JP3335956B2 - Focus adjustment system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art When a still camera has a contrast type automatic focusing means (hereinafter referred to as AF), when a subject having a predetermined luminance is photographed, reflected light from the subject is usually taken by a taking lens. The focus point can be detected by measuring the sharpness of the subject image and the 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, the focusing operation is performed by irradiating the subject with auxiliary light, taking in the reflected light through a taking lens, and measuring the sharpness of the subject image, separately from strobe irradiation. I do.

It is conceivable to use infrared light as the auxiliary light. However, if infrared light irradiating means is used, a removing mechanism for removing the infrared light cut filter is required, resulting in high cost and large size. .

[0004]

On the other hand, when the visible light is used as the auxiliary light, the above-mentioned removing mechanism is not required, and the cost and size can be reduced as compared with the case where the infrared light is used. . However, if the subject is a person, eyes may be closed at the moment of shooting because the auxiliary light is visible light. An object of the present invention is to provide a focus adjustment system that prevents eyes from being closed at the moment of photographing due to useless light that does not contribute to distance measurement.

[0005]

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 used for distance measurement or focusing control information generation. Focus adjustment system that is set as a dedicated or combined distance measurement area, and gradually displaces the focus adjustment element of the imaging optical system in a direction in which the sharpness of an image by the imaging optical system becomes higher. Which is obtained from the planar area set as the distance measuring area.
Extraction of high-frequency components from image signals to be detected and
Corresponding to the above sharpness by integrating over the area
Information representing the entire planar area
A contrast signal extracting means for obtaining a G value, and provided at a position having a predetermined parallax with respect to the imaging optical system so as to compensate for the lack of illuminance of the subject corresponding to the distance measurement area, without passing through the imaging optical system. A light source having a planar light projection unit having a predetermined irradiation pattern for irradiating a subject with visible light
And an auxiliary light irradiating means having a, the auxiliary light irradiation means, and a said visible light source and projection lens, the distance measuring field central axis of the illumination axis and the imaging optical system of the auxiliary light emitting means Α (角 0), and the angle β between the projection image plane of the light source surface of the visible light source in the subject space by the light projecting lens and the center axis of the distance measurement visual field of the imaging optical system is α ≦ Being configured to satisfy β, the entire range of the focus adjustment range of the imaging optical system by irradiation of the auxiliary light is set so that the subject irradiation range by the auxiliary light is substantially included in the distance measurement area. It is characterized by becoming.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the concept of the present invention will be described with reference to FIGS. As described above, in the present invention, the direction in which the sharpness of a subject image is higher, that is, the high-frequency component
The present invention relates to a so-called contrast-type focus adjustment system in which a focus adjustment element of an imaging optical system is gradually displaced in a direction in which the contrast value increases (hereinafter referred to as a contrast value). .

This system comprises an image sensor for detecting an image,
And, a contrast value detection circuit, having a focusing lens for imaging that is a focus adjustment element, and via a photographing lens including a focusing lens,
The reflected light of the irradiation pattern 63 detected by the auxiliary light irradiation means is captured as a pattern image signal, 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 from the surface light source LED4. Illuminate the subject through a certain projection lens,
It is assumed that an irradiation pattern 63 as shown in FIG. The irradiation pattern 6
3 is a pattern in which more high frequency components can be detected in the horizontal scanning direction H of the image sensor, that is,
A pattern in which a large number of pattern contours cross a scanning line in the horizontal scanning direction H within a resolvable range 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 is focused 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.

FIGS. 3A, 3B, and 3C show the state of image formation of the above-mentioned irradiation pattern. FIG. 3B shows an example in which the focusing distance is set to 1.7 m when the object distance is set to 1.7 m. Assuming that the subject is in focus, the irradiation pattern is also in focus as described above, and shows the irradiation pattern 63 in that case. FIG.
(A) and (C) show that the focusing lens is out of focus.
That is, the irradiation patterns 63 'and 63 "in a blurred state in the case of the front focus and the rear focus, respectively, are shown.
(D), (E), and (F) show FIGS.
Each of the irradiation patterns 63 ', 63, 63 "of (B) and (C)
Shows the change in the amount of light in the horizontal scanning direction H of the image input to the image sensor, and FIG. 3D or 3F is for an unfocused state. No contrast value is low. Therefore,
Subsequently, a focusing operation is performed, and when a sharpest pattern such as the irradiation pattern 63 is obtained, the waveform of the change in the light amount becomes sharp as shown in FIG. Will be completed.

In the above description, the projection lens of the auxiliary light irradiating means and the focusing lens for photographing are displaced correspondingly so as to be focused at the same distance.
It is not always necessary to change the projection lens, and the intersection angle between the light projection surface of the auxiliary light and the main plane of the projection lens which is an imaging optical system for the light projection is a predetermined angle (indicated by θ in FIGS. 6 and 10). ) And an auxiliary light projecting means such that any part of the irradiation pattern is kept in focus at any distance corresponding to the focus adjustment range of the imaging optical system. Is set, the focus adjustment system according to the present invention 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 is as follows.
A photographing lens (not shown in FIG. 1) including a focusing lens 1 which is a focus adjusting element of the image pickup optical system, a CCD 2 which is an image pickup device, and a displacement for focusing which is an auxiliary light irradiation means are possible. LE that is a projection lens 3 and a surface light source and has a planar light projection unit 4a having a predetermined pattern
D4 (see FIG. 2 (A)), 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 are extracted. A band-pass filter BPF6,
A detection circuit 12, an area integration circuit 7, 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 the focusing lens 1. A lens driving device 9 for displacing the projection lens 3 in the focusing direction, and an LED for driving the LED 4
It comprises a drive circuit 11 and a CPU 8.

Note that a high-pass filter HPF may be used instead of the BPF 6. The area integration circuit 7 outputs a signal obtained by detecting the high frequency component output from the BPF 6 by the detection circuit 12 to the irradiation panel 63 of the image frame 61.
This is to integrate the distance measurement area 62 including (see FIG. 2B) and output the value as a contrast value. Further, the CPU 8 controls each of the above circuits and simultaneously controls the focus driving based on the change in the contrast value. More specific configurations and arrangements of the imaging optical system, the auxiliary light irradiation optical system, and the lens driving device 9 will be described with reference to FIGS.

The taking lens of the image pickup optical system is a four-group lens, and the focusing lens 1 of the first group has an optical axis O.
The lens is fixed to a lens barrel 25 that can be displaced for focusing in the direction, and further includes a zooming variator lens 22 for zooming, a focus compensator lens 23, and a relay as other second to fourth lens groups. A lens 24 is provided along the optical axis O, and the CCD 2 is provided on a camera body (not shown) at an image forming position of the lens group. On the other hand, the projection lens 3 of the auxiliary light irradiation means is fixed to a lens barrel 26 which can be displaced in the direction of the optical axis O ′.
A planar light projection unit 4a whose light emitting surface is perpendicular to the optical axis O '.
Is fixed to the support member 31, and the support member is further supported by a camera body (not shown).

A gear 25 is provided on the outer periphery of the lens barrel 25.
a and a cam groove 25b that is displaced in the axial direction with the rotation of the lens barrel 25. 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 comprises a driving motor 27 and a gear train. The gear train is fixed to the output shaft of a motor 27, and is engaged with a gear 25a of a lens barrel 25, and a large gear 30a meshed with the gear 28.
And a small gear 30b which is integral therewith and meshes with the gear 26a of the lens barrel 26. The large gear 30a and the small gear 30b have an axis 29, and the camera body 3
It is supported by 2a and 32b.

FIG. 4B is a perspective view of the lens driving device 9 and the lens barrels 25 and 26 in an assembled state. The rotation of the drive motor 27 rotates the lens barrel 25 via the pinion gear 28, and at the same time, the lens barrel 26 also rotates via the gear train. The lens barrel 2 on which the focusing lens 1 is fixed following the respective cam grooves 25b and 26b.
5, and the lens barrel 26 to which the projection lens 3 is fixed are displaced in the directions of the optical axes O and O 'extending toward the subject.
As described in the description of the concept, the projection lens 3 is extended so that the focusing distance of the focusing lens 1 of the imaging system, which is changed by the focusing operation, matches the imaging distance of the irradiation pattern of the auxiliary light.

The amount of extension of the lens barrels 25 and 26 is determined by the focal length of both lenses, whereby the gear ratio of the gear train or the lead of the cam groove is determined. First,
In order to determine the amounts of extension of both lenses, the distance to the subject 35 in FIG. 4 is a, and the focal lengths of the focusing lens 1 and the projection lens 3 are fT and fI, respectively.
And the extension amounts ΔT and ΔI of the focusing lens 1 and the projection lens 3 for focusing on the subject 35 are respectively Becomes From these two equations, the relational expression between the feeding amounts ΔT and ΔI is obtained as follows.

[0018] And in general Therefore, the following expression may be used as an approximate expression.

[0019] The error for approximation of the above equation (2) is, for example, about 1.5% when the focal length fT is 30 mm, fl is 15 mm, and the closest shooting distance is 1 m.

Assuming that the ratio of the focal length of the focusing lens 1 to the focal length of the projection lens 3 is 2, The ratio of the extension amount ΔI of the projection lens 3 to the extension amount ΔT of the focusing lens 1 is given by the equation (2). Becomes Then, the cam grooves 25b and 26 of the lens barrels 25 and 26
From the equation (3), the ratio of the number of teeth of the above-mentioned gear train when the lead with b is equal is obtained as follows.

[0021] However, NT and NI are the gears 25 of the lens barrels 25 and 26, respectively.
a, 26a are the number of teeth, NG, NH are the large gears 30a, respectively.
And the number of teeth of the small gear 30b.

The operation of the focus adjusting system according to the present embodiment having the above-described configuration will be described. First, when the light amount is insufficient during the focusing operation, the irradiation pattern 63 is projected onto the subject by the auxiliary light irradiation means. However, since the focusing lens 1 is not focused, the irradiation pattern 6
3 is also in a state where the focus is out of focus as shown in FIG. Therefore, the contrast value of the image signal taken in from the CCD 2 is not a peak value. Subsequently, the focusing lens 1 and the projection lens 3 are
Is displaced by the lens driving device 9 in the focusing direction. 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 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 incorporated into the contrast value. The focusing operation can be effectively performed by the irradiation pattern without having any change in brightness or brightness. Further, since the irradiation area of the irradiation pattern is within a limited range and is in a pattern state, there is an advantage that the total 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 the present embodiment,
Although the projection lens 3 is displaced in order to focus the irradiation pattern 63, a focusing system having the same effect can be provided even if the focus is adjusted by displacing the LED 4 of the light source.

Next, as a modification of the focus adjustment system according to the first embodiment of the present invention, the focal lengths of the focusing lens 1 'and the projection lens 3' are equal to each other, and the amount of extension relating to focusing of both lenses. The structure of the lens barrel in the case where are equal to each other will be described with reference to FIG. Since the feeding amount is the same, a separate driving device is of course unnecessary, the lens barrel 25 'for the focusing lens 1' and the lens barrel 25 'for the projection lens 3' can be integrated, and the mechanical members around the lens barrel 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 require extension for focusing of the imaging optical system of the auxiliary light irradiation unit. Then, as shown in FIG. 6, a plane light projecting portion 44a having a predetermined pattern of the LED 44 as a surface light source with respect to a plane 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 tilting the light projection surface in this way, the above-mentioned pattern can be projected and imaged so that any part of the irradiation pattern is focused on the entire range where the focusing of the imaging optical system can be adjusted. . That is, if the distance a2 from the projection lens 43 is the closest focus position and the distance a1 is the farthest focus position, the distance range P is the focus adjustment range. And
The imaging portion on which the length d of the light projection surface 44a is projected is located between the point i2 and the point i1, and the intersection angle θ is set so as to correspond to the distances a2 and a1 respectively.

The method for obtaining the intersection angle θ will now be described. First, let the distances from the lower end and the upper end of the light projection unit 44a to the projection lens 43 be b1 and b2. And
The relational expression between the subject distances a1 and a2 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 intersection angle θ is obtained by substituting actual values, for example, the length d of the light projecting portion 44a of the LED 44 is 1 mm, the farthest distance a1 in the focusing range is 5 m, the closest distance a2 in the focusing range is 1 m, Assuming that the focal length fI of the projection lens is 15 mm, the intersection angle θ is 10 ° 36 ′ from equation (8).

Referring to FIG. 7, the configuration of a system using the auxiliary light irradiating means configured as described above will be described. A photographing lens (not shown) including a focusing lens 41 which is a focus adjusting element of an image pickup optical system. , A CCD 42 as an image sensor, and a projection lens 4 as an auxiliary light irradiating unit.
3, an LED 44 having a planar light projection unit 44a having a predetermined irradiation pattern obliquely provided with respect to the projection lens 43,
A pre-processing circuit 45 for outputting a video recording signal;
A band-pass filter BPF 46 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. It comprises a focus drive control circuit 49 for outputting an electric signal, a lens drive device 50 for displacing the focusing lens 41 in the focusing direction, an LED drive circuit 51 for driving the LED 44, and a CPU 48. .

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. What to go. At the same time as controlling the circuits, the CPU 48 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, there is always a portion where the image is sharpened by focusing on a part of the pattern if the subject distance is within the focusable range. 8 (A), (B),
(C) shows an image forming state of the irradiation pattern with respect to each object distance of the auxiliary light irradiation means.
1, H2 and H3 indicate horizontal scanning positions of the image sensor, respectively. FIG. 8A shows a case where the subject distance is the farthest distance a1 (for example, 5 m) within the focusing range, and the pattern 64 corresponding to the upper horizontal scanning position H1 is shown.
a 'is the focused portion, and the other pattern 64b' is out of focus, that is, the portion where the pattern is out of focus. FIG. 8B shows a case where the subject is located at the center position in the focusing range, and the pattern 64a corresponding to the horizontal operation position H2 at the center is a focused portion, and the other pattern 64a is in focus. Pattern 64b
Indicates an out-of-focus portion. Further, FIG.
(C) is a shortest distance a2 in which the subject distance is within the focusing range.
(For example, 1 m), and the pattern 64a ″ of the portion corresponding to the horizontal scanning position H3 at the lower position is the focused portion and the pattern 64 of the other portion is
"b" indicates an out-of-focus portion.

FIGS. 8D, 8G, and 8M are diagrams showing changes in light quantity corresponding to the horizontal scanning positions H1 to H3 of the irradiation patterns 64a 'and 64b' in FIG. 8A. It is a thing. The diagram in FIG. 8D corresponding to the scanning position H1 of the in-focus portion shows a sharp change. Therefore, if the focusing lens 41 is in focus, the pattern captured by the CPU 48 via the image sensor. Will also show high values. But,
8 (G) and 8 (M) correspond to the out-of-focus pattern portion, and therefore have a gentle waveform,
The partial contrast value captured at 48 is also low. Since the relationship between these contrast values does not reverse even when the focusing lens 41 is out of focus, the information held by the integration circuit 47 is the contrast value corresponding to the vicinity of the scanning line H1 in this case. .
8 (E), (J), (N) or (F), (K), (Q) also correspond to the in-focus portion of the corresponding irradiation pattern. FIG.
(J) and (Q) show sharper waveforms, and their partial contrast values are higher. However, the others correspond to the out-of-focus portion of the corresponding irradiation pattern, so that the local contrast value naturally becomes low. For this reason, the information held by the integration circuit 47 is a contrast value corresponding to the vicinity of the scanning line H2 in FIG. 8B, and to a vicinity of H3 in FIG. 8C.

Therefore, when the system according to the present embodiment is focused, when an irradiation pattern is projected on a subject within the focusing range, as described above, the subject is focused in accordance with the subject distance. The contrast value of the illuminated portion is obtained. Then, while monitoring the change in the contrast value, focusing drive of the focusing lens 41 is repeated. When the contrast value of the focused pattern portion in the irradiation pattern shows a peak value, the focusing lens 41 is focused. The impatience will end.

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

The LED 44, which is an auxiliary surface light source in the auxiliary light projection means, must be inclined at an angle of intersection θ with respect to the main plane of the projection lens 43 as described above. 9A and 9B show specific examples.
Shown in FIG. 9A is a vertical cross-sectional view of the mounting mechanism of the LED 44 (ZZ cross section in FIG. 9B), and FIG.
It is a Y arrow view of FIG. 9 (A). A screw portion 56a is provided on a support plate 56 supported by the camera body. Meanwhile, LED
44 is fixed to the LED mounting plate 55 with an adhesive or the like.
Adjustment screws 57a, 5 are provided in holes provided in the LED mounting plate 55.
7b and 57c, and a compression spring 58a
Is inserted into the screw portion 56a of the support plate 56, and the screwing amount is adjusted to set the intersection angle θ. 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 the auxiliary light projection has a very simple structure. It provides a means.

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

The second embodiment and its modification have been described on the assumption that the projection optical axis is parallel to the photographic lens optical axis. 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 axis O ″ of the direction in which the auxiliary light is emitted, where S indicates the principal point of the light projecting lens, and R and Q indicate the edges of the light source surface, respectively. Now, when the inclination is given between the main surface of the light projecting lens and the light source surface, the irradiation range is inside the extended lines lR and lQ of RS and QS, respectively. Therefore, the irradiation direction in this case is indicated by the bisector of the angle formed by lR and lQ. In other words, the irradiation direction axis O 'connects S with the inner center I of ΔQRS. It is defined as a straight line.
O 'does not always coincide with the optical axis of the projection lens.

Here, considering the function of the auxiliary light again,
“Irradiation of a pattern containing many high-frequency components” and “Illumination to compensate for insufficient illuminance” already described in the embodiment
However, for a normal subject other than a low-contrast subject, the illumination function is the main function. When considering parallax with the distance measurement field of view, it is important to determine which of these two functions is more important.

As shown in FIG. 13, a light projecting device for autofocus disclosed in Japanese Patent Application Laid-Open No. 1-112212 illuminates light at an angle α with a photographing optical axis O which is an optical axis of a photographing lens 60. Projection lens 61 having axis O ″ and light source 6
There is a concept that the image plane R'Q 'in the object space of the light source surface is set so as to overlap on the photographing optical axis, but this is an object using a line sensor as a distance measuring sensor. This is effective only when the distance measurement area is extremely small as described above, and is not suitable for a focus adjustment system in which the distance measurement area is planar as in the present invention. It is for the following reasons.

That is, as described above, the illumination function is mainly performed for a normal subject, and when considering this, as shown in FIG. , And the irradiation area for the closest subject is greatly shifted above the photographing optical axis O. Therefore, as 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 largely shifts below and above the distance measurement area, and extends beyond a predetermined area, so that the light use efficiency is significantly reduced. Even if the distance measurement area is enlarged so as not to protrude, the deviation of the irradiation range generated at this time becomes a deviation 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 is caused by the image plane R '.
This always occurs when an angle β between Q ′ and the photographing optical axis O is set to be smaller than an angle α between the irradiation direction axis O ″ and the photographing optical axis O.

To solve the above-mentioned 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 the sake of convenience. 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 regarded as substantially the center for convenience of use, depending on the shape of the area, for example, the center of gravity may be used as "Center axis of distance measurement field of view" corresponding to
(Defined as a tracing line of light rays from the center point of the region to the principal point of the photographing lens) may be applied in place of the optical axis O.

Finally, referring to the direction in which the light projecting lens and the light source surface are inclined, in the second embodiment and its modification, the line of intersection between the main surface of the light projecting lens and the light source surface is the scanning line direction (H This direction 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 the licking 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 has at least a sensitivity with respect to information detection of the applied system, Desirably, it may be tilted so as to be parallel to the direction of maximum sensitivity of detection.

[0045]

As described above, according to the focus adjustment system according to the present invention, the focus adjustment range by irradiating the auxiliary light is provided.
Over the entire region, because the subject irradiation range by the auxiliary light is set to be included substantially in the ranging area, if Asecho
It is possible to prevent eyes from being closed at the moment of photographing due to useless light that does not contribute to distance measurement over the entire node range . Further, since substantially no useless light is generated over the entire focus adjustment range , the light use efficiency is improved and power is saved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a focus adjustment system according to a first embodiment of the present invention;

FIG. 2A is a front view of an LED used as an auxiliary light source used in the focus adjustment system of FIG. 1,
(B) is a diagram 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,

3 (A), (B), (C) are irradiation pattern diagrams with respect to each focus state of the focus adjustment system of FIG. 1,
(D), (E), and (F) correspond to (A), (B),
FIG. 3C is a diagram illustrating a change in the amount of light in the horizontal scanning direction of the image sensor corresponding to each irradiation pattern of FIG.

4A is a longitudinal sectional view of a main part of a focusing lens, a projection lens, a drive device thereof, and the like of the focus adjustment system of FIG. 1, and FIG. 4B is a view of the drive device shown in FIG. Perspective view,

FIG. 5 is a vertical sectional view of a main part of an integrated lens barrel of a focusing lens and a projection lens, showing a modification of the focus adjustment system of FIG. 1;

FIG. 6 is a side view of an auxiliary light irradiation unit of a focus adjustment system according to a second embodiment of the present invention;

FIG. 7 is a block diagram of the focus adjustment system of FIG. 6;

8 (A), (B), and (C) are irradiation pattern diagrams of auxiliary light with respect to each subject distance in the focus adjustment system of FIG. 6, and (D), (E), (F), (F). G),
(J), (K), (M), (N), and (Q) are changes in the amount of light in the horizontal scanning direction of the image sensor corresponding to the irradiation patterns (A), (B), and (C), respectively. A diagram showing the

FIGS. 9A and 9B show an auxiliary light source mounting mechanism of the auxiliary light irradiating means of the focus adjustment system of FIG. 6;
(A) is a vertical cross-sectional view of a main part (ZZ cross section in FIG. 9 (B)),
FIG. 9B is a view taken in the direction of the arrow Y in FIG.

FIG. 10 is a side view of an auxiliary light irradiation unit showing a modification of the focus adjustment system of FIG. 6;

FIG. 11 is a side view showing an example of an auxiliary light projection state of the auxiliary light projection unit.

FIG. 12 is a side view showing a state in which auxiliary light irradiation means projects auxiliary light, showing another modification of the focus adjustment system according to the second embodiment of the present invention;

FIG. 13 is a longitudinal sectional view of an autofocus light emitting device of a conventional focus adjusting device.

14A and 14C show an irradiation pattern image on a subject by the light projecting device of FIG. 13; FIG. 14A shows an irradiation pattern on a subject at the farthest distance; )
7A and 7B are diagrams each showing an irradiation pattern on a subject at the shortest distance.

[Explanation of symbols]

1, 1 ', 41: Focusing lens (focus adjustment element) (imaging optical system) 2, 42: CCD (imaging optical system) 3, 3', 43, 43 ': Projection lens (auxiliary light irradiation means) 4 , 44, 44 '... LED (auxiliary light irradiating means) 4a, 44a, 44a' ... Light projection unit (auxiliary light irradiating means) 63, 63 ', 63 ", 64a, 64b, 64a', 6
4b ', 64a ", 64b" ... irradiation pattern

Claims (1)

(57) [Claims] An imaging function having a planar imaging region is provided, and at least a part of the planar region in the imaging region is set as a dedicated or shared ranging region for ranging or focusing control information. A focusing adjustment system that gradually displaces a focusing adjustment element of the imaging optical system in a direction in which the sharpness of an image by the imaging optical system is higher, wherein a surface set as the ranging area is provided. Image obtained from the shape area
High frequency components are extracted from the image signal and detected and applied to the planar area.
The information corresponding to the sharpness is obtained by performing the integration
As a report, a contrast value representing the entire planar area is calculated.
In order to compensate for the lack of illuminance of the subject corresponding to the distance measurement area,
A planar light projection unit provided in a position having a predetermined parallax with respect to the imaging optical system and configured to irradiate a subject with visible light without passing through the imaging optical system;
To an auxiliary light emitting means including a light source, the auxiliary light irradiation means, and a said visible light source and projection lens, the distance measuring field of the radiation axis and the imaging optical system of the auxiliary light emitting means An angle α (≠ 0) between the central axis and an angle β between a projection image plane of the light source surface of the visible light source in the subject space by the light projecting lens and the center axis of the distance measurement visual field of the imaging optical system is: By being configured to satisfy α ≦ β, over the entire range of the focus adjustment range of the imaging optical system by irradiation of the auxiliary light, the subject irradiation range by the auxiliary light is almost included in the distance measurement area. A focus adjustment system characterized by being set.