JPS58132219A - Discriminating device for set aperture value of interchangeable lens - Google Patents

Abstract

PURPOSE:To discriminate whether a preset aperture value reaches a prescribed value or not, comparting signals from two circuits, which generate signals changing in accordance with the difference of the number of stages between the preset aperture value for every interchangeable lens and an open F value and that between a prescribed aperture value and the open F value, with a prescribed reference signal. CONSTITUTION:A photometric output circuit A1 which generates a prescribed reference signal, the first circuit which generates the first signal changing in accordance with the difference of the number of stages between the preset aperture value for every interchangeable lens and the open F value for the prescribed reference signal and consists of the first variable resistance R1 and the first constant current attracting source I1, and the second circuit which generates the second signal changing in accordance with the difference of the number of stages between the prescribed aperture value and the open F value for every interchangeable lens for the reference signal and consists of the second variable resistance R2 and the second constant current attracting source I2 are provided. The first signal and the second signal are compared in a comparator CP to discriminate whether the preset aperture value reaches the prescribed value or not on a basis of the output from the comparator CP.

Description

[Detailed description of the invention] The present invention relates to a setting aperture value determination device for an interchangeable lens.

Conventionally, the following methods have been proposed to enable program automatic exposure control and shutter-priority-am output control.
Ru. That is, the aperture of the lens is narrowed down according to the shutter speed information determined according to the information on the subject brightness, or the shutter speed information set according to manual operation from the outside, and the subject brightness information. This is achieved with an automatic exposure control camera that automatically adjusts the shutter speed by photometry and automatically controls the shutter speed according to information on the adjusted aperture value and information on subject brightness (41111is No. 4-78124).

The interchangeable lenses that can be attached to this type of camera include:
The one disclosed in Utility Model Application Publication No. 85B-47017 is open.

In other words, the preset aperture is adjusted according to the operation of the pre-seventh aperture product.
a first signal member that transmits a first signal to the camera body in correspondence with the aperture r value of the interchangeable lens; and a second signal that corresponds to the aperture r value of the interchangeable lens to the camera body. This is an interchangeable lens with a 1IIIE2o signal member extending over the lens. 9. With this type of interchangeable lens, IRham
For rounding, set a preset aperture value other than the minimum aperture value for rounding that allows the aperture to be narrowed down from the open aperture (minimum n value) to the minimum aperture value (maximum aperture value). need to be. This is because this type of interchangeable lens has a configuration in which the aperture changes between the aperture (9 aperture) and the aperture (aperture) corresponding to the aperture p value set in the preset aperture.
In order to change the diameter of the aperture between the open aperture and the minimum aperture, the preset aperture ()ll corresponds to the vertical small aperture and a good aperture) value must be preset.

Therefore, the range of aperture values that can be automatically adjusted when automatically fixing the aperture in the automatic exposure control camera described above depends on the maximum aperture value and the preset aperture value set by the preset aperture wheel jjK. Determined. In general, the open r value of an interchangeable lens is in the direction of brightness KToJ? , Fl, 4 to F4 are relatively common. Therefore, during program or shutter priority automatic exposure control, the preset aperture)
If you preset the aperture value F1g as a preparatory action for photographing an event, the automatic aperture adjustment can be set to 1 to 4 stops. Therefore, it is necessary to determine whether the preset aperture value has reached a predetermined value during program or shutter-priority automatic exposure control, since it is related to the width of the automatic aperture adjustment range.

SUMMARY OF THE INVENTION An object of the present invention is to provide a set value determination device for an interchangeable lens that determines whether or not the iris value has reached a predetermined value based on the first signal and the second signal. It is. This purpose includes a first circuit that generates a first signal that changes according to the difference in steps (at a 7 pixel value) between the preset aperture value and the open F value for each interchangeable lens with respect to a predetermined reference signal; a second circuit that generates a second signal that changes according to the difference in the number of steps between a predetermined aperture value and an open r value for each interchangeable lens with respect to the reference signal, and a comparison that compares the first and second signals. (by having the means)). Predetermined Oj! For example, the L open dimming output can be used as the quasi-signal. If it is set to 5, it is convenient to obtain compatibility in circuit configuration with the automatic exposure control device.

The present invention will be explained below based on examples.

In the explanation, exposure factors will be indicated by apex display.

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, there is a photodiode FD that receives light that passes through the ↑TL photometry photometry circuit line 1 exchange lens O aperture. Film feel mg
v is applied from the film sensitivity introducing circuit to the TTL sensing circuit. The photometering circuit 1 sets the subject brightness to BV during open metering (before the release operation), and calculates the r value when the camera is fully open to BV.
In order to give proper exposure to K, a nine-open photometry output corresponding to the shutter speed ['rV, that is, TWO=BY+ a V-AVo ''' (1) is output to the signal line t. i
! When the light is on the subsequent aperture side, the shutter speed ML provides appropriate exposure for an arbitrary aperture value Va during the aperture reduction.
The stop-down photometry output corresponding to TVa, that is, TVthzllV+8V-AVa (3) is output to the signal line t1.

At the threshold between the signal line L and the 1-sline t, there is a variable resistor 8. and the first constant current sink source x1 (the first
circuit) and fJ2 variable resistor R, and the second constant current sink source! ,
A series circuit (second circuit) with is connected. t41 variable resistor B is the preset aperture value AT and opening Pr.
It changes according to the difference in the number of steps between the radial value To and the output r value To, and responds to the signal member 1111 of the interchangeable lens. Specifically, at the connection point between variable resistor R1 and constant current sink source! The connected brushes are configured to short-circuit the resistor. In the diaphragm setting operation using the preset diaphragm section, it is also possible to set the diaphragm at a certain point, so that a change in resistance value can be obtained continuously.

The resistance value of this 8-layer variable resistor increases as the difference in the number of stages increases. Therefore, the voltage v,l generated at the md point P@ is the preset aperture value vpres
et K corresponds to the shutter speed "vpreset" that provides proper exposure. That is, vl "Tvpreset (="O-(muvy+
r*set −AV, ) = l'y+5V−AVpr@I. , )...e) This voltage V□ decreases as the value pr@s increases.

On the other hand, the second variable resistor 8 responds to the second signal from the interchangeable lens and decreases its resistance value as the function r value increases. That is, when an interchangeable lens with an aperture r value of F-L4 is attached to the camera, the brush selects tap 1, and thereafter selectively selects taps .

The open F value of the interchangeable lens is 'F'1.4°F2. F2.8
The resistance value of the variable resistor R3 is set by selecting the taps e, .about.$. Now, the connection point P with 'I variable low resistance R1 and current sink source I! The voltage V, , can be expressed as follows. That is, Vp*oc
TVO+AV6-8 (=nv+5v-s)...
(4) Regarding the voltage V, I would like to add that; 2nd p variable resistor 8. shows the maximum resistance value when the open F value is F=1 (AV=0), and thereafter decreases as the open F value increases. And the open F value is F=16 (Muv=8)
When , the resistance value becomes zero. To the t9 voltage V□, a voltage corresponding to AV-8 with respect to the voltage of the signal line t is applied as a shift term. Therefore, the voltage V is expressed by equation (4), and when the tap is selected, the connection point P.

The voltage on signal line L becomes equal to the voltage on signal line L.

The comparator CP has a voltage vp1 applied to its positive input terminal, and voltages V and l applied to its negative input terminal. Oka, 1st
The change in the resistance value of the variable resistor R by one step (one step of AV) is equal to the change in the resistance value of the second variable resistor B1 by one step of the open r value. Second constant voltage R1jl
It is assumed that the sink current values of the included sources 11.1ffi are also equal.

However, the above-mentioned circuit is placed on the camera body side.

Next, the operation will be explained. Here, at the predetermined value, that is, in the program or shutter priority automatic exposure control mode,
[Aperture] A preset aperture for an interchangeable lens for setting a relatively wide automatic control range] value tF-16. This is achieved by applying the voltage at node P to the negative input terminal of comparator CP.

(1) When an interchangeable lens with open r value F=R2 is attached; At this time, the brush of the second variable resistor B is tapped.
Select. Therefore, the voltage V□ is (from the ship type, V□”
It will be TVo-6.

On the other hand, since the voltage V is given by equation (3), 1 For example, if the preset aperture 9 values are F-&6 (AV=5), V p t '' TVo-3. Therefore, if v > v The relationship holds: 1 Since the p value is greater, the comparator CP outputs 1H'.This relationship holds true while the preset aperture value is less than F-16.Now, the preset aperture value is set to F-111. Then the voltage v9 becomes v ``rv, -aj>
-etc., pl Vp,=Vp. Therefore, the output of comparator CP is inverted to %L'. This relationship is based on the preset aperture]
This is true when the value is F-16 or higher.

(2) [Assuming that an interchangeable lens with an aperture value of F-4 is attached; At this time, the brush of the wire 2 variable resistor R2 is tapped.
Select. Therefore, the voltage V is V ” T
It becomes V o -4. -pl pl On the other hand, the preset aperture value of the interchangeable lens is the open F value (mu v-
In the case of 4), the voltage vp is assumed to be V acTV. Konoto *V > PI

Since Pmvo, comparator CP outputs %H1. This relationship means that the preset aperture value is F-4.
Holds true while less than. Now, the preset aperture value is F.
-16 (mu v=8), the voltage v2. is Vp
1'' TVo -4, so the output of the comparator CP is inverted to 1L#. This relationship holds true when the preset aperture value is F-16 or higher.

As exemplified in (1) and (2) above, the comparator C
When the output of P becomes 1L', it can be determined that the resetting aperture value is set to a predetermined value (F-16) or more. By adopting a configuration in which the brush of the Hiroraku 2 variable resistor R is set to be equal to the open photometry output when the tap is selected, the stain pressure V is equal to the step difference between the predetermined value and the open r value P. This is possible because the voltages v and I correspond to the preset aperture value, the open F value, and the difference in the number of O steps. Therefore, what is the predetermined value? -11, tap the negative input terminal of comparator CP.
All you have to do is connect to your computer. This is because the voltage can be expressed as voltage Vp@e,:TVo+muv,-7.

Now, the output of comparator CP is used as follows. FIG. 2 is an explanatory diagram showing the state of display in the finder. The light emitting diodes LD to LD1o are used to indicate the set shutter speed (or appropriate aperture value).

The light emitting diodes LD 11 and LD 11 have photometry limits, exposure control limits, overexposure, underexposure, etc.
This is what is displayed. Now, when the output of the comparator CP is 1HI, predetermined ones of the light emitting diodes LD to LD1m, for example, LDII and LDl, blink alternately to indicate that the preset aperture p value does not differ by the predetermined value ( In this case, a so-called release lock may be performed to disable the self-release operation). And comparator C
This blinking stops when the output of P is reversed to % L l.

Next, referring to exposure control, the A point voltage v, the II point voltage v1, and the C point voltage m1 VC in the previously cited Japanese Patent Application Laid-Open No. 54-78124 are the voltage of the signal line L1 in this embodiment, P3
If the point voltage Vpt % and P and the point voltage vpl are respectively related as follows, the technique disclosed in the Cough Publication Publication No. 11 can be obtained.
Can be used for 2 purposes.

That is, let the voltage of the signal line L be the point voltage vA, and P1
Let the point voltage V,1 be the C point voltage vc, and P, the point voltage V
, l km point voltage V. Award, this time,
Since the P1 point voltage vpl includes a shift ring of (-8), this shift ring needs to be compensated for by a voltage divider or the like for constant setting that provides program characteristics.

According to the present invention as described above, it is possible to determine whether or not the preset aperture value has reached a predetermined value by simply connecting the comparing means to the first and eighth variable resistors that have been used in the past.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a viewfinder display situation according to the present invention. [Explanation of symbols of main parts] R1......First variable resistor B,...
......#I2 variable resistor ■1, work, ...constant current f
i@Komigen CP...e-...Comparator applicant 2
Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] L: A circuit that generates a predetermined reference signal, and a preset aperture p value and aperture r for each interchangeable lens with respect to the predetermined reference signal.
a first circuit that generates a t141 signal that changes according to the step difference between the predetermined oIRb value and the open r value of each interchangeable lens with respect to the reference signal; an interchangeable lens comprising: a second circuit for generating a signal, and a comparison means for comparing the first signal and the jlE2 signal, and determining from the output of the comparison means whether or not a preset aperture value is suitable for a predetermined value. The setting of the aperture determination device. zl# According to claim 1, the reference signal generation circuit is a TTL open photometry circuit, and its TTI, Ili radiometer photometry output quasi-signal is set for an interchangeable lens. ] Discrimination device.