JPS5811B2 - reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses light that enters from the entrance surface of the penta structure, is reflected by the two penta roof surfaces and the front reflecting surface, and exits from the upper part of the exit surface; This invention relates to a photometry device for a reflex camera that measures both two pentaloof surfaces and light that is reflected by a front reflective surface, directed back to the pentaloof surface, and directed to the upper part of an output surface by the pentaloof surface.

Here, the penta-structure is an optical element having at least an entrance surface, two penta-roof reflection surfaces, a front reflection surface, and an exit surface.

That is, this element is a pentalof prism formed of a plastic or glass block, or an element formed in a hollow shape by a reflecting mirror such as a flat glass.

In addition, since the penta structure is generally made of a glass block, the light enters from the entrance surface, is reflected by the two penta roof surfaces and the front reflecting surface, and is directed back to the penta roof surface.
The light that is reflected and directed to the upper part of the output surface by this pentalof surface is incident on the output surface at a total reflection angle and is totally reflected by the output surface, so that it does not originally come out from the output surface.

The device of the present invention includes a means for transmitting this light, which would normally be totally reflected by the exit surface of the pentagonal structure, through the exit surface;
For example, it is characterized in that the light is transmitted through the output surface by a light-transmitting block that is in close contact with the upper part of the output surface, which is substantially the same as the output surface, or has a refractive index higher than that, and the light is measured by a light-receiving element.

Furthermore, the feature of the device set 2 of the present invention is that the light transmitted through the exit surface is photometered by the above-mentioned means, and furthermore, the light that enters from the entrance surface of the penta structure is reflected by the two penta roof surfaces and the front reflection surface, and then the light is reflected by the two penta roof surfaces and the front reflecting surface. The feature is that the light emitted from the top of the surface is photometered.

Further, the apparatus of the present invention is characterized in that the above two lights are superimposed on one light receiving element and photometered.

Further features of the device of the invention will become clear from the description of the embodiments below.

Next, the features of the device of the present invention will be explained in comparison with known photometric devices.

It is known to photometer the light that enters from the entrance surface of the penta-roof structure, is reflected by the two penta-roof surfaces and the front reflective surface, and is directed toward the penta-roof surface.

However, in this method, a transmission aperture is provided on the pentaloof surface, and the light from this aperture is photometered.

Such a method requires that the transmission aperture be provided in the pentalof surface outside of the area where the light directed to the eyepiece is reflected.

This is because if a transmission aperture is provided in a portion where light directed toward the eyepiece is reflected, light that should be directed toward the eyepiece will pass through the transmission aperture and not reach the eyepiece.

Therefore, in order to provide a transmission aperture without adversely affecting the field of view of the finder, the roof surface must be relatively large, and conversely, the roof surface must be made relatively large without affecting the light directed toward the eyepiece. It is impossible to extract the light coming from the front reflective surface to the reflective portion of the roof surface, where the light directed toward the eyepiece is reflected.

However, in the device of the present invention, since the light is not extracted directly from the pentaloof surface, it does not affect the light directed toward the eyepiece in any way.

It is also known to photometer the light from two parts of the image plane formed on the focal plane.

For example, there is a method in which two light-receiving elements are arranged on the left and right sides of the output surface of the pentagonal structure to receive light from the left and right parts of the center of the image plane.

However, although there is room for arranging light-receiving elements on the left and right sides of the output surface of the pentagonal structure, there is no space in the vertical direction.

Although it is possible to provide two light-receiving elements in the vertical direction by increasing the output surface of the penta structure, this method increases the size of the penta structure.

However, according to the device of the present invention, since the light receiving element receives the light that is reflected by the penta roof surface and transmitted through the output surface by an optical means such as a prism, the output surface of the penta structure is enlarged in the vertical direction. It is possible to photometer the light coming from above and below the center of the image plane without any interference.

Note that the photometry device to which the present invention is applied does not only measure light from two positions in the upper and lower directions of the image plane, but may also be used to measure light from other parts, for example, light from left and right parts. .

Further, due to the third feature, the apparatus of the present invention can photometer light from above and below the center of the image plane using one light receiving element.

Therefore, the object of the present invention is to reduce the amount of light that enters from the entrance surface of the pentagonal structure, reflects off the two roof surfaces and the front reflective surface, and returns to the roof surface, and is reflected by the roof surface and directed toward the exit surface. Light is inherently totally reflected by the exit surface.

) to provide a photometry device for a reflex camera.

The purpose of this is to closely attach a means for transmitting the light that is originally totally reflected, such as a prism, to the exit surface of the pentagonal structure, and use this means to guide the light that is originally totally reflected to the light receiving element. This makes it possible to check the viewfinder field of view and measure light of any distribution at the same time with a compact penta structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photometric device for a reflex camera according to the present invention will be described below with reference to the accompanying drawings.

1 and 3 are diagrams showing the main parts of the photometric device of the present invention, and FIG. 1 shows the pentagonal structure as an exploded view.

In the figure, 1 is a focusing plate. An image of the subject is formed on this focusing plate by an objective lens.

2 is a condenser lens. 3 is a penta structure.

This penta structure has at least an entrance surface 4, penta roof surfaces 5 and 6, a front reflection surface 1, and an exit surface 8.

Reference numeral 9 denotes an optical means provided above the output surface 8, such as a glass block.

It is preferable that the refractive index of this glass block 9 is approximately equal to the refractive index of the inside of the exit surface.

10 is a total reflection surface provided on the prism block 9.

11 and 12 are first and second light receiving elements.

This light receiving element may be a CDS or a silicon photocell.

13 is an eyepiece. From focus plate 1 to penta structure 3
The light 14,15 that enters the block, is reflected by the roof surfaces 5, 6, and the front reflecting surface 7, exits from the upper part of the exit surface 8, and then passes through the block 9 is photometered by the first light receiving element.

This light 14 and 15 is light from the focusing plate 1 except for the upper part.

This is because the light from the upper part of the focusing plate 1 is rejected by the pentagonal body 3 as shown by the light ray 16 and does not reach the first light receiving element.

Therefore, the light from the area 17 of the focusing plate 1 shown in FIG. 2 is photometered by the first light receiving element 11.

That is, the photometric distribution on the focal plane is close to the average photometric distribution.

Further, the light enters the incident surface 4 from the focusing plate 1, and enters the roof surface 5.
The light 18 and 19 reflected by the front reflecting surface 7 and reflected again by the roof surfaces 5 and 6 is originally totally reflected by the exit surface 8 as shown by the dotted line.

However, this light 18 , 19 is emitted from the output surface 8 by the glass block 9 , is reflected by the reflection surface 10 , and is photometered by the second light receiving element 12 .

The curtains 18 and 19 are light from the area shown at 20 in FIG.

That is, the photometric distribution on the focal plane is close to the partial photometric distribution.

By adopting such an arrangement, the apparatus of the present invention has the following advantages.

First, by obtaining the output of both light-receiving elements, the difference in the exit pupil position due to the type of photographic lens, such as the difference in focal length and aperture f-number caused by the light-receiving element not being placed in the focal plane, or the same lens This contributes to the improvement of photometry errors based on the aperture.

That is, the photometric luminous flux changes in size due to the type of lens or aperture, and the effect is similar to that of arranging a light-receiving element of a considerable size.

Furthermore, center-weighted photometry is achieved by overlapping the outputs of both light receiving elements.

Further, a light shielding means (not shown) may be arranged in the optical path of at least one of the light to the first and second light receiving elements, or
, spot photometry, average photometry,
It is possible to switch to center-weighted metering.

Note that it is desirable to arrange a condensing or imaging lens in front of the first and second light receiving elements.

It is desirable that the imaging lens is arranged so that its front focal plane is the focusing plate or the aperture position of the objective lens, and its rear focal plane is the light receiving element surface.

Furthermore, this imaging lens can be moved along the photometric light beam or lateral axis so that the size of the image on the light-receiving surface or the photometric focal point can be changed, or the lens can be replaced or moved. It is desirable to do so.

Alternatively, a zoom lens may be used.

These are effective for increasing the amount of light to the light-receiving element, varying the photometry area on the focal plane, or controlling the aperture.

FIG. 4 is a diagram showing a second embodiment of the present invention.

This second embodiment is almost the same as the first embodiment, except that two photometric light beams 14 and 15 degrees 18.19 are superimposed on one light receiving element.

That is, the light beams 18 and 19 transmitted through the output surface 8 are directed toward the light receiving element 11 by the deflecting means, in the figure, the reflecting surface 23 of the glass block 9.

The figure also shows the light shielding means 24 and lens 25 described above.

26 is a light shielding plate for cutting harmful light directed toward the light receiving element 11.

FIG. 5 shows a third embodiment of the present invention.

This embodiment is characterized in that a light-receiving element 11 is provided at the lower part of the penta structure 3, and the photometric light beams 14, 15, 18, and 19 are directed toward the light-receiving element by deflection means, respectively.

That is, a parallel plane plate 27 is closely attached to the output surface 8 of the pentagonal structure, and the photometric light flux is directed toward the light receiving element 11 by the reflecting surfaces 23.28.

FIG. 6 shows a fourth embodiment of the present invention.

This embodiment is almost the same as the second embodiment, except that a sawtooth wedge prism 29 is used instead of the glass block 9, and a Fresnel lens 30 is used instead of the lens 25.

Furthermore, it can be used in a cylindrical manner by giving direction to the power.

Hereinafter, an example in which the photometric device of the present invention is applied to a single-lens reflex camera with open photometry and priority on shutter speed will be described with reference to FIGS. 7 to 9.

FIG. 7 is a diagram showing the back surface of the objective lens.

This lens is already available from Canon Co., Ltd., the applicant.
It is sold as a D lens.

31 is a preset aperture lever.

When the aperture setting ring A shown in FIG. 8 is rotated, this aperture lever 31 is placed in a position corresponding to the set aperture value.

That is, when the aperture is set wide open, it moves to the upper position, and when the aperture is closed down, it gradually moves to the lower position.

When the aperture lever 31 is set to a certain aperture value, for example, an intermediate aperture value, the aperture lever 31 cannot be moved in the aperture direction, that is, downward, unless the aperture setting ring A is rotated, but it cannot be moved in the aperture setting ring A. It can be moved in the upward direction by pushing up.

When the aperture lever 31 is stopped from being pushed up, the lever 31 returns to the aperture position set by the spring bias.

When the aperture setting ring is set to auto, the aperture lever 31 is located at the aperture position, that is, at the lower position.

This lever is moved upward by being pushed up, but when this pushing up is released, it is returned to its original position, that is, the lower position, by a spring (not shown).

32 is an open signal pin. This pin tells the camera the aperture f-number of the lens depending on its height.

33 is an automatic aperture lever. This lever 33 narrows down the aperture to the aperture diameter set by the 1 preset aperture lever 31 by moving to the right.

34 is an EE switching signal pin.

This pin protrudes when switched to EE. 35 is a shirt release button.

36 is a lever operated by the shutter release button.

This lever 36 is rotated counterclockwise around a pin 37 by pressing down the release button 35.

38 is a spring that returns the lever 36 to its original position.

Further, the lever 36 has a locking portion 39 at the other end.

Reference numeral 40 denotes a preset aperture lever 31 of the objective lens, which is rotated clockwise at a constant speed by a spring 41 and a governor 42.
It is a control ring.

This ring 40 has a pawl 43 that engages with the locking portion 39 of the lever 36.

It also has a protrusion 44 that comes into contact with the preset aperture lever 31.

A resistor 45 is fixed to the ring 40 and rotates as the ring rotates.

46 is a slider. This slider 46 is connected to the resistance plate and the terminal, respectively, and is configured to obtain a lower resistance value as the ring 40 rotates.

That is, a resistance value commensurate with the rotation angle of the ring 40 can be obtained.

47 is a notch for stopping the rotation of the ring.

Incidentally, after the rotation ring is rotated, it is rotated counterclockwise by, for example, a film winding operation, and the locking portion 39 of the lever 36 is rotated.
It is locked by.

48 is an electromagnetic magnet for controlling the rotating ring 40.

49 is a rotating ring 4 controlled by a magnet 48
0 rotation stop lever.

That is, when the lever 49 rotates counterclockwise around the shaft 50 by turning on the magnet 48, the lever 49 rotates counterclockwise around the shaft 50.
The tip end of the ring 9 falls into the notch 47 of the rotating quad ring 40 and stops the rotation of the ring 40.

When the magnet 48 is turned off, the lever 49 is rotated clockwise by the spring 51, and the ring 40 is rotated clockwise by the spring 51.
Release the rotation stop.

52 is a swing-up mirror. This swing-up mirror 52 flips up after the rotation of the rotating ring 40 is completed.

For this reason, it may be activated by the ON signal of the magnet 48.

53 is a aperture lever. This lever engages the automatic aperture lever 33 of the lens.

This aperture lever operates before the shutter is operated, and narrows down the aperture to a set aperture value in response to, for example, a swing mirror activation signal.

55 is a leading curtain control lever.

This lever 55 is activated after the lens is stopped down and the mirror 52 is flipped up.

Therefore, this lever may be configured to be actuated, for example, by a signal indicating that the lever has been actuated.

56 is a pin that allows the lever 55 to rotate freely.

Note that the lever 55 is limited in its return to its original position and in its rotation angle by a natural spring, dowel, or the like.

By rotating the lever 55, a known leading curtain start member 57 is actuated to start the leading curtain 58.

59 is a magnet for controlling the trailing curtain.

When the magnet 59 is turned on, the trailing curtain start lever 60 rotates clockwise about the shaft 61.

This lever 60 naturally has a spring, a dowel, etc. so that it returns to its original position when the magnet 59 is turned off.

By operating this lever 61, a known trailing curtain start member 6 is opened.
2, the second curtain 63 starts.

All of these movable members are configured to be returned to their original positions by a known method, such as a film winding operation.

64 is a variable resistor whose resistance value is changed depending on the height of the open signal pin 32.

65 is the resistor 64 when the lens is removed from the camera.
This is the spring that restores the slider.

66 is a light meter.

This meter displays the aperture value based on the apex photographic calculation based on the maximum aperture value of the lens being used.

That is, it displays how many stops the appropriate aperture value is from the open aperture value.

67 is an aperture scale.

This aperture scale is shifted depending on the height of the opening signal pin 32.

This is because the meter displays the number of steps based on the lens's maximum aperture value, so it is necessary to align the position of the maximum aperture scale with the starting position of the meter pointer.

68 is a shutter speed setting dial.

By rotating this dial 68, the first and second
A resistance value corresponding to the set seconds is obtained at each output terminal of the resistors 69 and 70.

However, from the resistor 69, a resistance value for performing photographic calculations is obtained, and from the resistor 70, a resistance value for a geometric progression for performing shutter timing is obtained.

71 is a variable resistor for setting film sensitivity.

Reference numeral 74 denotes a switch means for selectively inputting the outputs of the light receiving elements 11 and 12 to an electric circuit, and all switches linked to 74 are turned on during center-weighted photometry.

Reference numeral 75 is a switch mechanism that is linked to the servo EE switching pin 34 of the lens and is turned off when the pin protrudes, that is, when the aperture ring A is placed in the auto position.

FIG. 9 shows an electric circuit for controlling the aperture and shutter of the camera shown in FIG.

This circuit is broadly divided into a shooting information setting section 76, a photometry section 77, a calculation section 78, an exposure display section 79, an aperture control section 80, a shutter control section 81, and a power supply section 82.

The photographing information setting unit 76 includes a resistor 64 for correcting the difference in the amount of light to the light receiving element due to non-focal plane photometry depending on the type of objective lens as explained earlier in FIG. (the resistance value increases), the film sensitivity setting resistor 71 (this resistor 71 increases when a film with high sensitivity is set), and the shutter speed setting resistor 69.
(This resistance increases when a high speed setting is made.)

83 is a constant current source. 84 is a buffer mump.

Therefore, the output information from this photographing information setting section 76 is 5v-
Tv+Avc; Sv is the film sensitivity, TV is the shutter speed, and Avc is the amount of correction depending on the type of lens.

This output information is input to the calculation section 18.

The photometry section 77 includes light receiving elements 11 and 12 that are selectively turned on by the switch 74.

85 is a bias circuit.

86 is an operational amplifier. Reference numeral 87 denotes a logarithmic compression element disposed in the feedback circuit of the operational amplifier 86, which compresses the output of the light receiving element into an arithmetic progression change to match the arithmetic progression signal from the imaging information setting section.

88 is a temperature correction element.

The output information from this photometry section is Bv-(Avo+Avc)
; Bv is the amount of light from the subject; Avc is the amount of change that occurs because the photometry is performed on a non-focal plane.

This output information is input to the calculation section 787.

The calculation section 78 has a calculation operational amplifier 89.

This arithmetic operational amplifier 89 adds the outputs of the photographing information setting section 76 and the photometry section 77.

Therefore, the output of the calculation section 78 is Bv+5v-Tv-Avo
It is.

As is clear from this, Avc has been removed.

This is because the output of the resistor 64 corrects changes in the amount of light to the light receiving element caused by non-focal plane photometry depending on the type of lens.

Therefore, the output of the calculation section 89 is Bv+5v-Tv-Avo
It is.

This shows Av-Avo, that is, information indicating how many steps the aperture should be stopped down based on the maximum aperture value.

The output of this arithmetic circuit is input to the exposure display section 79.

The exposure meter 66 of this exposure display section indicates the number of aperture steps based on the open aperture value.

Therefore, the scale plate 69 in FIG. 8 is moved by the signal pin 32, which has a different height depending on the type of objective lens.

The aperture control section 80 includes sliding resistors 45 and 46, a manual-automatic changeover switch 75, and a magnet 48.

90 is a constant current circuit, and 100 is a comparison circuit.

One of the two input terminals of the comparator circuit 100 receives the output of the arithmetic unit, that is, information on how many steps to narrow down the aperture from the open aperture value.

The outputs of resistors 45 and 46 are input to the other end.

That is, the output of this resistor decreases as the aperture control ring moves from the open position to the constricted position.

When the output of the calculation section and the output of the resistors 45 and 46 are in equilibrium, the magnet 48 is turned on.

The shutter control section 81 includes a second time setting resistor 70.59.

101 is a capacitor for time limit, and 102 is a start switch which is turned off when the front curtain lever 55 is operated.

103 is a control circuit that energizes the magnet 59 when the capacitor 101 reaches a predetermined voltage.

A power switch 104 is turned on by pressing the release button 35.

105 is a power source. The operation will be explained below.

First, a case where automatic photography is set by the aperture ring A of the objective lens in FIG. 8 will be described.

In this case, the pin 34 of the objective lens allows the switch 75 to be
is OFF.

Further, the preset lever 31 is positioned upward, that is, at the open aperture position, and is urged downward by the protrusion 44 of the aperture control ring 43 on the camera side, as described above.

Also, due to the open signal pin 32, the resistor 64 exhibits a predetermined resistance output, and the scale plate is shifted to a predetermined position.

Other details are as shown in the drawing. Shutter release button 35
By pressing down, the power switch 104 in FIG. 9 is first closed.

By turning on the power switch, the output of the arithmetic circuit 78 inputs voltage signals corresponding to the number of aperture stages based on the open aperture value of the objective lens to the input terminal of the comparator.

Further, the aperture signal is displayed by a meter 66.

Next, by pressing down the further button 35, the lever 36 is rotated.

This rotation causes the aperture control ring 43 to rotate.

By rotating the aperture control ring, the objective lens preset lever follows the projection 44 and changes its position.

Along with this, the output resistances of the resistors 45 and 46 also differ.

That is, the output of the resistors 45 and 46 changes in accordance with the preset value of the objective lens.

When this resistance output and the output of the arithmetic circuit 78 are in equilibrium, the magnet 48 is turned on.

By turning on this magnet, the lever 49 rotates,
The rotation of the aperture ring 43 is stopped.

That is, a preset aperture value commensurate with the output of the arithmetic circuit 78 is set.

After the preset aperture value is set, the swing-up mirror 52 moves up, and the lever 53 further narrows down the aperture to the set aperture value.

Furthermore, the first curtain 58 starts.

Along with this, the start switch 10 of the shutter control circuit
2 turns OFF.

After a predetermined time, the magnet 59 is activated to start the rear membrane 63.

This completes the shutter time limit operation.

After the shutter operation is completed, the state shown in FIG. 8 is restored by turning off the power switch and winding the film.

Next, in the case of manual photography, the switch 75 is turned on.

Therefore, the magnet 48 does not operate under any conditions.

Further, as described above, the preset aperture lever 31 changes its position when the ring A is rotated, but in this case, it does not change its position because it is in contact with the protrusion 44.

However, by rotating the ring 43, it moves to the position set by the aperture ring A.

The rest of the operation is the same as automatic, so the explanation will be omitted.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining the first embodiment of the photometric device of the present invention, FIGS. 4 to 6 are diagrams for explaining the second to fourth embodiments of the present invention, and FIGS. 7 to 3 are diagrams for explaining the second to fourth embodiments of the present invention. FIG. 9 is a diagram illustrating a camera to which the photometric device of the present invention is applied. In the figure, 1 is a focusing plate, 2 is a condenser lens, 3 is a pentagonal structure, 9 is an optical element, 10 is a reflective surface, 11 and 12 are first and second light receiving elements, and 13 is an eyepiece.

Claims (1)

[Claims] 1. A penta structure having an objective lens, an entrance surface for receiving a light beam from the objective lens, two penta roof surfaces, a front reflecting surface, and an exit surface, and having two transmitting surfaces and one reflecting surface. one of the transmission surfaces has a prism block attached above the exit surface of the pentagonal structure; and a light receiving element behind the prism block for receiving the light beam emitted from the prism block; A part of the light beam from the objective lens enters the entrance surface of the penta structure, is reflected by the two penta roof surfaces and the front reflective surface, and passes through the exit surface of the penta structure and the prism block. After passing through the surface, the light beam is incident on the light receiving element, and a part of the light beam from the objective lens other than the part of the light beam is incident on the entrance surface of the pentagonal structure, and It is reflected by the pental roof surface and the front reflective surface, and after being reflected again by the pental roof surface, it is transmitted through the exit surface of the pental structure and the transmitting surface on the bonding side of the prism block, and then at the reflective surface of the prism block. A photometry device for a reflex camera, characterized in that the light is reflected and transmitted through the transmission surface of the prism block, and then enters the light receiving element.