JPS6023838A - Changer for visual field frame of finder of autofocusing camera - Google Patents

Abstract

PURPOSE:To enable change of a visual field by simple constitution by providing a hologram on which >=2 visual field frames corresponding to object distances are multiplex-recorded to a finder optical system. CONSTITUTION:The optical system of a finder consists of an objective lens 10, an eyepiece lens 12, a hologram 14 which is provided between the lens 10 and the lens 12 and on which three visual field frames 22, 24, 26 are multiplex-recorded and light sources 16, 18, 20 which irradiate reconstructing light to the hologram 14. The frame 22 which corrects parallax with the distance on a long distance side, the frame 24 which corrects the parallax with the distance on a middle distance side and the frame 26 which corrects the parallax with the distance on a short distance side are multiplex-recorded on the hologram 14 in such a way that the respective frames can be reconstructed by the light sources 16, 18, 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a finder field frame converting device for an autofocus camera, and more particularly to a finder field frame converting device for an autofocus camera that automatically switches the field frame in response to a change in shooting distance.

- In cameras other than eye-reflex cameras, the optical axis of the photographic lens and the optical axis of the finder are misaligned, resulting in a misalignment (balarax) between the photographic screen and the viewfinder field of view. For this reason, in such a camera, it is necessary to maintain the position of the field frame visible in the finder so that the field of view to be photographed coincides with the photographic screen on the film. This balarax becomes very large when shooting at close range.

On the other hand, autofocus cameras measure the shooting distance from the photographing lens to the subject using a distance measuring device that includes a sensor, and automatically perform focusing operations based on this shooting distance. Demand is increasing. Even in such an autofocus camera,
- In cases other than the eye reflex system, the above-mentioned problem of vararax occurs.

In order to correct such variation, 1. In order to match the viewfinder field of view with the photographic screen, it is necessary to change the field of view frame according to the photographing distance. Conventionally proposed field frame conversion devices have a structure in which the field frame is moved mechanically, making the viewfinder structure extremely complicated, making it difficult to apply them to simple amateur autofocus cameras due to the size of the camera. , weight and price are difficult.

The present invention has been made in view of the above circumstances, and provides a finder field frame conversion device for an autofocus camera that automatically changes the field frame according to the shooting distance without requiring mechanical movable members. It is intended to.

The present invention provides a finder optical system with a hologram in which at least two or more field frames corresponding to the photographing distance are multiplex recorded or a plurality of bolograms in which at least two or more field frames corresponding to the photographing distance are individually recorded. At least two or more light sources are provided to reproduce the field of view frames individually, and the distance is output in proportion to the reference voltage and the measured shooting distance, which are determined according to two or more predetermined shooting distance zones. The present invention is characterized in that it includes a control unit that compares the measured signal voltage and selects one of the plurality of light sources to turn on based on the comparison result.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a viewfinder field frame converting device for an automatic zoom camera according to the present invention will be described in detail below with reference to the accompanying drawings.

An example of a finder optical system is shown in FIG. 1, where 10 is an objective lens that constitutes the finder optical system,
is an eyepiece; 14 is an objective lens 10 and an eyepiece 12;
A hologram 16, 18, and 20 is disposed between the hologram 14 and has three field frames multiplexed thereon, and a light source 16, 18, and 20 irradiates the hologram 14 with reproduction light. As shown in FIG. 2, the hologram 14 has a field frame 22 with vararax corrected at a distance on the far side, a field frame 24 with vararax corrected at a distance δ11 on the middle distance side, and a field frame 24 with vararax corrected at a distance on the near side, as shown in FIG. Each field frame 26 whose lux has been corrected is multiplex recorded so that it can be reproduced by the light sources 16, 18, and 20, respectively.

In the finder optical system shown in Figure 1, the virtual image of the subject is
For example, it is designed to be formed about 1 m in front of the finder. The hologram 14 also includes light sources 16, 18, .
A field frame is recorded in advance on the hologram surface so that when light is emitted from any one of the holograms 20, a virtual image of the field frame is formed at approximately the same position on the optical axis of the finder as a virtual image of the subject.

The field frames 22, 24, and 26 are switched by comparing the distance signal from the autofocus camera sensor converted into an electrical signal with a reference voltage determined according to the distance corresponding to each field frame. Select the light source that should be used. This-
FIG. 3 shows an example of processing.

First, an autofocus camera takes in a distance measurement signal obtained from a sensor or module (or a signal that converts the amount of lens extension into a resistance value and makes a current value or voltage value), and calculates a voltage corresponding to this distance. The light source to be turned on is determined by comparing the voltage with a voltage predetermined according to the shooting distance zone.

In other words, the actual shooting distance D...
・Voltage V 1st zone D1-D2 (short distance)...Reference voltage v1-v2 2nd zone D2-D3 (middle distance)...
・Reference voltage v2 to v3 3rd zone D3 or higher (long distance)・
...Determine each voltage according to the distance, such as the reference voltage ν3 or more, and regenerate the field of view frame 26 by lighting the light source 20 in a short distance area where D1≦D<02 (v1≦v<V2) holds; Mouth 2
≦D <03 (V2≦V<v3) is established, the light source 18 is turned on to reproduce the field of view frame 24, and D3≦D
The light source 16 is turned on in a long-distance area where (V3≦■) holds, and the visual field frame 22 is reproduced. In this way, the visual field frame can be sequentially reproduced according to each distance zone, and vararax can be corrected without requiring a mechanical movable structure.

FIG. 4 shows an embodiment of the present invention that executes the process shown in FIG. 3.

In FIG. 4, reference numeral 28 denotes a distance signal generator of an autofocus camera that outputs a voltage V according to the shooting distance, and 30
．． 32. 34 is a voltage dividing resistor for dividing the power supply voltage Vcc to create a reference voltage. 36 is a voltage dividing resistor for dividing the power supply voltage Vcc and creating a reference voltage. 36 compares the voltage V from the distance signal generator 28 and the divided voltage Va, and when V>Va, it becomes high level. A comparator 38 is a comparator that compares the voltage V and the divided voltage vb and generates a high level output voltage when V>Vb. Further, 40.42 is an inverter that inverts and outputs the output signal of the comparator 36.38, 44 is a gate circuit that generates a gate voltage Vg for a certain period of time at a predetermined time, and 46
is the NA at which the output is at a low level only when the gate voltage Vg and the output of the comparator 36 are both at a high level.
ND circuit 48 is a NAND circuit whose output becomes low level only when the outputs of the inverter 40, comparator 38, and gate circuit 44 are all at high level;
50 is a NAND circuit whose output becomes low level only when the outputs of the inverter 42 and the gate signal generation circuit 44 are both at high level. NAND circuit 4
Each output terminal of 6.48.50 is connected to a current limiting resistor 52.
．． 54 and 56, respectively. 58, 60, and 62 are transistors whose bases are connected to the resistors 52, 54, and 56, and whose collectors are connected to the light sources 16, 18, and 20, and whose emitters are commonly grounded;
Current limiting resistors 64, 66, and 68 are connected in series to 6, 18, and 20, respectively.

In the above configuration, assuming that the voltage V increases in proportion to the shooting distance d, when in the short distance zone,
Voltage ■ is lower than both reference voltages Va and Vb (v<Vb<Va), comparator 36.38
The output voltage of becomes low level. However, when comparator 36.3B is at low level, inverter 40.4
27'J<high level, only the NAND circuit 50 satisfies the NAND condition due to the output voltage of the inverter 42 and the gate voltage Vg, and the output is set to low level and the transistor 62 is turned on to cause the load current to convulse, and the light source 20 In order to light up the field frame 26 for short distances, the field of view frame 26 is reproduced.

In the middle distance zone where the voltage V exceeds the reference voltage vb (Vb<v<Va), only the comparator 38 outputs a high level, and since the comparator 36 does not operate, the inverter 40 still outputs a low level. , and the gate voltage Vg, NA
Only the ND circuit 48 satisfies the NAND condition and sets the output to low level, turning on the 1-ranji star 0 and turning on the lamp 1.
8, the medium-distance viewing frame 24 is regenerated.

Furthermore, in a long distance zone where the voltage V exceeds the reference voltages νa and Vb (v > Va > Vb), both the comparators 36 and 38 output a high level, and the inverter 4
As a result of setting the output voltage of 0.42 to low level, NAND
The NAND condition is satisfied only in the circuit 46, the output is set to low level, the transistor 58 is turned on, the light source 16 is turned on, and the long-distance viewing frame 22 is reproduced.

Although the embodiment shown in FIG. 4 shows an example in which a dedicated circuit is configured to determine which light source should be lit, the present invention can be achieved by using a microcomputer and implementing the flow shown in FIG. 3 in software. It is also possible.

Further, in the above embodiment, three viewing frames are reproduced, but the number of viewing frames may be any number as required.

As is clear from the above, according to the finder field frame conversion device for an autofocus camera according to the present invention, a plurality of field frames are recorded in a hologram in the finder according to the photographing distance, and a light source for reproducing the field frame is set at the photographing distance. By automatically selecting from distance measurement signals according to the distance measurement signal, a paralanx-corrected field frame can be reproduced, and field frame conversion can be performed with a simple configuration that does not include a movable member.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an outline of a reverse Galilean type finder to which this embodiment is applied, Fig. 2 is an explanatory diagram showing a field of view frame according to this embodiment, and Fig. 3 is an example of control of this embodiment. The flowchart shown in FIG. 4 is a circuit diagram showing this embodiment. 10... Objective lens, 12... Eyepiece lens, 1
4...Hologram, 16.18.20...Light source,
22.24.26... Field of view frame, 28... Auto focus circuit, 30.32.34... Voltage dividing resistor,
36.38... Comparator, 40.42... Inverter: 44... Gate circuit, 46.48.50
...NAND circuit, 16.18.20...Light source,
52, 541.56.64.66.68...Resistance,
58.60.62...1~Rangister. Agent Patent Attorney Kenzo Matsuura Figure 1 Figure 2 = 214

Claims (1)

[Claims] In an autofocus camera that measures the photographing distance by a distance measuring means including a sensor and automatically performs a focusing operation based on the measured photographing distance, at least A hologram in which two or more field frames are multiplex recorded or a plurality of bolograms in which at least two or more field frames corresponding to the shooting distance are individually recorded, and at least 21 [ A light source of 1i1 or more is compared with each reference signal level determined according to two or more predetermined shooting distance zones and a distance measurement signal level output in proportion to the measured shooting distance. A finder field frame conversion device comprising: a control section that selects and lights up one of the plurality of light sources based on a comparison result.