Abstract:
A single-lens reflex camera includes a protruding housing portion enclosing a pentagonal prism and an eyepiece optical system. The housing portion has at least two lateral faces connecting a front face and a rear face. The camera includes a flash unit having two arm members fixed thereto. The two arm members can rotate about axis passing through the protruding portion between the lateral faces. The two arm members can assume a first position where the flash unit is disabled and a second position where the flash unit is enabled.

Description:
This is a continuation of application Ser. No. 055,150 filed May 28, 1987, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a photographic camera provided with a flash device. 
     2. Related Background Art 
     In the field of such cameras, there is already known, as disclosed in the Japanese Paten Laid-open No. 2271/1978, a single-lens reflex camers with flash device, in which a light-emitting unit of the flash device is articulated to the top of the pentagonal prism cover of the camera. The flash device is lifted up to be positioned farther away from the optical axis of the image-taking lens at use and, when not used, is folded back toward the eyepiece of the finder for being accommodated in a recess provided in the back of said pentagonal prism cover. In such known camera, the light-emitting face of the flash device is positioned upwards and is exposed to the outside, and is apt to be smeared or damaged while the unit is folded. 
     In order to resolve this drawback, there is already proposed, as disclosed in the Japanese Patent Laid-open No. 208735/1983, a single-lens reflex camera in which a light-emitting unit articulated to the top of the pentagonal prism cover is folded from its standing state to the front when not used, and is held along the front surface of the pentagonal prism cover so that the light-emitting face is positioned downwards. 
     However, in such conventional cameras with flash devices, the light-emitting unit is supported by a hinge shaft of limited strength provided at the top of narrow pentagonal prism case and is therefore unstably supported when it is lifted. Also, since the light-emitting face is positioned upward or downward in the folded state, the light-emitting unit has to be rotated by 90° or more for reaching the standing state for use. For this reason, the lead wires connecting the flash tube in the light-emitting unit with the main capacitor and the high-voltage circuit provided in the camera body are moved or twisted as said unit is rotated between the folded state and the standing state, thus reducing durability. 
     Furthermore, as disclosed in the Japanese Utility Model No. 66320/1986, there is already known a single-lens reflex camera with flash device, in which a light-emitting unit is provided at the upper front portion of the camera body opposite to the grip portion thereof. The unit is rotated approximately 180° about a hinge shaft, from a folded position along the front wall of the camera body to a lifted position where the light-emitting face is directed forward for use. In such camera, the camera body has a space for accommodating the battery, main capacitor, electric circuits, trigger coil, etc., and the rotatable unit principally contains the flash tube. In such case the lead wires connecting the flash tube with the electric circuits provided in the camera body are inevitably moved or twisted. Also, at the activation of the flash device, noises generated by the high-voltage trigger coil provided in the camera body adversely affect other control circuits in the camera, thus causing erroneous operation of the camera. 
     SUMMARY OF THE INVENTION 
     In consideration of the foregoing, an object of the present invention is to provide a camera with flash device in which the light-emitting unit requires only a limited angle of rotation between its folded position and its position for use, and in which the light-emitting face of the unit is safely protected in said folded position and is sufficiently separated from the optical axis of the image-taking lens in said position for use. 
     Another object of the present invention is to provide a camera with flash device in which the light-emitting unit is securely supported in its position of use is compact, and still has a space therein for accommodating at least the trigger coil. 
     The above-mentioned objects can be achieved, according to the present invention, by a structure in which the rotary shaft means of a rotatable light-emitting unit is provided at the rear side of the camera, with ends of the shaft means at both sides of the pentagonal prism cover house a finder optical system and protrudes on the upper part of the camera, and which said light-emitting unit of the flash device is positioned along the front surface of said pentagonal prism cover in the folded position, with the light-emitting face directed diagonally downwards in front of the camera. In this manner the distance from the light-emitting unit to the rotating shaft can be sufficiently long, so that the light-emitting face can be sufficiently separated from the optical axis of the image taking lens with a limited rotating angle. Also, the light-emitting face can be brought to a position substantially coinciding with the front side of the camera with a rotating angle smaller than 90°. Consequently the lead wires connecting the flash lamp of the light-emitting unit with the high-voltage circuit in the camera are subjected to relatively little twisting, resulting in a longer service life. 
     In addition, an increased distance between the bearings for the rotation shaft allows more secure support of the light-emitting unit at the position of use. Also, the trigger coil is incorporated in an arm of the arch-shaped light-emitting unit, so that electrical noises generated by said trigger coil in the position of use of said unit do not affect the electric circuits in the camera, such as the exposure control circuit or sequence control circuit. In this manner erroneous functions of the camera are prevented. 
    
    
     Still other objects of the present invention, and the features and advantages thereof, will become fully apparent from the following description which is to be taken in conjunction with the appended drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic lateral view of a single-lens reflex camera with flash device embodying the present invention. 
     FIG. 2 is a perspective view of a single-lens reflex camera with flash device shown in FIG. 1; 
     FIG. 3 is a cross-sectional view along a line III--III in FIG. 1; 
     FIG. 4 is a cross-sectional view along a line IV--IV of FIG. 3; 
     FIGS. 5 and 6 are cross-sectional views for explaining a click stop mechanism of a rotary shaft shown in FIG. 4; wherein FIG. 5 shows a state in which the flash device is set in a normal flash position while FIG. 6 shows a state in which said unit is set in a bounce flash position; 
     FIG. 7 is a cross-sectional view along a line VII--VII shown in FIG. 3, showing a state in which the flash device is locked in a folded state; 
     FIG. 8 is a cross-sectional view of a locking device showing a state in which the locking of the flash device shown in FIG. 7 is released; 
     FIG. 9 is a perspective view of the flash device shown in FIG. 1 in a state rotated to a normal flash position; 
     FIG. 10 is a schematic circuit diagram of the flash device embodying the present invention; and 
     FIG. 11 is a partial cross-sectional view of a flash device according to another embodiment of the present invention, wherein a trigger coil is provided in a supporting frame of the device shown in FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a schematic lateral view of a single-lens reflex camera with flash device embodying the present invention; and FIG. 2 is a perspective view of said camera in which the flash device is locked in a folded position. 
     At the upper central part of the camera body 1 a flash device 40 mounted for rotation about a rotary shaft means 0 positioned at the rear side of the camera and above a finder optical system 60 as shown in FIGS. 1 and 2. More particularly, flash device 40 is rotatable from a folded position A (solid lines in FIG. 1) and positions B1, B2 (phantom lines in FIG. 1) for use. The position of use B1 is a normal flash position in which a light-emitting face F of the flash device is perpendicular to the optical axis of an image taking lens L and therefore faces an object to be photographed while the position B2 is a bounce flash position for so-called bounce flashing in which the light-emitting face F is directed above the object. In the present embodiment the flash device 40 is rotated, from the folded position A, by about 35° to reach the position of use B1, or by about 80° to reach the position B2. In FIG. 1, a pentagonal prism 61 and an eyepiece constitute the finder optical system 60. An accessory shoe 10 is provided for accepting an additional electronic flash device 11 different from the flash device 40. 
     Now referred also to FIG. 3 which is a cross-sectional view along a line III--III in FIG. 1, an upper cover (pentagonal prism cover) 100 positioned over the prism 61 surrounds the finder optical system 60 composed of the eyepiece 62 and said prism 61. Said cover 100 is provided, on lateral faces 103, 104 thereof, respectively with a solid support shaft 21 and a hollow support shaft 22 on the same axis, and said shafts 21, 22 rotatably support, through bearings 42, 43, an arch-shaped support member 41 constituting an outer part of the flash device 40. As shown in FIG. 3, the support shafts 21, 22 extending outwardly to the support frame 41 are positioned at the rear side of the lateral walls 103, 104 of the upper cover 100 surrounding the sides of the finder optical system 60. In the support frame 41 there is provided a flash lamp 44 such as a xenon lamp, from which lead wires 45 are connected through the center of the hollow support shaft 22 to a voltage elevating circuit V1 (FIG. 10) provided in the camera body 1. The flahs tube 44 is covered, at a side corresponding to the front side of the camera, for example with a translucent plastic plate which constitues the light-emitting face F. Reference number 102 indicates the back side of the upper cover 100. 
     In the following discussion there will be explained a rotating mechanism for the flash device 40. Referring to FIG. 3, around the solid support shaft 21 and the bearing 42 there is provided a torsion coil spring 46, of which an end 46a engages with a hook pin 41A protruding from the support frame 41 while the other end 46b is connected to a spring ring 24 fixed to the solid support shaft 21 with a screw 23. The support frame 41 is thus constantly biased toward the positions of use B1, B2 (or above the plane of FIG. 3). Support frame 41 is held fixed against the action of the biasing force at the folded position A and the positions of use B1, B2 as will now be explained. 
     In said positions of use B1, B2, the support frame 41 is supported and fixed in the following manner. As shown in FIG. 3, the shaft 21 is provided on the periphery thereof with a hole 25, in which a compression coil spring 26 and a ball 27 are inserted, whereby said ball 27 is biased to the outside by said spring 26. On the other hand, on the internal periphery of the bearing 42 fitted on the solid support shaft 21, there are formed a cam face 42a and cam grooves 42b, 42c as shown in FIGS. 4 to 6, and the ball 27 engages with said cam face 42a in the folded position A. 
     When the support frame 41 is rotated from the folded position A to the position of use B1 (FIG. 5), the ball 27 engages with the cam groove 42b, whereby the support frame 41 is fixed in said position B1. When the support frame 41 is further rotated to the position of use B2 (FIG. 6), the ball 27 then engages with the cam groove 42c whereby the support frame 41 is fixed in said position B2. As shown in FIGS. 4 and 5, elastic switch contacts 2, 3 are provided inside an upper cover 20 camera body 1, and said contact 3 is provided, at an end thereof, with a pin 4 penetrating through and projecting from the upper cover 20 by the elastic force of said contact 3. Thus, when the support frame 41 is in the folded position A, the pin 4 is pushed into the upper cover 20 as shown in FIG. 4 so that the movable contact 3 is separated from the fixed contact 2. On the other hand, when the support frame 41 is maintained at the position B1 or B2, the movable contact 3 touches the fixed contact 2 as shown in FIG. 5 to enable the use of the flash device. 
     In the following discussion there will be explained a locking mechanism in the folded position A, while making reference to FIG. 3, and the cross-sectional views shown in FIGS. 7 and 8. 
     An upper wall 28 of the upper cover 100 is provided with a slidable knob 5, connected through a pin 6 to a lever 7 positioned inside said upper wall 28. Said lever 7 is provided, on both ends 7a, 7b thereof, with fingers 8a, 8b protruding to the front of the camera from a front face 101 of the upper cover 100. Said fingers 8a, 8b are constantly biased toward the front of the camera (toward left in FIG. 3) by means of a torsion coil spring 9 provided on a pin 29 protruding from the upper cover 100. Corresponding to the fingers 8a, 8b, the support frame 41 is provided with holes 41B, 41C into which the fingers 8a, 8b are inserted as shown in FIGS. 3 and 7 when the support frame 41 is in the folded position, thereby locking the support frame against the rotative force of the torsion coil spring 46. 
     When the knob 5 is moved toward the rear of the camers (the right in FIG. 8) against the biasing force of the spring 9, the fingers 8a, 8b are retracted from the holes 41B, 41C, where upon the support frame 41 is rotated toward the position B1 and B2 shown in FIG. 1 by the force of the torsion coil spring 46. Then, as shown in FIG. 5, the ball 27 engages with the cam groove 42b to stop said rotation, whereby the support frame 41 is fixed at the upward slanted position B1. In this state shown in FIG. 1 the light-emitting face F is directed to the object to be photographed. When the support frame 41 is further rotated from said position B1 to the position B2, the ball 27 is disengaged from the cam groove 42b and the support frame 41 is rotated by the force of the torsion coil spring 46. Then the ball 27 engages with the cam groove 42c as shown in FIG. 6 to fix the support frame 41 at said position B2. In this state the light-emitting face F is directed higher than the object, thereby enabling so-called bounce flash photography. 
     As the support frame 41 in the position B1 or B2 is manually rotated toward the folded position A, an intermediate wall 41D (FIG. 7) of the support frame 41 enclosing the flash lamp 44 presses respective front slanted faces of the fingers 8a, 8b protruding from the upper case 100. 
     When the support frame 41 reaches said position A, said fingers 8a, 8b engage with the holes 41B, 41C under the force of spring 9 whereby the support frame 41 is again fixed in the folded position. As will be appreciated from FIGS. 3 and 7, an upper wall 28 of cover 100 is exposed between the bearings 42, 43 of the square-C shaped support frame 41 there is an accessory shoe 10 provided on upper wall 28, as shown in FIG. 2, for mounting an additional flash unit 11 (represented by broken lines in FIG. 1), which can be activated as an alternative to the flash device 40. 
     Lead wires 45 (FIG. 3) pass through the center of the support shaft 22 and are prevented from excessive twisting or movement, thus providing a longer service life. 
     In the following discussion there will be explained the circuit structure of the present embodiment, while making reference to FIG. 10. 
     As shown in FIG. 10, a power source E1 is connected, through a switch SW composed of the contacts 2, 3, to a voltage booster circuit V1 provided with a control terminal P for controlling said voltage booster by a signal from a central processing unit (CPU) 70. Said voltage booster is further connected to a main capacitor C1. A thyristor SCR1 which is activated by a pulse signal from CPU 70 for triggering a is connected to a trigger capacitor C2, which is in turn connected to the primary side of a trigger coil T1. The secondary side thereof is connected to a xenon flash tube 44. A thyristor SCR2 is activated by a pulse signal for terminating the flash, supplied from the CPU. In the present embodiment, the CPU, main capacitor C1, trigger capacitor C2, thyristors SCR1, SCR2, resistor R1, and trigger coil T1 are placed in the camera body, while the xenon flash tube 44 is provided in the flash device 40 articulated to the camera body 1. 
     The above-explained circuit functions in the following manner. Prior to photographing with flash, the flash device 40 is rotated upwards to close the switch SW. In the present embodiment, said switch SW is closed as shown in FIG. 5 to enable the use of the flash device when the flash device 40 is rotated to the position of use B1 or B2. In the folded position A, said switch SW remains open, so that the flash device cannot be used. When said switch SW is closed, the control signal from the CPU is supplied through the control terminal P to activate the voltage booster, thereby charging the main capacitor C1 to a voltage of about 330 V. Simultaneously, the trigger capacitor C2 is charged with an electric charge corresponding to the capacitance thereof. When the shutter of hte camera is released, a synchronization contact (not shown) provided in the camera body 1 is closed, whereby the CPU 70 emits a pulse signal S1 for starting the flash. The thyristor SCR1 is triggered at the rise of said start pulse, whereby the trigger cpacitor C2 is discharged through said thyristor SCR1. Said discharge induces a current in the primary side of the trigger coil T1, thus generating a high voltage at the secondary side thereof and thus triggering the xenon flash tube 44. Thus the charge in the main capacitor C1 is discharged through said flash tube 44, generating a flash therefrom. As the flash is projected onto the object being photographed the reflected light is transmitted through the lens L and a diaphragm (not shown) and illuminates a photographic film, and the reflected light therefrom is guided to a photosensor (not shown). The CPU measures the amount of light falling on the film based on a detection signal from said photosensor, and generates a signal S2 for terminating the flash when said quantity reaches an appropriate value. Said signal S2 activates the thyristor SC2, whereby the main capacitor C2 is now discharged through the resistor R1. In the embodiment shown in FIG. 3, the trigger coil T1 is provided in the camera body 1, so that the flash device 40 contains the flash tube 44 only. 
     The CPU 70 prohibits the generation of a flash start pulse S1&#39; and a flash terminating pulse S2&#39; when the switch SW is closed, and prohibits the generation of the aforementioned signals S1 and S2 when said switch SW is open. In this manner the CPU 70 activates either the flash device 40 or the electronic flash unit 11 according to the state of the switch SW. 
     As will be apparent from FIG. 3, the arm of the support frame 41 corresponding to the bearing 42 and fitted with the shaft 21 has a space 41E suitable for housing the trigger coil T1. It is therefore possible to place said trigger coil T1 in said space as shown in FIG. 11. 
     If the trigger coil T1 is placed in an arm of the support frame 41 of the flash device 40 as shown in FIG. 11, the trigger coil T1 will be moved away from the camera body 1 when the flash device is rotated from the folded position A to the operating position B1 or B2. Thus, the trigger coil will be spaced substantially from the electric circuits in the camera body 1, such as an exposure control circuit, a sequence control circuit, etc. Consequently, the noises generated by the trigger coil T1 do not affect such electric circuits, and the erroneous function of the camera is effectively prevented. In practice integrated circuits for light measurement and exposure control are often placed on top of the pentagonal prism, but the above-explained embodiment in which the trigger coil T1 is placed in the flash device 40 effectively prevents adverse effects of trigger coil electrical noise on such integrated circuits as well. 
     Also, in such an embodiment the lead wires connecting the trigger coil T1 with the trigger capacitor C2 placed in the camera body 1 are contained in the flash device 40 and do not pass the vicinity of the electric circuits in the camera body 1. This contributes to the reduction in noise effects on such circuits. 
     In the embodiment shown in FIG. 11, the flash device 40 only contains the flash lamp 44 and the trigger coil T1 only. It is, however, possible also to incorporate the trigger capacitor C2 and thyristor SCR1, and such an arrangement is free from the influence of noise generated by the high voltage of the trigger coil T1.