JPS58116524A - Exposure control circuit of camera - Google Patents

Abstract

PURPOSE:To adjust error time finely within adjustment time even when the overlap time of shutter curtains becomes shorter than the reaction delay time of a magnet, by counting the exposure time and adjustment time of the shutter simultaneously. CONSTITUTION:For example, each output of a register RE is low, a gate N1 is selected by the output of a decoder DE, and the shutter is released. In this case, a shutter control state circuit ST generates a low-level output and the output of a comparator COM is inverted after time corresponding to a time constant RC to put the magnet Mg1 for front curtain control in operation, running a front curtain. A gate 6 is turned on by the output of the circuit ST and pulses from an oscillator OSC are supplied to a main counter MC to measure exposure time. Then, the output of the counter MC is supplied through the operation of the gate N1 to the counter MC through a gate A1 and its output is sent out as a shutter closure signal through a gate 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil output control circuit that has a shutter that can independently control the leading and trailing curtains and a timer circuit that digitally measures seconds.

In general, a camera with a 7-ocal plane shutter that can control the first and second shutters independently starts counting seconds as soon as the first magnet is overloaded, and when the count is finished, the second shutter is released! The p exposure time is controlled by over-charging Dunnett.

However, in the case of a 7-ocal plane shutter, as shown in Figure 1, when charging the shutter and before starting operation, it is necessary to partially overlap the leading and trailing shutter curtains, and Since there is a delay in the response of both hold magnets, the starting positions of the front shutter curtain and the rear curtain of the shutter are different, and due to the delay in the response of the magnets, it is necessary to make the measured exposure time match the actual time the film is exposed. Since this is not possible, the timer circuit is simply used to measure time while the front curtain of the shutter is running.
Accurate exposure control could not be achieved by running the shutter rear curtain at the end of the timer cycle.

(In Figure 1111, FS is the first position, R8 is the rear curtain position, and J to a are the apertures.) In this round camera with a conventional focal plane shutter, in addition to the exposure time, The above-mentioned drawbacks are solved by adding a predetermined 0III integral relation to the circle. In other words, the operating characteristics of the shutter front curtain and shutter rear curtain are $IK
As shown in Figure 2 O, the actual shutter opening time Tm is expressed by the following formula with respect to the shutter time TK, where Tg=T-
(TF÷Tag1) + (Tm÷Tag,).

Here, T: Shutter time Tm: Shutter opening time Tν: Time from energization to opening of the first curtain T: O time from energization of the second curtain to opening T-g* eResponse delay time of first curtain - Second curtain Response delay time Tk: Overlapping time between the first number and the second number.

Here, (TF “TmgB)” (Tm÷Tm,,
), ideally T = Ta, but in general, the end speed of the first and second curtains is the same, or even if the end speeds are the same, the end overlaps, and the time is ``Tk''.
Ty + Tag, >'ra ” T
becomes ag〇(Ty + Tag-1 (Tm÷T,,)
If it is z-, then T is T and T is T-α, which is shorter than the actual shutter time T by jI 礪.

Conventionally, a predetermined adjustment time is added to the IIi exposure time O in rounding to solve this problem.

The operation of the shutter front curtain and the shutter rear curtain according to such a conventional method is shown in Figures 1Ibt-1JIa, and T-Ta is made possible by adding the adjustment time α. However, with the conventional method, the speed of the second curtain is slower than that of the first curtain, or the response speed is slow (that is, "l" T
ag, > Ty + 'f-,), the Fi adjustment time α becomes negative, and time adjustment becomes impossible.

The present invention was developed in view of the above-mentioned circumstances, and treats the amount of X deviation of the shutter base and the amount of response delay of the magnet as analog amounts, and provides a separate timer circuit for these analog amounts, and operates the timer at the same time as the timer circuit. Therefore, it is an object of the present invention to provide a camera exposure control circuit that is effective for cameras having a shutter control circuit that controls the shutter speed, which corrects exposure errors caused by the above-mentioned shutter speed. Hereinafter, one implementation of this threat will be explained with reference to Figures 4 to 6. Figure JI4 shows the exposure control circuit of the camera.
is a clock pulse oscillator, and the oscillator outputs four pulses. The main counter for the shutter second clock is a 15-bit counter of F, ~-. The counter is as described above (since it counts 6410h pulses, the output pulse of F is 8KHz).
, F4 is MHz, F, is 2KEh, F, is 1fC
Hz, F, is 512Hz SFa is 256, F, is 1
2g&, Fl, 6 peaks, Fu 32Hz, FB 1
Outputs 6, F&, outputs 8, F- outputs mountain, F, earth O, and <Rus, respectively. -/m is the shutter time information output circuit generated in the analog output corresponding to the shutter time value TvK at 9 apex based on brightness etc., and D is the analog -
A digital conversion circuit converts the output from the information output circuit jm into a digital value with one-stage precision. The arm is a latch register consisting of 7 lip-flops from Kumi to D, and the information below the decimal point is D4 to 5u, that is, the information above the decimal point is 1.
1 is ordinary, D is -, D4 is -1, crow is 2, crow is 4, A
lattes 8 weighted digital information. DH
is a decoder, which decodes information beyond the decimal point in some registers. N1 to NL are NOR gates, and are configured so that a predetermined gate is selected by the output of the decoder DE. The relationship between the contents of these registers, the output of the decoder DE, the selection state of the NOR gate, and the shutter time value is as shown in FIG. A is Noah Gate N1
The AND gate CoN connected to the output terminal of ~N is a counter consisting of slip frogs FF and ~FF, and together with the main counter set, constitutes a counter for counting seconds. lX4 to I are provided to control the shutter time using information below the decimal point (maru exclusive or game), Nu is a Nant gate for outputting a shutter close signal, k) is a magneto tod 2 bar, M
gs is a magnet for holding the shutter trailing curtain, and this magnet has the above-mentioned response delay time Tl1lJh t-. RlC is the above-mentioned *m time αt-leg determination circuit, and αM is a comparator. -ter, ON is a one-shot circuit, MDi is a magnet driver, and Mgs is a shutter number control magnet, which has the above-mentioned response delay.

N is an inverter, Tr@ is a transistor, and ST is a shutter control status circuit.

Note that the counter performs a counting operation in synchronization with the falling edge of the pulse 9, and the CcM performs a counting operation in synchronization with the rising edge of the pulse.

Next, the operation of the above configuration will be described. First, it is assumed that the output of the information circuit is 10, which corresponds to seconds and generates a force of 000 rounded. In this state, all outputs from registers to registers are at low level (hereinafter referred to as "O") as shown in diagram N5.
A high level (hereinafter referred to as "l") is output from the output terminal O of the decoder, and the Nant gate is selected. When the shutter release operation is performed in this state, the shutter control status circuit BT is at O'' level, and the transistor T
When the input of the comparator α is 1IIJIk from the O'' level, the charging force of the capacitor C starts, and after a time determined by the time constant of the capacitor C and the resistor R. When the output of the comparator CQM is inverted to the 0" level, the one-shot circuit ON is activated and a pulse of a certain period of time is generated. The pulse activates the magnet driver MD, and the first operation control magnet Mg1 is activated. After the response delay time of the magnet MIKs, the shutter leading curtain starts running t--.

In addition, the shutter control status circuit transmits the pulse from the cipher oscillator O8C to the main counter when the AND gate input is opened at the same time as the shutter control status circuit reaches the O'' level.
The timing operation of the start time is displayed. As mentioned above, since the exposure time is seconds, the Nant gate N is selected, so in response to the output from the 7 lip-flops F and O to the counter, the Nant gate N1 outputs a pulse, and the pulse is output via the AND gate A1. Inform counter CQN. When the counter CQN counts 8 pulses, it converts the 7 lip-flop FF, (with the D output as @l) and the Nant gate N.
If you believe that the shutter is closed from u and count 8 pulses, - x 8 = knee 1ms, and after # time, the shutter will close.
KHz IKt (z Gumannet driver MD moves the trailing curtain hold magnet Mg* t iK, and after a response delay time Tmg* of the magnet, the shutter trailing curtain is run to end the dust source.

Next, exposure control in seconds will be explained.

In this case, @l'' is output from the output terminal 1 of the decoder DE as shown in Figure #I5, and the Nant gate is selected.

Since the shutter Comp input is changed from the 10" level to r41 when the shutter release operation is performed, the CR constant determines the time to be rated.Con7
When the rate output reaches the ``0'' level, the one-shot circuit is activated and a pulse of a certain duration is created. .This magnet h/G
After a response delay time of 1, the shutter leading curtain starts running. -Also, at the same time as the shutter control status circuit ST reaches the θ'' level, the AND gate input opens and the n1 main power counter M
C starts counting. Counter CoN FIX
8] When the number of clocks is counted, it will be output from FF4 to l'', and the shutter close signal will be output from Nantes gate N14.Dad, at this time, Nantes gate 8 is selected, and 79 gates are selected. Pulse 4 KHz k 8 pulses from 1F, -L-×
8=-2--2ms, 74K) h after cough threshold
The trailing curtain hold magnet Mgt is driven by the I KJiz magnet driver MD2, and after the response delay time of the magnet Mgt t-1, the shutter trailing curtain is run and the exposure is completed.

Thereafter, exposure control is performed in the same manner for up to 4 seconds, but in both cases, the time α created by the CR constant and the shutter time (kakun) start at the same time as the shutter control status enters. In particular, ri, (TB + Trng2) − (Ty ”
Trngl) = α can be satisfied.

FIG. 6 shows an explanation of the operations of the front shutter curtain and the rear shutter curtain according to the present invention. In this way, the correct shutter time can be obtained by causing the correction time to work at the same time as the start of the shutter time count so as to delay the energization of the shutter leading curtain, and by energizing the leading number when the correction time ends.

And (TB + Tmgx) - (Ty + T
m1r1) Adjust αt'l1ll so that zα, energize the leading curtain after the correction time α has elapsed, and energize the trailing curtain after the seconds count ends.

The above explanation is for the case where the shutter speed value changes by one step, but the shutter speed value changes by Crusive Noah! Town... Etasuru Shipnoah Gate @XN,~@XNg is 11”
Since the shutter closing signal is output from the Nantes gate N14 and the shutter time is controlled, accurate time control can be performed at all times even if the shutter time is at an intermediate stage value. Become.

As detailed above, in the Fujiyama control circuit according to this investigation, by counting the exposure ##f darkness of the shutter and the adjustment time at the same time, the shutter curtain speed is continuously controlled, and the timing of the shutter turn is controlled. This creates a difference in time of 0,1IllIi41, and is very effective in an exposure control circuit that controls the shutter speed.

[Brief explanation of drawings]

Figure Jli1 is a configuration diagram showing the driving position of the focal plane shunter with respect to the exposure aperture, and Figure 2 is the operation of the shutter leading and trailing curtains! Figure JIg3 is an explanatory diagram of the operation of the first shutter number and the rear shutter curtain corrected by the conventional method for the number , FIG. 5 is an explanatory diagram for explaining the relationship between the contents of the register REo, the output of the decoder DE, the Nantes gates N, ~N, 6, and the shutter time value in FIG. 4, and FIG. This is an explanatory diagram of the operation of the front shutter curtain and rear shutter curtain operated by the circuit. CON...counter, R...resistance, C...
・Capacitor, Tr...Transistor, Mgl...
Magnet for shirts, M-...Shutter curtain r magnet. Applicant: C. Canon Co., Ltd. Shiro Shioiri: Gi Marushima 1. . Lu Yi 1 Figure 3

Claims (1)

[Claims] It has a shutter that can independently and electrically control the leading and trailing curtains, and is equipped with a 7-plane shutter that corrects exposure errors caused by the shutter device 4110 configuration. A camera O that is characterized by counting @hours at the same time as light hours
Exposure control - path.