JP2997964B2 - Distance measuring device and camera having this distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device used for an autofocus camera.

[0002]

2. Description of the Related Art FIG. 9 shows a light receiving section of a distance measuring device used in a conventional autofocus camera. The light receiving lens 21 is held at one end of the holder 20, and the substrate holding frame 20a is formed at the other end. Substrate holding frame 20
The first printed circuit board 22 held by the optical sensor (PS) for detecting a distance, which is a discrete component,
D) 23 is connected, and is located on the main axis (same as the geometric center line) 21 a of the light receiving lens 21 via the opening 20 b of the lens holder 20. One end of a flexible cable (hereinafter referred to as “FPC”) 23 is connected to the first printed circuit board 22, and the other end of the FPC 23 is connected to a second printed circuit board 25 located in the cover 24.
Is connected to the second printed circuit board 25.
C26 is implemented. Other electrical components (such as resistors and capacitors) 27 for forming the distance measuring circuit are also provided by the second
Is mounted on the printed circuit board 25.

[0003]

In the above-described conventional distance measuring device, a first printed circuit board 22 having an optical sensor 23 mounted thereon and a second printed circuit board 25 having a distance measuring IC 26 mounted thereon are used. ing. Therefore, the FPC 23 for connecting the printed circuit boards 22 and 25 and the holder 2
0 requires a member for holding the second printed circuit board 25, and the number of components is increased. In particular, optical sensors 2 packaged as discrete components
3 and the use of the IC 26, it is difficult to implement a small package.

Further, the second printed circuit board 25 and the cover 24 need to be changed in shape and size for each camera model in order to be easily housed in the camera, and there is no compatibility. In this way, it becomes a design constraint of the camera,
This hinders miniaturization.

Since the optical sensor 23 and the IC 26 are provided at a distance from each other and are connected by the FPC 23, noise is apt to be mixed while a signal is transmitted between the two. In order to prevent this, it is necessary to take a shield structure, which complicates the configuration.

Accordingly, an object of the present invention is to provide a highly reliable distance measuring device which has a small number of parts, has a simplified configuration, is easy to manufacture, and is less likely to cause electrical noise between the optical sensor and the IC. The object of the present invention is to provide a camera having: Another object is to provide a distance measuring device compatible with various cameras.

[0007]

A distance measuring apparatus according to the present invention comprises: a light receiving lens mounted on a holder; a printed circuit board disposed on the holder at a focal position of the light receiving lens and having conductive patterns on both surfaces; It has an optical sensor, a distance measuring IC, and electric parts connected to the IC and forming a part of a distance measuring circuit. The optical sensor and the distance measuring IC are provided on a surface of the printed circuit board facing the light receiving lens. Has been implemented. This optical sensor is located on the optical axis of the light receiving lens and is connected to the IC. An electric component is mounted on the surface of the printed circuit board opposite to the IC.

The optical sensor and the IC are both bare chip components, and are sealed by a protective resin that transmits light of a specific wavelength and is filled in a sealing frame provided on the outer peripheral portion of the printed circuit board. A light shielding member is provided in front of the IC. This light shielding member is preferably formed integrally with the holder.

Further, a partition wall integral with the sealing frame may be located between the optical sensor as a bare chip component and the IC. In this case, the optical sensor may be sealed with a protective resin that transmits light of a specific wavelength, and the IC may be sealed with a light-shielding protective resin.

It is desirable that an electromagnetic shield layer to which a ground potential is supplied be provided between the surface on the optical sensor side and the surface on the opposite side of the printed circuit board.

[0011]

FIG. 1 shows a first embodiment of a distance measuring apparatus according to the present invention. The light receiving lens 2 is held at one end of the holder 1, and the printed circuit board 3 is held at the other end. An optical sensor (PSD) 4 for detecting a distance, which is a bare chip, an IC 5 for distance measurement, which is a bare chip, and electric components such as a resistor R and a capacitor C are mounted on the printed circuit board 3.

The holder 1 is a cylindrical member made of a light-shielding plastic or the like. A lens receiver 1a is provided at one end, and an opening 1b, a light-shielding portion 1c, and a substrate holding frame 1d are integrally provided at the other end. Have been.

As shown in FIGS.
Is a multilayer wiring board having a GND layer (electrode layer supplied with a ground potential and acting as an electromagnetic shield) 3a in an intermediate portion, and a conductive pattern formed on both surfaces.
Are drilled. On one surface of the printed circuit board 3, a sealing frame 6 is provided so as to surround the outer periphery of the printed circuit board 3. The optical sensor 4 and the distance measuring IC are provided in a space 3c of the sealing frame 6.
5 is die-bonded and connected to the conductive pattern 3d by wire bonding. In this state, the sealing frame 6 is filled with a protective resin 7 made of an epoxy resin or the like and cured, thereby sealing the optical sensor 4 and the IC 5. On the opposite surface of the printed board 3, a resistor R and a capacitor C are connected by soldering on a conductive pattern (not shown). The conductive patterns on both sides of the printed board 3 are electrically connected to each other by through holes (not shown).

As shown in FIGS. 4 and 5, the light-receiving lens 2 according to the present embodiment has an asymmetric shape in which one end is thick and the other end is thin, that is, a light-receiving lens 2 in which one end of a normal symmetric lens is cut. The optical axis 2a is displaced from the geometric center line 2b.

As shown in FIG. 1, when the light receiving lens 2 and the printed board 3 are mounted on the holder 1, the optical sensor 4 is located on the optical axis 2a through the opening 1b, and the IC 5 is shielded from light. It is covered with the portion 1c so that light does not shine. For this reason, light (infrared rays) transmitted through the light receiving lens 2 can enter the optical sensor 4, but the light of the IC 5 is blocked by the light shielding unit 1 c,
Malfunction due to light can be prevented.

Next, the distance measuring circuit shown in FIG. 6 will be described. The optical sensor 4, the light projecting means 10, the oscillation circuit 1
1. The capacitors C1, C2 and C3 are connected. The light projecting means 10 comprises an LED (light emitting diode) 10a, resistors R1, R2, R3, R4, R5 for voltage adjustment, transistors Tr1, Tr2, and a capacitor C4. In this embodiment, 880 to 880 are used as the LED 10a.
An optical sensor that emits near-infrared light having a wavelength of 940 nm is used, and an optical sensor 4 that can receive near-infrared light of this wavelength and a protective resin 7 that transmits near-infrared light of this wavelength are used. I have.

The oscillation circuit 11 includes a resistor R6 and a capacitor C
5, and supplies a reference clock signal to the control circuit 8. Capacitor C
1 and C2 are for storing the light level of the steady light (the light level in a normal environment when near-infrared rays are not irradiated) in the form of a voltage level. (Not shown) for storing the light level of the reflected light in the form of a voltage level. The VCC terminal and the VDD terminal are connected to a power supply (not shown), and the GND terminal is connected to the GND layer 3a shown in FIG. The connection terminals 12a and 12b are connected to a microcomputer (not shown) provided in the camera body.

Next, the operation of the distance measuring circuit having the above configuration will be described. First, when the user presses a release button (not shown) of the camera, a microcomputer in the camera body supplies a signal S1 for starting a distance measuring operation to the control circuit 8. Then, the control circuit 8 sends a start signal S2 to the light projecting means 10, and the transistors Tr1, Tr
2 is turned on, and the LED 10a emits near-infrared light.

When this near-infrared ray hits an object (not shown) and is reflected, this reflected light is received by the optical sensor 4 and its output is transmitted to the control circuit 8. Then, the control circuit 8 calculates the distance to the subject based on the output of the optical sensor 4. Specifically, the optical sensor 4 (FIG. 2)
When the reference current is a PSD (position sensitive detector), the output currents i1 and i2 are supplied to the control circuit 8, and the distance is calculated based on the magnitude of the output currents i1 and i2. The distance data signal S3 obtained in this way is transmitted to a microcomputer in the camera body, and the microcomputer drives a lens extension mechanism (not shown) according to the distance data signal S3 to perform focusing. .

Since the light levels of the stationary light are held in the capacitors C 1 and C 2, the data based on the stationary light is removed from the received light data of the optical sensor 4 by the light projecting means 10 using this. Only the data based on the illuminated near-infrared reflected light is extracted, and the control circuit 8 can perform an accurate distance calculation.

Actually, the near-infrared light emission is performed a plurality of times, and the setting is made so that the distance can be calculated more accurately based on the data of the plurality of received light. That is, based on the reference clock signal of the oscillation circuit 11, the start signal is supplied from the control circuit 8 to the light emitting means 10 a predetermined number of times at regular intervals, whereby the LED 10a emits light intermittently.

FIGS. 7 and 8 show a second embodiment of the light receiving section of the distance measuring apparatus according to the present invention. The printed circuit board 3 is a multilayer wiring board similar to that of the previous embodiment. On one surface thereof, a sealing frame 13 is provided so as to surround the outer periphery. 14 are integrally formed. The partition 14 allows the sealing frame 13
Is divided into two areas 15a and 15b. The optical sensor 4 as a bare chip is die-bonded to the first area 15a, and the distance measuring IC 5 as a bare chip is die-bonded to the second area 15b, and are connected to the wiring pattern 3d by wire bonding. . The first region 15a is filled with a protective resin 7 that transmits near-infrared light as in the previous embodiment, and the second region 15b is made of epoxy resin mixed with a pigment or the like to provide light-shielding protection. Resin 16 is filled. These protective resins 7 and 16 are respectively cured, and the optical sensor 4 and the IC 5 are sealed. On the opposite surface of the printed circuit board 3, a resistor R and a capacitor C are mounted on a conductive pattern (not shown), and the patterns on both surfaces of the printed circuit board 3 are electrically connected by through holes (not shown). Other configurations are substantially the same as the previous embodiment.

In the case of this embodiment, since the optical sensor 4 is sealed with a protective resin 7 capable of transmitting near infrared rays,
Near infrared rays can be received, and distance detection is possible. On the other hand, since the IC 5 is sealed with the light-shielding protective resin 16, there is no possibility of malfunction due to receiving light.
Since the protective resins 7 and 16 are separated by the partition wall 14, there is no possibility of mixing during filling, and the near-infrared transmittance and light-shielding properties of each resin are reliably maintained.

As described above, according to the distance measuring apparatus of the present invention, since the optical sensor 4 and the distance measuring IC 5 are mounted on the same printed circuit board 3, the mounting area is extremely small as compared with the conventional one. Further, since the second printed circuit board, a member for holding the second printed circuit board, an FPC, and the like are not required, the number of components is reduced and the cost is reduced. In particular, since the optical sensor 4 and the IC 5 are each die-bonded to the printed circuit board 3 in the state of a bare chip and sealed with the protective resin 7, the size and thickness can be reduced, and the operation is simplified. .

Further, the holder 1 having substantially the same shape as the conventional one
Almost all parts of the light receiving unit can be united without providing a cover or the like. Therefore, the configuration is simple and compact, and the distance measuring device light receiving section can be configured in the camera by mounting only the holder on the camera.
A compatible distance measuring apparatus can be provided without changing the design for each camera model. Especially when producing various types of cameras, the production cost is greatly reduced. Further, it is also possible to form a holding member of the light projecting means 10 integrally with the holder, and to form the light projecting means 10 and the light receiving section shown in FIG. 1 as one unit.

Since the position of the optical sensor 4 and the position of the IC 5 are close to each other, mixing of electric noise between them is reduced. Furthermore, the printed circuit board 3 has a GND layer 3
Since a is provided, an electromagnetic shielding effect is obtained, and it is hard to receive external noise.

In the first embodiment, since the light-shielding portion 1c of the holder 1 covers the IC 5, malfunctions due to light shining on the IC 5 hardly occur. In this embodiment, the light shielding member 1c is formed integrally with the holder 1, but may be provided as a separate member.

Further, in the second embodiment, since the IC 5 is sealed with the protective resin 16 having a light-shielding property, the light can be more reliably blocked and malfunction of the IC 5 can be prevented.

In the above two embodiments, the lens 2 has an asymmetric shape, and the optical axis 2a does not coincide with the geometric center 2b. That is, even if the optical sensor 4 is mounted on a biased position on the printed circuit board 3 (for example, on the left side in FIGS. 2 and 3),
Since the lens is formed so that the optical axis 2a is located there, the IC 5 can be provided without increasing the size of the substrate or using a two-layer configuration in order to arrange the optical sensor in the center of the printed circuit board as in the related art. The optical sensor 4 can be formed on the same surface as the.

In this embodiment, the near-infrared ray having a wavelength of 880 to 940 nm is projected from the light projecting means 11. However, the present invention is not limited to this, and means for projecting light rays of various wavelengths can be used. Of course, in this case, the optical sensor 4 and the protective resin 8 are capable of receiving or transmitting the light beam of the wavelength. Further, the configuration of the present invention can also be applied to a so-called passive type distance measuring device that measures distance using external light without providing a light projecting unit.

Although the optical sensors 4 and ICs 5 as bare chips are used in the above two embodiments, the present invention can be applied to a case where optical sensors and ICs as discrete components are used.

[0032]

According to the distance measuring apparatus of the present invention, since the optical sensor and the distance measuring IC are mounted on the same printed circuit board, the mounting area can be reduced and the size can be reduced. Also, since most parts of the light receiving part can be mounted on the holder, the structure is simple and compact, the number of parts is reduced and the cost is low, and the compatibility is high, especially when mass-producing various types of cameras. Can be greatly reduced.

Further, since the position of the optical sensor and the position of the IC are close to each other, mixing of electric noise can be reduced and reliability is improved.

If the optical sensor and the IC are mounted on a printed circuit board in the form of bare chips and sealed with a protective resin, the size and thickness can be reduced and the work can be simplified.

By providing a light-blocking member in front of the IC bear chip, it is possible to prevent light from shining on the IC bear chip and prevent malfunction of the IC. Also, if the IC bear chip mounting area and the optical sensor bear chip mounting area are separated on the printed circuit board and a partition is provided between them, light incident on the optical sensor bear chip may hit the IC bear chip from the side and cause a malfunction. There is no. And in this case,
When only the IC bear chip is sealed with a potting resin having a light-shielding property, light is reliably blocked, and malfunction of the IC bear chip is more reliably prevented.

If the light receiving lens is asymmetrical and the geometric center and the optical axis are shifted and the optical axis is formed in a shape corresponding to the position of the optical sensor on the printed circuit board, the IC and the optical sensor can be connected without increasing the size of the printed circuit board. They can be formed on the same plane.

When a layer to which a ground potential is supplied is provided between the surface of the printed circuit board on the optical sensor side and the surface on the opposite side, electromagnetic shielding can be performed on both surfaces, so that noise contamination can be further reduced. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a distance measuring apparatus according to the present invention.

FIG. 2 is an enlarged sectional view of a circuit block according to the first embodiment;

FIG. 3 is an enlarged plan view of the circuit block in FIG. 2 before filling with a protective resin.

FIG. 4 is an enlarged side sectional view of the light receiving lens of the first embodiment.

FIG. 5 is an enlarged front view of the light receiving lens of the first embodiment.

FIG. 6 is a circuit diagram of an embodiment of a distance measuring circuit.

FIG. 7 is an enlarged sectional view of a circuit block according to a second embodiment.

FIG. 8 is an enlarged plan view of the circuit block of FIG. 7 before filling with a protective resin.

FIG. 9 is a sectional view of a conventional distance measuring device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Holder 1c Light-shielding part (light-shielding member) 2 Light-receiving lens 2a Optical axis 2b Geometric center line 3 Printed circuit board 3a GND layer (electromagnetic shield layer to which ground potential is supplied) 3d Conduction pattern 4 Optical sensor bear chip 5 IC bear chip 6 Sealing frame 7 Protective resin 13 Sealing frame 14 Partition 16 Protective resin R Resistance (electrical component) C Capacitor (electrical component)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-28610 (JP, A) JP-A-3-102727 (JP, A) JP-A-63-255926 (JP, A) JP-A-2- 12009 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01C 3/00-3/32 G01S ⁷ /48-7/50 G01S 17/00-17/88 G02B 7/32

Claims (9)

(57) [Claims] 1. A light receiving lens mounted on a holder, a printed circuit board disposed on the holder at a focal position of the light receiving lens, and having a conductive pattern on both surfaces, and facing the light receiving lens of the printed circuit board. An optical sensor mounted on a surface and positioned on the optical axis of the light receiving lens; and a ranging IC mounted on the optical sensor side surface of the printed circuit board and connected to the optical sensor.
And mounted on the opposite side of the printed circuit board from the IC,
And an electric part connected to the IC and forming a part of a distance measuring circuit. 2. The optical sensor according to claim 1, wherein the optical sensor and the IC are both bare chip components and transmit light of a specific wavelength filled in a sealing frame provided on an outer peripheral portion of the printed circuit board. A distance measuring device characterized by being sealed with a protective resin. 3. The distance measuring apparatus according to claim 2, wherein a light shielding member is provided in front of said IC. 4. The distance measuring apparatus according to claim 3, wherein the light shielding member is formed integrally with the holder. 5. The distance measuring apparatus according to claim 2, wherein a partition wall integral with the sealing frame is located between the optical sensor as a bare chip component and the IC. 6. The distance measuring apparatus according to claim 5, wherein the optical sensor is sealed with a protective resin that transmits light of a specific wavelength, and the IC is sealed with a light-shielding protective resin. . 7. The light-receiving lens according to claim 1, wherein an optical axis of the light-receiving lens and a geometric center are shifted, and an arrangement position of the light-receiving lens is shifted from a center of the printed circuit board. Distance measuring device. 8. The electromagnetic shield layer according to claim 1, wherein a ground potential is supplied between the surface on the optical sensor side and the surface on the side opposite to the optical sensor. A distance measuring device, characterized in that: 9. A camera comprising the distance measuring device according to claim 1.