JPH03163421A - Automatic focus camera with infrared photographing mode - Google Patents

Abstract

PURPOSE:To allow automatic focusing even in IR photographing by moving a focusing lens to a position where an IR image focuses in accordance with the focusing position information obtd. by visible light at the time of IR photographing and the IR focus information corresponding thereto. CONSTITUTION:This camera has a focus detecting means and a lens driving means which moves the focusing lens L up to the focusing position based on the focusing position information of the focusing lens L obtd. by this means. An IC card 55 in which the IR photographing information is stored is loaded in the camera at the time of IR photographing and an IR mode is selected, by which the automatic focusing operation by the automatic focusing device is executed. The operation is, therefore, extremely easy and since the rapid photographing is possible, the missing of a shuttering chance is prevented. The IR photographing is not possible when the IC card 55 is not loaded in the camera. Such an accident that the photographing is done by erroneously setting the IR photographing mode at the time of ordinary photographing is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an autofocus camera with an infrared photography mode that is capable of autofocusing in infrared photography using an infrared film. "Prior art and its problems" In recent years, single-lens reflex cameras have been equipped with automatic focusing devices (
Hereinafter referred to as an "autofocus camera". ) has become mainstream. This type of autofocus camera includes a focus detection device and a focusing lens drive device that drives a focusing lens of a photographic lens to an in-focus position based on detection data of the focus detection device. This type of automatic focus detection device performs focus detection using a portion of the subject's light beam that passes through the photographic lens. For example, a part of the subject light beam that has passed through the photographic lens is divided into two parts and imaged on a distance measurement sensor installed at a position equivalent to the film surface, and the phase difference between the pair of images formed on the distance measurement sensor is determined by Focus detection is performed by determining the amount of defocus.

The focusing lens driving device drives the focusing lens based on the amount of defocus obtained by the focus detection device. By the way, it is known that lenses have chromatic aberration, that is, their focal lengths differ depending on the wavelength of light. Therefore, an achromatic lens or an avochromat lens is usually used as a photographic lens to substantially eliminate chromatic aberration for visible light. However, chromatic aberration is not taken into account for infrared radiation. Therefore, for example, in FIG. 3A, if the visible light focus position is Xl, the infrared light focus position will be a position x2 that is shifted from the visible light focus position x1. Therefore, when taking pictures using infrared film with a conventional autofocus camera, in other words, when taking infrared pictures, the autofocus device is once focused on the desired subject, and then the autofocus device is canceled and the photographer manually focuses the subject. I had to rotate the adjustment ring to correct the focus to the position of the infrared indicator indicated on the lens barrel. Therefore, even when shooting with an autofocus camera, infrared photography ultimately requires the photographer to manually adjust the focus, which poses problems such as cumbersome and time-consuming operations. ．． ``Object of the Invention'' The present invention has been made based on the above-mentioned problem awareness of the conventional auto-focus camera, and is an auto-focus camera with an infrared shooting mode that can focus with an auto-focus device even when shooting using infrared film. The purpose is to provide the following. "Summary of the Invention" The present invention that achieves the above object includes a focus detection means and a lens drive for moving the focusing lens to the focus position based on focus position information of the focusing lens obtained by the focus detection means. In the autofocus camera, the lens driving means includes an infrared focus information converting means for obtaining infrared focus information based on visible light focus information obtained by the focus detection means during infrared photography. , the focusing lens is moved to an infrared focusing position based on this infrared focusing information. According to this structure, in the autofocus camera, the autofocus device can focus even during infrared photography. In addition, since infrared photography is infrequent, it is possible to store information regarding the infrared photography mode on a removable IC card in the camera, and configure the camera to take infrared photography when this IC card is loaded. The number of mode settings is reduced, making mode setting operations easier, and it also prevents the accident of accidentally setting infrared photography mode during normal photography, resulting in blurry photographs. "Embodiments of the Invention" The present invention will be explained below based on illustrated embodiments. First, the configuration of the AF control system of an autofocus single-lens reflex camera to which the present invention is applied will be explained with reference to FIG. A main mirror l3 is provided within the camera body 11 to reflect the subject light beam that has passed through the photographic lens L.
The subject light beam reflected upward by the main mirror l3 is
The light passes through the focusing screen l5, is reflected by the pentaprism l7, and exits from the eyepiece lens 19. Above main mirror 13, force single screen 15
, a pentaprism l7 and an eyepiece l9 constitute a finder optical system. The central portion of the main mirror 13 is a half mirror, which transmits a portion of the subject light beam. The subject light beam that has passed through the main mirror 13 is reflected downward by a submirror 2l provided at the rear of the main mirror l3, and is guided to the distance measurement sensor 23. The main mirror 13, submirror 2l, and distance measurement sensor 23 described above constitute an AF optical system. The distance measurement sensor 23 is a known phase difference detection type distance measurement sensor, and has a CCD line sensor (not shown) consisting of a large number of pixels arranged in one row. An aerial image of the subject divided into two is formed on this CCD line sensor, and by detecting the phase difference (interval) between this pair of subject images, the defocus value and its direction (defocus amount) are determined. It will be done. The pixel data obtained by the ranging sensor 23 is transmitted to the DPU (D
The data is output to the DPU 25, amplified by the DPU 25, and converted into distance measurement data in a format that can be processed by the CPU 27. Also DPL
The I25 performs data communication with the CPU 27, and transfers the distance measurement data to the CPLI 27 through this data communication. The CPU 27 is. The distance measurement data transferred from the DPU 25 is A/D converted, and a predetermined calculation (predictor calculation) is executed to obtain the defocus amount. The above distance measuring sensor 23
, the DPU 25 and the CPU 27 constitute a focus detection means. Then, the CPU 27 drives the AF motor 31 via the motor driver 29 based on this defocus amount. The rotation of the AF motor 31 is transmitted to the AF cover 35 via the gear mechanism 33. The gear mechanism 33 is provided with detection means for detecting the rotation speed of the AF motor 35. Although this detection means is well known, the one of this embodiment consists of a decoder disk and a photocoupler (not shown) that rotate in conjunction with the AF motor 31. A large number of slits are formed at equal intervals on the same circumference of the decoder disk, and a photocoupler is provided at the position where the slits pass. The output of the photocoupler changes each time the decoder disk rotates and the slit passes. This change in the output of the photocoupler is converted into a pulse signal of a predetermined level by the encoder 37 and output to the CPU 27. The CPU 27 detects the rotation speed of the AF motor 3l by counting this pulse signal. That is, the CPU 27 calculates the amount of movement of the focusing lens L according to the defocus amount using the number of pulses output by the encoder 37 (the number of slits on the decoder disk), and the CPU 27 uses the AF motor 31 until this number of pulses reaches a predetermined value. It is driven to rotate. Note that, hereinafter, the pulse output by the encoder 3.7 will be referred to as "rAF pulse".

The E"FROM 41 is connected to the CPU 27. The E"FROM 41 stores various photographic conditions and photographic data in advance, and is also used as a memory for the CPU 27 during photographing. On the other hand, the photographing lens 43 includes a focusing lens L that is movable in the optical axis direction. Focusing lens L
is driven in the optical axis direction by a lens drive gear mechanism 45. The rotation of the AF motor 31 is transmitted to the lens drive gear mechanism 45 through the connection between the lens-side AP coverr 47 and the body-side AF coverr 35. The above-mentioned CPU 27, AF motor 3l, and lens drive gear machine 45 constitute the main part of the lens drive means. Further, the photographing lens 43 is equipped with a lens CPU 49. The lens CPU 49 stores information unique to the photographic lens 43, and this information is sent to the DPU 25 via the mount contact bins 5l and 53. The cover 47 and the mount contact bin 5l are mounted on the lens side mount L.
The AF cover 35 and the mount contact bin 53 are provided on the camera side mount CM, and these are arranged at positions where they are connected to each other when the photographing lens 43 is attached to the camera body 11. It has been done. Further, the camera body 11 is provided with an adapter 56 to which an IC card 55 storing program information related to infrared photography can be attached and detached, and the IC card 55 attached to the adapter 56 is connected to the CPU 27 via a data path. It will be done. Next to the camera system, we will explain the overall configuration of the control system of this camera.
This will be explained with reference to the figure. The CPU 27 is a microcomputer that centrally controls the entire system of this camera. This CPU 27 includes switches such as a photometry switch SWS, a release switch SWR,
Mode switch SWM, up switch SWUP, and down switch SWDN are input. The photometry switch SWS and release switch SWR are
As is well known, it is linked to the release button (not shown), and when the release button is pressed halfway, the light metering switch SWS is turned on.
Press L fully to turn on the release switch SWR. The mode switch SWM is a switch for switching the shooting mode to normal mode, infrared shooting mode, etc.
The up switch SWUP and the down switch SWD are switches that change the photographing mode in cooperation with the mode switch SWM, and are selectively turned on. Furthermore, an exposure control circuit 57 is connected to the CPU 27 as exposure control means for controlling the drive of the aperture drive mechanism. Further, a wind motor 59 for winding and rewinding the film, and a mechanical motor 6l for performing mechanical charging such as shutter charging are connected to the CPU 27 via a motor driver 63. The DPU 25 is a microcomputer that mainly converts pixel data from the photometric sensor 23 described above and photometric data from a photometric IC 59 (described later) into data that can be processed by the CPU 27. This DPU 25 includes the above-mentioned distance measuring sensor 2.
In addition to 3, there is also a photometric IC59 for detecting subject brightness.
is connected. Although not shown, the photometric IC 59 includes a light receiving element and a photometric calculation circuit, and logarithmically compresses the output signal of the light receiving element that receives the object beam and outputs the logarithmically compressed signal to the DPU 25. The DPU 25 converts this photometry data into a predetermined subject brightness Bv and outputs it to the CPU 27. Furthermore, the DPU 25 is connected to a flash circuit 65 that controls the emission of built-in and external flashes.
When the U25 receives the light emission signal from the CPU 27, it prepares for flash emission (charges) via the flash circuit 65.
The device receives the light emission signal, outputs a trigger signal to the flash, and causes the flash to fire. On the other hand, the DPU 25 receives from the flash circuit 65 a light emission preparation completion signal before light emission and a light emission signal during light emission, and outputs them to the CPU 27 respectively. Further, connected to the CPU 27 is an IPU 67 that controls an LCD (liquid crystal display) 69 for informing the photographer of photographic information and the like. CPU27 and IPU67
The CPLJ 27 performs predetermined data communication with each other, and the CPLJ 27 sends shooting information such as the distinction between normal shooting mode and infrared shooting mode and the number of shots to be taken. The LCD 69 is provided on the external upper surface of the camera body 1l and within the viewfinder field of view, and displays information related to photography such as normal photography mode and infrared photography mode, strobe information, etc.
Displayed under the control of DPU25 and IPU above
67 is centrally controlled by the CPU 27. Fortune-telling! Next, focus correction in the infrared imaging mode will be explained with reference to FIGS. 3A and 3B. FIG. 3A shows the case of the front bin. For example, if a visible light image of a certain subject is focused on XI, an infrared image of the same subject will be focused on x2, which is farther away. The distances from each of these focusing positions X1 and X2 to the film surface F, that is, the defocus amount of visible light and the defocus amount of infrared rays, are respectively b. Let it be a. Furthermore, if the difference between the visible light focus position XI and the infrared focus position X2 (hereinafter referred to as "infrared movement amount") is C, then the following formula holds true. a==b−c ・・・・・・■ The visible light defocus amount b is calculated by a predetermined calculation from the distance between a pair of images formed on the CCD line sensor of the range sensor 23. Ru. Here, during normal shooting, the CPU 27 controls the AF motor 3l based on the following formula.
is activated and the focusing lens L is moved to the in-focus position. P. =b/k ・・・・・・■ In addition, P. is the number of AF pulses required to move the focal position Xi of visible light to the film plane F, and k is the number of AF pulses required to move the focal position XI (defocus) 1llI1. ．． From the above equations (■) and (■), the number of AF pulses P1 required to align the in-focus position x2 with the film surface F is:
It can be calculated using the following formula. Pg = a/k = (b-c)/k ・-・■ Note that the above c and k are constants that differ depending on the shooting lens,
These values are stored in the lens CPU 49. These values are then read into the CPU 27 through communication, and read out during the above calculation.The above lenses CPtJ49 and C
The PU 27 constitutes the main part of the infrared focus information conversion means. The above is the case of the so-called front bin, but in the case of the so-called rear bin shown in Fig. 3B, the above formulas ``■'' and ``■'' become as follows, respectively. a==b+c Ps=a/k=(b+c)/
k Also, the position of the infrared focus position x2 when the visible light focus position Xt coincides with the film surface F, that is, the infrared defocus amount a when the visible light defocus amount b is O, is a = C becomes. The number of infrared correction AF pulses PC required to move the infrared focused position from this visible light focused state to the film equivalent plane F is P C = c / k.
・・・・・・■. Next, the operation of the present invention will be explained with reference to the flowcharts shown in FIGS. 4 to 6. This operation is performed by CPU2
The CPU 27 performs the processing in an integrated manner based on the program stored in the CPU 27. First, the mode setting operation for deciding between normal photography and infrared photography will be explained based on the mode setting flowchart shown in FIG. This flowchart is entered when the mode switch SWM is ONL. In the mode setting operation, first all segments of the LCD 69 are turned off (Sll). Then the up switch is turned on
Check whether the down switch is ON or both are ON (513,
S15). When the up switch swup is ONL, U
P/ DOWN timer counter starts (S
l7). If the time has not elapsed, it is considered that there is an abnormality such as chattering, so the process returns immediately, and if the time has elapsed, it proceeds to the next process (S19). In S21, it is checked whether the IC card 55 storing a program related to the infrared photography mode is inserted. If it is attached, infrared photography is possible, so the photography mode including the infrared photography mode is changed by one in the up direction (S23). If it is not attached, the infrared photography mode is skipped and the photography mode is changed by one in the up direction (S25). And then return.
The information stored in the IC card 55 is read into the CPU 27 through communication and stored in the E''FROM 41 when the IC card 55 is attached to the adapter 56 and the main switch of the camera is turned on. Up switch swup is OFF and down switch S
If the WDN is ONL, the process advances from S15 to 327. In S27, an IJP/DOWN timer counter is started, and in S29, it is checked whether this counter has timed up. If the time is not up, return, if the time is up, S31
Proceed to. In S31, it is checked whether the IC card 55 storing a program related to infrared photography is installed. If the IC card 55 is installed, infrared photography is possible, so the photography mode including the infrared cotton photography mode is changed by one downward direction (S33). If it is not attached, the prescribed infrared photography cannot be performed, so the infrared photography mode is skipped and the photography mode is changed by one downward direction (S35). And then return. The above mode change operation selects infrared photography mode, normal photography mode, etc. Next, an example of the photographing operation in the infrared photographing mode will be described with reference to the flowcharts of FIGS. 5 and 6. The program on which this flowchart is based is an infrared photography program stored in the IC card 55. The embodiment shown in FIG. 5 has a configuration in which after automatic focusing is performed based on visible light, the focus is corrected by infrared rays. The photographer loads an infrared film into the camera body 11 and sets the infrared photography mode using the mode setting operation described above. When you press the release button (when you turn on the metering switch SWS)
, enter this flowchart. This flowchart is
It is executed repeatedly while the photometry switch SWS is ONL. Please note that an infrared filter is not attached. When entering this flowchart, first the distance measurement operation is started, and the distance measurement sensor 23 is made to start integration (accumulation of signal charge) (S4
1). The CPU 27 sequentially takes in the pixel data integrated by the CCD line sensor of the distance measurement sensor 23 via the DPU 25, converts the data into A/D, and stores it in the internal RAM (S
43, S45). After all pixel data of the CCD line sensor has been memorized, a predetermined calculation is performed based on the memorized data to obtain the defocus amount b (S47). Then, it is checked whether the image is in focus, that is, whether the defocus amount b is O (S49). If the image is not in focus, the process advances to S51. In S51,
A predetermined calculation (
pi. = b/k) to calculate the lens drive amount (AF pulse number Pκ).

Next, the number of AF pulses P obtained in S51. The lens is driven based on (S53). Then, the process returns to S41 and the normal focusing process of S41-353 is repeated until the camera is in focus. If it is confirmed in S49 that the image is in focus, the process advances to S55 to check whether the infrared photography mode is on. AF because no focus correction is required unless you are in infrared shooting mode
The operation will end, but if you are in infrared mode, you will need to correct the focus. Therefore, in the case of infrared mode, a predetermined calculation (Pc=c/k) is executed based on the infrared movement amount C read from the lens CPU 49, and the focus correction amount (infrared correction AF pulse number PC) is calculated. (S57). Then, based on this infrared correction AF pulse number Pc, AF
The motor 3l is started, the focusing lens L is driven to the infrared focusing position, and the AF operation is completed (S59). With the above operations, an infrared image of the subject is focused on the infrared film. The above is an example in which the focusing lens L is driven to the infrared focusing position after performing a normal focusing operation using visible light.Next, an example in which the focusing lens L is driven to the infrared focusing position from the beginning The operation will be explained with reference to the flowchart shown in FIG. The operations of S61, S63, S65 and S67 are the same as those of S61, S63, S65 and S67.
41, S43, S43 and S45, and the pixel data of the CCD line sensor is transferred to the RA of the CPU 27.
It is stored in M. In S69, it is checked whether the mode is infrared shooting mode, and if it is in infrared shooting mode, S71 is checked.
Then, the infrared defocus amount a is calculated based on the infrared movement amount C read by the lens CPU 49. In S73, it is checked whether the focus is achieved, that is, whether the infrared defocus amount a is O. If it is O, the focus is established, and the process proceeds to end the AF. If it is not 0, it is not in focus, so proceed to S75. And the formula, PI = (b
-c)/k. Calculate the number of infrared AF pulses P, by
This infrared AF pulse number P. Activate the AF motor 3l based on and move the photographing lens L to the infrared focusing position (
S77). The above operations in S61-377 are repeated until focus is achieved. On the other hand, if it is not the infrared photography mode, the process proceeds from S69 to S79, where it is checked whether the focus is in focus, that is, whether the defocus amount b is O, and if it is O, the process proceeds to end the AF. If it is not 0, the number of AF pulses Pr is calculated based on the defocus amount b (S81), and the AF motor 3l is activated based on this number of AF pulses Pt to drive the focusing lens L (S83). Then, the operations of S61 to S71 and S77 to S83 are repeated until the image is brought into focus. With the above operations, the autofocus device can quickly focus even in infrared photography. As described above, according to the single-lens reflex camera of this embodiment, when performing infrared photography, the I
By loading the C card 55 into the camera and selecting the infrared mode, the automatic focusing device performs automatic focusing, making operation very easy and allowing quick shooting, so you never miss a photo opportunity. There will be no more.

In addition, since infrared photography cannot be performed when the IC card 55 is not loaded, removing the IC card 55 during normal photography reduces the number of mode settings, and also prevents the infrared photography mode from being set by mistake during normal photography. You can prevent accidents such as setting the camera and taking pictures. As described above, in this embodiment, in view of the low frequency of infrared photography, information regarding infrared photography is stored in the IC card 55, and infrared photography is made possible by loading this IC card 55. may be stored in the CPU 27 or the E''FROM 41 in advance.The amount of infrared movement C varies depending on the wavelength of the reference infrared ray, so it may be set to a standard value, or multiple settings may be made to The configuration may be selected by the photographer according to the sensitivity characteristics of Based on the focus detection information and the corresponding infrared focus information, the focusing lens is moved to the position where the infrared image is focused, so it automatically and quickly focuses even in infrared photography.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an overview of an AF device for a single-lens reflex camera to which the present invention is applied; FIG. 2 is a block diagram showing an overview of the entire system of the same-lens reflex camera; FIG. 3A; Figure 3B is a diagram for explaining the deviation of the 6 focusing positions during infrared photography, Figure 4 is a flowchart regarding the infrared photography mode selection operation in the same reflex camera, and Figures 5 and 6 are , are operation flowcharts showing different embodiments of infrared photographing operations in the same reflex camera. 1l...Camera body, 23...Distance sensor, 25
...DPU. 27...CPU% 31...AF motor, 41...E"PROM, 4 3...Photographing lens, 49...Lens CPU, 55...IC card, L...Focusing lens ．．

Claims (5)

[Claims] (1) An autofocus camera comprising a focus detection means and a lens drive means for moving the focusing lens to the focus position based on focus position information of the focusing lens obtained by the focus detection means, , the lens driving means includes an infrared focus information converting means for obtaining infrared focus information based on the visible light focus information obtained by the focus detection means during infrared photography; An automatic focusing camera with an infrared photography mode, characterized in that the focusing lens is moved to an infrared focusing position. (2) A focus detection means for detecting the amount of defocus of visible light, and a lens drive means for moving the focusing lens to a position where the amount of defocus becomes 0 based on the amount of defocus obtained by the focus detection means. In the autofocus camera, the lens driving means operates the focusing lens based on the defocus amount of the infrared rays when the defocus amount of the visible light obtained by the focus detection means becomes 0 during infrared photography. An automatic focusing camera with an infrared photography mode, characterized in that the camera is moved to a focusing position where the amount of defocus of infrared rays becomes 0. (3) In claim 2, the lens driving means moves the focusing lens to a focus position based on the amount of defocus of visible light obtained by the focus detection means, and then moves the focusing lens based on the amount of defocus of infrared rays. An autofocus camera with an infrared photography mode that moves the lens to the infrared focusing position. (4) In claim 2 or 3, the amount of defocusing due to infrared rays when the amount of defocusing due to visible light is 0 is stored in a lens memory mounted on a photographing lens, and the amount of defocusing due to infrared rays when the amount of defocusing due to visible light is 0 is stored in a lens memory mounted on a photographing lens, and the amount of defocusing due to infrared rays is stored from the lens memory to drive the lens of the camera body. An autofocus camera with an infrared photography mode, characterized in that it is read into the means. (5) In claim 2 or 3, the autofocus camera includes an IC in which focus adjustment information during infrared photography is stored.
An autofocus camera with an infrared photography mode, characterized in that a card is formed to be removable, and focus adjustment operation information during infrared photography is read from the IC card.