped in step S11, the operation returns to the step S2, and the photo 
taking sequence repeats again. 
If the film end is detected (YES) in step S4, the flow advances to a 
sequence for rewinding the film 13. 
The motor 22 is connected to the film rewinding mechanism 21 by changing 
over a clutch (not shown) to the film winding mechanism 21 from the film 
winding mechanism 20 (step S12). Then, the surrounding noise is measured 
by the noise level measuring circuit 19 (step S13), and the measured 
surrounding noise level is compared with the predetermined reference noise 
level (step S14). 
As a result of the comparison, if the measured surrounding noise level is 
lower than the reference noise level, a low voltage V.sub.L is applied to 
the motor 22 to be driven (step S15) as shown in FIG. 5. When the film 
counter K becomes zero (step S19), the motor 22 is stopped (step S19). 
Moreover, if the measured surrounding noise level is higher than the 
reference noise level, a high voltage V.sub.H is applied to the motor 22 
to be driven (step S17) as shown in FIG. 5. When the film counter K 
becomes zero (step S18), the motor 22 is stopped (step S19). 
Then, after the motor 22 is stopped and the rewinding operation is 
finished, the rewind mechanism 21, which is connected to the motor 22, is 
released therefrom by a clutch (not shown). Then, the winding mechanism 20 
is connected to the motor 22, and all of the operation sequence are 
finished. 
FIG. 4 specifically shows the embodiment described in steps S6 to S9 and 
S14, S15, and S17 of the flow chart shown in FIG. 3. 
When the surrounding noise level L is inputted, the surrounding noise level 
L is compared with the predetermined reference level L.sub.0 (step S31). 
As a result of the comparison, if the surrounding noise level L is lower 
than the predetermined reference level L.sub.0 (NO), the drive voltage V 
to be applied to the motor 22 is set to the low voltage V.sub.L as shown 
in FIG. 5, so that the motor 22 is driven with the low voltage V.sub.L 
(step S33). 
If the surrounding noise level L is higher than the predetermined reference 
level L.sub.0 (YES), the drive voltage V to be applied to the motor 22 is 
set to the high voltage V.sub.H as shown in FIG. 5, so that the motor 22 
is driven with the low voltage V.sub.H (step S35). 
In this embodiment, the revolution of the motor is regulated by controlling 
(varying) the drive voltage to be applied to the motor. However, the 
method of regulating the revolution of the motor is not limited to the 
above embodiment. 
The flow chart in FIG. 6 shows another operating procedure of a pulsed 
driving method by varying a duty ratio of the drive voltage to be applied 
to the motor. 
When the surrounding noise level L is inputted, the surrounding noise level 
L is compared with the predetermined reference level L.sub.0 (step S41). 
As a result of the comparison, if the surrounding noise level L is lower 
than the predetermined reference level L.sub.0 (NO), the motor 22 is 
driven with a pulsed drive voltage V.sub.1 having a small duty ratio as 
shown in FIG. 7B. 
If the surrounding noise level L is higher than the predetermined reference 
level L.sub.0 (YES) in the comparison in step S41, the motor 22 is driven 
by applying a fixed voltage V.sub.2 thereto (FIG. 7A). 
Therefore, the revolution of the motor can be regulated by varying the duty 
ratio of the motor drive voltage. 
As a result, according to the above-explained embodiment, the film feed 
mode is automatically changed to the silent mode in response to the 
surrounding noise level of the camera and the revolution of the motor is 
controlled to be low, so that the noise, which is generated in both 
winding and rewinding the film, can be reduced. 
As mentioned above, according to the present invention, there is provided a 
camera, which can feed the film in the silent mode in response to the 
surrounding noise level. 
Additional advantages and modifications will readily occur to those skilled 
in the art. Therefore, the invention in its broader aspects is not limited 
to the specific details, and representative devices shown and described 
herein. Accordingly, various modifications may be made without departing 
from the spirit or scope of the general inventive concept as defined by 
the appended claims and their equivalents.