JPS58150921A - Information detector of automatic focusing camera - Google Patents

Abstract

PURPOSE:To decrease transmission systems in number and to simplify constitution, by using either one of two distance information on focal length and subject distance and the movement extent of an image plane, and then finding the other piece of distance information. CONSTITUTION:The extent DELTAX of displacement of the image plane from the image formation plane of an actual object image is detected by a focus detector 14 and a reversible motor 19 is driven forward or backward by the outpt of a control circuit 18 to perform focusing. As the motor 19 rotates, a signal for the movement extent of the image plane is obtained from a comparator 25 in the control circuit 18 through the pattern 23 of generating device 22 and 23 for the signal for the movement extent of the image plane. In infinite-distance focusing, when the extent of displacement is DELTAX, focal length is (f), and subject distance is R, R=f<2>/DELTAX+2f. For this purpose, only the (f) is transmitted from an interchangeable lens and the output of said comparator 25 is used as the DELTAX. Consequently, the R is calculated on a camera side, it is not necessary to obtain the R from the interchangeable lens side, and transmission systems are decreased in number to simplify the constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a so-called T camera that detects a forbidden point and focuses the eye dynamically by receiving transmitted light from an exchangeable photographic lens.
This invention relates to an information detection device for a 'J' L-type automatic focusing camera.

The 31m light from the camera lens attached to the camera body is received by the light-receiving element installed in the camera body. So-called TTL that detects image plane misalignment
A type focus detection device is known, for example, from Japanese Patent Application Laid-Open No. 54-159259, which calculates the amount of movement of the photographing lens from the detected amount of image surface deviation, and detects the entire photographic lens or a part thereof. Regarding a system that focuses by moving all the focusing groups, the amount of deviation △ of the image plane between a predetermined focal plane (for example, film plane) 2 of the photographing lens 1 and the actual subject imaging plane 3
Detection of X 1-1 Assuming that the lens is moved by a movement amount Δd corresponding to the shift amount ΔX to align the image of the subject P on the focal plane 2, the following relationship holds true.

R-DD+Δx f where R is the photographing distance from the focal plane 2 to the subject, D is the distance between the lens position before correcting the amount of deviation and the focal plane, and f is the focal length of the lens. In this case, if R is the usual shooting distance, that is, R is extremely larger than the lens movement amount Δd, then ΔX=Δd. In addition, in the case of the so-called internal focusing type in which a part of the focusing lens of the photographic lens is moved, the amount of movement X of the image plane and the amount of lens movement Δd are approximately equal to R) Δd. Since it is proportional, if the proportionality constant is known, the image plane movement amount X can be determined from X0 and Δd (k is the proportionality constant).

One way to control the amount of lens movement Δd corresponding to the predetermined image plane movement of 1°X as described above is to control the relative image plane movement '1jdJ amount χ.

A control circuit installed in the camera body is provided with means for generating electric pulses according to the number of electric pulses, and the number of electric pulses is counted by a control circuit installed in the camera body. Measures are taken to issue a drive signal.

Interchange the above pulse generating means with the lens driving device, ≠
When installed inside the lens body, power and control signals for controlling the drive device t are transmitted from the camera body side via a contact terminal provided at the joint between the camera body and the interchangeable lens, and vice versa. The pulse signal must be sent to the control circuit on the camera body side via another contact terminal. moreover,
In order to perform automatic focus adjustment accurately, focal length information, subject distance information (
Distance scale information), aperture value information, and other aperture value information are sent from the interchangeable lens side to the camera body side, but each of these pieces of information is transmitted independently.
If you try to do so, you will receive information about each tragedy!
1. An electric circuit system consisting of a means for converting the electric signal into an electric signal, a means for detecting the electric signal, and a connector contact for transmitting the electric signal from the interchangeable lens to the camera body.
Each is required. Therefore, the configuration of the electric circuit becomes complicated, and the number of components thereof becomes unnecessarily large, which increases the space required, resulting in disadvantages that not only the size of the camera becomes large but also the cost becomes high. Therefore, it is important to reduce the number of connector contacts.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome the above-mentioned drawbacks and to provide an information detection device that uses a small number of signal transmission systems to obtain information necessary for detecting a larger number of focal points than the signal transmission system. It is about providing.

In order to achieve the above object, the present invention takes into account that a certain physical correlation exists between the amount of image plane movement, the focal length of the interchangeable lens, and the subject distance, and uses the image plane shift ot signal. In an autofocus camera that uses lens control to control the lens drive, distance information of either focal length information or subject distance information and distance information? By calculating the W distance information of Senkata from the motion information, the number of Ikiho legends is reduced.

ν below, 'The date of publication l based on the examples shown in the attached drawings.
Learn more about the details.

Figure 2 is a cross-sectional view for explaining the present invention in detail, and shows the photographic lens 11 of the exchangeable l/ring assembly 7 transmitted through 1-#11t.
%! ? The light from the body passes through a part of the accompaniment 9-19 in the camera body B of the reflex camera.1. The light is reflected downward by a sub-mirror 13 that is disposed behind the swinging mirror 12 and moves together with the swinging mirror, and enters the intermediary and output device 14 . The light-receiving surface 1/:i of this Benkei detection device 14 is conjugate to the film surface F. The large shift amount ΔX at the image top 1 of is excluded by this focus detection signal 14. The sign (±) of this large shift amount ΔX indicates that the image plane is 4 and the front of the light plane is behind, On the other hand, the light reflected by the movable mirror 12 to the mirror 15 is reflected on the focus plate 15, and the eclipsed image is formed by the pentaprism 16 and the contact lens 15. Through the lens 17,
observed.

The output of the expansion/deflation detection device 14 is sent to the control 1 circuit 18 for understanding. This control circuit 18 generates a drive signal that causes a reversible motor 19 in the interchangeable lens assembly to rotate forward, reverse, start, and stop, based on the output of the Benkei detection device 14, which reverberates in ±△X. The motor 19 moves 1. Since the photographing lens 11 is held in place by a screw, the rotation direction of the reversible motor 19 varies depending on the rotation direction of the reversible motor 19.
Moves back and forth along (stops when the photographing lens 11 comes to the focusing position. Which motor 16, p heavy chain 1) machine $
20. A lens driving means for reconnaissance focusing is constructed with the lens nose 21 and the lead screw 21a.

It is provided adjacent to the gear interlocking mechanism 20, and the amount of movement of the rotational speed of the reversible motor 19 or the operating amount of the lens 1 is provided in detail later. Based on this, an image plane movement amount signal representing the movement amount of the image plane due to lens movement is output. This image plane movement amount signal is transmitted from the interchangeable lens assembly to the camera body B and sent to the control device 18. When this image plane movement amount signal reaches a level corresponding to the magnitude of the focus detection signal, the motor drive is abruptly stopped.

In this way, the photographing lens 11 is driven so that the image plane is moved by the same amount as the deviation Δ of the image plane detected by the focus detection device 14.

FIG. 3 shows a specific configuration of the image plane movement amount signal generating means 22 and 23 for obtaining an image plane movement amount signal. Connector contacts P1 to P5 are provided for transmitting and receiving signals to and from the reversible motor 19.
It is formed so as to receive the drive output of the control device 18 on the camera body B side via the camera body B side. The rotation of this reversible motor 19 is controlled by the reduction gears 20A, 20B, 2 of the gear interlocking mechanism 20.
The signal is transmitted via 0C to a reduction gear 20D with a wide tooth width provided on the movable lens barrel 21. This final stage reduction gear 2
The rotation of 0D is converted into a movement in the optical axis direction by the lead screw 21a, and the photographing lens 11'ff moves in the optical axis direction. Furthermore, a pattern 23 for detecting the amount of image plane shift Irl1 is provided on the end surface of the intermediate gear 20B. This pattern 23
is formed by dividing a circle into four equal parts by a high reflection part 23& having a high light reflectance and a low reflection part 23b having a low reflectance.

Light sound projection 1 to a specific part of the pattern 23 of the light source 22A,
The reflected light is received by the light receiving device 22B. 2. The light receiving device 22B responds to the rotation of the pattern 23 with the rotation of the intermediate gear 20B.
Two pulses are generated per revolution.

In response to this pulse output, seven or more signals are sent to the control device 18 in the camera body B through the connector contact P3' as an image plane movement amount signal representing the amount of movement of the image plane that moves in response to the amount of movement of the lens. The pattern 23, the light source 22A, and the light receiving device 22B constitute image plane movement amount<=S generating means.

FIG. 4 shows a specific configuration example of an electric circuit for obtaining the above-mentioned pulse output. In the interchangeable lens assembly, a light emitting diode 22A' is connected to a resistor R1 as a light source 22A.
A phototransistor 22B' is provided as a light receiving device 22B, and its emitter is grounded and its collector is connected to a connector contact P3. On the camera body B side, a contact P3' that contacts the contact P3 is connected to the power source via a resistor R2, and this contact P3' enters one input terminal of the comparator 25. A constant voltage source 26 is connected to the other input terminal of the comparator 25 as a reference voltage. With the above configuration, the photographing lens 11
The light reflected intermittently by the pattern 23 for detecting the amount of image plane movement, which rotates with the movement of the image plane, turns on and off the phototransistor 22B' of the light receiving device 22B. collector or contactor P3 or P
The voltage appearing at 3' becomes a rectangular pulse. By comparing this number with reference to an appropriate constant voltage source 26, the output of the comparator 25 is a pulse output whose waveform has been shaped in a number proportional to the relative image plane movement amount X. .

Now, in equation (1) above, the distance between the focusing lens l and the focal plane 2 is made equal to the focal length of the focusing lens 1, and the focusing lens is set so as to focus at infinity. When the lens 1 is placed and the deviation of the image plane of the subject P when the swallow-limit combined focus is taken as a reference as shown in Fig. 7, that is, the absolute image plane deviation amount △X, the equation (1) is obtained. By substituting D=f and ΔX−Δχ into , the following equation is obtained.

R=Niji' +2f (2) ΔX If the above equation (2) is used, one piece of information, for example focal length information, can be obtained by using the image plane movement amount signal output from the comparator 25 described above. By simply transmitting information from all interchangeable lenses L to the camera body side, the subject distance can be calculated and determined on the camera body side, and there is no need to obtain this subject distance information from the interchangeable lens side. However, the image plane movement amount signal obtained in the above embodiment is a relative one that changes depending on the distance between the focusing lens and a predetermined focal plane, that is, D in equation (1). What is required is the absolute amount of image plane movement X corresponding to the image plane deviation 14i'm X with respect to the infinity combined focus position.Therefore, the joint lens always moves from 1 to 1 from the infinity focus position as the starting point. In an automatic focusing camera that is driven to focus, equation (2) can be used to its fullest extent.

However, in general, a relative image plane shift is detected as shown in FIG. 1, so the relative image plane shift amount a obtained in the example of FIG. A conversion means is required to convert it into .

FIG. 5 shows a specific example in which the camera body B 11411 is equipped with this conversion means and calculates the object distance using the image plane movement amount signal and the focal length information, and the comparator 25
The pulse of the relative image plane movement amount signal thus output is sent to the control circuit 18 for driving the lens, and is also input to the up/down counter 27. The drive direction signal from the control circuit 18 is input to the up/down selection terminal of the up/down counter 27, and the infinity signal from the interchangeable lens L is input to the reset terminal Re. This infinity signal is transmitted to the contact P4 on the interchangeable lens L side, the switch S~v1 connected between the contact P4 and the ground, and the contact P4 on the camera body B side.
' and a resistor R3 connected between the 'l1lt source and the distance ring 2 outside the interchangeable lens system.
The switch SWI is configured to close only when the lens 8 (a (see FIG. 2)) is at the infinity position, that is, when the photographing lens 11 is at the infinity focusing position.

The output of the up/down counter 27 passes through the conversion means 29 and enters one input of the calculation means 30. On the other hand, the resistor R4- inside the interchangeable lens assembly is a fixed resistor with a certain relationship between the attached interchangeable lens (C, its resistance value and focal length f) (however, for zoom lenses, (variable resistor), one end of which is grounded and the other end connected to contact P5. A constant current source 31 is connected to a contact P5' on the camera body side that contacts the contact P5, and further enters a converting means 32. The output of this conversion means 32 also enters another input of the performance means 30.

Since the circuit shown in FIG. 5 is configured as described above, the box-to-image plane movement amount signal pulse outputted from the comparator 25 is sent to the up-down counter 27 at the infinite distal point t of the photographing lens.
When i is O (zero), the driving direction, that is, the sign of
The JO is counted, and the output is a digital output with a value proportional to the absolute image plane movement it. On the other hand, as the current from the constant current source 31 flows through the resistor R4 via the welders P5 and P5', a voltage proportional to the resistance value of the resistor R4 is generated at the contact P5'. Therefore, this voltage has a certain relationship with the focal length of the attached photographic lens. Therefore, the output of the up-down counter representing the amount of image plane movement and the voltage of the contact P5' representing the focal length are converted into appropriate forms by the converting means 29 and 32, and the respective values X and f are used. Then, by calculating the above-mentioned equation (2) in the calculating means 30, information R on the object distance can be obtained from the output of the calculating means 30.

Next, the contacts P5 and P5' for transmitting focal length IM information in the actual example shown in FIG.
3. Commonly used with P3' (7. An embodiment in which the number of contacts is reduced by one set is shown in FIG. 6.

In FIG. 6, the phototransistor 22B' of the light receiving device 22B is connected to the phototransistor 1 in the cross-lens structure, and the contact P3 is connected to the contact P3.
A resistor R4' having a resistance value r having a certain relationship with the focal length 4f of the photographic lens 11 is connected to the collector of . On the camera body B side, a voltage detection means 33 is connected between a constant current source 31' that outputs a current of current value i to the contact P3' and the ground, and the contact P3' is connected to one side of the comparator 25. enter the input. A constant voltage source 26 is connected to the other input of the comparator 25. The output of the voltage detection means 33 enters the conversion means 32. Other parts are the same as the embodiment shown in FIG.

) With the above configuration, the light that is intermittently reflected by the detection pattern 23 that rotates with the movement of the photographic lens 11 is turned on and off by the phototransistor 22B''!
A constant current i caused by 1' flows through the phototransistor 22B' and the resistor R4', and the voltage appearing at the contact P3 or P3' becomes a rectangular wave pulse. The voltage of this pulse is low level (approximately 0 voltage) when the phototransistor 22B' is on, and high level (voltage V=i-) when it is off.
r). This signal is connected to a suitable constant voltage source 2 lower than V.
6 as the standard and 1. Compare with V Koyori, scolding (earnings 25
As the output of the image plane 4, a number of waveform-shaped pulse outputs proportional to the amount of movement of the image plane 4 is obtained. Here, the voltage ■ appearing at the contact P3 when the phototransistor 22B' is off is the resistance value rv of the resistor R4J.
c Proportional. Since this resistance value r is set to have a certain relationship with the focal length f of the photographic lens 11, this voltage V also has a certain relationship with the focal length f of the photographic lens 11.
have a thread. Therefore, if the voltage detection means 33 detects the voltage of the phototransistor 22B when it is off,
It becomes possible to obtain focal length information by using the contact between the interchangeable lens assembly and the camera body B as the contact for transmitting the image plane movement amount signal. The operation of determining the object distance using the image plane movement amount signal pulse and the output of the voltage detection means 33 representing the focal length of the photographing lens is the same as in the embodiment shown in FIG.

In the two embodiments shown in FIGS. 5 and 6 above,
In both cases, focal length information was detected, and the ``q-body distance was obtained by calculation processing, but object distance information based on the position of the distance ring 28 of the father's structure in the furnace was detected, Calculation of the focal length can also be realized by a completely similar embodiment. In this case, the above-mentioned equation (2) may be modified as follows.

f--△x+V]iTV available...(3) And the fifth
If the resistance values of R4 in the figure and R4' in FIG.
0, the focal length f of the photographic lens can be obtained. .

In addition, in the above embodiment, focus adjustment is performed on the condition that the image plane movement amount X or For example, in cases where a proportional relationship does not hold between the amount of movement of the image plane and the amount of lens movement in the case of internal focusing type adjustment due to the construction of the lens, The pattern 23 is rotated in conjunction with the movement of the lens 20D, and a correction cam or the like is provided to adjust the rotation speed of the pattern 23 representing the lens movement amount s and the image corresponding to the lens movement amount. It may be corrected so that the amount of surface movement is in a linear relationship.

As is clear from the above description, according to the present invention, in a camera and an interchangeable lens that perform focusing control using an image plane movement amount signal, it is necessary to In order to detect two types of information on the camera body side: the focal length information of the interchangeable lens and the subject distance information, only one of the two types of information is transferred from the interchangeable lens side to the camera body side. Once transmitted, the other information is calculated and determined on the camera body side, which simplifies the information transmission system and allows both the interchangeable lens and the camera body to be made smaller, lighter, and lower in cost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the relationship between the photographic lens and the imaging plane, Fig. 2 is a sectional view of an embodiment of the present invention, and Fig. 3 is a perspective view showing the internal structure of the interchangeable lens side of the embodiment of Fig. 2. 4 is a circuit diagram of the image plane movement t('i signal) used in an embodiment of the present invention, FIGS. 5 and 6 are block diagrams showing different embodiments of the present invention, and FIG. is an optical arrangement diagram for explaining the absolute image plane shift fth vertically.] 4... Focus, Q detection means, 18... Control means 19.20.21... Focusing R4... distance information means, 30... calculation means 3
1...Constant current source applicant Takao Watanabe (21), agent of Nippon Kogaku Kogyo Co., Ltd. Figure 4

Claims (1)

[Claims] 1. According to the detection output of a focus detection means, which is provided on the camera body side and which receives transmitted light from an interchangeable lens and detects the amount of deviation between a predetermined focal plane and an imaging plane of a subject. In an automatic focusing camera that automatically adjusts the focus by driving a focusing lens driving means provided in the interchangeable lens structure, the deviation between the focal plane for an infinite distance and the imaging plane for the subject to be focused on. An image plane movement amount signal generator that outputs a signal representing an image plane movement amount corresponding to a lens movement amount according to the lens, and an image plane movement amount signal generator that is provided on the intersecting lens side and that is one of the focal length and object distance of the interchangeable lens. Distance information generating means for outputting one distance information; receiving output signals from the image plane shift amount signal generating device and the distance information generating means; In the information detecting device, the image plane movement amount signal generating device (l'j: determines the image plane # relative to the subject according to the driving direction of the focusing lens driving means.
Relative image plane movement amount signal generation means for outputting a signal representing the amount of movement; and an output signal of the relative image plane movement amount signal generation means is manually input, and a focal plane for an infinite distance is set as a reference based on the human input signal. 1. An information detection device for an automatic focusing camera, comprising: absolute image plane movement arrival signal generating means for outputting an absolute image plane movement amount signal corresponding to the deviation of the image plane of a subject; and h. 3% Allowable Claims Paragraph 2 h In the information detecting device set forth in the publication, the relative image plane movement arrival signal generating means is interlocked with the focusing lens drive #l+ stage (], 9.20.21). An information detection device for an automatic focusing camera, characterized in that it comprises a pattern for detecting image plane movement (23), a light source (22A) for illuminating the pattern, and the pattern. (2) 4 In the TG signal detection device according to claim 2, the output signal of the absolute image plane shift #I signal generation means fd and the relative image plane movement new signal generation means (22, 23, 25) The automatic combination is characterized by being an up/down counter (27) that converts the output of the infinite image plane position detection means (SW+. Information detection device in a focal camera. 5. In the information detection device according to claim 4, from the resistor (R4, JL4') representing the focal length (f) and the object distance (■◇) and the constant DC source (31, 31') converting means (32,
29). An information detection device for an automatic focusing camera, characterized in that the calculation means (30) is configured to receive input via an information detecting device (30). 6% In the information detection device according to claim 5, a resistor (R4') representing either the focal length or the object distance is added to the relative image plane movement leaf generating means, An information detection device for an automatic focusing camera, characterized in that the output voltage thereof is input to the output means (30) via a voltage detection means (33).