JP3262874B2 - Strobe system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe system, and more particularly, to a wireless strobe which emits light based on a signal from a camera.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 57-56830 discloses a strobe system comprising a camera and a strobe device which can be arranged at a position spatially separated from the camera. It discloses a method of performing interlocked light emission by detecting with a differentiating circuit of a light receiving element of a slave strobe. In Japanese Patent Application Laid-Open No. 51-94820, the start and stop of light emission of the slave strobe are controlled by a radio signal.

[0003]

However, in the strobe system disclosed in Japanese Patent Laid-Open Publication No. 57-56830, since the master strobe and the slave strobe always emit light at the same timing, only the slave strobe is independently and at an arbitrary timing. No light could be emitted. or,
The strobe device disclosed in Japanese Patent Application Laid-Open No. 51-94820 has a disadvantage that the size of the device is increased and the cost is increased since it has an extra antenna and the like for transmission and reception.

The strobe system of the present invention has been made in view of such a problem, and a purpose thereof is to provide a strobe system capable of emitting a slave strobe at an arbitrary timing during opening of a shutter. To provide.

[0005]

In order to achieve the above object, the present invention provides a camera and a camera which is spatially separated from the camera.
Stroboscope consisting of a strobe device that can be placed in a different position
In the stem, the strobe device is provided from the camera.
A receiving means for receiving the information of the camera,
Is a transmission for transmitting information to the strobe device.
Communication means and the main function of the above-mentioned strobe device in relation to the photographing operation.
Transmit light emission timing information a predetermined time before the light timing
Flash timing communication means, wherein the strobe device is a camera
Received the flash timing information sent from the
After a predetermined time from the start, light emission is started.

[0006]

[0007]

That is, in the present invention, the strobe device is
In connection with the shooting operation, the camera
Light emission timing information transmitted a predetermined time before the light timing
The light emission is started after a predetermined time from the reception of the command.

[0008]

[0009]

1A and 1B are block diagrams of a first embodiment.

First, the configuration of the camera will be described with reference to FIG. A control circuit 1 controls a sequence operation function of the camera. A transmission circuit 2 generates a transmission signal to the slave strobe. Reference numeral 3 denotes an infrared light emitting diode (IR) that generates infrared light in conjunction with the output of the transmission circuit 2.
ED). A receiving circuit 4 receives a signal from a slave strobe. Reference numeral 5 denotes a photodiode having sensitivity in the infrared region. Reference numeral 6 denotes a charging circuit for accumulating high-voltage energy in a main capacitor to emit light from a built-in strobe. Reference numeral 7 denotes a light emission start circuit for starting light emission of the xenon tube according to a signal from the control circuit 1. Numeral 8 denotes a light emission stop circuit for stopping light emission of the xenon tube halfway by a signal of the control circuit 7. Reference numeral 9 denotes a strobe light-emitting unit composed of a reflective cover and a xenon tube.

Reference numeral 10 denotes a distance measuring circuit (A) for measuring a subject distance.
F). Reference numeral 11 denotes three AF infrared light emitting diodes (IRED): left (L), center (C), and right (R).
Reference numeral 12 denotes three left (L), center (C), and right (R) light position detecting elements (PSDs) for AF, which are configured to perform three-point AF. Distance measuring circuit 10, IRED1
1. The PSD 12 constitutes a distance measuring device.

Reference numeral 13 denotes a photometric circuit for controlling exposure. 1
Reference numeral 4 denotes a photodiode having sensitivity in the visible light range.
Reference numeral 15 denotes an exposure control circuit that drives a shutter based on a photometric result. Reference numeral 16 denotes a lens driving circuit that drives the lens to an appropriate position based on the result of the distance measuring circuit 10. 17 is a film feeding circuit. Reference numeral 18 denotes a release button.
It consists of stage (1R, 2R) switches. By pressing the release button, distance measurement, photometry, exposure, and the like are performed.

Next, the configuration of the slave strobe will be described with reference to FIG. Reference numeral 21 denotes a control circuit for performing sequence control of the slave strobe. Reference numerals 22 and 23 denote a transmission circuit and an infrared light emitting diode, respectively, which serve the same role as the transmission circuit 2 and the infrared light emitting diode 3 on the camera side. Reference numerals 24 and 25 denote a receiving circuit and a photodiode, respectively, which have the same role as the receiving circuit 4 and the photodiode 5 on the camera side. Reference numerals 26, 27, 28, and 29 denote a charging circuit, a light emission start circuit, a light emission stop circuit, and a strobe light emitting unit, each having the same configuration as the camera side. Reference numeral 30 denotes a light emitting circuit for controlling pre-emission before main emission. Reference numeral 31 denotes an infrared light emitting diode that performs pre-light emission. The infrared light emitting diode 31 has a light distribution characteristic substantially equal to the light distribution angle of the strobe light emitting unit 29.

FIG. 2A is a block diagram showing a configuration of the receiving circuits 4 and 24, and FIG. 2B is a waveform diagram of a signal output from each block. As shown in FIG. 2B, the communication signal is received at a frequency around 30 kHz as a carrier, and is amplified by the preamplifier 34. Next, the noise having other frequency components is removed by passing through the band-pass filter 35, the carrier is removed by the peak detection and integration circuit 36, and the signal is converted into a complete digital signal by passing through the waveform shaping circuit 37.

FIGS. 3A to 3E are diagrams showing transmission and reception of code data.

When a code "10101101" is transmitted, a code as shown in (b) is put on a carrier as shown in (c) to emit light in synchronization with a synchronous clock as shown in (a). . The receiving circuit 4 (24) can code the receiving pattern shown in (d) as shown in (e) by the above configuration.

FIG. 4 shows a general flowchart of the first embodiment. In the first embodiment, there is one slave strobe and the built-in strobe on the camera side does not emit light. First, after confirming that the slave strobe mode on the camera side is set (S1), the camera side includes the transmission circuit 2 and
A power ON signal is transmitted to the slave strobe by the infrared light emitting diode 3 (S2). Thereafter, data communication for necessary information exchange between the camera and the slave strobe is performed (S4), and then charging of the slave strobe is started (S5).

Next, the release button of the camera is half-pressed (1R
When it is turned ON (S6), charging display, distance measurement operation, and photometry operation are performed (S7, S8, S9). If it is determined that the luminance is low enough to require the emission of the slave strobe (S1).
0), the camera instructs the slave strobe to perform pre-emission, the infrared light emitting diode 31 performs pre-emission a predetermined number of times (S11), and the subject reflected light is integrated by the light receiving element (PSD) 12 of the distance measuring circuit of the camera. The control circuit 1 calculates the amount of light required for the main light emission, and transmits the information to the slave strobe together with information on the light emission timing (S12, S1).
3).

Next, when the release button is pressed to the bottom in step S14 (2 RON), after the lens is extended, a flash start signal is transmitted to the strobe to execute shutter control (S15, S16, S17). The strobe is opened during a waiting period during the above-mentioned light emission timing information, and emits a predetermined amount of light based on the light emission amount data. On the camera side, the AF light receiving element (PS
D) Integrate the photocurrent in 12 and confirm that the strobe emission has been tuned by confirming that it has reached the predetermined voltage, and display it (S18, S19). Finally, the film is fed (S20).

In the case of No in S1 and S10, a normal mode process is performed (S3), and the process ends.

FIGS. 5 to 8 are detailed flowcharts of the first embodiment, and FIG. 9 is a time chart thereof.

In FIG. 5, when the camera is set to the slave mode, the transmission circuit 2 transmits a single pulse (S
21, S22). The slave strobe is in a standby mode in which only the light receiving element 25 is turned on, but the receiving circuit is turned on by receiving this pulse light (S
23).

After the camera waits for a predetermined time sufficient for the receiving circuit of the slave strobe to be turned on, the CH1 POW based on the communication format shown in FIG.
An ERON signal is transmitted (S24, S25). This means that the upper three bits are "100" to designate CH1, and the subsequent 5 bits are "10001" to indicate a POWER ON command. An 8-bit data code is not added after the POWER ON instruction. The receiving circuit 24 on the strobe side is C
When H1 POWER ON is recognized, it is transmitted to the control circuit 21 to turn on the power of the entire strobe and enter the operation mode (S26, S27). Control circuit 1 is CH1 P
The same code as that received is transmitted to the camera by using the transmission circuit 22 in order to notify the camera that the POWER ON has been received (S28). The camera receives this signal at the receiving circuit 4 and notifies the control circuit 1 that the communication with the slave strobe was successful (S29).

Next, the control circuit 1 sets the flag of CH1 (S31). Next, the control circuit 1 _{causes the} transmission circuit 2 to communicate a code n _vp (apex value) indicating how many times the light is projected to the light projection circuit 30 during the pre-light projection (S32). For example, represents 100 10010 00000100 CH1 be pre projection number n _vp n _vp = 3 upper 3bit is the CH1 of the following as 5bit is a communication of the pre-light projection count n _vp, following 8bit is projection number Represents data.

When this code is received by the receiving circuit 24 on the strobe side (S33), the control circuit 21 stores the data of the number of times of pre-emission in a predetermined RAM. 5 to 8.
Although not described in the flow chart of the above, it is also possible to perform a method of transmitting the same data as the data received for confirmation again to the other party in all data communications.

Next, the strobe side communicates its own guide number G _vp per pre-emission to the camera by the transmission circuit 22 (S34, S35). For example, 100 10011 00000100 CH1 pre-illumination guide G _vp = 0 When a code having a number of G _vp is transmitted, G _vp = 0.

The above-mentioned n _vp and G _vp are so-called apex values defined by the logarithm with the base 2 of the pre-lighting number n _p and the pre-guide number G _p as described later. Thus n
_vp = 3 represents the number of pre-emissions n _p = 2 ³ = 8 times, and G _vp = 3
0 represents the pre-light projection guide number G _p = 2 ⁰ = 1.
Hereinafter, all subscripts of "v" represent apex values. Next, the strobe side _communicates the apex value G _vmax of the maximum guide number G _{max and} the apex value G _vmin of the minimum guide number G _{min possessed} by the _strobe to the camera (S36 to S39).

When the communication is completed, the control circuit 21 sends an ON signal to the charging circuit 26 to start charging the main capacitor (S40). When reaching the predetermined potential, the charging circuit
FF, and transmits the following charge completion signal code (S41, S42, S43). 100 10110 CH1 Charging completed Upon receiving this signal, the camera sets a charging completed flag and waits for the release button to be pressed (S44, S4)
5).

In the case of No in S21 and S29, normal mode processing is performed (S30), and the processing is terminated.

Next, in FIG. 6, when the release button is half-pressed (1 RON), the control circuit 1 checks whether the charging completion flag is set (S51, S5).
2) If set, a charge completion display is performed, and then the AF operation is started (S53, S54). The left (L), center (C), and right (R) IREDs 11 and PSD 12 are selected by the distance measuring circuit 10, and the IREDs are projected a predetermined number of times, and the photocurrent of the PSD due to the reflected light from the subject is integrated. The distance is obtained (S55, S56).

In this case, since the position where the reflected light enters depends on the distance, the output currents i ₁ and i _{2 of the} PSD are different from each other.

(Equation 1) Ratio calculation output to obtain the distance by

(Equation 2) And a light intensity integration output for obtaining a distance.
Data of the closest channel from among the three points measured for L, C, and R is adopted. A detailed description of AF will be made separately.

Next, the control circuit 1 turns on the photometric circuit 13 to measure the luminance of the subject. As a result, when it is determined that the luminance is low enough to require the strobe (S57), the control circuit 1
Performs a pre-emission operation and enters an operation for obtaining a required light amount of the slave strobe. First, the light receiving circuits of the channels (L, C, R) used during AF are turned on (S58). Here, in the case of No in S57, the normal mode processing is performed (S59), and the process ends.

Next, a pre-lighting start signal is transmitted to the strobe (S60). After waiting for a certain time (S61),
The integration operation of turning on the light quantity integration circuit (i ₁ + i ₂ ) of the distance measuring circuit 10 during t ₁ and off during t ₂ is performed n _p times (S62 to S66). n _p is the code n _vp (n _p = 2 ^nvp ) communicated to the strobe earlier. Here, n _vp = 3
Therefore, n _p = 8. Therefore, after performing the integration operation eight times, the second integration operation is performed to confirm the value, and the integrated voltage _Vout is obtained (S67, S75).

As the reflected light from the subject increases, the current (i ₁ + i ₂ ) flowing through the PSD increases, and _Vout increases.

[0035] When the flash unit receives the pre-light projection start signal (S68), after a certain time waiting so as to synchronize the camera side of the integration operation (S69), while the light projecting circuit 30 is t ₁ O
N, the operation of between OFF of t ₂ is repeated n _p times (S7
0 to S74). The t _1, t _2, n _p is designed so as to completely synchronize to t _1, t _2, n _p of the distance measuring circuit of the camera.

The pre-light emitting means 31 is an infrared light emitting diode, and has substantially the same light distribution characteristics as the strobe light emitting section 29 due to a reflection cover (not shown).

Next, if the camera is the value of V _out is larger than the predetermined value V ₁ obtained by double integration operation in S76, the flash is too close, the light projection number n because the integral operation is overflowing _{The program} is executed again with _vp reduced (S77). Conversely, if the value of V _out is smaller than the predetermined value V ₁ and smaller than the predetermined value V ₂ (V ₁ > V ₂ ), an accurate value cannot be obtained, so that the number of light projections n _vp is increased and re-executed ( S78, S79).

The guide number (G) required for the main light emission can be obtained by the following equation.

[0039]

(Equation 3) Here, K: constant G _p : guide number per pre-light emission _Fo : open F number of photographing lens n _p : number of pre-light emission V _out : object reflection obtained by performing pre-light emission n _p times Integral voltage depending on light quantity ISO: Film sensitivity When these are defined as logarithms with a base of 2 and converted into an apex value, K _v = log ₂ (K / 3 · 1) constant G _vp = log ₂ (G _p ) pre guide number per ² once floodlight a _v0 = log ^₂ F _{0 2} aperture n _vp = log ₂ n _p pre floodlight number _v v = log ₂ V _out integrated voltage _{S v = log 2 (ISO /} 3 · 1) Film sensitivity Therefore, equation (1) is

(Equation 4) (S80).

The control circuit 1 obtains the amount G _v necessary for the present light by equation (2). G _v If the maximum guide number G _vmax larger than that transmitted from the earlier flash in S81 generates a warning signal for even emit light becomes underexposed (S82).

[0041] G _vmin <G _v <Since it is possible in the case of G _vmax to correct exposure camera side toward the Surotobo G _v
The code and the data are transmitted (S83, S84).
In addition, a light emission timing code indicating the length of time after the light emission start signal to be sent when the light is actually emitted and the shutter fully opened and its data are also transmitted (S85).

[0042] Further, G _v is overexposed if the minimum guide number G _vmin less put out the strobe at S83. Therefore, it is necessary to emit main light before the aperture is fully opened. That is, it is necessary to set the aperture to an apex value and _reduce the aperture by (G _vmin -G _v ), so the emission timing signal must be shifted accordingly (S89). If the apex value of the shutter fully open time is T _vo as shown in FIG.

(Equation 5) It is necessary to transmit the light emission timing signal after the _Gv code (S90, S91).

The strobe has received the G _v code and emission timing code obtains the necessary emission time (t ₃₎ from the value of G _v by the control circuit 21 (S86, S87, S8
8). This may be obtained from a table of _Gv values and light emission times or may be obtained by calculation.

Next, in FIG. 8, the camera waits until the next release button is pressed until the second stroke (2 RON) (S101). When the 2R is turned on, the lens is driven out by the lens driving circuit 16 based on the distance measurement data, and a light emission start signal is transmitted. Then turn on the shutter plunger
To start the timer (S102 to S10).
5). t ₄ since elapsed shutter at is fully opened where the light receiving circuit of the distance measuring circuit 10 of the adopted channel for flash synchronization check (integrated circuits) allowed to ON until t _5, the shutter has passed t ₆ By the way, it is turned off (S106 to S110).

When the flash side receives the light emission start signal,
The light emission timing is adjusted (117 to S118). This waits for the light emission timing data received earlier. In the time charts of FIG. 9 and FIG. 10, it corresponds to a time of approximately t ₄ . After the standby is over, the control circuit 1
The emission start circuit 27 is ON, when to start emission of the flash starts a timer at the same time, the t ₃ after this time obtained just stops the light emission by turning ON the light emission stop circuit 28 (S119~S122).

After the plunger is turned off, the camera checks the subject reflected light of the main emission received by the distance measuring circuit 10.
A second integration operation is performed. The output V _out is carried out by tuning confirmation depending on whether you are exceeding a predetermined V _o (S111
To S113). That is, when the determination is Yes in S113, the tuning display is performed, and when the determination is No, the non-tuning display is performed (S114, S116). After that, the film feeding circuit 17
Winds up the film by one frame (S115). Note that FIG.
FIG. 10 is a flowchart showing the operation in the case of a long distance, and FIG.

Next, the optical system and the light receiving section of the distance measuring device will be described in detail. This optical system and light receiving unit are shown in FIG.
As shown in FIG. 7, light emitting and receiving lenses 41 and 42 having two optical axes 41a and 42a separated by a fixed base line length (S), an IRED (near infrared light emitting diode) 43 for light emitting, and a light receiving length t (Position Detecting Element) 44.

The PSD 4 is positioned so that the end face of the PSD 44 is located at a position a away from the optical axis 42a of the light receiving lens 42.
When the object distance is D and the focal length of the light receiving lens 42 is f _j , the center of gravity of the reflected spot 46 from the object 45 is (Sf _j / D) from the end face of the PSD 44.
It returns to the position of + a. Since the PSD 44 generates a current output proportional to the position of the reflection spot 46, the side closer to the light projecting lens 41 of the PSD 44 is used as the first electrode (1ch), and the output change current when the light projecting IRED 43 emits light. Is i _{1 on one} side and i ₂ on the other side.
The following equation (4) holds.

[0049]

(Equation 6) When the above equation (4) is modified, the following equation (5) is obtained.

[0050]

(Equation 7) Therefore, from the currents i ₁ and i ₂ , i ₂ / (i ₁ + i ₂ )
Is calculated, the reciprocal 1 / D of the subject distance can be obtained based on the above equation (5).

FIG. 15 is a diagram showing a configuration of the distance measuring circuit 10 of the distance measuring apparatus. This circuit is formed into an IC (hereinafter, referred to as AFIC 47), and includes a ratio calculation circuit unit 47A and a light amount integration circuit unit 47B.

First, the configuration of the ratio calculation circuit section 47A will be described. Two PSDs, PSD-L and PSD-R
Output of AFIC by connecting 1ch and 2ch respectively
47 is input. The 1ch and 2ch input terminals i ₁ and i ₂ of the AFIC 47 are connected to the inputs of the preamplifiers A1 and A2,
The collectors of the transistors Q3 and Q4 through which the SD steady-state photocurrent flows are connected to the bases of the transistors Q1 and Q2 for amplifying the signal current (change) when the IRED3 emits light.

The emitters of the signal current amplifying transistors Q1 and Q2 are connected to the outputs of the preamplifiers A1 and A2, and the collectors are connected to logarithmic compression diodes D1 and D2. The cathodes of these diodes D1 and D2 are input to one side of feedback amplifiers A3 and A4 to form a feedback loop for steady light storage.

Diodes D3 and D4 are connected to the other inputs of the feedback amplifiers A3 and A4 in order to make the same level as the bias point of the diodes D1 and D2. The outputs of the feedback amplifiers A3 and A4 are connected to the stationary light level storage capacitors C1 and C2 and the transistor Q
3, connected to the base of Q4. The feedback amplifiers A3 and A4 can control the operation of the amplifiers, that is, whether or not to perform the feedback of the steady-state light storage, by turning on / off the switches SW1 and SW2.

The cathodes of the diodes D1 and D2 are
It is connected to the bases of transistors Q5 and Q6 forming a differential circuit. These emitters of transistors Q5, Q6 are connected to the same, constant current source I ₀ and the switch SW5
Is connected to GND via. Transistor Q6
Of the transistor Q5 is connected to _Vcc via an integrating capacitor C3.
Further, the collector of the transistor Q5 is connected to the switch SW.
4 and is connected to V _cc through a constant current source I _G, is connected to V _ref via a switch SW3. Furthermore, the collector of the transistor Q5 is also connected to the input of the comparator COM1. The other input of the comparator COM1 is connected to _Vref , and the output is output to the outside of the AFIC 47 and connected to the arithmetic unit.

Next, the configuration of the light amount integration circuit section 47B will be described.

The common terminals of PSD-L and PSD-R are
It is connected to the COM terminal of the AFIC 47 and is connected to the collector of the diode-connected transistor Q9 in the AFIC 47. This transistor Q9 is
7, and the collector of the transistor Q7 is connected to the collector of the steady-state light storage transistor Q8 via four analog switches SW6 to SW9 connected in series and parallel.

The two input terminals of the differential amplifier A5 for steady light storage are connected to V1 via R1 and R2 having the same resistance.
Connected to _ref . An intermediate point on one side of the serial / parallel analog switch is input to one side of the amplifier A5.
The output of the amplifier A5 is connected to the stationary optical storage capacitor C4 and the base of the transistor Q8. The other intermediate point of the serial / parallel analog switch is connected to the input terminal of the integrating amplifier A6, the integrating capacitor C5, and the switch SW10.
It is connected to the. Switch SW10 is a constant current source I _G
Is connected to GND. Integration capacitor C5
Is the output of the integrating amplifier A6 and the comparator CO
It is connected to the input of M2. The inputs on one side of the integrating amplifier A6 and the comparator COM2 are connected to _Vref .

Next, the ratio calculation operation and the light amount integration operation will be described with reference to the timing chart of FIG.

First, in the ratio calculating section 6A, the IRED
Before starting the light emission of No. 3, the switch SW3 is turned on once, and the potential of the integrating capacitor C3 is made equal to _Vref . Before the emission of the IRED, the switches SW1 and SW2 are turned on and the switch SW5 is turned off, and the feedback loop operates, so that the steady photocurrent of the PSD4 flows to the transistors Q3 and Q4 and does not flow to the bases of the transistors Q1 and Q2. The capacitors C1 and C2 are charged to a voltage corresponding to the steady light level.

The switch S is synchronized with the light emission of the IRED3.
When the switches W1 and SW2 are turned off and the switch SW5 is turned on, the transistors Q3 and Q4 continue to flow only the steady-state photocurrent immediately before the emission of the IRED. The photocurrent due to the reflected light from the object of the IRED 3 is determined by i according to the incident position on the PSD.
₁ and i ₂ . The signal currents i ₁ and i ₂ are multiplied by β (current amplification factor) by the amplification transistors Q1 and Q2, and flow through the diodes D1 and D2.

Here, assuming that the current flowing through the collector of the transistor Q5 is I _INT , the voltage relationship between the diodes D1 and D2 and the transistors Q5 and Q6 is as shown in the following equations (8) and (9).

[0063]

(Equation 8) Therefore, the integration capacitor C3 is I _INT, i.e., i ₂ /
A current proportional to (i ₁ + i ₂ ) flows, and the potential decreases.

When the switches SW1 and SW2 are turned on and the switch SW5 is turned off again in synchronization with the end of the IRED light emission, the feedback loop operates again, and the integration capacitor C is turned on.
The integration operation to 3 is also completed.

The IRED 3 repeats the above-mentioned integration operation n times by emitting light n times at a predetermined interval T _INT during one light emission time t _INT . The above is the first integration operation.

Next, when the switch SW4 is turned on, electric charge was Tsu the integrating capacitor C3 is gradually discharged with a constant current I _G. Therefore, the potential of the integration capacitor C3 rises linearly, and when it reaches _Vref , the comparator C3
The output of OM1 is inverted.

[0067] computing device, by measuring the time T ₂ of the from the switch SW4 is turned on until the comparator COM1 is inverted, will recognize the distance to the subject. The above is the second integration operation.

When the above is quantitatively analyzed, the amount of charge / discharge (Q = CV = i) is obtained by the first integration and the second integration.
Since t) are equal,

(Equation 9) From the above equations (6), (9), and (10),

(Equation 10) From this, I / D is

[Equation 11] Becomes In other words, by determining the time T _2, it can be obtained from equation (12) (subject distance) ^-1.

Next, the operation of the light quantity integration circuit 47B will be described.

The signal current i _s (= i ₁ + i ₂ ) flowing from the COM terminal of the AFIC 47 to the common terminal of the PSD is expressed by the following equation (13).

[0071]

(Equation 12) Here, τ _t and τ _j are the transmittance of the light emitting and receiving lens, d
P ₀ / dΩ is the light emission intensity [W / sr] of IRED 3 and S _P
Is the light receiving sensitivity [A / W] of PSD-L and PSD-R, d _j
The effective aperture, F _t is the projection lens F-number, [rho is subject reflectivity of the light receiving lens, D is a subject distance.

Since the values other than ρ and D are constants determined by design, if this is set to A, the above equation (13) becomes the following equation (14)
It looks like an expression.

[0073]

(Equation 13) Before the emission of the IRED, the switch SW11 is turned on by the switch SW11.
It turns on at the same timing as 3, and discharges the charge of the capacitor C5. Before emitting the IRED, switch S
Since W6 and SW7 are ON, a feedback loop is formed by the amplifier A5, and the current flowing from the COM terminal of the AFIC 47 is equal to the collector current of the transistor Q7 due to the current mirror of the transistors Q7 and Q9. This becomes the collector current of the transistor Q8 through the switches SW6 and SW7. The capacitor C4 is charged with a charge depending on the steady-state photocurrent.

In synchronization with the IRED emission of the ratio calculation, the switches SW6 and SW7 are turned off, the switches SW8 and SW9 are turned on, and the switch SW12 is turned off. Therefore, a steady-state photocurrent immediately before the emission of the IRED flows through the transistor Q8 through the transistor Q7 and the switches SW8 and SW9.
The signal current i _s (= i ₁ + i ₂ ) due to IRED emission is
The current does not flow through the transistor Q8, and the capacitor C5 is charged. Therefore, the output voltage of the amplifier A6 is gradually lowered depending on the value of i _s.

When the light emission of the IRED 3 is completed, the switches SW6, SW7 and SW12 are turned on again, and the switch SW
8, SW9 is turned off, and a feedback loop is formed.

The above operation is repeated n times. afterwards,
When the switch SW10 is turned on, electric charges charged in the capacitor C5 is discharged at a constant current I _G. Therefore, when the potential of the amplifier A6 increases and reaches _Vref , the output of the comparator COM2 is inverted. The time T ₃ from the on switch SW10 to the comparator COM2 inversion measured by computing device.

When the above is quantitatively analyzed, as in the previous case, the amount of charge charged and discharged in the first integration and the second integration is equal,

[Equation 14] From the above equations (14) and (15),

(Equation 15) Therefore, the value of ρ / D ₂ can be obtained by obtaining T3.

From the following equation (15 '), from T ₃ to i
_s can be determined.

[0079]

(Equation 16) Then, a wide range theta _M is projected by driving both areas emitting portion and the spot light emitting portion, considered the output of AFIC47 when multiple objects within the irradiation range is present.

[0080] n-number of the object exists in an irradiation range of the IRED 3, its distance of the m-th object D _m, the reflectance [rho _m, the ratio of total radiation range and h _m. Therefore,

[Equation 17] It is. The signal currents i _1M and i _2M output from the PSD-L and PSD-R are the sum of the signal currents generated by the respective subjects. Also, i _SM is the sum of i _1M and i _2M . Based on the signal of the sum, the AFIC 47 recognizes that one certain subject is at the distance D _M. Therefore, the following equation (18) is obtained from the above equations (6) and (14).

FIG. 11 is a general flowchart showing a second embodiment of the present invention. In the second embodiment, two slave strobes are used. S131 to S1
As shown in step 57, CH1 and CH2
The flash unit performs data communication using the following codes and performs the same control as in the first embodiment. The main flash is fired at the same time when the shutter of the camera is fully opened, or the flash is emitted before only one of the strobes is fully opened. The light emission timing signal is adjusted so as to perform the operation. In the first embodiment, since there is only one light source, a lizard is generated on one side.
The strobe 1 and the strobe CH2 are arranged on the left and right sides of the subject and emit light so as to have the same amount of light.

It is also possible to set the illumination ratio of the subject of CH1 and CH2 to a predetermined ratio.

FIG. 12 is a general flowchart showing a third embodiment of the present invention. FIG. 13 is a time chart thereof. In the third embodiment, as shown in steps S161 to S190, the built-in strobe emits light in addition to the slave strobe control of CH1 and CH2. Since red-eye occurs when the built-in strobe light controls the exposure, the amount of light emitted here is sufficient to give catchlight to the eyes of the subject. Therefore, the built-in strobe emits a small amount of light at a position where the aperture of the shutter is small, the CH1 strobe is emitted before the aperture is fully opened, and the CH2 strobe is generated at a point where the aperture is fully opened as a main light source. By illuminating the three strobes in this manner, a natural lizard can be formed, and a photograph in which the subject is lit with a catch light can be obtained.

Further, in this embodiment, the PSD for AF is used as the light receiving element of the pre-projection, but a light receiving element of the photometric circuit or a dedicated light receiving circuit may be provided. The calculation of the light emission amount is performed by the control circuit 1 on the camera side, but may be performed by the control circuit 21 on the strobe side. In addition, although the camera and the strobe are both built in the transmission and reception circuits, they may be connected by an adapter.

FIG. 19 is a timing chart describing the light emission timing in detail. That is, 1 RON
, A timing signal (data t _x1 or t _x2 ) is transmitted. After the camera receives this light emission start signal, the slave strobe counts t _x1 or t _x2 with a timer and starts light emission of the xenon tube. Therefore, at t _x1 , the strobe emits light when the shutter is fully opened, and at t _x2 , the strobe emits light halfway through the opening.

FIG. 20 is a timing chart showing an embodiment in which a light emission timing signal is not transmitted from the camera. In this case, after 2 RON by the timer on the camera side, t _y1 or t _y2 is counted, and then the light emission start signal is transmitted. The strobe side always starts generating after a fixed time (t ₀ ) after receiving the light emission start signal, but since it has been adjusted by the camera, t
_{At y1,} a shutter is fully opened, and at t _y2 , a strobe is generated halfway through the opening.

FIG. 21 is a general chart showing a fourth embodiment of the present invention.

Up to now, the pre-emission has been performed in the infrared region in conjunction with 1 RON. However, as shown in steps ST1 to ST22, the main-emission light-emitting portion also serves as the pre-emission. Accordingly, the pre-emission is not performed in 1RON, and the pre-emission of a predetermined amount is performed by the main-emission light-emitting portion in conjunction with 2RON, and the subject reflected light is received and integrated by a photometry circuit having a spectral sensitivity in the visible region, and the main emission is performed. The required light quantity at the time is obtained, and the information is communicated to a slave strobe to take an image. In the fourth embodiment, it is not necessary to specially provide a pre-light-emitting portion, so that the cost is low and the power is larger than that of the pre-emission by the infrared LED, so that the light quantity can be accurately integrated even for a relatively distant subject.

[0089]

As described above, according to the present invention, the slave strobe can be emitted at an arbitrary timing during the opening of the lens shutter.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment.

FIG. 2A is a block diagram illustrating a configuration of a receiving circuit, and FIG. 2B is a waveform diagram of a signal output from each block.

FIG. 3 is a diagram illustrating transmission and reception of code data.

FIG. 4 is a general flowchart of the first embodiment.

FIG. 5 is a part of a detailed flowchart of the first embodiment.

FIG. 6 is a part of a detailed flowchart of the first embodiment.

FIG. 7 is a part of a detailed flowchart of the first embodiment.

FIG. 8 is a part of a detailed flowchart of the first embodiment.

FIG. 9 is a time chart of the first embodiment.

FIG. 10 is a time chart showing another example of the first embodiment.

FIG. 11 is a general flowchart showing a second embodiment of the present invention.

FIG. 12 is a general flowchart showing a third embodiment of the present invention.

FIG. 13 is a time chart showing a third embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of an optical system and a light receiving unit of the distance measuring device.

FIG. 15 is a diagram showing a configuration of a distance measuring circuit of the distance measuring device.

FIG. 16 is a timing chart showing a ratio calculation operation and a light amount integration operation.

FIG. 17 is a diagram showing a communication format.

FIG. 18 is a diagram for calculating an amount to shift a light emission timing.

FIG. 19 is a timing chart showing light emission timing in detail.

FIG. 20 is a timing chart showing an embodiment when a light emission timing signal is not transmitted from a camera.

FIG. 21 is a general flowchart showing a fourth embodiment of the present invention.

[Explanation of symbols]

1, 21, control circuit, 2, 22, transmission circuit, 3, 23,
31 ... infrared light emitting diode, 4, 24 ... receiving circuit, 5,
14, 25: photodiode, 6, 26: charging circuit,
7, 27 ... light emission start circuit, 8, 28 ... light emission stop circuit,
9, 29: strobe light emitting section, 10: distance measuring circuit, 11: A
Infrared light emitting diode for F, 12: light position detecting element for AF, 13: photometric circuit, 15: exposure control circuit, 16: lens driving circuit, 17: film feeding circuit, 30: light emitting circuit, 32: channel setting switch.

Claims (1)

(57) [Claims] A camera and a spatially separated camera
Strobe system consisting of a strobe device that can be placed at a position
In the system , the strobe device receives information from the camera
Receiving means for transmitting the information to the flash device, and transmitting the flash timing information a predetermined time before the main flash timing of the flash device in relation to the photographing operation. A flash timing communication unit for transmitting, wherein the flash device starts flashing a predetermined time after receiving the flash timing information transmitted from the camera.