JPS6137566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure meter for photography, particularly to an exposure meter for spot photometry. Conventionally, an exposure meter has been proposed that measures the brightness of a narrow part of a subject using spot photometry, for example, when the light receiving angle of the photometer is 1 degree. The present invention relates to an improvement of such a light meter, in which the photometry section is equipped with a memory circuit as a memory that can store the measurement output at any point in time during measurement, and the display section displays the measurement output at every moment during measurement. At the same time, the present invention proposes a new exposure meter that simultaneously displays the information stored in the storage circuit.

According to the light meter of the present invention, it is possible to know the difference in brightness between two or more arbitrary different parts of a subject, and it is possible to set more appropriate exposure.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In Fig. 1, reference numeral 1 denotes an objective lens, and a subject image produced by this lens is guided to an observer 5 via mirrors 2, 3 and an eyepiece 4, and is set to a spot photometer with a light receiving angle of 1°, for example. The light is guided to a photoelectric element 7 via an aperture 6 that limits the photometric area. 8 is an operational amplifier having a pair of input ends connected between the input and output ends of the photoelectric element 7; 9 is a diode for logarithmic conversion connected between one input end and the output end of the operational amplifier 8; It is.

These circuit elements 7, 8, and 9 are well-known photoelectric conversion circuits, that is, a voltage proportional to the logarithm of the brightness of the light of the object image incident on the photoelectric element 7, in other words, the object brightness B _V (based on the apex display). A circuit that outputs a voltage corresponding to the voltage is configured. 10
The A-D conversion circuit includes the photoelectric conversion circuits 7, 8,
It converts the analog output voltage of No. 9 into a digital value, and for example, a well-known follow-up comparison method is used. The switch 11 sends the digital output of the A-D conversion circuit 10 to the decoder 20 while the switch 16 is closed, and therefore, the digital output of the photoelectric conversion circuit is sent through the decoder 20 while the switch 16 closes the contact 17. Output is dot display section 2
1 is displayed. 12 and 13 are a pair of switches,
Reference numerals 14 and 15 designate a pair of memory circuits such as latch circuits, and when the switches 12 and 13 are closed, the corresponding memory circuits 14 and 15 are switched to A.
While reading the output of the -D conversion circuit 10, when the switches 12 and 13 are open, the corresponding memory circuits 14 and 15 are in a latched state.

The decoder 20 converts the binary outputs input from the A-D converter circuit 10 and the memory circuits 14 and 15 via the switch 16 into outputs suitable for display. For example, if the binary input is 4 bits, “0001” except for the reset state of “0001”
The remaining 15 states are shown in the dot display section 21, which is composed of 15 light emitting elements _L1 to _L15 arranged in a row and row, such as light emitting diodes, liquid crystals, etc., as shown in FIG. A display signal that lights up any one light emitting element is output. The switch 16 rotates periodically and contacts 17, 18, 19
is sequentially switched, and three pieces of information from the A-D conversion circuit 10 and the storage circuits 14 and 15 are time-divided and sent to the decoder 20. However, in reality, it appears to the measurer that three light emitting elements are lit at the same time due to the afterimage phenomenon. The switch 16 is constituted by a logic circuit or the like as described later.

Reference numeral 22 denotes a calculation section connected to the storage circuits 14 and 15, which calculates a predetermined value using the information in the storage circuits 14 and 15, information on film sensitivity, lens aperture, or shutter speed in the information setting section 23, and predetermined constants to be described later. The calculation is performed, and the calculation result is displayed on the segment display section 24 using decimal numbers.
The display section 24 can be in the form of a dot display as well as a segment display. Therefore, for example, when information on film sensitivity and shutter speed is set in the information setting section 23, the larger or smaller of the two brightness information of the subject stored in the storage circuits 14 and 15, and In this case, an appropriate aperture value, such as an average value, is displayed on the display unit 24 according to brightness information according to a predetermined mode.
Further, when the aperture value is set in place of the shutter speed in the information setting section 23, the appropriate shutter speed is displayed on the display section 24.

When a subject is observed through the eyepiece section 28 of the exposure meter 27 as shown in FIG. 3 having the above configuration, the image field 25, the light emitting element group (dot display section) 21, and the photometry area are shown as shown in FIG. Mark 26 can be seen. Now, when the switch button 30 provided on the grip 29 of the exposure meter 27 is pressed, the switch 11 shown in FIG. One light emitting element at one of the positions of the dot display section 21 lights up, and when the brightness of the subject changes, the position of the light emitting element that lights up also changes accordingly. When the switch button 30 is pressed one more step, the output of the A-D conversion circuit 10 at that time is read into the memory circuit 14 via the switch 12.
The data is read into the memory circuit 15 via the. In this case, one storage command causes storage circuits 14 and 15 to
It is preferable to configure the system so that new data is read in alternately.

The information written in the memory circuits 14 and 15 lights up the corresponding light emitting elements on the dot display section 21 via the switch 16, respectively.

For example, a measurer observes the brightness of two parts, a bright part and a dark part, of an object to be photographed, and assumes that each of them corresponds to, for example, B _V =5 and B _V =9 in the apex display method. If it is stored in the memory circuits 14 and 15, the display unit 21 will display a series of B in sequence as shown in FIG.
Among the many light-emitting elements arranged to display _{the V} value, two light-emitting elements corresponding to B _V =5 and B _V =9 are lit, so the brightness of the subject is different from the bright part to the dark part. The difference is B _V =5, B _V =6, B _V =7, B _V =
It can be seen that there are four stages (4E _V ) between 8 and B _V =9. Furthermore, if the switch 11 is also closed in this display state, the brightness of the subject located at the mark 26 in the photometry area is also displayed at the same time, allowing the user to know the difference between this and the brightness of the bright and dark parts of the subject that are stored respectively. I can do it.

Next, in the calculation section 22, the current memory circuit 1
The signals output from 4 and 15 are the brightness values B _VH and B _VL
Assuming that the larger one of these is B _VH and the smaller one is B _VL , the value shown as B _V = (B _VH - B _VL )K+B _VL (1) is first calculated. In equation (1), K is a constant arbitrarily selected by the measurer, but the exposure meter is set in advance to 0, 0.25, 0.5, 0.75, etc.
A value of 1 is prepared, and one of these values is selected. Now, when any one constant K is selected from these, the encoder provided in the information setting section 22 converts it into a binary signal suitable for the logic circuit of the arithmetic section 22.

In equation (1), when K=0, it corresponds to using the smaller one of the stored brightnesses as B _V , and when K=1, the larger one of the stored brightnesses is used _. corresponds to When K=0.5, this corresponds to using the arithmetic mean of two stored brightness values, that is, the geometric mean of brightness. When the brightness value B _V is calculated in this way, the film sensitivity value S _V , the aperture aperture value A _V or the exposure time value T
The appropriate exposure time or appropriate aperture for the brightness value B _V is calculated based on the information of _V , and the segment display section 24
The value is displayed as a single number.

Next, more specific circuits for displaying dots on the display section 21 are shown in FIGS. 4 and 5. In FIG. 4, an analog voltage comparison circuit 31 consisting of a comparator, a pulse generator 32, an up-and-down reversible counter 33, and a D-
The circuit consisting of the A converter 34 constitutes one follow-up comparison type A-D converter, and when a signal voltage from the photoelectric conversion circuit is applied to the input terminal 31a, a digital signal corresponding to the signal voltage is output to the counter. 33
It is output from The counter 33 is composed of 6 bits, and the lowest digit LBS is associated with, for example, 1/4 _EV , and the upper 4 digits are in charge of the amount in units of 1 _EV . Dot display shall be performed. and gate 35,
36, 37, 38 are switches 11 in FIG.
When a signal of "1" is given to the terminal 39, the output of the counter 33 is
Sent to 2, 43, 44, 45. Reference numerals 40 and 41 indicate latch circuits which function as the memory circuits 14 and 15 in FIG. 1, and when a signal of "1" is applied to the terminals 40a and 41a, the output of the counter 33 is read into the respective latch circuits 14 and 15. These latch circuits 40 and 41 store 5-bit data, of which the upper 4 bits are used as a signal for dot display, while the 5-bit signals of the latch circuits 40 and 41 are The signal is supplied to the arithmetic unit 22 shown in the figure. ANDGATE 42-53
together with the ring counter 54 performs the function of the switch 16 in FIG. The ring counter 54 has its output terminals 54a, 54b,
54c sequentially outputs pulses of "1" to sequentially open AND gates whose inputs are connected to the respective output terminals. Therefore, the output of the counter 33 and the output of the latch circuits 40 and 41 are passed through the AND gates 35 to 38 to the ring counter 54.
The signal is time-divided and input to a decoder 59 via OR gates 55-58. Decoder 59 is 4
It is configured to light up any one of the 15 light emitting elements _L1 to _L15 connected to the output terminal according to the binary signal of the bit. However, if the binary signal corresponds to a signal of "0000", There is no output terminal that lights up.

The light emitting elements L ₁ to _{L 15} are arranged in a row in a row in the light emitting element section 21 in the viewfinder as shown in FIG. 2, and the interval between adjacent light emitting elements is set to _1EV .

Now, if the period of the pulse from each output terminal of the ring counter 54, which is output in time division as described above, is made shorter than the afterimage time of the eye of the measurer, then 3
This makes it appear as if multiple light-emitting elements are lit at the same time.

In order to set the contents of the latch circuits 40 and 41 to 0, it is sufficient to reset the counter 33 so that its output is 0, and to apply a pulse of "1" to the terminals 40a and 41a. In the measurement state after the counter 33 has been reset, when a gate opening signal "1" is applied to the terminal 39, only the output of the counter 33 is displayed, and when data is read into the latch circuits 40 and 41, a corresponding display is made. Become so.

FIG. 5 shows another embodiment for dot display that does not use the time-division method as shown in FIG. In FIG. 5, three decoders 60, 61, and 62, which are the same as the decoder 59 in FIG. 4, are connected to AND gates 35 to 38 and latch circuits 40, 41 in FIG. By connecting three output terminals at the same position to the input terminal of one OR gate 63 to 77, and connecting the light emitting elements L ₁ to L ₁₅ to the output terminal of each OR gate 63 to 77. , three light emitting elements can be turned on at the same time.

Note that in the above embodiment, the light emitting elements L ₁ to L ₁₅ in the display section display images at intervals of 1E _V ;
Other configurations such as 0.5E _V spacing are also easily possible. Further, the brightness value B _V calculated by the calculation unit 22 is displayed on the dot display unit 21, and at this time, the brightness value B _V
You can freely do things such as making the light-emitting element blink and light up.

As described in detail in the above embodiments, the exposure meter according to the present invention includes a photoelectric conversion circuit that measures the brightness of a relatively narrow area of a subject to be photometered and outputs an electrical signal according to the brightness, and the photoelectric conversion circuit. and a dot display device using a plurality of light emitting elements (including liquid crystal) arranged in a row for displaying information, and in the dot display device, the output of the photoelectric conversion circuit is stored. and the memory output of the memory circuit can be displayed simultaneously, and it is possible to easily know the difference in brightness between any two parts of the subject.

Furthermore, it goes without saying that the exposure meter according to the present invention can also be used by incorporating it into a camera.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention, FIG. 2 is a diagram showing the arrangement of light emitting elements in the dot display section of the exposure meter according to the invention, FIG. 3 is an external view of the exposure meter, and FIG. The figure is a first circuit diagram for displaying three pieces of information simultaneously, and FIG. 5 is a circuit diagram showing a modification of FIG. 4. 1...Objective lens, 2, 3...Mirror, 4...
Eyepiece lens, 6...Aperture, 7...Photoelectric element, 8...
...Arithmetic amplifier, 9...Diode, 10...A-
D conversion circuit, 11, 12, 13, 16... switch, 14, 15... memory, 20... decoder,
21... Dot display section, 22... Calculation section, 23...
...Encoder, 24...Segment display section.

Claims (1)

[Claims] 1. A spot photometry circuit that receives light from a relatively narrow area of the photometry target via an objective lens and momentarily outputs an electric signal according to the result, and at least 1 spot photometry circuit for storing the output of the photometry circuit. a memory circuit; a memory execution operation means for manually storing the output of the photometric circuit in the memory circuit at any time; a display device having a large number of display sections arranged in a row; and the memory circuit. and a control circuit that simultaneously selects a plurality of display sections from among the display sections of the display device for display, respectively, corresponding to the stored output of the photometer and the current output momentarily output from the photometric circuit. , an exposure characterized in that a previously stored fixed photometry result and a current photometry result that is output every moment are displayed simultaneously and in such a way that the relationship between them can be quantitatively visually recognized as the width between the display parts. Total.