JPS6132824A - Determining device for photographic exposure time - Google Patents

Abstract

PURPOSE:To calculate the slowest shutter speed with which the movement extent of an image is within the range of some determined values by arranging a line sensor on a surface conjugate to a film surface and detecting the movement extent of the image within some fixed time from the photoelectric conversion output of the sensor. CONSTITUTION:Light incident from an image forming lens 1 is reflected by a half-mirror 3 to form an image on a viewfinder screen 13, and light transmitted through the half-mirror 3 is reflected by the submirror 4 of a total reflecting mirror to form an image on the line sensor 7 on the surface 6 conjugate to the film surface 5. The line sensor 7 detects the movement extent of the image within the determined time and a monitor photodiode 8 performs exposure control over the line sensor 7. The line sensor 7 and monitor photodiode 8 are arranged on an image pickup element substrate and a CPU calculates and determines a shutter speed and an aperture value to send output signals to the aperture control mechanism and shutter control mechanism of a camera.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a photographing exposure time determining device, and more particularly to a program/auto device for an eye reflex camera.

(Prior art) As is well known, program auto is a combination of an aperture value Av value and a time value Tv value determined for the EV value determined by the output of a photometric sensor installed in the camera. Determine according to the program diagram, its Av value, T
Some attempt to perform aperture control and shutter control according to the v value. Using Program Auto, the photographer does not have to decide on the aperture or shutter speed, and is great in that he can concentrate on other shooting operations such as focusing, 7V-mink, and shutter timing. .

However, when using this program auto k-eye V7 Rex camera, depending on the interchangeable lens used,
The aperture F value or focal length is different. For this reason, the longer the focal length of the telephoto lens, the more likely it is that camera shake will occur.
It becomes necessary to use a high-speed shutter. Additionally, as the lens becomes wider, camera shake becomes less likely to occur, and the possibility of using a slow shutter increases. When taking photographs, it is generally desirable to release the shutter as slowly as possible without causing camera shake. This is to widen the depth of field and make focusing easier.

Considering this, it is impossible to perform program auto using one type of program diagram.

For this reason, cameras have recently come out that have several types of program modes, such as those for telephoto lenses, wide-angle lenses, and standard lenses. However, such a camera requires a changeover switch to change the program mode, and the photographer also needs to change the program mode depending on the interchangeable lens being used. In addition, in single-lens 7Rex cameras that use Program Autora, accurate program control is not possible unless the aperture f-number of the interchangeable lens being used is transmitted to the camera, and the aperture f-number is printed on the lens mount surface.
There is a problem in that it becomes necessary to provide a signal pin for transmitting values.

(Purpose) In view of the above points, the present invention provides conditions under which camera shake does not always occur, regardless of the type of interchangeable lens used, or regardless of the way the camera is held, such as hand-held or tripod. A telephoto lens attached to a camera with the purpose of realizing programmed auto that allows shooting at the lowest shutter speed.

To provide an apparatus for determining the opening time of a photographic camera without the need to switch the program mode using a wide-angle lens, a standard lens, etc., and without the need to transmit the aperture F value of the lens to the camera body.

(Summary) When taking pictures with a single-lens 7-lens camera, the photographer can roughly guess whether or not it is necessary to use a high-speed shutter while looking through the viewfinder. For example, 3
When you attach the 00WIk telephoto lens to a 35116-format single-lens reflex camera and look through the viewfinder e, you will notice that the image on the finder screen is very blurry and requires a fairly high-speed shutter release.
It can be seen that when a μs wide-angle lens is used, the blur of the image on the finder screen is small and it is possible to use a slow shutter speed.

In the present invention, utilizing this principle, a line sensor is placed on a surface conjugate to the film surface, and the photoelectric conversion output is used to detect the amount of image movement within a predetermined time. Also, the amount of movement of the image is set to a certain amount (
For example, find the lowest shutter speed that falls within the range of the diameter of the circle of least confusion. Then, the aperture value is determined from the EV values obtained from other photometric elements and the above-mentioned minimum shutter speed, and the shutter and aperture are controlled.

(Example) Hereinafter, the present invention will be described in detail based on the drawings. 1st
The figure shows a photographic exposure time determining device t- which shows an embodiment of the present invention.
This shows the case where a single-lens reflex camera is applied, and the light incident from the imaging lens l is reflected by the half mirror 3 and forms an image on the finder screen 13.
The light transmitted through the half mirror 3 is reflected by a sub-mirror 4, which is a total reflection mirror, and is imaged on a line sensor 7 on a surface 6 that is conjugate with the film surface 5. 7, code 2 is the imaging lens l
On the optical axis, reference numeral 8 is a monitor photodiode. The image on the finder screen 13 is observed through the pentagonal roof prism 9 and the eyepiece lens 12, which form the finder optical system, and a part of the luminous flux is incident on the photometric sensor 11 through the half mirror 1O. It looks like this.

FIG. 2 is a partially enlarged view of the line sensor 7 and the sub-mirror 4 of the total reflection mirror of the monitor photodiode 8, which are arranged on the main surface 6 together with the above-mentioned film. The line sensor 7 is for detecting the movement of the image within a certain predetermined time, and in this embodiment a CCD line sensor is used. The monitor photodiode 8 controls the exposure of the line sensor 7. If the light incident on the monitor photodiode 8 is strong, the integration time of the line sensor 7 becomes short; The integration time of the line sensor 7 becomes longer.

Next, the electrical processing system of this embodiment will be explained based on FIG. The line sensor 7 and monitor photodiode 8 are arranged on the image sensor substrate 20, and the line sensor 7 is connected to a CCD transfer path 21, and the monitor photodiode 8 is connected to a comparator. 22 are connected and arranged on the image manipulation element board 20, respectively. This image sensor board 20 has a CCD drive circuit 23.
controlled by The photoelectric conversion output from the CCD transfer path 21 is converted by an A/D converter 24 and sent to a storage circuit 26 via a changeover switch 25. This memory circuit 26 is composed of two memory circuits, a memory (21), and a memory (1), each storing one line of photoelectric conversion output of the COD of the line sensor 7. ), memory (2) C correlator 27
are connected to the memory (1) and the image pattern stored in the memory (2) to perform a correlation calculation and detect the movement of the image. This signal is then output to a processor (hereinafter abbreviated as CPLT) 28.

On the other hand, the photometric circuit 30 is a circuit for determining the Bv value from the output of the photometric sensor 11 in the finder optical system. That is, the photometer which is the photometric sensor 11
Diode 14. Operational amplifier 31. Diode 32 for logarithmic compression. It consists of a diode 33 for temperature compensation and a constant current source 34. The output signal from this photometric circuit 30 is converted into a Φ by a Φ converter 35, and
It is output to the PU 28 as a Bv value.

The CPU 28 calculates the above Bv value and the image movement amount d! It's film sensitivity setting dial 39 on the camera body.
) All Sv values are input, the shutter speed (Tv value) and aperture value (Av value) are calculated and determined, and output signals are sent to the aperture 9 control mechanism 36 and shutter control mechanism 37 of the camera (not shown) for control. It is supposed to be done.

Next, regarding the operation of this embodiment, the timing diagram shown in FIG.
Explain using charts. First, by setting the mode changeover switch 38 (switching switch for aperture or priority AE mode, shutter speed priority AE mode, program AE mode, manual mode, etc.) provided on the outside of the camera to program AB mode, the start pulse is transferred to the CPU.
28. Then, the CPU 28 executes the program AE.
mode, the integral start pulse Is(
Integ・5tart) is immediately connected to the CCD drive circuit 23.
Output to. These pulses l5ij are output one after another at certain predetermined time intervals. Upon receiving the integral start pulse l5Th, the COD drive circuit 23 immediately outputs a reset pulse 96R'fc to the image pickup element substrate 20.

By inputting this pulse OR, each photodiode of the line sensor 7 and the monitor photodiode 8 are initialized. The monitor photodiode 8 is a storage charge type photodiode,
Since it is initially reset and reverse biased at nine moments, the monitor potential of the monitor photodiode 8 becomes a high potential, but as it receives light, the potential drops over time. The output part of this monitor photodiode 8 is connected to the inverting input terminal of the comparator 22, and the reference voltage Vref is input to one non-inverting input terminal, so the output of the comparator 22 is connected to the inverting input terminal of the comparator 22. Output (MOS)
signal)) to the CCD drive circuit 23. The COD drive circuit 23 detects the rise of the MO8 and outputs a transfer gate pulse OT to the image sensor board 20.The image sensor board 20 inputs this pulse Tt to the line sensor 7. The charge accumulated in each photodiode 'eCC1) is transferred to the transfer path 21. On the other hand, this CCD transfer path 21 is connected to the CCD drive circuit 2.
It is always operating due to the two-phase transfer lock A from 3 to 3. Therefore, immediately after charges are transferred to the transfer path by the transfer gate pulse date, this CCD transfer path 21
outputs the full time-series photoelectric conversion output. Furthermore, the CCD drive circuit 23 starts to output 0. conversion pulse (ADS) with a defined relationship between
It is output to the t-AzΦ converter 24.

This converter 24 sequentially converts N time-series photoelectric conversion outputs from the CCD transfer path 21. This is the first time Cn=1
), the photoelectric conversion output was obtained by integrating
Here, the switch SWI of the selector switch 25 is turned on and the switch SW2t is turned off, and the photoelectric conversion output is stored in the memory circuit 26 in the memo IJ-(ll).

Next, we perform the second integration (n=2),
For the second time, the changeover switch 25t switch SW1't is turned off and the switch 8W2 is turned on, and the photoelectric conversion output is stored in the memory (2) of the storage circuit 26.

In this way, by two integrations, the memory (”)
Two image patterns are stored in (2), but since these image patterns are from different times, they cannot be easily affected by camera shake as shown in Figure 5 (B). It's out of sync. On the other hand, as soon as the n=20 photoelectric conversion outputs are stored in the memory (2), the correlator 27 performs a correlation calculation on the image pattern and outputs the result to the deviation amount d1'kcPU2B.

Next, the third integration (n=3) is performed, but this time, selector switch 25 is turned on,
Switch 5W2tl - Leave it off. Therefore, the contents of the memory (1) of the storage circuit 26 are once reset, and the n=30 yuan electric conversion output is stored. At this time, the photoelectric conversion output of n=2 is stored in the memory (2) at tt. Therefore, at this point memory (1).

(2) stores patterns as shown in FIGS. 5(B) and 5(C), respectively. As soon as the photoelectric conversion output of 11=3 is stored in the memory (r), the correlator 27
and outputs the amount of deviation to the dit-CPU 28. In this way, when n is an odd number, the switch SWl of the gold ore changeover switch 25 is turned on 9, and the photoelectric conversion output is stored in the memo IJ-(11) of the storage circuit 26. When n is an even number, the changeover switch 25 is turned on. The switch SW2 is turned on and stored in the memory (2) of the storage circuit 26.The changeover switch 25 is controlled by the CPU 28, and its control pulse SW is output as shown in the bottom row of FIG. be done.

Furthermore, by performing n-times integration, it is possible to perform m''n 1 correlation calculations and detect the amount of image shift m times.

FIG. 6 shows an example of the change in the value of ldl when the image shift amount dt-5 is obtained by performing six integrations. As shown in this figure, the value of the deviation amount 1dl varies depending on the number of times m. Among these, the one with the largest Idl value is selected. That is, in this example, the Idl value of m=2 and i is the thickest. Here, 'l'w=
Assuming that 1oom8eC and ld1max=0.3m, the amount of image deviation per unit time is as follows. Here, is the allowable amount of camera shake during actual shooting tt? Assuming that E is the minimum circle of confusion diameter of 30 μm, the longest film exposure time T required to prevent camera shake from occurring by 30 μm is 0.03 1 T = −= −(sec). In other words, if the shutter is released at a lower speed than 17100 seconds, the camera shake will not be noticeable. l/100 seconds is T
When converted to v value, it becomes 7.

On the other hand, the CPU 2B receives the Bv value from the photometry circuit 30 and the ySv value from the film sensitivity setting dial 39 provided outside the camera. In the CPU 28, the Tv value is calculated based on the value of ld1max mentioned above. Therefore, the aperture value Av can be determined by Av = Bv + Sv - Tv. The aperture control horizontal groove 36 and shutter control mechanism 37 of the camera' are controlled by the Av value and Tv value thus obtained.

In this embodiment, the CPU 28 is used not only for calculations but also for overall sequence control.

That is, the COD drive circuit 23. converter 24, 3
5. Selector switch 25. Memory circuit 26 and correlator 2
7 is a CPU 28 according to a certain predetermined program.
However, its detailed timing chart is omitted as it is not directly related to the present invention.

Furthermore, the series of operations shown in this embodiment must be completed immediately before the shirt release operation. However, the user is free to decide when to perform the series of operations described above. For example, when the shutter release button is pressed halfway, a series of operations starts, and when the calculation operations up to the point of calculating the Tv value and Av value are completed, the standby state is entered. Alternatively, even if the shutter button is fully pressed, the shutter release operation may be performed after the diaphragm 9 control mechanism 36 and the shutter control mechanism 37 operate. Just in case, in this case, the LE in the viewfinder indicates that it is in standby mode.
Operations such as displaying on D are required. In addition, a series of operations starts when the shirt button is pressed, and when the series of operations is completed, the aperture and shutter control mechanisms operate.
The shutter release operation may be performed after that, but in this case, there is a large time lag between pressing the release button and the actual release operation starting, and when photographing a moving subject, etc. Not suitable for

The electrical processing system shown in FIG. 3 is merely an example, and various modifications are possible. For example, the output of the monitor photodiode 8 is used to control the exposure of the line sensor 7, but this is eliminated and a photometric circuit 30 is used instead.
Exposure control may be performed using the By value that is the output of . Conversely, the photometric circuit 30 may be omitted and the J) By value may be determined from the pulse width of the output MO8 of the monitor photodiode 8. However, in this case, spot metering is used instead of average metering.

In addition, as the line sensor 7, in this embodiment, U C
Although a CD image sensor 7t is used, a MOS type image sensor may be used instead. Not a stored charge type,
An original current readout type image sensor may be used.

Furthermore, a memory function may be included in C)) U28, and the correlation calculation may be performed within the CPU. In this way, the memory circuit 26. Correlator 27 and CPU 28
can be integrated, and the changeover switch 25 becomes unnecessary.

Further, if an analog correlator such as a COD correlator is used for correlation calculation, the converter 24 becomes unnecessary.

In the above example, the allowable value for the amount of camera shake is also 30, which is the minimum turbulence circle diameter.
Although the thickness is set to 15 μm, it may be half that value, 15 μm. In addition, to obtain the amount of image shift per unit time, integration was performed six times, and the value of 1d1 was obtained five times, and the maximum value ld1max was obtained, but instead of the maximum value, the average value ld
1mean' and ldlmean #) Even if you find D, 7j)-! No.

Further, in this embodiment, the integration period Tw is determined in advance, but the integration period Tw may be made variable depending on the illuminance of the light receiving surface. That is, when the integration time of the line sensor is short, the integration period Twv! -Short,
Furthermore, when the period is long, the integral period length may be made longer.

When the program auto camera shown in this embodiment is held on a tripod and photographed, there is almost no image blurring, so the Tv value calculated from ldlmax becomes very small. Therefore, the Av value becomes unreasonably large, and in some cases AV = 8 (F 16 ) * Av = 9 (F
22). However, when the F number exceeds 11K, the sharpness of the p-image generally decreases due to diffraction in the optical system. Therefore, it is not very desirable to take pictures at F16 or F22 unless you want to obtain a very wide depth of field. Therefore, in order to prevent this phenomenon, Av
Upper limit of value (F value) t-Avmax= 7 (Fh1ax
= 11),! : You may also set it as follows.

Next, another modification of the line sensor will be explained based on FIG. 7. In the above embodiment, the line sensor 7
The shape of each photocell was made vertically long as shown in FIG.

The reason for this is that although the line sensor 7 is arranged in the X direction and the amount of image movement in the NX direction is detected, in reality the image also moves in the y direction. However, the movement of the image in the y direction has a negative effect on detecting the movement of the image in the x direction. This is because the correlation between the two image patterns decreases as the images move in the y direction.

Therefore, in the above embodiment, the length of each cell in the y direction is increased to reduce the influence of image movement in the y direction.

In this modified example, instead of making each cell of the line sensor vertically elongated, a cylindrical lens 51 is placed on the light incident side of the line sensor 7 to blur the image in the y direction and to suppress the movement of the image in the y direction. The impact has been reduced. Note that the reference numeral 50 is a line sensor, and the shape of the element is square.

Next, another modification of the line sensor will be explained based on FIG. The line sensor in the above embodiments and modified examples detects the amount of movement only in the X direction, but in this example, it detects the movement of the image in both the X direction and the X direction.

Therefore, a line sensor 53Ar and a line sensor 53B Kl are placed in the X direction of the image sensor board 52, respectively.
Deploy. In this way, the movement of the image in the X direction and the X direction can be detected by both the line sensors 53A and 53B.

Furthermore, FIG. 9 shows another modification. In this example, the line sensor for detecting the movement of the image is also used as the line sensor for autofocus. An image sensor substrate 61 shown in FIG. 9 represents a part of a sensor of a device that detects lateral displacement of an image and performs focus detection. Reference numeral 60 denotes a line sensor provided on the image sensor substrate 61, and a stripe mask 70 is placed on the light incident side of the line sensor 60 at a certain distance. Regarding the principle of this focus detection device,
As disclosed in Japanese Patent Application Laid-open No. 59-15207,
The explanation thereof will be omitted here.

In this it, each cell 6 of the line sensor 60
0-A,, 6O-Bt+--...6O-An,
60- Sequential photoelectric conversion output AI, B□...
・・・・・・An, Bn is obtained Cn= An
+Bn By adding the outputs of A and H of each pair, at t 'C2r...Cn
What is necessary is to find f and, based on this output, find the amount of movement of the image within a certain predetermined time.

Note that it may be combined with other focus detection devices. However, the focus detection device must have at least one row of one-dimensional 2-in sensors ft.

Above, in both the embodiment and the modified example, the case has been described in which the line sensor is arranged on the surface 6 that is conjugate with the film, but the line sensor may be intentionally shifted from the surface 6 that is conjugate with the film. It's a trap. If the line sensor is placed on a plane 6 that is conjugate with all the films, the contrast of the image will be the highest during focusing, and at the same time the high frequency components of the image will be emphasized. However, when the frequency components of the image become higher than the Nyquist frequency determined by the cell spacing of the line sensor, it becomes impossible to accurately detect the image pattern, and as a result, the amount of image movement is inaccurately detected. This is because there is a risk of it becoming. For this reason, it is also effective to intentionally shift the line sensor by 106 degrees, which is conjugate with the film, and lower the high frequency components of the image by 6 degrees. Alternatively, in order to reduce the frequency components of the image, an optical low-pass filter may be placed on the light incident side of the line sensor.

The photographing exposure time determining device of the present invention can be applied not only to cameras using iron block film systems but also to electronic cameras. In the case of a secondary camera, since it originally has a two-dimensional image sensor as an imaging device, it is possible to use the image sensor to capture images in two-dimensional directions without adding a new line sensor. Movement can be detected.

(Effects of the Invention) As explained above, according to the present invention, the camera can be held regardless of the type of interchangeable lens used when taking pictures with a single-lens reflex camera, or whether the camera is held in the hand or on a tripod. Regardless of this, it is possible to provide a photographing exposure time determining device that can automatically obtain the lowest shutter speed within a range that does not cause camera shake and can photograph under appropriate exposure conditions.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a single-lens 7-lens camera to which a photographing exposure time determining device according to an embodiment of the present invention is applied, and FIG. 2 is a diagram showing the line sensor and monitor photodiode shown in FIG. 3 is a block diagram showing the electric circuit of the photographing exposure time determining device shown in FIG. 1 above, and FIG. 4 is a partial enlarged view showing the sub-mirror.
5 is a diagram showing the photoelectric conversion output and the amount of deviation stored in the storage circuit in the electric circuit of FIG. 3, and FIG. Fig. 7 is an enlarged perspective view showing another modification of the line sensor shown in Fig. 1 above. , FIGS. 8 and 9 are enlarged plan views showing still other modifications of the line sensor shown in FIG. 1, respectively. l...Imaging optical system 5...
......Film surface (imaging surface) 6...
・・・・・・・・・・・・ Surface conjugate to film 7・
・・・・・・・・・・・・・・・ Line sensor 5th
Zui 6in T:) 7inma 8th ward and 9th ward procedure amendment book (voluntary)

Claims (1)

[Claims] On or near the imaging surface of the imaging optical system, there is at least one
Photography characterized by arranging line sensors in rows, using the line sensors to detect at least two consecutive time image patterns, and determining the upper limit of the photographing exposure time from the amount of movement of the image patterns. Exposure time determining device.