JPH0318690B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a camera with an exposure control device.

Cameras having means for sensing light to adjust exposure are well known. The light sensing means produces an electrical current associated with the light rays entering the means. When the camera shutter opens, the current charges the capacitor. Once the capacitor is charged to the required voltage corresponding to the desired exposure, an end-of-exposure signal is generated. When photographing using a chemical flash valve, an electromagnet responsive to a termination signal is activated to close the shutter. When using an electronic strobe, certain circuits are energized to also terminate the strobe.

Green plants reflect a relatively high amount of infrared radiation. The light sensing means, which is sensitive to both infrared and visible light, is provided with a filter to prevent infrared radiation from entering the light sensing means in order to prevent its capacitor from being prematurely charged in the open air and causing the shutter to close prematurely. is known to be used. eastman
The EK4 and EK6 instant cameras sold by the Kodatsu Company are equipped with such a filter, and their structure is covered by the U.S. Patent No.
Disclosed in No. 4040070. The filter used in the EK4 and EK6 instant cameras is an infrared filter.

Photographers may also use a flash when photographing outdoors in daylight. That is, when bright sunlight creates a shadow, it is used to lighten the shadow and is generally known as a fill-flash.

EK4 and EK6 cameras are capable of flash photography and are equipped with an exposure control device that includes light sensing means. The light sensing means controls the exposure time as a function of visible light and infrared light. These cameras are equipped with spectral filters that pass visible light and block infrared light. When photographing is performed without using a flash, means for moving the filter is provided on the light incident path of the light sensing means. In such known constructions, an infrared filter covers the light sensing means when the flash is not installed in the camera socket, and uncovers the sensing means when the flash device is installed in the camera socket. This has the disadvantage that when photographing with a film flash outdoors in bright light, the exposure will be insufficient. This underexposure is due to infrared radiation entering the light sensing means and thus causing the shutter to close prematurely.

That is, the camera according to the present invention includes a light sensing means that generates an output signal as a function of the amount of visible light and infrared rays incident from the scene to be photographed, and a light sensing means that generates an output signal as a function of the amount of visible light and infrared rays incident from the scene to be photographed, and a light sensing means that generates an output signal as a function of the amount of visible light and infrared rays incident from the scene to be photographed. In a camera having means for responsively closing the shutter device and a filter device for adjusting the amount of light incident on the light sensing means, the filter device is adapted to absorb infrared rays, and the filter device is adapted to absorb infrared rays so as to prevent flash photography from bright surroundings. It is characterized in that it enters the above-mentioned light beam incidence path when the process is performed in light, and exits from the same light beam incidence path when the process is performed in relatively dark ambient light.

Preferably, the control means causes an infrared attenuation filter to cover the light sensing means when the flash illumination is not in use.

In one embodiment of the invention, the control means comprises a diaphragm for adjusting the size of the exposure aperture. The diaphragm is in the first position for bright scenes and in the second position for dark scenes.
take the position. The control means also includes means for sensing whether flash photography is to be performed.

If the camera has a socket for receiving a flash device, the sensing means has means for sensing whether a flash device is present in the socket and for sending a signal when this is the case. This is when there is a flush device such as a flush valve in the socket.
This is advantageous because it automatically communicates to the control means that the flash is being illuminated.

The filter has two infrared attenuating sections and a non-attenuating section between them. The filter is biased toward a third position in which one of its infrared attenuating portions covers the light sensing means. The filter is movable through a second position and into a first position in response to return movement of the shutter release button, in which the other damping portion of the filter covers the light sensing means. The flash device sensing means includes a stop member for preventing the filter from moving from the first position to the second position and bringing the unattenuated portion in front of the light beam sensing means when it senses the absence of the flash device. has. This arrangement is particularly advantageous and simple in that the filter moves to the first position in response to return movement of the shutter release button. The filter is biased for movement from the first position. The filter is held in a first position against a biasing force thereof by a first stop member, in a second position by a second stop member, and in a third position by a third stop member. . A stop in the path of the filter moves depending on the brightness of the scene and whether flash photography is being performed.

In a preferred embodiment, the diaphragm has a stop that prevents movement of the filter from the second position to the third position when the diaphragm is in the second position for low light photography. This stop allows the filter to move from a second position to a third position when the diaphragm is in its first position for photographing a bright scene.

Since the structure of a camera is well known, in the embodiments described below with reference to the accompanying drawings, only those components that are relevant to the present invention will be described. Furthermore, although the following embodiments will be explained in connection with chemical flash photography, they can also be applied to electronic strobe photography.

Both flash bulbs and electronic strobes emit infrared and visible light. When photographing a subject wearing dark clothing indoors, the subject reflects relatively little visible light. The light sensing means generates a small amount of electrical current in response to this reflected visible light. If only visible light reaches the light sensing means, bright areas within the subject will be overexposed. This is because if only visible light were to reach the light sensing means, the exposure end signal would be delayed.

Regardless of color, clothing tends to be more reflective of infrared light than visible light, and also tends to reflect infrared light more uniformly. When visible light as well as visible light enters a light sensing means that is sensitive to both, a large electrical current is generated. This large current advances the end-of-exposure signal for indoor flash photography of generally dark scenes to ensure that any bright scene areas are not overexposed.
On the other hand, for flash photography indoors when it is generally bright, visible light is more dominant than infrared light, and the exposure end signal is sent at an appropriate time regardless of whether the infrared light reaches the light sensing means or not. arise.

When a generally dark scene is photographed indoors using flash, the above-mentioned improvement in bright areas within the scene results in a certain reduction in the quality of reproduction of background and clothing parts. However, the beneficial effects on the reproduction of bright areas, especially those with bright and sharp tones,
This is more important than any reduction in the quality of playback in other scene areas.

Outdoors with green vegetation, the periodic infrared radiation is strong, so whether a flash is used or not, if the infrared radiation reaches the light sensing means, it will be underexposed. Therefore, there are advantages gained by the entry of infrared light into the light-sensing means in flash photography of mostly dark scenes indoors, and advantages obtained by the infrared light entering the light sensing means when photographing outdoors, with or without flash. The effects of infrared light on exposure are contradictory, with the disadvantages of reaching the light sensing means.

The present invention provides means for selectively adjusting infrared light entering a light sensing means (hereinafter referred to as a photo sensor) to adjust and control indoor flash photography. This means inserts and removes an infrared attenuating filter in the light input path to the photo sensor as a function of (1) the presence or absence of a flash device and (2) the size of the adjustable exposure aperture. Particularly when using a flash device and when the exposure aperture is large, mostly when taking indoor flash photography, the control means removes the filter from the path of light incidence to the photo sensor, thereby allowing infrared rays to reach the photo sensor. This allows for good flash photography. When a flash device is used and the exposure aperture is small, most of the time flash photography is carried out outdoors in daylight, and the above means inserts a filter into the light path to the photo sensor to block infrared rays. This filter for flash photography in daylight is preferable because the flash illumination is merely auxiliary and infrared rays entering the photo sensor should be blocked, as in normal daylight photography without flash. When photographing is performed using only ambient light, the filter covers the photo sensor regardless of the size of the exposure aperture. The reason for this is that shooting with only ambient light is usually done outdoors, and both when the ambient light is bright and the exposure aperture is small, and when the ambient light is dark and the exposure aperture is large, there is underexposure due to infrared light. It is from the origin.

FIG. 1 shows a photoconductively controlled shutter 10 that controls exposure time as a function of light intensity.
The shutter 10 has blades 12, 13, which are biased by springs 14, 16, respectively, and an aperture 1 through which the incident light of the camera passes.
8 to open and close.

A pivot latch 20 locks the blade 12 in the open and closed position. Spring 20a biases latch 20 into its locked position. A shutter release button 22 is provided above the latch 20 and is intended to be moved downwardly by the camera user. A spring-loaded triangular cam 22a is operatively connected to the release button 22 for movement therewith.

When the camera user depresses the release button 22, the cam 22a moves from left to right in response (see Figures 1 and 2a). This movement occurs before the shutter 10 opens. The user presses button 22
When fully depressed, latch 20 pivots clockwise around pin 23 to release blade 12. When latch 20 releases blade 12, spring 14 rotates blade 12 counterclockwise into engagement with stop member 29, thereby beginning exposure.

Armature 24 attached to electromagnet 26
normally holds the blade 13 in an open position to the left of the aperture 18. The drive spring 28 is the armature 2
4 in a counterclockwise direction around a pin 27. When this rotation of the armature occurs, the spring 16 rotates the shutter blade 13 counterclockwise into a position where it engages the shutter blade 12. In this position, the blade 13 is inserted into the opening 18
close and end the exposure.

The electronic circuit 30 has a photo sensor 31 adapted to receive light from the scene to be photographed. Circuit 30 controls electromagnet 26 in relation to the intensity of visible and infrared radiation entering photo sensor 31 . When exposure begins, circuit 30 energizes electromagnet 26 to magnetically attract armature 24 to the electromagnet. While the armature 24 is retracted, the shutter blade 13 is held in a position that does not close the exposed opening.

Switch S ₁ shorts timing capacitor 34 before exposure begins. When switch _S1 opens, the current passing through photo sensor 31 charges capacitor 34 at a rate proportional to the magnitude of the current. The current is proportional to the intensity of visible and infrared radiation entering the photo sensor 31. When the photo sensor 31 is exposed to bright visible light and strong infrared light, the capacitor 31 is rapidly charged. Photo sensor 31
When exposed to weak visible and infrared radiation, capacitor 34 charges correspondingly slower.

When blade 12 moves from its locked position, switch S ₁ opens and the charge in capacitor 34 is transferred to shutter 1.
Synchronized with the release of 0. Once capacitor 34 is charged to a predetermined voltage corresponding to the required exposure time,
An exposure stop signal is generated. Electromagnet 26 is deenergized in response to that signal. The armature is no longer magnetically attracted and the spring 28 rotates the armature 24 counterclockwise. When this happens, spring 16
moves the shutter blade 13 to the opening/closing position and the exposure is completed.

A spring loaded diaphragm or diaphragm lever 36 is shown in FIG. The lever has an opening 36a at one end and a neutral density filter 39 at the other end. Lever 36 is pivotable about pivot 37;
It is movable between a first position shown in solid lines and a second position (or operative position) shown in dashed lines adjacent to the stop member 38. When the lever is in its actuated position, aperture 36a is aligned with aperture 12 and filter 39 is aligned with photo sensor 31.
cover. In the activated position, the size of the camera's exposure aperture is reduced to the size of aperture 36a. Filter 39 attenuates the light rays entering photo sensor 31, but this attenuation is equivalent to a reduction in the size of the exposure aperture by aperture 36a, so that photo sensor 31 senses light rays proportional to the proper exposure aperture size.

Diaphragm setting mechanism 40 controls diaphragm lever 36 so that the size of the exposure aperture varies as a function of light intensity. When the surroundings are dark, the larger aperture 18 of the two apertures is used, and when the surroundings are bright, the smaller aperture 36a is used. Mechanism 40 is configured such that lever 36 is manually adjusted by a user, and preferably such that lever 36 is automatically adjusted according to the intensity of light entering photo sensor 31. US Pat. No. 4,059,836 shows a mechanism for automatically setting a diaphragm to one of two positions as a function of light intensity. Photo sensor 3 mentioned above
The electronic circuit 30 including 1 and the diaphragm setting mechanism 40 constitute exposure determining means.

5 and 6, a pivoting lever 42 is shown having a flash sensing finger 44 at one end and a stop member 46 at the other end. The spring 47 biases the lever 42 clockwise (see Figures 5 and 6).
(Fig.), towards the bottom of the socket 48 adapted to receive the flush valve. If the flush valve is not in socket 48 (FIG. 5), spring 47 biases lever 42 toward the bottom of the socket, causing finger 44 to extend into the socket. In this position, stop member 46 is positioned as shown in FIG.

When the flush valve 48a is installed in the socket 48 (FIG. 6), the bottom of the flush valve moves the sensing finger 44 downwardly, thereby rotating the lever 42 counterclockwise against the spring 41. do. In this position, the stop member 46 is moved to the right (FIGS. 3 and 4).

In FIG. 2, means 50 is provided for selectively controlling infrared rays entering the photo sensor 31 depending on (1) whether or not flash photography is to be performed and (2) the size of the exposure aperture. This means 50 includes a filter carrier 52 on which an infrared attenuation filter 54 is mounted. The filter 54 protects the photo sensor 31 from approximately 700 nanometers, which is the limit of visible light.
It has the effect of selectively attenuating and blocking electromagnetic waves up to the longest wavelength that can be detected. The longest wavelength is approximately 1100 nanometers when the photo sensor is a silicon photo sensor.

Filter 54 has attenuated regions A, B separated by a non-attenuated region 57 . Spring 6
0 biases the carrier 52 counterclockwise about the pivot 59 to rotate it through first, second and third positions relative to the light input path of the photo sensor. In the first position, area A is
cover. In the second position, as shown in FIG.
Neither areas A nor B cover the photo sensor 31, and the third
At the position, region B covers the photo sensor 31, as shown in FIG.

The carrier 52 has two stops 65, 66, 67.
has. The stop 65 normally abuts the lower surface 68a of the cam 22a, which holds the carrier in the first position. When the user presses the release button 22 prior to exposure, the cam 22a moves in response and its lower surface 68a disengages from the stop 65 (FIG. 2a).

Latch 20, biased by spring 20a, returns button 22 from its fully depressed position to its normal up position. Spring 69 causes cam 22a to follow the button during its return movement. When the button 22 returns to the upper position, the cam 22a
The surface 68 biases the stop 65 counterclockwise, thereby returning the carrier 52 to its first position.

If the flush valve is not in the socket (5th
), the spring 47 causes the lever 42 to move its stop member 4
6 is positioned so that it abuts against the stop portion 66 (FIG. 2). The spring 47 is connected to the carrier 52 by the spring 60.
A force greater than that applied to the lever 42 is applied to the lever 42 . Stop member 46 thus prevents movement of carrier 52 from its first position when the flush valve is not in socket 48.

When flush valve 48a is in socket 48 (FIG. 6), stop member 46 is positioned as shown in FIGS.
2 is not held in the first position. Therefore, cam 2
When 2a moves in response to actuation of shutter release button 22, spring 60 pivots carrier 52 from the first position.

When the diaphragm lever 36 is positioned for low-light photography, as shown in solid lines in FIGS. is positioned. When the spring pivots the carrier 52, the stop 67 abuts the stop 76 and the carrier is held in the second position (FIG. 3).

When the lever 36 is positioned for photographing in a bright place (FIG. 4), the stop member 76 is moved to the stop portion 67.
deviate from the path of In this position, spring 60 can move carrier 52 from the second position to the third position. a spring 60 biasing to move the filter 54 in one direction; a stop member 46 holding the filter carrier in a first position against such movement of the filter; The stop 76 and the stop 67 below which hold the filter in the second position constitute control means for the filter. The control means and the filter 54 constitute response modification means for varying the response of the exposure determining means to infrared radiation as compared to the response of the exposure determining means to visible radiation.

We will explain camera operations for four shooting situations. These situations depend on whether the location to be photographed is bright or dark and whether a flash bulb is used or not.

First situation Shooting scene - Bright Flash bulb - Not used This corresponds to shooting outdoors in daylight, and infrared rays are strong. When the flush valve is not used, the carrier is held in the first position (FIG. 2). This is because the stop member 4 of the flash device sensing lever 42
6 comes into contact with the stop portion 66 of the carrier. Area A of the filter 54 blocks infrared rays from the photo sensor 31. Therefore, infrared rays are prevented from affecting exposure control.

Second Situation Photography Scene - Dark Flash Bulb - Use Flash photography in a dark place is usually carried out indoors, and the intensity of infrared rays is lower than that outdoors. In this situation, the photo sensor 31 receives infrared radiation,
Speed up the shutter closing time.

When taking flash photography in a dark place, the user sets the camera as shown in FIG. The flash valve 48a is the stop member 46 of the lever 42.
to the right and remove it from the path of the stop 66 of the carrier 52. Since the surroundings are dark, the diaphragm lever 36 is positioned to use the large opening 18. In this position, the stop member 76
Enter route 7.

When the shutter release button 22 is pressed, the cam 22a is urged downward (Fig. 2), and the spring 60
rotates the carrier 52 counterclockwise from the first position. Stop 67 engages stop member 76, thereby retaining carrier 52 in the second position. Therefore, the filter 54 does not cover the photo sensor 31, leaving the area 57 in front of the photo sensor.

When the user fully presses button 22, shutter 10 opens. Infrared rays (including those emitted by the flash valve 48a) enter the photo sensor 31,
This helps control exposure.

When the scene is generally dark, the infrared radiation entering the photo sensor in addition to the visible light is sufficient to hasten the closing of the shutter so that bright scene areas are not overexposed. If the photographic scene is generally bright, the reflected visible light will dominate the infrared rays entering the photo sensor, and the shutter will not close as quickly as the infrared rays will. Therefore, no underexposure occurs.

Third Situation Shooting Scene - Bright Flash Bulb Use This situation often applies when shooting outdoors in daylight and when using a flash to soften the shadows created by daylight.

In this case, the camera is set as shown in FIG. In response to flush valve 48a, stop member 46 of lever 42 is moved to the right.
Since daylight is bright, the diaphragm lever 36 is positioned to photograph through the small exposure aperture 36a. In this position, the diaphragm lever 36
The stop member 76 is placed out of the path of the carrier stop 67.

When you press down the release button 22,
Spring 60 places carrier 52 in the first position (FIG. 2)
4 to a third position (FIG. 4), where area B of the filter 54 is aligned with the light incident path of the photo sensor 31. Therefore, infrared rays from the photographing location are not entered into the photo sensor, thereby preventing underexposure.

Fourth Situation Shooting scene - Dark Flash bulb - Not used This situation generally corresponds to when shooting outdoors on a cloudy day. Visible light is weak, but if there are green plants in the shooting scene, infrared rays are strong and may cause underexposure. Therefore, it is preferable to prevent infrared rays from entering the photo sensor 31.

When the flush valve is not in use, as in the first situation, the stop member 46 is positioned and engaged with the carrier stop 66 as shown in FIG. is held in position. Area A of the filter 54 is the photo sensor 3
1 to prevent infrared rays from entering the photo sensor.

Although the present invention has been described above based on the illustrated embodiments, the present invention is not limited thereto.
For example, the filter 54 could have only one filter area and the carrier 52 could have two positions, with the infrared filter 5 in the first position
4 may cover the photo sensor 31 and in the second position may not cover the photo sensor.
Additionally, the diaphragm is configured and arranged so that the size of the exposure aperture is linearly adjustable as a function of the intensity of the light, and the filter 54 is configured to attenuate the infrared radiation by a varying amount in accordance with the size of the exposure aperture. You can also.

Also, the flash device may not be set up by the camera's socket, but may be built into the camera itself. In this case, the signal indicating whether or not to take a flash image may be generated, for example, by a manual on/off switch that energizes the flash device. Assuming that the flash device is automatically controlled and that manual means are provided for flash use in daylight, the decision whether or not to take a flash image may be made electronically or partially electronically and partially manually. It can be done.

In the embodiments described above, the use of flash is optional. It has been proposed to use flash in all photography. When the present invention is applied to such a camera, the control device according to the present invention covers an infrared attenuating filter over the photo sensor when using the flash in a bright place, and covers the filter when using the flash in a dark place. Just make sure to remove it.

[Brief explanation of the drawing]

Figure 1 shows a shutter control mechanism in which a photo sensor controls exposure according to the intensity of the light beam; Figure 2 shows an infrared attenuation filter inserted into and exited from the light input path to the photo sensor in Figure 1. A diagram showing the mechanism and diaphragm, and the position of the filter when photographing without flash; Figure 2a is a view taken along line 2a-2a in Figure 2, and shows the shutter in Figure 1; Figure 3 shows the cam responsive to the shutter release button for activation; Figure 3 shows the position of the diaphragm and filter shown in Figure 2 when photographing in low light with a flash; Figure 4 The figure shows the position of the filter and diaphragm when performing flash photography in daylight; Figure 5 shows the flash valve sensing means when no flash valve is attached; Figure 6 shows the FIG. 3 is a diagram showing a flash valve sensing means when a flash valve is attached.

Claims (1)

[Claims] 1. A light sensing means 31 that generates an output signal as a function of the amount of visible light and infrared rays incident from the scene to be photographed, and a shutter device 10 that activates the shutter device 10 in response to the output signal of the light sensing means reaching a predetermined value. In a camera having a closing means 30 and a filter device 54 for adjusting the amount of light incident on the light sensing means, the filter device 54 is adapted to absorb infrared radiation and allows flash photography to be carried out in bright ambient light. The camera is characterized in that the camera enters the light beam incidence path when the camera is operated in a relatively dark ambient light, and moves out of the light beam incidence path when the camera operates in relatively dark ambient light.