JPS59123806A - Focus detecting device of camera - Google Patents

Abstract

PURPOSE:To detect a focus by a visible light and other light by a low loss of the light quantity by providing a beam splitter having the surface of reflection whose reflection factor and transmittivity are different so as to select the wavelength, in a focus detecting optical system. CONSTITUTION:A surface of reflection 7a of a beam splitter 7 is constituted so as to reflect infrared rays and to make a visible light transmit. Accordingly, a light passing through an interchangeable lens 2 is reflected by a submirror 6, the visible light is made incident to a photoelectric converting means 9a, and the infrared rays are made incident to a photoelectric converting means 9b. Outputs of said means 9a, 9b are inputted to a discriminating circuit 11 and a selecting circuit 12, respectively, and whether the outputs of both the photoelectric converting means are large or small are discriminated by the circuit 11, and one output is selected by the circuit 12 and sent to focus detecting and operating circuit 13. A signal from this circuit 13 is sent to a motor driving controlling circuit 14, the signal from said circuit 14 drives a motor MO, and a photographic lens is moved to the focused position.

Description

Detailed Description of the Invention Technical Field This invention relates to a camera focus detection device that detects the focus of a photographic lens based on photoelectric conversion of subject light that has passed through the photographic lens, and in particular to focus detection in visible light and infrared light. The present invention relates to a focus detection device for a camera that is capable of detecting focus using light other than visible light such as. BACKGROUND OF THE INVENTION A focus detection device for a camera as described above is known, for example, from Japanese Patent Application Laid-open No. 150808/1983. This focus detection device was proposed to perform focus detection using visible light during normal visible light photography, and to detect focus using infrared light during infrared light photography when an infrared filter is attached to the photographic lens. It is equipped with photoelectric conversion means for visible light and infrared light, and the focus detection optical system includes:
A beam splitter is provided that splits the subject light into light that is incident on the photoelectric conversion means for visible light and light that is incident on the photoelectric conversion means for infrared light, and the beam splitter and the photoelectric conversion means for visible light are An infrared cut filter that blocks the passage of infrared light is provided between the two. Each photoelectric conversion means is connected to a selection circuit and a focus detection circuit via a discrimination circuit that discriminates the ratio of their outputs. In other words, in this focus detection device, when photographing with visible light without using an infrared filter, the discrimination circuit uses the assumption that the ratio of the outputs of the two photoelectric conversion means is constant regardless of the brightness of the subject. The selection circuit outputs the output of the photoelectric conversion means for visible light to the focus detection circuit. On the other hand, in the case of infrared light photography using an infrared filter, the output of the photoelectric conversion means for visible light is smaller than that of the photoelectric conversion means for infrared light, so the discrimination circuit is This is discriminated and the selection circuit is made to output the output of the infrared photoelectric conversion means. However, in the focus detection device proposed in JP-A-57-15O8O8, since the beam splitter splits the subject light in terms of light quantity, there is a loss in the light quantity of the light incident on each of the two photoelectric conversion means. is large and the intensity of the subject light itself is small, it is expected that focus detection will become difficult. Purpose The present invention addresses the drawbacks of the prior art described above and is capable of detecting focus using both visible light and non-visible light such as infrared light. It is an object of the present invention to provide a camera focus detection device in which the loss of the amount of light received by the photoelectric conversion means and the focus detection photoelectric conversion means for light other than visible light is extremely reduced. The device is equipped with a beam splitter in the focus detection optical system, in which at least one reflecting surface is formed with a different reflection rate and transmittance depending on the branch length, and the reflection surface of this beam splitter reflects visible light. If the transmittance is high, the structure is configured to have a high transmittance for light other than visible light such as infrared light, and conversely, if the transmittance is high for visible light, the transmittance is high for light other than visible light such as infrared light. The light transmitted through the reflective surface of this beam splitter and the light reflected by it enter separate photoelectric conversion means.
The output of one of the photoelectric conversion means is guided to the focus detection calculation circuit by the selection means. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.The present invention is configured so that focus detection using infrared light is also possible. That is, photoelectric conversion means such as CCI (CCI) and photodiodes used for focus detection generally have better charge conversion efficiency (sensitivity) for infrared light than for visible light. It is also known that even black objects reflect infrared light relatively well, and that organic objects have a relatively high reflectance to infrared light. Furthermore, if the subject is dark, focus detection can be performed by projecting an auxiliary light onto the subject, but using visible light as the auxiliary light may have negative effects such as dazzling the subject when the subject is a person. Therefore, light other than visible light such as infrared light is desirable as the auxiliary light. Therefore, there is no reason why focus detection during visible light photography must always be performed using visible light, and it is desirable to be able to perform focus detection using both visible light and light other than visible light such as infrared light. First, FIGS. 1 to 7 show a lens-interchangeable eye reflex camera configured to perform automatic focus adjustment using an example of the focus detection device of the present invention. 'In the ff11 diagram showing the optical and electrical arrangement of this camera, the main mirror (1), the photographic lens (2) in the interchangeable lens, the pentaprism ( 3), focus plate (4), eyepiece (5)
constitutes a known finder optical system, which has a sub-mirror (6) attached to a raw mirror (1), and first and second reflective surfaces ('7a) (7b) that are parallel to each other. B,
-Mus splitter (7), relay lens (saX8b)
Of the light that swells and enters the beam splitter (7),
Most of the infrared light is reflected toward the second reflective surface (7b), while most of the visible light is transmitted as is, in a wavelength-selective manner. It is configured as a reflecting surface that almost completely reflects the infrared light reflected by the first reflection 111] (7a). Photoelectric conversion means (9a) (9b) provided on the same substrate
) is the '1st reflecting surface (7a) of the beam splitter (7).
), a focus detection unit dedicated to visible light that receives infrared light transmitted through the beam splitter (7), and a focus detection unit dedicated to infrared light that receives infrared light reflected by the second reflection 1 (7b,) of the beam splitter (7). As shown by the broken lines in FIG. 2, the detectors each have a common relative spectral sensitivity (with the highest sensitivity being 1) that is relatively sensitive to infrared light. The outputs of the photoelectric conversion means (9a) and (9b) are respectively '
It is input to the dlJ circuit (11) and the selection circuit (12). Here, the discrimination circuit (11) discriminates the magnitude of the output of both optical 4 conversion means, and a signal indicating the result is sent to the selection circuit (12).
Output to. The 1A separate circuit (12) selects either the output 7J of the visible light photoelectric conversion means (9a) or the output of the infrared photoelectric conversion means (9b) according to the signal from the discrimination circuit (11).
Focus detection calculation ゛,: Output to the 2m circuit (13),
1. Then, this circuit (13) uses one of these outputs to control the photographic lens (2) at the time of focus detection.
Indicates the amount of deviation (defocus amount) of the focal position from the film direction (preloaded imaging plane) (10) and the direction of the deviation (defocus direction, i.e. front bin-like appearance or rear vibrator-like appearance). A signal is output, and the motor drive sub needle circuit (14) drives the lens drive motor (Mo) based on the signal, thereby moving the photographing lens to the in-focus position. Note that the focus detection method called the so-called phase difference method can detect both the amount of defocus and the direction of defocus in this way, but this only detects the direction of the defocus. A focus detection method called a so-called contrast method that can detect The driving of the photographing lens drive motor may be stopped at the point in time when the focus detection arithmetic circuit no longer receives the signal shown in FIG. 2. The determination circuit (11) also determines whether the output of the visible light photoelectric conversion means (9a) and the output of the infrared photoelectric conversion means (9b) exceed a predetermined level, If the prescribed level is not reached,
A signal for activating the auxiliary light generation circuit (15) is output, thereby causing the infrared light emitting LED (IRL) to emit light. In the above configuration, in addition to the photographing lens (2), the infrared relay lens (8b) or the infrared photoelectric conversion means (9b)
The optical distance from the photographing lens (2) to the visible light relay lens (8a) or the visible light photoelectric conversion means (9a) is longer than that from the beam splitter
(7) The distance d between the first and second reflecting surfaces (7a, 7b) is divided by the refractive index n of the optical member constituting the beam splitter, which is equal to d/n. Of the light from the subject that passes through the photographic lens (2), infrared light forms an image farther than visible light, but if the distance d is chosen appropriately, the relay lens (8a) (8b) and beam splitter -(7)
Even if they are placed equidistant from each other, visible light and infrared light can be imaged simultaneously on the visible light photoelectric conversion means (9a) and the infrared and X-electric conversion means (9b), respectively. That is, according to this, when the relay lens for infrared light (8a) is placed at a position conjugate with the film plane (lO) with respect to the photographic lens (2), the light from the subject is projected onto the relay lens for infrared light (8b). If our infrared light forms an image, the film surface (10
), and by detecting the focus using infrared light, it is possible to detect the focus of the visible light on the film plane (10) (= film/L). However, when various interchangeable lenses are used in a camera, the imaging position of infrared light differs depending on the type of interchangeable lens, so the above-mentioned interval d has to be set to a standard value. Six corrections are required for the electrical signal of the infrared photoelectric conversion means (9b). In other words, the amount of deviation between the focal position of the photographic lens (2) due to visible light and the focal position due to infrared light is caused by the chromatic aberration of the photographic lens (2) as described above, and it is due to the optical design and focal length of the lens. It varies depending on various requirements such as. now,
If the amount of deviation is ΔIRo, then ΔIRo-d, /, = ΔIR. In this case, ΔIR is a value that is fixed to the photographing lens (2), that is, the interchangeable lens that has it, so we will introduce this. Must-have. In this embodiment, the interchangeable lens is provided with a data output circuit (16) that outputs a signal corresponding to ΔIR data, and its output connects a contact or connection cord that becomes conductive when the interchangeable lens is attached to the camera. Infrared light of a desired wavelength may be used as the basis for calculating ΔIR, which is input to the focus detection calculation circuit 4 (13) on the camera side via the reflective surface. A wavelength of about 8 30 nm is used where the product of the relative reflectance of (7a) and the relative spectral sensitivity of the photoelectric conversion means (9b) is the largest. Figure 3 shows the above-mentioned discrimination circuit (11) and selection circuit (12).
, focus detection calculation circuit (13), heptad drive port path (14)
, auxiliary light emitting circuit (15) and data output circuit (16)
A concrete example of one river route of this first embodiment including the following is shown. (IRD) is an infrared light monitoring photoelectric conversion element provided in the photoelectric conversion means (9b) in FIG. 1, and (VSD) is the first photoelectric conversion element.
This is a photoelectric conversion element for monitoring visible light provided in the photoelectric conversion means (9a) in the figure. These photoelectric conversion elements constitute a photometric circuit for monitoring with operational amplifiers (OA4, 1, (OA2) and logarithmic compression diodes (DI) (D2). Operational amplifiers (OA +), (0A)
The outputs of z) are compared by a comparator (ACI), and if the monitor output of infrared light is larger than the monitor output of visible light, the output of the comparator (Act) becomes °“High.
h''', uJ (for monitoring the l light; if the force is larger than the monitor output of the infrared light, the output of the comparator (Act) will be 'Low''. Also, the operational amplifier (O
The output of Al) is compared with the output of the constant voltage source (CE2) by the comparator (AC3), and if the monitor output of infrared light is smaller than the output of the constant voltage source (CEr), the output of the comparator (AC3) is ' In addition, the output of the operational amplifier (OA2) goes to the comparator (A
C2) is compared with the output of the constant voltage source (CE◇),
If the monitor output for visible light is smaller than the output of the constant voltage source (CEI), the output of the comparator (AC2) will be “H”.
Inverter (INI), AND circuit (ANl), (
AN2), OR circuit (OR+), (OR2) converts the photoelectric conversion means (9b) for infrared light and the photoelectric conversion means (9b) for visible light based on the output of the above-mentioned comparator (AC, l. (AC2>, (Ac3)). Photoelectric conversion means (
9a) Which one to use and the auxiliary infrared LED
(IRL) outputs a signal indicating whether to emit light. Table 11 Comparator (ACI), (AC2)
, shows the relationship between the output of (AC3) and the output of this logic circuit. Table 1 (φ or H may be used) As is clear from Table 1, if the monitor output of infrared light is larger than the monitor output of visible light, an infrared light receiver must be used, and this When the monitor output of infrared light is below a certain value, the infrared illumination light source is turned on. on the other hand,
If the monitor output of infrared light is smaller than the monitor output of visible light, and if the monitor power of visible light is above a certain value, the light receiver for visible light is used and the light source for illumination is not turned on.
If the monitor output of visible light is smaller than a certain value, the infrared illumination light source is turned on and the infrared light receiving section is used. The output of the OR circuit (a+<,) is the D flip-flop (
The output of the OR circuit (OR2') is D to the D input of DFl).
Flip-flops (D flip-flops (DPI), (1) F
2) Since a photometry operation start signal for focus detection from a microcomputer (MCO), IJ), etc., which will be described later, is input to the clock terminal of 2), an OR circuit (OR+) based on the monitor output at the start of photometry operation is input. , (OR2) is the D flip-flop (DF+), (D
F2). (COT) is a controller that controls the timing of photometry operation for focus detection, (IRC) is a CCD for focus detection provided in the infrared photoelectric conversion means (9b), (VS
C> is a CCL for focus detection provided in the photoelectric conversion means (9a) for visible light. (SH) is CCD (JR
C) or a circuit that samples and holds the analog signal from (VSC), (AD) is a sample and hold circuit (
This is a circuit that converts the output of SH) from analog to digital. Microcomputer (MCO) output terminal (03)
When a pulse is sent to the terminal (ST) of the controller (COT) to command the start of photometry operation for focus detection, the controller (COT) sends an analog switch (AS
5) Send the reset pulse that makes (AS6) conductive to the terminal (≠
1), and this analog switch (AS, s)
(AS6) conducts, CCD (IRC) (V
SC) is connected to the terminal (IA) up to the output potential of the constant voltage source (CE5).
D) Charged via (VAD). This terminal (-R)
The reset pulse from the flip-flop (FF1
) is also input to the set terminal, and this terminal (φR)
The flip-flop (FFI) is set by the pulse from Transistor (BTU)
conducts, and the infrared light emitting diode (IRL) for illumination lights up. The CCD (IRC) and (VSC) accumulate the charges output by their light receiving parts (A1 separate photoelectric conversion elements), and the terminals (IAD) and (VAI) output a potential corresponding to the accumulated charges. do. At this time, if the Q output of the D flip-flop (DF2) is "'High'" (when using an infrared CCD (IRC)), the analog switch (AS4) becomes conductive and the CCU (J
The potential from the output terminal (IAD) of RC is input to the converter/NO regulator (AC4). - If the output of the D flip-flop (DF2) is "High" (when using CC1 for visible light (VSC)), the analog switch (AS'3) conducts and the CCD ( VSC)
The comparator (A) output terminal (VAD) or Rano potential
C,). Comparator (AC4) is connected to terminal (IAD) or (VAD
potential and constant voltage source (cha) corresponding to the accumulated charge from the
, and if they match, it becomes “High”.
A signal of "" is sent to the controller (C0). Then, the controller (CUT) outputs a transfer pulse from the terminal (φ) and transfers the charges accumulated in CC1) (IRC) and (VSC) to the transfer gate. This transfer pulse is a flip
The signal is also sent to the reset terminal of the flop (FFI), the flip-flop (FFI) is reset and the light emitting diode (IRL) for lighting is turned off. And from now on C
CU (IRC), (VSC) output terminal (IKS),
(VSS) Transfer clocks (φ1), (φ2)
, (φ3) are sequentially output. At this time, if the D flip-flop (DF 2 ) output is “High”, the analog switch (A
S+) becomes conductive and inputs the infrared light reception output from the terminal (IKS) to the sample and hold circuit (S)1),
On the other hand, the D flip-flop (D slope output is “High”)
h”, the analog switch (AS2) conducts and inputs the active light reception output from the terminal (VSS) to the sample-and-hold circuit (SH).The controller (co'r) connects the terminal (φS ) outputs pulses for sampling and holding, and then outputs a pulse for starting A-D conversion from the terminal (φC).Then, A
-D converter (AD) is a tertiary controller (co'r) that converts the output of the sample and hold circuit (SH) from A to D.
) is connected from the terminal (TR) to the microcomputer (MCO).
) indicates that data is transferred to the input terminal (i4) of
It outputs a pulse and outputs the data converted by the A-D converter (AD) to the input port ('IPI) of the microcomputer (MCO). After this, the operations t') of outputting the accumulated charge, sample and hold, A-D conversion, and data transfer are repeated, and the CCD (JRC
), (VSC), etc. When the data transfer is completed, the controller (COT) connects the terminal (EN).
from the input terminal of the microcomputer (MCO) (
Send a data transmission completion pulse to la, i, m) J
stop the work. In this embodiment, it is a monitor output photoelectric conversion device (IRD). (VSD), but even if such a monitor photoelectric conversion element is not provided, either CCD
It is possible to switch whether or not to use the output of the light emitting diode and to determine whether or not to turn on the light emitting diode for illumination. That is, before the photometry operation for focus detection, the CCU (IRC)
, (VSC), the outputs of the terminals (IAD) and (VAD) based on this accumulated charge are made the same as the discrimination circuit shown in Fig. 3, and the discrimination result is focused. (before the start of photometry operation) D flip-flop (L)
F + ), (DF2) # This should be latched. Next, the remaining circuit portions in FIG. 3 will be explained. (To) is a battery for power supply, (MS) is a switch that is closed when the release button (not shown) is pressed in the first step, and this switch (M
S) is closed, the output of the inverter (IN2) becomes “H”.
The microcomputer (MCO) starts focus detection and focus adjustment operations, while the exposure metering/arithmetic/display circuit (LM) also starts operating. ) is the switch (M
S) is closed, the terminal (01) becomes High, the output of the inverter (IN3) becomes l Low II, the transistor (BT2') is made conductive, and the power supply line (
Power is supplied from Vcc). The switch (RS) is a switch that closes/L at the second step of pressing the release button, and when this switch is closed, the inverter (IN4
) becomes II High II. At this time, the exposure control/immediate circuit (EC) is in the $ state and the inverter (I
If the output of NoJ is High, the output of the AND circuit (ANO) will be High, and around the time of microcomputer G, focus detection and focus adjustment operations will be stopped and the exposure control operation will be stopped. .Exposure control circuit (E
In C), when the switch (R5) is closed, the exposure control operation is performed based on the exposure control value from the photometry/arithmetic/display circuit (LM), and when the exposure control operation is completed, the micro-
“'Hi” to input terminal (11) of computer (MCO)
gh''' operation completion signal is sent. This signal becomes ``Low'' when the exposure control mechanism is fully charged and ready for exposure control operation. Computer (MCO)
Based on the data from the output port (OP) of the camera, display of "center focus", "rear focus", and "focus" is performed. Motor drive circuit (
MDR) rotates the motor (MO) forward or reverse based on the data from the output port (OP2), and moves the lens to the in-focus position via the lens drive mechanism (LDR). Further, (EN) is an encoder for monitoring the amount of rotation of the lens drive mechanism (L, DR), and outputs one normal signal every time the lens drive mechanism (Ll, R) rotates by a predetermined amount. (IF) is a microcomputer (MCO)
(7) 94 Interchangeable lens data output circuit (LDO) that uses pulses from child (02) to output lens data
From here, data ΔIR indicating the amount of deviation between the infrared focus position and the visible light focus position and the lens WAwtA structure (LDR
) predetermined rotation amount (predetermined 4II from encoder (EN)
The data on the ratio of the lens shift 1itH1 to the AM tZ Lus) is sent. The circuit shown in FIG. 3 has been schematically explained above. In FIG. 3, the circuit (il) (12) (14) (1
5) The parts corresponding to (16) are indicated by dashed lines or parentheses, (LM) (EC) (LDR) (EN)
The remaining portion except for corresponds to the circuit (13). Next, a specific example of the interface circuit (IF) and a specific example of the data output circuit (LDO) shown in FIG. 3 will be explained. In Fig. 4, when a "High" pulse is input from the terminal (02) of the microcomputer (MOO),
The flip-flop (FF'5) is set and D is set at the rising edge of the next clock pulse from the oscillator (OSC).
Q output of flip-flop (DF5) is “'High”
”'. This opens the AND circuit (AN, .), so the clock pulse from the oscillator (OSC) is input to the ring counter (CO□), and the ring counter (Cod) receives the clock pulse. From one rising edge to the next rising edge, terminals (bo), (bl)...
・(b9L(bo),(bl) ・・・-(b9)“
On the other hand, the D flip-flop (
The Q output of DF5) is output from the lens side data output circuit (Fig. 6).
It is also transmitted to the LDO) through the terminals (Jl) and (Jl). When this Q output rises to 'High', the latch circuit (LA3) is sent from the photographing distance output part (DD) to the analog switch. The 5-bit shooting distance data input via (AS+s) to (ASI9) is latched. Then, after a time determined by the delay time of the delay circuit (DL), the output of the delay circuit (DL) is “ “High”,
The output of the inverter (IN+o) becomes "Low", the analog switches (SAio) to (AS14) become conductive, and the 5-bit focal length data from the focal length data output section (FD) is sent to the latch circuit (LA3). The input focal length data output unit (FD) and shooting distance data output unit (DD) are both composed of code boards, and the total of these data is 10 bits, which is 6 if the above configuration is used.
It becomes possible to input data to the IC circuit (circuit portion surrounded by a chain line in FIG. 4) using the terminal of the book. In addition, in the example of FIG. 4, the above-mentioned data ΔIR
, K is shown as an example of an interchangeable lens in which K changes, so that
The above two pieces of data are required. The photographing distance data from the latch circuit (LA3) and the focal length b data from the analog switches (AS+o) to (AS+4') are manually input to the decoder (DE3) and converted into zero-pit data. And this data is RO
It is input to the address terminal of the lower 6 bits of M(RO). In addition, the terminal (Jl') connected to the Q output of the D flip-flop (DFs) becomes "High", so that the terminal 02
A clock pulse from the oscillator (OSC) inputted via the oscillator (OSC) passes through the AND circuit (AN+4) and is inputted to the ring counter (CO2) having the same configuration as the ring counter (COt) in FIG. Ring counter (COI) terminal (bl) in Figure 4
When becomes "High", a "High" signal is input to the counter (COa) via the terminal (J3), 03'), and the output Q1. Qo becomes "01". The output of this counter (9) is input to the upper 2-bit address terminal of ROMCRO), and
O) is designated with the address "0IXXXXXX" (x...x is the output of the decoder (DE)) and outputs ΔIR data corresponding to the focal length and shooting distance. Then, when the terminal (L2) of the ring counter (CO□) rises, this ΔIH data is transferred to the shift register (SR2).
Afterwards, in synchronization with the rise and rise of the clock pulse, the ΔIR data is sequentially transferred to the output terminal (OUT
), and is taken into the shift register (SRI) in the camera-side interface circuit (IF) via the terminal 0 < , '-(J, ). This shift register (SRI) is designed to take in data at the falling edge of the clock pulse, so 8-bit data can be read from the terminal (b2) or from the falling edge of the clock pulse when it is "High" to the terminal (b9). The shift register (SRI
). Then, when the terminal (bl) rises to 'High' for the second time, the Q output of the D flip-flop (ppy) becomes '
At this time, the G output of the D flimp fist flow knob (DF8) is "High", so the AND circuit (ANn) outputs a "High" output from the terminal (bo). At this rising edge, the latch circuit (LAI) latches the data ΔIR from the shift register (SRI).Then, the ring counter (
When the terminal (bl) of COt) becomes f(igh" for the second time, the counter (C03) changes to terminals 03), 03'
) receives this Ilight” signal and outputs its output Q+.
, Qo becomes "'10"", R(AM(RO) is specified by address "'l0XXXXXX", and outputs K data corresponding to the focal length and shooting distance. This data is sent to the ring counter (CO2). ) is taken into the shift register (SR2) at the rising edge of the terminal (L2), and then sent one bit at a time in synchronization with the rising edge of the clock pulse via the terminals (J4') and (J4) to the camera side in Figure 5. The clock pulse is input to the shift register (SRI) in the interface circuit (IF) and taken into the shift register (SR1) in synchronization with the falling edge of the clock pulse, and when the terminal (b2) is "High". 8-bit data K is taken into the shift register (SRI) between the falling edge of the clock pulse and the falling edge of the clock pulse when the terminal (b,) is l n igh I+. Next, the ring counter (co,) Terminal (b.) is “lh”
When you get up to rghl+, D flip flop 7 (DF
The Q output of s) becomes l Hlgh n, and the AND circuit (
The output of AN12) is “High” from the terminal (bo).
” pulse is output and the data K stored in the shift register (SRx) is latched into the latch circuit (LA2).The output of the AND circuit (ANI2) is output through the OR circuit (OR1°). Flip-flop (FF,
), D flip-flops (DFs), CDFa), (
DFy), (L)I's), ring counter (COl
) is sent to the reset terminal of the AND circuit (AN□i), and the rising edge of the output of the AND circuit (AN
5. The signal in which the C output of 1 falls to °' Low is sent to the counter (CO2), (Co,, ) cent terminal via the terminals (L), (L') and the OR circuit (OR, □). sent to these counters (CO2)
, l, CU3) are also reset. By repeating the above operations, the data of JIR and NI depending on the status of the photographing lens is sequentially imported into the camera side interface circuit CIF), and the data is transferred to the microcomputer (CIF).
Input port of MC(J) (If'2.+, (I P
The microcomputer (MCOI i) is taken in from the microcomputer (U'o+) and (PO2) are power-on reset circuits, and the third transistor (B10)
When conductive and power supply starts from the power supply line (Vcc), each outputs a reset signal. These reset signals are OR circuits, <OX<, respectively. ), (
, OR11) and outputs C through -(-, flip-flop (, FF, ), i) flip-flop 70 tube (DF5
) + (DF 6 ) r (1,) F t J T
k1. ) F Hノ, counter (COI), (
CO□), '(CO3) is reset. FIG. 5 shows an embodiment of a data output circuit (LDO) for an interchangeable lens in which dIR and K change depending on either the focal length or the photographing distance. Components or circuit elements similar to those in FIG. 4 are given the same reference numerals. In the case of this interchangeable lens, the upper two bits of the ROM (RO) are addressed by the output of the counter (CO3),
The least significant bit is connected to ground, and the remaining 5 pins are used for focal length data output (FD) or shooting distance data output (
DD). The remaining two circuits are the same as those shown in FIG. FIG. 6 shows an embodiment of a data output circuit (LDO) for an interchangeable lens in which JIR and K are fixed. In this example: Using a diode array (DIA) instead of ROM, the terminal (QO) of the counter CL; Oa) is “High”.
When this happens, the JIR data of the diode array (DIA) connected to this terminal (00 month) is output, and when the terminal (Q,) becomes "High", these 4 terminals (Q
) The data of K of the diode array (DIA) connected to is output. The other parts are the same as in FIG. 4. Next 1. Figure 7 shows the microcomputer (MC).
The operation of the circuit of FIG. 3 will be explained based on the flowchart of O). While the microcomputer (MCO) G switch (MS) is open, the microcomputer (MCO) enters the state of "HAL", which consumes low power and is inactive while the switch (MS) is open.
S) is closed, the “Hi” of the inverter (IN2)
gh” output is input to the interlaced terminal (it),
The microcomputer (MCO) starts all operations from step #0. In step #0, the terminal (0,) is set to "High" and the output of the inverter (IN3) is set to "L".
ow” to make the transistor (B'r2) conductive. Therefore, power supply from the power supply line (Vcc) is started. Then, in step #1, the switch (R5) is closed and the output of the inverter (IN4) is turned on. It is determined whether the input terminal (i3) is "High" and the input terminal (i3) is "High". If the input terminal (i3) is "High", the exposure example aS operation is performed, so follow #41 described later. If the terminal (i3) is "Low", a "High" pulse is output to the output terminal (03) to start the photometry operation for focus detection described above, and roughly #
In step 3, the terminal (0□) is set to ``High''.
R) Output the response and obtain the data ΔI from the above-mentioned interchangeable lens.
Start the reading operation of R and K. Next, in step #4, the input terminal (i4) is set to °'High.
Wait until it becomes ``h'', then (i4) becomes 11 Hlgh TT
Then, from the input port (ip+) to the controller (C
It is determined whether the terminal (i6) is "High" (the value obtained by A-D conversion of the accumulated charge by one light receiving section of the CCD (VSC) or (IRC)). If it is "Low", the process returns to step #4 and takes in the next data. On the other hand, the #6 Stereo knob determines that the input terminal (i6) is "L Hlgh u", mark D (VSC,) or CIR
The acquisition of the A-D conversion value of the tffl charge by all the light receiving parts in C) has been completed. It is determined again whether (+,) is ")light". And (i3) is it High
If n, the process moves to step #41. In step #7, input terminal (i3) or “'Higl]”
Otherwise, move to step #8 and connect the input port (
∆■R data from the input port (IP2)
, ). Then, in step #lO, the focus shift amount and direction are calculated based on the data taken in from the input port (IPl). This calculation may be performed, for example, as shown in Japanese Patent Laid-Open No. 67-45510. Then, in step #11, it is determined whether the input terminal (i5) is "High" and
If it is "High", ΔI! (focus shift amount and direction) was calculated using the output of the infrared CCU (IRC), so the shift amount of the focus position between infrared light and visible light. Based on the data ΔIR and the data K of the ratio of (b) rotation amount of the lens drive mechanism to the lens movement amount
)=H to calculate the number N of pulses to be input from the encoder (EN). On the other hand, if it is determined that the input terminal (i5) is not "High" in step #11, it means that a visible light CCD (VSC) is used, so the data of ΔIR is not used, and K. Δf=
The number N of pulses to be input from the encoder (EN) is calculated by performing the calculation of N. In step #14, the focus matching state is displayed in one line, and the input terminal (i3) is determined in the same manner as described above.
In step #16, it is determined whether the number N of pulses is 0 or not. Then, if N is 0, the process moves to step #38, which will be described later, while if N\0, the process moves to step #17, where N is set in the register M in the microcomputer (MCOI). ) starts forward or reverse rotation depending on the direction of focus shift, and data P is stored in the register P in the microcomputer+, MC0). Set. Then, a pulse is input from the encoder (EN) and it is determined whether the input terminal (iρ) has become "High". If it is "Low", go to step #27.
If it is "High", proceed to step #21. In step #27, it is determined whether the switch (R5) is closed and the input terminal ('i3) is "High".
° If it is “High”, the exposure control operation will start, so after stopping the rotation of the motor (MO) and resetting the flag JF in the microcomputer, which will be described later, move to step #41. do. On the other hand, input terminal (i3)
If is “Low”, register P’ is set in step #28.
Subtract 1 from the content of P to determine whether the content of P is O. Then, if (P)\0, determine whether flag JF is 0 in step #30, and if it is O, return to #20,
It is determined whether the input terminal (12) is "High". If it is "Low", the process returns to step #27. Therefore, the above operation is repeated until the input terminal (12) becomes "High", and if the terminal (12) does not become ")right" until (p) = o (a certain period of time), the motor ( MO) but for some reason (for example, the lens has been moved to the closest position)
Since the lens drive mechanism cannot move any further, stop the rotation of the motor (MO) in step #33, display a warning, reset flag JF, and move to step #38. . If it is determined in step #20 that the input terminal (12) is "High", then in step #21 subtract 1 from gN in register M and check whether the contents of M have become 0. Determine. (m) If the loss is 0, set flag JF to 1 and set register P to P. It is determined whether the input terminal (12) is set to "Low". J and “High”
If it remains the same, the process moves to step #27 described above and moves to the flow for counting a certain period of time. In this case, since the flag JF is 1, the process returns to step #25. In this case, if (P) = 0, it means that the lens has been driven to the closest position, so the flow shifts to FI:33, stops the motor, displays a warning, and - (Reset the flag JF and move to step #38. Then, in step #25, input terminal (12
) becomes “Low”′, the flag J
Reset F and return to step #19. Note that when it is determined that the input terminal (12) becomes "High", 1 is subtracted from the contents of the register M, but the register M is also subtracted when the input terminal (12) becomes "LOW". , subtract 1 from the content of M to determine whether the content of M has become 0. If (M) is 20, move to step #36, and the value of N is 2' times the value of this example. (The rise and fall of the pulse from the f1 encoder (EN) will be counted, which will improve the precision of lens focus adjustment. In step #22, (M) = 0. When it is determined, the lens has been moved to the in-focus position, the motor (MO) is stopped in step #36, and the focus is displayed in step #37. In step #38, the switch (MS ) is closed and determines whether the input terminal (17) is "l High'gh I+". If the input terminal (17) is "High", #1
Go back to the step and repeat the same operation as above, (iy
) is "Low", the display is turned off and the terminal (01) is set to "Low" in step #39, and the transistor (BT
, 1 stops the power supply from the power line (Vcc), and the microcomputer (MCO) enters the HALT" state. Furthermore, if it is determined that the switch (R8) is closed, 1. Wait for the input terminal (11) to become "High" in step #41. Then, when the exposure control operation is completed and a "High" pulse is input from the exposure control circuit (EC) to the input terminal (11). #38
Move on to step 3. Next, we will explain a modification of the first embodiment.The photoelectric conversion means for focus detection outputs a signal corresponding to the instantaneous light intensity, like a photodiode array, rather than an integral type like a CCD. Δ
In the calculation of l, an example was shown in which digital calculation is performed based on the digital value obtained by A-D converting the photoelectric conversion output, but analog calculation is performed based on the analog output, and the calculation result is A-D converted. Motor control and display may be performed based on digital values. Sohaku Next, Figure 8 shows the beam splitter (7) shown in Figure 1.
A first specific modification example will be shown. The beam splitter of this first variant (7 parallelogram glass blocks (5
6) and a triangular glass block (57), and a multilayer thin film (58) with a 23-layer structure shown in Table 2 below is deposited on the joint surface of both glass blocks. (This bonded surface acts as a reflective surface with the relative reflectance shown in Figure 9. Table 2 (λO' = 1100 nm) The refractive index of the glass block (56) C57) is
1.5168, the low refractive index layer with a refractive index of 1.38 in the multilayer thin film (58) is made of MgFz, and the high refractive index layer with a refractive index of 2.30 is made of TiO2 or ceo2. Also, Figure 9 shows the reflectance in the visible range of 460 to 6600 m.
It is 10% or less in the range of , and 90% or more in the infrared range of 800 to 37 Qnm. And MgFz, which is a thin film material
, Ti0z, and Ce0z are dielectrics, so there is no light absorption in the multilayer thin film (58), and the transmittance Tλ (%) is Tλ
″: Can be expressed as 100−Rλ, 460 to 660
It is 90% or more in the visible range of nm, and 10% or less in the infrared range of 800 to 8700 m. Therefore, if these seven beam splitters are used, the incident light can be separated into visible light and infrared light with almost no loss in light quantity. Figure 10 shows the second specific modification of the beam splitter (7). An example is shown in which the beam splitter (7') of this second modification is a mirror consisting of a glass substrate (60) and 13 multilayer thin films (61) deposited on the surface of the glass substrate (60). The structure of the multilayer thin film (61) is as shown in Table 3 below, and in this case too, the low refractive index layer with n=1.38 is MgFz, and the high refractive layer with n=2.30. The refractive index of the glass substrate (58) is 1.516'8.Table 3 (λO=1000 nm) Figure 11 shows the relative j ratio when light is incident at an incident angle of 45°.From this figure, it is clear that the ratio is 40
Low reflectance (high 0 transmittance) in the visible range from 0 to 700 nm
is obtained, and a high fouling rate (low transmittance) is obtained in the infrared region from soon to 100 nm. Figure 12 shows the configuration of the main parts of the focus detection optical system when seven beam splitters are used.
2) is an optical member having a full anti-fouling mirror (8 is an optical member having a relay lens portion (8') (8'b). The present invention has been described above in detail with reference to the drawings, but this invention is not limited to the above-mentioned For example, in the beam splitter (7) shown in FIG. It is also possible to use reflective surfaces with different reflectances and transmittances. That is, if the second reflective surface (7b) has a relative reflectance shown by the dashed line in FIG. 2(A),
The wavelength range of infrared light received by the focus detection photoelectric conversion means (9b) for infrared light becomes narrower, and by calculating ΔIR based on a predetermined wavelength within that wavelength range, correction of ΔIR is performed as described above. If this is done, more accurate correction becomes possible. Also, when projecting auxiliary light, an infrared laser or an infrared LED that emits monochromatic infrared light in a wavelength range in which the relative reflectance of the first reflecting surface (7a) and the second reflecting surface (7b) is high is used. By using this, it is possible to improve the accuracy of correction of ΔIR. In this case, in order to prevent the light transmitted through the second reflecting surface (7b) from being reflected on the left end surface of the beam splitter (7), it is desirable to provide a light absorber on the left end surface of the beam splitter (7).
0Also, in the embodiments and modified examples, a beam splitter is shown in which the transmittance of visible light and the reflectance of infrared light are the same.
Conversely, a beam splitter with high reflectance for visible light and high transmittance for infrared light may be used. Furthermore, the beam splitter is provided with first, second, and third reflecting surfaces, and the first reflecting surface transmits visible light and reflects light in a second predetermined wavelength range. The reflective surfaces are arranged so as to reflect the infrared light in the second predetermined wavelength range reflected by the second reflective surface, and one of the reflective surfaces is arranged to receive the infrared light from the third reflective surface. Furthermore, in the above-mentioned embodiment, the focus detection is performed based on the larger output of the output of the photoelectric conversion means for visible light and the output of the photoelectric conversion means for infrared light. In the description of the above embodiment, the case of infrared light photography was not explained, but infrared light photography is used. Since the output of the photoelectric conversion element for light monitoring (IRD) is higher than the output of the photoelectric conversion element for visible light monitoring (VSD'), the output of C1) (IRC) is used for focus detection. Effects As explained above, in the focus detection device of the present invention, the beam splitter provided in the focus detection optical system
The beam splitter is equipped with a reflective surface with different reflectance and transmittance depending on the wavelength, and this reflective surface splits the light incident on the beam splitter into visible light and other light, so focus detection for visible light is possible. The loss in the amount of light incident on the photoelectric conversion means and other light focus detection photoelectric conversion means is extremely small, and focus detection becomes difficult even when the intensity of the light incident on the Beams 1 Ritter is small. do not have.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the optical and electrical arrangement of an eye reflex camera with interchangeable lenses using an embodiment of the focus detection device of the present invention, and FIG. 2(A) shows the beam splitter of FIG. 1. Figure 2 shows the relative reflectance of the first reflecting surface and the spectral sensitivity of the photoelectric conversion means (Bl is a diagram showing the relative transmittance of the first reflecting surface and the spectral sensitivity of the photoelectric conversion means, and Figure 3 shows the relative transmittance of the first reflecting surface and the spectral sensitivity of the photoelectric conversion means).
The figure is a specific circuit diagram of the focus adjustment device in the camera shown in Figure 1, Figure 4 is a circuit diagram showing the circuit configuration of the interface circuit and data output circuit in Figure 3, and Figures 5 and 6.
The figures are circuit diagrams showing other configurations of the data output circuit of the interchangeable lens, FIG. 7 is a flowchart showing the operation of the focus adjusting device having the circuit configuration of FIG. 3, and FIG. Schematic diagram showing a specific modification example, No. 9
The figure shows the relative reflectance of the beam splitter of the first modified example, FIG. 10 shows the f-product equation diagram of the second specific modified example of the beam splitter, and FIG. 11 shows the second modified example. FIG. 12 is a diagram showing the main parts of a focus detection optical system using the beam splitter of FIG. 11. (2) ... photographing lens, (6) (71 (8b)
)...Optical system for focus detection, (9b piece...Photoelectric conversion means for focus detection. (11)...Judging means, (12 pieces...Selecting means, (7
1 (7 beam splitters) 2 (7 beam splitters)
...Reflecting surface with different reflectance and transmittance depending on wavelength. Applicant Kai Ai Minolta Camera Co., Ltd. (N7Lf) Osaka Kokusai Building Minolta Camera Co., Ltd., 2-30 Azuchi-cho, Higashi-ku, Osaka Inventor Shuzo Matsushita Osaka Kokusai Building Minolta Camera Co., Ltd. 2-30 Azuchi-cho, Higashi-ku, Osaka Inside

Claims (1)

[Claims] 1. A focus detection optical system that guides the subject light that has passed through the photographic lens to a plurality of focus detection photoelectric conversion means, and selects any one of the outputs of these focus detection photoelectric conversion means. In the focus detection device for a camera, the focus detection device includes a selection means for detecting a subject, and a focus detection calculation means for detecting whether or not the photographing lens is in a focused position with respect to a subject based on the output selected by the selection means. The optical system for use is provided with a beam splitter in which at least one reflecting surface with different reflectance and transmittance is formed in a wavelength-selective manner, and the transmitted light passing through this reflecting surface and the reflected light reflected by this reflecting surface are separated. A focus detection device characterized in that the focus detection device is configured such that the light beams are incident on separate photoelectric conversion means of the focus detection photoelectric conversion means. 2. The reflecting surface of the beam splitter is constructed of a reflecting surface that has a high reflectance for infrared light in a predetermined wavelength range and a high transmittance for visible light. Focus detection device.