JP3003937B2 - Focus adjustment system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus adjustment system, and more particularly, to a focus adjustment element of an imaging optical system in a direction in which the sharpness of a subject image by the imaging optical system is higher. In which the focus adjustment operation is performed by irradiating auxiliary light.

[Prior Art] When a still camera has a contrast type automatic focusing unit (hereinafter, referred to as AF), usually,
When photographing a subject having a predetermined luminance, the reflected light from the subject is captured via a taking lens, and the focus is detected by measuring the sharpness of the subject image.
A focusing operation can be performed. However, when photographing a low light quantity subject, the sharpness of the image cannot be measured because the amount of reflected light from the subject is small. In such a case,
In a conventional camera, a focusing operation is performed by irradiating a subject with auxiliary light, taking in reflected light of the subject through a taking lens, and measuring the sharpness of the subject image, separately from strobe irradiation.

The irradiation range of the auxiliary light is generally set so as to irradiate a part of the subject in order to save power. That is, as shown in FIG. 2, the auxiliary light irradiation range for the image frame 61 is limited to a narrow range indicated by the irradiation unit 62, and the consumption of the battery is reduced as much as possible.

As an auto-focusing light projecting device for another focus adjusting device, one disclosed in Japanese Patent Application Laid-Open No. 1-112212 relates to an auxiliary light projecting device for focusing, and a photographing lens light device. The projection image of the auxiliary light is formed on an axis.

[Problems to be Solved by the Invention] However, according to the above-described conventional contrast type AF apparatus using the auxiliary light for irradiation, since the auxiliary light irradiation system is a fixed focus system, the contour of the irradiation unit 62 is blurred. In the case where the subject is in a state where the subject is located near the auxiliary light irradiating portion 62 and has little unevenness and little change in brightness, that is, a so-called low-contrast subject, the contrast value for focus detection is set. That is, there is a problem that the high frequency component of the image is low and the focusing accuracy is reduced.

An object of the present invention is to provide a so-called contrast-type focusing adjustment system in which a focusing adjustment element of an imaging optical system is gradually displaced so as to increase the sharpness of imaging, in order to solve the above-described disadvantage. When performing AF using light, the contrast of the pattern image on the subject can be detected by the illumination pattern of the auxiliary light that is at least partially focused on the subject. An object of the present invention is to provide a focus adjustment system that enables AF operation.

[Means and Actions for Solving the Problems] A focus adjustment system according to the present invention has an imaging function having a planar imaging region, and at least a part of the planar region in the imaging region is subjected to distance measurement or focusing control. It is set as a dedicated or dual-purpose distance measurement area for informationization, and the imaging optical system is directed in a direction in which the sharpness of an image by the imaging optical system related to predetermined irradiation of auxiliary light by the auxiliary light irradiation unit becomes higher. A focus adjusting system of a system for gradually displacing a focus adjusting element, wherein the auxiliary light irradiating means has a planar light projecting portion having a predetermined pattern, and a light projecting surface of the light projecting portion and a light projecting surface of the light projecting portion. When the arrangement form with the light projection imaging optical system corresponding to the above is sufficient irradiation for detecting the sharpness of the image at any applicable distance within at least a predetermined range of the focus adjustment range of the imaging optical system. Patter As the focus state of the image is obtained for at least a part of the same pattern, the intersection angle between the light projection surface and the main plane of the light projection imaging optical system is configured to maintain a predetermined angle, and At least within the predetermined range of the focus adjustable range, the subject irradiation range by the auxiliary light is set to have a substantially uniform distribution with respect to the center of the distance measurement field corresponding to the distance measurement region at any applicable distance. It is characterized by being done.

[Embodiment] First, before describing an embodiment of the present invention, the second and third embodiments will be described.
The concept of the present invention will be described with reference to the drawings.

As described above, according to the present invention, the focus adjustment element of the imaging optical system is adjusted in a direction in which the sharpness of the subject image is higher, that is, in a direction in which the high frequency component (hereinafter, referred to as a contrast value) of the imaging signal is larger. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called contrast-type focusing adjustment system in which an auxiliary light irradiating means is used for focusing.

This system has an image sensor for detecting an image, a circuit for detecting a contrast value, and a focusing lens for imaging which is a focus adjusting element, and irradiates an auxiliary light through a photographing lens including the focusing lens. The reflected light of the irradiation pattern 63 detected by the means is taken in as an image pickup signal of the pattern, and its sharpness is detected to perform a focusing operation.

The auxiliary light irradiating means is a light projecting optical system having a planar light projecting portion 4a having a predetermined pattern as shown in FIG. 2A and capable of focusing light of the surface light source LED4. Irradiation is performed on the subject through the lens, and an irradiation pattern 63 as shown in FIG. Note that the irradiation pattern 63 is a pattern in which more high-frequency components can be detected in the horizontal scanning direction H of the image sensor, that is, the pattern contour is resolved with respect to the scanning lines in the horizontal scanning direction H. A pattern that crosses as many as possible is preferable in terms of focusing accuracy. Further, the irradiation pattern 63 is related to the focusing operation of the focusing lens for photographing, and the displacement of the focusing lens for focusing is performed so that the focus of the irradiation pattern 63 matches the focusing distance. The projection lens is displaced. Therefore, when the focusing lens is displaced in the focusing direction, the projection lens is also displaced in accordance with the change, and changes so that the sharpness of the contour of the irradiation pattern 63 becomes higher. When the contour of the pattern 63 becomes sharpest on the subject, the focusing lens is also focused on the subject.

3 (A), (B) and (C) show the state of image formation of the above-mentioned irradiation pattern. FIG. 3 (B) shows an example in which the object distance is set to, for example, 1.7 m and the focusing lens is applied to the object. Assuming that the object is in focus, the irradiation pattern is also in focus as described above, and shows the irradiation pattern 63 in that case. FIG. 3 (A),
3C shows the irradiation patterns 63 'and 63 "when the focusing lens is out of focus, that is, when the focusing lens is in the front focus or the back focus, respectively.
(E) and (F) are FIGS. 3 (A), (B),
Each of the irradiation patterns 63 ', 63, 63 "of (C) is input to the image sensor, and shows a change in the amount of light of the image in the horizontal scanning direction H. FIG. 3 (D) or (F) Since the waveform is not sharp and the contrast value is low because the waveform is for an unfocused state, when the focusing operation is continuously performed and the sharpest pattern such as the irradiation pattern 63 is obtained, the light amount becomes large. The waveform of the change becomes sharp as shown in FIG. 3 (E), the contrast value becomes maximum, and the focusing of the focusing lens is completed.

In the above description, the projection lens of the auxiliary light irradiating means and the focusing lens for photographing are changed so as to correspond to focus at the same distance. However, it is not always necessary to change the projection lens. The intersection angle between the light projection surface of the light and the main plane of the projection lens, which is an imaging optical system for the light projection, is arranged to be inclined at a predetermined angle (indicated by θ in FIGS. 6 and 10), If the auxiliary light projecting means is set so that any part of the irradiation pattern is kept in focus at any distance corresponding to the focus adjustable range of the imaging optical system, the focus adjustment according to the present invention can be performed. The system can be realized.

Next, a focus adjustment system according to a first embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the configuration of the focus adjustment system includes a photographic lens (not shown in FIG. 1) including a focusing lens 1 which is a focus adjustment element of an imaging optical system, and an image sensor. A CCD 2, a projection lens 3 that is displaceable for focusing, which is an auxiliary light irradiating unit, and a surface light source, having a planar light projecting unit 4 a having a predetermined pattern
An LED 4 (see FIG. 2 (A)), a sample-and-hold circuit for the CCD2 image pickup signal, a pre-processing circuit 5 for outputting a video recording signal, and a high-frequency component of the output of the pre-processing circuit 5 A band-pass filter BPF6 to be extracted, a detection circuit 12, an area integration circuit 7, and a focus drive control circuit 10 for outputting an electric signal for driving the focusing lens 1 and the projection lens 3 in relation to the change in the contrast value. And a lens driving device 9 for displacing the focusing lens 1 and the projection lens 3 in the focusing direction.
And an LED drive circuit 11 for driving the LED 4 and a CPU
Consists of eight.

Note that a high-pass filter HPF may be used instead of the BPF 6 described above. Further, the area integration circuit 7 includes a BPF 6
The signal obtained by detecting the high frequency component output from the detection circuit 12 by the detection circuit 12 is integrated with respect to the distance measurement area 62 including the irradiation pan 63 (see FIG. 2B) of the image frame 61, and the value is output as a contrast value. Things. Further, the CPU 8 controls each of the above circuits and simultaneously controls the focus drive based on the change in the contrast value.

FIGS. 4A and 4B show more specific configurations and arrangements of the imaging optical system, the auxiliary light irradiation optical system, and the lens driving device 9.
This will be described with reference to FIG.

The imaging lens of the imaging optical system is a four-group lens, and the first-group focusing lens 1 is fixed to a lens barrel 25 that can be displaced for focusing in the optical axis O direction. A variator lens 22 for zooming, a compensator lens 23 for focusing, and a relay lens 24 are disposed along the optical axis O as the second to fourth lens groups, and the CCD 2 is located at the image forming position of the lens group. It is arranged on a camera body (not shown). On the other hand, the projection lens 3 of the auxiliary light irradiating means is fixed to a lens barrel 26 displaceable in the direction of the optical axis O ', and faces the lens 3 and has a light emitting surface perpendicular to the optical axis O'. The LED 4 having the light projecting portion 4a is fixed to a support member 33, and the support member is supported by a camera body (not shown).

The outer peripheral portion of the lens barrel 25 has a gear 25a and a cam groove 25b that is displaced in the axial direction as the lens barrel 25 rotates. Similarly, the outer peripheral portion of the lens barrel 26 has a gear 26a and a cam groove 26b that is displaced in the axial direction as the lens barrel 26 rotates. Pins 33 and 34 fixed to the camera body are fitted into the cam grooves 25b and 26b of the lens barrels 25 and 26, respectively.

The lens driving device 9 controlled by the focus driving control circuit 10 includes a driving motor 27 and a gear train. The gear train is fitted on the output shaft of the motor 27,
A pinion gear 28 meshing with 25a, and further, a gear 2
8 is composed of a large gear 30a meshing therewith and a small gear 30b integral therewith and meshing with the gear 26a of the lens barrel 26. The large gear 30a and the small gear 30b have a shaft 29 and are supported by camera bodies 32a and 32b.

FIG. 4 (B) shows the lens driving device 9 and the lens barrel 2.
It is a perspective view in the assembled state of 5,26. The rotation of the drive motor 27 rotates the lens barrel 25 via the pinion gear 28,
At the same time, the lens barrel 26 rotates via the gear train. The focusing lens 1 follows the respective cam grooves 25b and 26b.
The lens barrel 25 to which the projection lens 3 is fixed and the lens barrel 25 to which the projection lens 3 is fixed extend along the optical axis O,
The projection lens 3 is extended so as to be displaced in the O 'direction and to change the focusing distance of the focusing lens 1 of the imaging system, which is changed by the focusing operation as described in the explanation of the concept, to the imaging distance of the irradiation pattern of the auxiliary light. Will be.

The extension amount of the lens barrels 25 and 26 is determined by the focal length of both lenses, and thereby the gear ratio of the gear train or the lead of the cam groove is determined. First, in order to obtain the extension amounts of both lenses, the distance to the subject 35 is set to a in FIG. 4, the focal lengths of the focusing lens 1 and the projection lens 3 are set to f _T and f _I , respectively, and focusing on the subject 35 is performed. movement amount of the focusing lens 1 and the projection lens 3 for delta _T, delta _I each Becomes Relationship from the two equations feeding amount delta _T and delta _I is determined as follows.

And in general Therefore, the following expression may be used as an approximate expression.

The error for approximation of the above equation (2) is, for example,
Focal length f _T = 30 mm, f _I = 15 mm, approx.
1.5%.

Now, assuming that the ratio of the focal length between the focusing lens 1 and the projection lens 3 is 2, Next, the feed-out amount delta _I of the projection lens 3, the ratio of the feeding amount delta _T of the focusing lens 1 from (2) Becomes The ratio of the number of teeth of the gear train when the leads of the cam grooves 25b and 26b of the lens barrels 25 and 26 are equally set is as follows from equation (3).

However, N _T, N _I shows gear 25a of each barrel 25 and 26, tooth number N _G of 26a, respectively N _H is large gear 30a and the number of teeth of the pinion 30b.

The operation of the focus adjustment system according to the present embodiment configured as described above will be described.First, when the light amount is insufficient during the focus operation, the irradiation pattern 63 is projected onto the subject by the auxiliary light irradiation unit. Focusing lens 1
Is not focused, so that the irradiation pattern 63 is also shown in FIG. 3 (A).
Or the state is out of focus as shown in FIG. Therefore, the contrast value of the photographing signal captured from the CCD 2 is not a peak value. Subsequently, the focusing lens 1 and the projection lens 3 are displaced in the focusing direction by the lens driving device 9 in accordance with a command from the CPU 8. Then, the sharpness of the irradiation pattern 63 gradually increases, and finally the state shown in FIG. 3B is reached, and the peak value of the contrast value of the imaging signal is detected by the area integration circuit 7 to complete the focusing.

According to the present focusing system, the sharpness of the irradiation pattern 63 is changed according to the degree of focusing, and the sharpness is taken into a contrast value. Even if there is no change or the like, the focusing operation can be effectively performed by the irradiation pattern. In addition, since the irradiation area of the irradiation pattern is within a limited range and is in a pattern state, there is an advantage that a combined irradiation area is reduced and power consumption is reduced. If the subject itself has irregularities and the change in brightness is abundant, focusing is performed by the contrast value of the sum of the contrast value based on the sharpness of the subject itself and the contrast value based on the sharpness of the irradiation pattern. Will be determined. In this embodiment, the irradiation pattern 63
Although the projection lens 3 is displaced in order to focus the light, the focus effect can be provided by displacing the LED 4 of the light source to adjust the focus.

Next, as a modification of the focus adjustment system of the first embodiment of the present invention, a focusing lens 1 'and a projection lens 3'
The structure of the lens barrel in a case where the focal lengths of the lens barrels are equal to each other and the amounts of extension related to focusing of both lenses are equal will be described with reference to FIG. Since the feeding amount is the same, a separate driving device is not required, and the lens barrel 25 'for the focusing lens 1' and the lens barrel 25 'for the projection lens 3' can be integrally formed. It can be very simplified and provide useful things.

Next, a focus adjustment system according to a second embodiment of the present invention will be described with reference to FIGS.

The focus adjustment system of the present embodiment is a system that does not need to be extended for focusing of the image forming optical system of the auxiliary light irradiation unit. Then, as shown in FIG. 6, a planar light projecting portion 44a having a predetermined pattern of the LED 44 as the surface light source with respect to a surface g parallel to the main plane of the projection lens 43 as the auxiliary light irradiating means. The plane is inclined at the intersection angle θ. By inclining the light projection surface in this manner, the pattern can be projected and imaged so that any part of the irradiation pattern is focused on the entire range in which the focusing of the imaging optical system can be adjusted. That is, the distance a ₂ from the projection lens 43 is the closest focus position and the distance.
If a ₁ is the farthest position of focusing, the distance range P is the focusing adjustment range. The imaging portion length d of the light projection surface 44a is projected is located in between the points i ₁ from point i _2, respectively, the distance
The intersection angle θ is set to correspond to a ₂ and a ₁ .

A method for obtaining the above-mentioned intersection angle θ will be described first.
The distance from the lower and upper ends of the light projecting portion 44a to the projection lens 43 and b ₁ and b _2. And the relational expression between the subject distances a ₁ and a ₂ related to these two values is On the other hand, the intersection angle θ is Here, d indicates the length of the light projection unit 44a. (4),
From the equations (5) and (6), the intersection angle θ is Becomes Furthermore, the approximate expression is Becomes When the actual value is substituted to obtain the intersection angle θ, for example, the length d of the light projecting portion 44a of the LED 44 is 1 mm, the farthest distance a ₁ in the focusing range is 5 m, and the closest distance a ₂ in the focusing range is When the focal length f1 of the projection lens is ₁ mm and the focal length f1 of the projection lens is 15 mm, the intersection angle θ is 10
゜ 36 '.

The configuration of a system using the auxiliary light irradiating means configured as described above will be described with reference to FIG. 7. An imaging lens (not shown) including a focusing lens 41 which is a focusing adjustment element of an imaging optical system, CCD42 which is an image sensor
, A projection lens 43 as an auxiliary light irradiation unit, and a projection lens
An LED 44 having a planar light projecting portion 44a having a predetermined irradiation pattern obliquely arranged with respect to 43; a sample-and-hold circuit for an image signal of the CCD 42; a pre-processing circuit 45 for outputting a video recording signal; A band-pass filter BPF for extracting a high-frequency component of the output of the pre-processing circuit 45, a detection circuit 52, an integration circuit 47 having a peak hold function, and a driving circuit for driving the focusing lens 41 for focusing operation. A focus drive control circuit 49 for outputting an electric signal, a lens driving device 50 for displacing the focusing lens 41 in a focusing direction, and L for driving the LED 44
An ED drive circuit 51 and a CPU 48 are provided.

The integration circuit 47 integrates the detection output of the high-frequency component of the image signal every horizontal scan or every several horizontal scans, and holds the peak value of the integrated value until the end of the field. is there. The CPU 48 controls each circuit and outputs a control signal for driving the focusing lens 41 so as to obtain the peak value of the partial contrast value for each focusing operation.

The operation of the focus adjustment system according to the present embodiment configured as described above will be described. In the irradiation pattern by the auxiliary light irradiation unit of the present embodiment, if the subject distance is within the focusable range, there is always a part where the pattern is focused and the image becomes sharp. Figure 8 (A), (B), (C) shows the imaging state of the illumination pattern for each object distance of the auxiliary light emitting means, and in _{FIG., H 1, H 2, H} 3 , respectively 5 shows a horizontal scanning position of the image sensor. FIG. 8A shows a case where the subject distance is the farthest distance a ₁ (for example, 5 m) within the focusing range, and the horizontal scanning position H _{1 at the} upper position.
Are the in-focus portions, and the other portions of the pattern 64b 'are out of focus, that is, the portions where the pattern is out of focus. Further, Figure 8 (B) shows a case where the subject is in a central position within the focusing range, the pattern 64a in the portion corresponding to the horizontal operating position of H ₂ central portion a focus region in focus,
The other pattern 64b indicates a part that is out of focus. Further, FIG. 8 (C) is the closest distance a ₂ of the subject distance is within the focusing range (e.g., 1 m) shows a case where the pattern 64a in the portion corresponding to the horizontal scanning position H ₃ lower position " Is a focused portion, and the other pattern 64b ″ indicates an out-of-focus portion.

Then, FIG. 8 (D), (G), (M) illumination pattern 64a of the FIG. 8 (A) ', 64b' horizontal scanning position H ₁ to H of
₃ shows a diagram of a change in light amount corresponding to _3. FIG. The diagram of Figure 8 corresponding to the scanning position H ₁ of the matching portion of focus (D) shows a sharp change, therefore, Tokoma the CPU48 through the imaging device if the focusing lens 41 is long been focused The partial contrast value of the pattern to be displayed also shows a high value. However, the diagrams in FIGS. 8 (G) and 8 (M) correspond to the pattern portion which is out of focus, so that the waveform is gentle and the partial contrast value taken into the CPU 48 is low. Height relationship of these contrast values, because not reversed even when the focusing lens 41 is not focused, the information held by the integrating circuit 47 and the contrast value that corresponds to the vicinity of this case, the scanning lines H ₁ Become. In addition, the other FIGS. 8 (E), (J),
The same applies to the diagrams of (N) or (F), (K) and (Q), and the diagrams of FIGS. 8 (J) and (Q) corresponding to the in-focus portions of the corresponding irradiation patterns are similar. A sharp waveform is shown, and a partial contrast value corresponding thereto is also increased. However, the others correspond to the out-of-focus portion of the corresponding irradiation pattern, and the partial contrast value naturally becomes low. Therefore, the integration circuit
Information is held by 47, FIG. 8 (B) near the scanning lines H ₂ for, a contrast value corresponding to the vicinity of H ₃ for (C).

Therefore, when the system according to the present embodiment is in focus, when an irradiation pattern is projected on a subject within the focusing range, the irradiation pattern is focused in accordance with the subject distance as described above. The contrast value of the part is obtained.
Then, while monitoring the change in the contrast value, the focusing lens 41 is repeatedly driven for focusing. When the contrast value of the focused pattern portion in the irradiation pattern reaches a peak value, the focusing lens 41 is focused. Will end.

In this example, the integration circuit 47 is provided with a peak hold function so that only the information of the high contrast part in the irradiation pattern can be used. However, the area integration circuit similar to the first embodiment can be used. good. The reverse is also true.

LED4 which is an auxiliary surface light source in this auxiliary light projection means
4 must be inclined at an angle of intersection θ with respect to the main plane of the projection lens 43 as described above. One specific example of the assembling mechanism is shown in FIGS. 9 (A) and 9 (B). . 9 (A) is a vertical cross-sectional view (Z-Z cross section of FIG. 9 (B)) of the mounting mechanism of the LED 44, and FIG. 9 (B) is a view taken along the arrow Y of FIG. 9 (A). FIG. A screw portion 56a is provided on a support plate 56 supported by the camera body. On the other hand, the LED 44 is fixed to the LED mounting plate 55 with an adhesive or the like. The adjusting screws 57a, 57b, 57c are inserted into the holes 55a provided in the LED mounting plate 55, and the compression springs 58a are further inserted into the holes 55a. The intersection angle θ is set by adjusting the amount. After the adjustment, the screwed portion is fixed with an adhesive or the like. Although the setting angle of the above-mentioned mounting mechanism is variable, an angle-fixing mounting mechanism may be employed if no particular adjustment is required.

As described above, the focusing adjustment system of the present embodiment does not need to displace the projection lens 43 in accordance with the focusing operation as compared with the first embodiment, and provides an auxiliary light projection unit having a very simple structure. Is what you do.

In the auxiliary light projecting means of the second embodiment described above, the auxiliary light source is inclined at the time of setting the intersection angle, but as a modified example, the projection lens is oriented with respect to the photographing optical axis O '. The system according to the second embodiment can be realized by obliquely mounting. FIG. 10 shows a side view of the projection means, and shows a plane g perpendicular to the optical axis O '.
An LED 44 ′ having a light projecting portion 44 a ′ disposed thereon and a projection lens 43 ′ obliquely arranged at an intersection angle θ with respect to the vertical plane g, the focus range P of the light projecting portion 44 a ′ is The focus adjustment range is set similarly to the above-described second embodiment. In this modification, since the LED 44 'of the auxiliary light source is disposed perpendicular to the projection optical axis O', it can be assembled in parallel with other electric components, and the production and assembly of the electric components are simplified. Become.

By the way, the second embodiment and its modification have been described on the assumption that the projection optical axis is parallel to the photographing lens optical axis. However, in practice, the parallax between the distance measurement field and the auxiliary light ( In order to reduce parallax, the relationship between the two optical axes may be inclined. In such a case, it is necessary to pay some attention to the irradiation range of the auxiliary light, and this will be described with reference to the drawings.

Fig. 11 illustrates the auxiliary light irradiation direction axis O ", where S indicates the principal point of the light projecting lens, and R and Q indicate the edges of the light source surface, respectively. In this case, when the inclination is given between the main surface of the projection lens and the light source surface, the irradiation range is within the extended lines l _R and l _Q of RS and QS. Therefore, the irradiation direction in this case is represented by a bisector of the angle formed by l _R and l _{Q. In} other words, the irradiation direction axis O ′ is S and
It is defined as a straight line connecting ΔQRS and the inner center I. In addition,
As can be seen from the figure, O 'does not always coincide with the optical axis of the projection lens.

Here, considering the function of the auxiliary light again, it has two functions of "irradiation of a pattern containing many high-frequency components" and "illumination for compensating for insufficient illuminance", which have already been described in the embodiment. That said, the illumination function is mainly used for normal subjects other than low-contrast subjects. When considering the parallax with the lateral distance field of view, it is important to determine which of these two functions is more important.

That is, as shown in FIG. 13, the light projecting device for autofocus disclosed in the above-mentioned JP-A-1-112212,
A projection lens 61 having an illumination optical axis O ″ forming an angle α with an imaging optical axis O, which is an optical axis of the imaging lens 60, and a light source 62 are provided, and an image plane R′Q of the light source surface in the subject space is provided. 'Is set so that it overlaps the optical axis of the photographing. This is effective only when the distance measurement area is extremely narrow, such as an object using a line sensor as the distance measurement sensor. It is not suitable for a focus adjustment system having a planar ranging area as in the present invention for the following reasons.

That is, as described above, since the illumination function is mainly performed for a normal subject, the illumination area is considered to be below the photographic optical axis O for a distant subject as shown in FIG. , And the irradiation area for the closest subject is greatly shifted above the photographing optical axis O. Therefore,
As the patterns corresponding to the irradiation patterns shown in FIGS. 3 and 8, the irradiation pattern for the farthest object shown in FIG. 14A and the irradiation pattern for the closest object shown in FIG. As described above, the irradiation range of the auxiliary light greatly deviates below and above the distance measurement region, and protrudes from a predetermined region, so that the light use efficiency is significantly reduced. Even if the distance measurement area is expanded so as not to protrude,
In this case, the resulting shift of the irradiation range becomes a shift of the distance measurement area in the dark, which is not preferable. In addition, it is necessary to avoid a reduction in the degree of freedom in designing the distance measurement area due to such restrictions. Such a problem occurs because the angle β between the image plane R'Q 'and the photographing optical axis O is defined by the irradiation direction axis O "and the photographing optical axis O.
This is inevitable when trying to set a smaller angle α.

To solve the above problem, FIGS. 12A and 12B show irradiation states of auxiliary light irradiation means showing another modification of the focus adjustment system of the second embodiment. According to this irradiation means, the relationship between the angles α and β is set so as to satisfy α ≦ β, the deviation of the irradiation range is relatively small, and the distribution is substantially uniform with respect to the photographing optical axis O. It can be suppressed to the extent that it can be regarded as.

In the above description, the photographing optical axis O is used as a reference for parallax for convenience, but this is because the distance measurement area is usually set to a shape symmetrical with respect to the optical axis O,
If the distance measurement area is not symmetrical with respect to the optical axis O, the center point of the area (meaning a point that can be substantially regarded as the center for convenience of use, and depending on the shape of the area, for example, the center of gravity may be the center of the area. ) May be applied instead of the optical axis O (defined as a tracing line of light rays from the center of the area toward the principal point of the photographing lens).

Finally, when touching the direction in which the light projecting lens and the light source surface are inclined, in the second embodiment and its modifications, the intersection line between the light projecting lens main surface and the light source surface is in the scanning line direction (H direction) of the image sensor. The tilt is made in such a direction as to be parallel, which corresponds to the fact that the information detection direction is in the H direction due to the configuration of the contrast signal extraction circuit of the embodiment. If the detection direction is the vertical direction (V direction), it is desirable that the intersection line is inclined so as to be parallel to the V direction. The same applies to slanting directions other than the H and V directions.In general, the line of intersection between the main surface of the light projecting lens and the light source surface is a direction having at least sensitivity with respect to information detection of the applied system, preferably. May be tilted so as to be parallel to the direction of maximum sensitivity of detection.

[Effects of the Invention] As described above, the focus adjustment system according to the present invention irradiates the subject with the irradiation pattern using the auxiliary light, and detects the sharpness of the irradiation pattern to perform the focusing operation. Even if the subject itself has little unevenness and a small difference in brightness, that is, a so-called low-contrast subject, the focusing signal is detected by the above-described irradiation pattern, so that highly accurate focusing can be performed. ,Also,
Since the pattern light is employed as the auxiliary light, it is possible to provide a focusing adjustment system having remarkable features such as a small total irradiation area and power saving.

[Brief description of the drawings]

FIG. 1 is a block diagram of a focus adjustment system showing a first embodiment of the present invention, and FIG. 2 (A) is a diagram of an LED used as an auxiliary light source used in the focus adjustment system of FIG. FIG. 2 (B) is a view showing an irradiation pattern by the auxiliary light of the focus adjustment system of FIG. 1 and a conventional irradiation pattern of the auxiliary light, and FIGS. 3 (A), (B), ( C) is an irradiation pattern diagram for each focus state of the focus adjustment system of FIG. 1, and FIGS. 3 (D), (E), and (F) are FIGS.
4B is a diagram showing a change in light amount in the horizontal scanning direction of the image sensor corresponding to each of the irradiation patterns of FIGS. 4B and 4C. FIG. 4A is a diagram showing the focusing lens of the focusing adjustment system of FIG. FIG. 4 (B) is a perspective view of the driving device shown in FIG. 4 (A), and FIG. 5 is a focusing view of FIG. 1; FIG. 6 is a longitudinal sectional view of a main part of an integrated lens barrel of a focusing lens and a projection lens showing a modification of the adjustment system. FIG. 6 is a side view of auxiliary light irradiation means of a focusing adjustment system showing a second embodiment of the present invention. FIG. 7 is a block diagram of the focus adjustment system of FIG. 6, and FIGS. 8 (A), (B) and (C) are respective object distances of the focus adjustment system of FIG. 8 (D), (E), (F), (G), (G) J),
(K), (M), (N), and (Q) show changes in the amount of light in the horizontal scanning direction of the image sensor corresponding to the irradiation patterns of FIGS. 8A, 8B, and 8C, respectively. FIGS. 9 (A) and 9 (B) show the mounting mechanism of the auxiliary light source of the auxiliary light irradiating means of the focus adjustment system of FIG.
9A is a longitudinal sectional view (Z-Z section of FIG. 9B) of a main part, FIG. 9B is a view taken on arrow Y of FIG. 9A, and FIG. FIG. 11 is a side view of an auxiliary light irradiating means showing a modification of the focus adjustment system of FIG. 6, FIG. 11 is a side view showing an example of an auxiliary light projecting state of the auxiliary light projecting means, FIG. FIG. 13 is a side view showing an auxiliary light projecting state of auxiliary light irradiating means showing another modification of the focus adjusting system of the second embodiment. FIG. 13 is a longitudinal section of an autofocus light projecting device of a conventional focus adjusting device. 14 (A) and (C) show an irradiation pattern image on a subject by the light projecting device of FIG. 13, and FIG. 14 (A) shows a pattern on a subject at the farthest distance. Irradiation pattern, Fig. 14 (C)
7A and 7B are diagrams each showing an irradiation pattern on a subject at the shortest distance. 1,1 ', 41: Focusing lens (focusing adjustment element) (imaging optical system) 2,42 ... CCD (imaging optical system) 3,3', 43,43 ': Projection lens (irradiation of auxiliary light) Means) 4,44,44 'LED (Auxiliary light irradiating means) 4a, 44a, 44a' Light projecting unit (Auxiliary light irradiating means) 63,63 ', 63 ", 64a, 64b, 64a', 64b ′, 64a ″, 64b ″ ... irradiation pattern

Claims (1)

(57) [Claims] An imaging function having a planar imaging area;
At least a part of the planar area in the imaging area is set as a dedicated or combined distance measurement area for distance measurement or focusing control informationization, and the imaging optical system according to predetermined irradiation of auxiliary light by auxiliary light irradiation means A focus adjustment system of a system in which the focus adjustment element of the imaging optical system is gradually displaced in a direction in which the sharpness of an image is further increased, wherein the auxiliary light irradiation means has a planar light projection unit having a predetermined pattern. And the arrangement of the light projection surface of the light projection unit and the corresponding light projection imaging optical system corresponds to at least a predetermined range of the focus adjustable range of the imaging optical system. At any distance, the main part of the light projection surface and the light projection imaging optical system is so arranged that a focused state of the irradiation pattern sufficient to detect the sharpness of the image is obtained for at least a part of the pattern. The intersection angle with the plane is configured to maintain a predetermined angle, and at least within the predetermined range of the focus adjustable range, the subject irradiation range of the auxiliary light at any corresponding distance is in the distance measurement area. In order to achieve a substantially uniform distribution with respect to the center of the corresponding ranging field of view,
A focus adjustment system characterized by being set.