JPS58166329A - Automatic focusing converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention In particular, the amount of correction (defocus amount and deviation signal) to the in-focus position of the subject that is focused by the master lens, and the drive amount of the master lens is adjusted using this correction signal. This article relates to an automatic focusing converter that enables automatic focusing.

The amount of correction to the in-focus position of the subject is detected at the end image on the camera side or an equivalent position, and this amount of correction is input to the motor drive circuit for moving the master lens to move the master lens to the in-focus position. Automatic focus detection devices are known that drive the focus to a position where the focus is obtained.

When a converter is installed between the master lens and camera of the device described above, the focal length of the entire lens optical system changes, and if only the master lens is used, the correction information for moving the master lens is insufficient for automatic focus detection. Problems that cannot be solved will arise.

In order to solve the above-mentioned problem, the present invention provides a means for correcting a signal corresponding to a change in the focal length of the converter in the converter, and when the converter is installed between a master lens and a camera, a correction signal from the correction means is provided. An object of the present invention is to provide an automatic focusing converter that can control the movement of a master lens to a focusing position based on the following.

When the converter is installed between the master lens and the film, driving the master lens's 7 focusing mechanism and moving the master lens in the optical axis direction for focusing will reduce the converter's performance compared to when only the master lens is used. The amount of defocus changes by the square of the magnification. Therefore, focusing when using a converter must be done very precisely, and even though the focusing mechanism of the master lens has been moved slightly, the amount of defocus may be large because the converter is used. The problem was that it was difficult to focus. Furthermore, tcTTLm fixed method (
In automatic focusing devices that use blur detection (internal light reception method) or phase difference detection method, the amount of defocus in the master lens's own image is detected by an image sensor, so the control system for the focusing mechanism of the master lens One is a system that controls the defocus amount of the master lens using the 7-focus driving time, and the other is a system that controls the defocus amount of the master lens by receiving a pulse signal generated from the 7-focus mechanism. etc. are used. However, according to the control systems of these focusing mechanisms, when the focusing mechanism receives a signal that corrects the amount of defocus on the image plane by ΔX, the focusing mechanism adjusts the master lens so that the image plane by only the master lens is moved by ΔX. Move the lens -t6, so
Actually, the image plane of the lens using the converter is Δx−
Since the lens moves by 7, if 7>2, the automatic focusing operation will oscillate and the focus will not be obtained.

In view of the above points, the present invention has been made in order to eliminate the above drawbacks. It is an object of the present invention to provide a converter capable of automatic focus detection, in which the signal correction means automatically functions when a camera is attached, and performs a proper focusing operation together with the focusing mechanism of the camera.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. With the type that controls the amount of defocus on the image plane by time or pulse number, it is not possible to directly detect whether the object is moving accurately to the in-focus position due to load fluctuations, inertia, etc., so the non-point detection unit refocuses. I have to check. Therefore, FIG. 1 shows a case where a pulse signal corresponding to the amount of defocus on the image plane is generated by the focusing mechanism.

In Fig. 1, L is a master lens, QM is a quick return mirror, KM is a submirror, I8 is an image sensor 41, an ego analysis processing section, 2 is a focus condition determination section, 3 is a drive signal generation section, and 4 is a motor. A lens moving mechanism consisting of a drive amplifier, 5 a motor, and 6 gears. 9
is the pulse generator, and as the master lens L moves,
A pulse corresponding to the amount of movement is generated. Since the pitch of these pulses is related to the ruin accuracy in the final forging, it is set as finely as possible so as to generate as many pulses as possible per unit movement of the master lens L. Reference numeral 8 denotes a pulse converter for lens displacement, which receives pulses generated from the pulse generator 9 as the master lens L moves, and allows the defocus of the image plane to be calculated by the number of pulses.

Reference numeral 10 denotes a motor drive signal generating means for determining the correlation between the amount of movement of the lens L and the motor drive pulse for moving the lens. For example, when the lens moving ring is moved by a pulse signal, it moves at 100 #ml per pulse. Yo5
This is a circuit that emits a signal to set the Now, assuming that the master lens L is in the defocus position, master lens L → quick return mirror QM → sub mirror RM
The light flux that has passed through is projected onto the image sensor I8.

A drive signal for the motor 5 for moving the Δ spindle on the image plane of the master lens L is outputted from the image sensor Is via the surface contrast analysis processing section 1 → focus condition determination section 2 at the drive signal generation section 3. Ru. Depending on this drive signal,
The motor 5 operates and the master lens L moves. At this time, pulses are sent out from the pulse generator 9 in accordance with the signal set by the motor drive signal generator 10, and -
Which number of pulses corresponds to ΔX bin) movement in the lens displacement pulse converter 8, then the drive signal generator! i+ is motor 5
Stop giving the drive signal to. Next, a case where a converter is used in this automatic focus detection device will be explained with reference to FIG. When a converter is inserted between the master lens L and a film (not shown), the converter is equipped with a signal correction means 11 according to its performance, and the signal from this signal correction means 11 is connected to be inputted to the drive signal generation IIK. be done. For example, in the case of Figure 1), when the focal length of the master lens is f, the motor drive signal generating means outputs a signal of 2 ports and is set to drive the lens at 100 μ- per pulse. .

When the converter C is installed, the signal generating means 10
The output of 2 volts is corrected to 1 volt by the signal correction means, and as a result, if the motor drive signal is corrected to obtain a motor drive signal of 50 seconds per pulse, it is possible to perform an appropriate automatic node detection operation when a converter is installed. can.

Assuming that the threat star lens L is in the defocus position,! The light beam passing through the star lens L→converter→tight return power QM→submirror RM is projected onto the image sensor I8. Further images Amansa I8
A drive signal for moving the focus by ΔX on the image plane of the lens is outputted from the drive signal generation section 3 via the -> image analysis processing section 1 -> focus condition determination section 2. When the master lens L is moved according to this drive signal, the focus of the image plane of these lenses will be moved by Δx-7 because a converter with a magnification of X is actually used as described above. Therefore, when using a converter with a magnification of X,
It can be seen that it is sufficient to increase the amount of focus movement of the image plane of the lens by 1/x2.

3 to 5 show specific examples of the signal correction means 11 of the converter C mentioned above.

In FIG. 3, 1 to 1 represent signal terminals for transmitting and receiving electrical signals between the camera body and the converter, and 1 to 1 represent terminals for transmitting and receiving electrical signals between the converter and the master lens.

Signal lines 11 and 12 are for supplying power energy from the camera side to the master lens.

The embodiment shown in FIG. 3 shows an example in which a T-type attenuation circuit consisting of a resistor Ra@Rb@Re is used as the correction signal generating means of the converter C.

The example in Fig. 4 uses a π-type attenuation circuit consisting of resistors Rd-Re and Rf, and the example in Fig. 5 uses an amplification circuit consisting of an operational amplifier p and a resistor. As an example, the signal from the above-mentioned screen drive signal generating means 10 is attenuated and amplified without changing the impedance.

In the example shown in FIG. 3, R4 is the impedance on the camera side, and if the resistance value is R1, the resistance value of 载 and quotient can be attenuated twice without changing the impedance.

In addition, in the case of Figure 5, it is encouraged to convert Wear.

As described above, the present invention can be used without disturbing the automatic focus detection system between the master lens and the camera even in a photographing system in which a converter is connected, and in particular can be made into a relatively simple structure.

Using the present invention, it is also possible to connect converters in multiple ways, and the signal correction between each converter and the composite converter can also be adjusted accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing each side of the constituent signal correction means in an embodiment with and without a converter according to the present invention. 1.e.Face analysis processing section 2.Focus condition judgment 6..Drive signal generation section 4..Motor drive lamp 5..Motor C..Converter applicant Canon Co., Ltd. p-

Claims (1)

[Claims] In an automatic focus detection device that detects the amount of correction to focus in iui by a master lens and drives and displaces the master lens by the amount of correction, when a converter is used, the change in focal length El due to the front Ie converter function is used.
l! IL? An automatic focusing controller characterized by outputting a correction signal.