JP7413426B2 - Light projecting equipment, ranging equipment, and electronic equipment - Google Patents

Description

The present disclosure relates to the field of optical elements, and specifically relates to a light projector, a distance measuring device, and an electronic device.

In recent years, distance measurement modules that measure the distance to objects have become smaller and smaller, and even smartphones are equipped with distance measurement modules. As mentioned above, a ToF (Time of Flight) distance measurement module irradiates light toward an object, detects the light reflected from the object's surface, and calculates the flight time of that light. Based on this, the distance to the object is calculated.

The irradiation methods include a method in which irradiation is performed as a plurality of dots arranged in a matrix through a diffractive optical element (DOE) from a light emitting element in the projection optical system, and a method in which irradiation is performed as a plurality of dots arranged in a matrix. There is a surface irradiation method that transmits continuous diffused light.

In the case of dot irradiation, the light is focused to a point and the intensity of the light is maintained even at a long distance, so it is possible to measure the distance of a relatively distant object with limited light source power. On the other hand, in the case of surface irradiation, the light is uniformly irradiated within the irradiation surface, so it can be irradiated with high resolution.

A disadvantage of dot irradiation is that in-plane resolution is limited by the distance between adjacent dots. Further, a disadvantage of surface irradiation is that the amount of light irradiated within a unit plane decreases as the distance between objects increases, so the measurement distance is limited to short distances.

A collimator lens is inserted between the light source and the DOE to correct the light emitted from the light source into parallel light, but the irradiation attenuates as the distance to the measurement target increases due to atmospheric attenuation. On the other hand, in the conventional method, the focal length of the projection optical system is made variable for each subject distance to switch between dot irradiation and surface irradiation. However, the optical system uses a lens that is driven in the optical axis direction within the projection optical system, and is not suitable for smartphones and the like that have limited thickness.

Another method in the prior art uses two illumination modules, dot illumination and diffused illumination, to obtain the benefits of both within certain thickness limitations. However, although this method solves the problem in the thickness direction, the cost increases due to the two irradiation modules and the size in the width direction becomes extremely large.

In at least one embodiment of the present disclosure, a light projector, a distance measuring device, and an electronic device are provided. It is possible to maintain the size of the light projection optical system used in the distance measurement module and switch to dot irradiation or surface irradiation depending on the distance to be measured.

In order to solve the above technical problem, the present disclosure is realized as follows.

In a first aspect, an embodiment of the present disclosure is a light projecting device including a light emitting light source and a light projecting optical system in which a variable focus lens is arranged on an optical axis, and the variable focus lens does not move in the optical axis direction. In this case, the variable focus lens changes its focal position in response to a drive signal.

In a second aspect, an embodiment of the present disclosure is a distance measuring device that includes a light receiving element and a light receiving optical system, and further includes the light projecting device.

In a third aspect, an embodiment of the present disclosure is an electronic device including the distance measuring device.

Compared with the prior art, the disclosed embodiment provides a light projecting device, a distance measuring device, and an electronic device, and by using a variable focus lens, dot illumination or surface illumination can be realized by switching in the light projection optical system. , which is useful for downsizing the device structure.

FIG. 2 is a conceptual diagram of a dot irradiation technique proposed in the prior art. FIG. 2 is a conceptual diagram of one structure of a light projecting device in an embodiment of the present disclosure. FIG. 2 is a conceptual diagram of dot irradiation by a light projection device in an embodiment of the present disclosure. FIG. 3 is a conceptual diagram of surface illumination by a light projection device in an embodiment of the present disclosure. FIG. 7 is a conceptual diagram of one structure of a light projecting device in another embodiment of the present disclosure. FIG. 7 is a conceptual diagram of reducing the dot diameter by a light projection device in another embodiment of the present disclosure. FIG. 7 is a conceptual diagram of normal dot irradiation in another embodiment of the present disclosure. FIG. 7 is a conceptual diagram of dot irradiation after reducing the dot diameter in another example of the present disclosure. FIG. 7 is a conceptual diagram of one structure of a light projecting device in another embodiment of the present disclosure. FIG. 7 is a conceptual diagram of irradiation by a light projecting device in another embodiment of the present disclosure.

In the following, the technical means of the embodiments of the present disclosure will be clearly and completely described together with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments that can be made by those skilled in the art based on the embodiments of the present disclosure without any creative work shall fall within the protection scope of the present disclosure.

The terms "first", "second", etc. in the specification and claims of the present disclosure are used to distinguish between similar objects and are not necessarily used to describe a particular order or priority. do not have. It is to be understood that the data so used may be interchanged where appropriate, such that the embodiments of the disclosure described herein may be practiced, for example, in an order other than as illustrated or described herein. In addition, the objects distinguished by the terms "first", "second", etc. are usually of the same type, and the number of objects is not limited. For example, there may be one or more first objects. Note that "and/or" in the specification and claims represents at least one connection target. The character "/" generally indicates that context-related objects have an "or" relationship.

In order to understand the technical solution according to the present disclosure, related concepts according to the present disclosure will be explained below.

The variable focus lens described in the embodiments of the present disclosure is based on an element that changes the focal position by applying a voltage without moving in the optical axis direction, and there are several candidates such as a liquid lens, a film lens, and a liquid crystal lens. be.

Further, the distance measuring device described in the present disclosure includes a light emitting element, a light projecting optical system, a light receiving element, a light receiving optical system, and the like. This distance measuring device calculates a distance from information about light that is reflected by a light emitter from a light emitting element on an object, returns to a light receiving element, and forms an image. Calculating the distance from the information of the imaged light refers to a type that calculates the distance from the interval between the imaged points, or a type that calculates the distance to the object from the time from emission to reception, and calculates the distance from the time. There are two types: those that calculate time from direct time measurement and those that calculate time from the phase difference between emitted light and received light.

Embodiments of the present disclosure are particularly useful for improving the performance of a light projecting optical system in a light projecting device. This light projecting device includes a light emitting source and a light projecting optical system in which a variable focus lens is arranged on an optical axis. Here, when the variable focus lens does not move in the optical axis direction, the variable focus lens changes its focal position in accordance with the drive signal.

Specifically, the variable focus lens may include a first drive state and a second drive state. Here, after the light emitted from the light emitting light source in the first driving state passes through the light projection optical system, dot irradiation is set, and the light emitted from the light emitting light source in the second driving state passes through the light projection optical system. After passing through, it is set to surface illumination. The variable focus lens includes, but is not limited to, a liquid lens, a thin film lens, or a liquid crystal lens.

In this way, the light projection device in the embodiment of the present disclosure disposes the variable focus lens in the optical axis direction at an appropriate position within the lens of the light projection optical system, drives the variable focus lens according to the distance measurement, It is possible to switch to a suitable illumination method, for example dot illumination or area illumination. Therefore, the light projection device of the embodiment of the present disclosure may further include a drive module for driving the variable focus lens according to the measured distance, and the light projection device is switched to point illumination or surface illumination.

As shown in FIG. 1, in the conventional dot irradiation method for a distance measuring device, this distance measuring device includes a light projecting device including a light emitting light source 11 and a light projecting optical system 12, a light receiving element 13, and a light receiving optical system 14. including a light receiving device. The light projection optical system 12 includes a collimator lens 102 and a DOE 101. Here, laser light emitted from the light emitting element is transmitted to the DOE 101 via the collimator lens 102, and a plurality of dots arranged in a matrix are irradiated onto the measurement area.

In one embodiment of the present disclosure, the light projecting device effectively arranges a variable focus lens that does not move in the optical axis direction within the lens of the light projecting optical system, and uses it together with a DOE to perform dot irradiation and surface irradiation. Switch. Specifically, as shown in FIG. 2, the light projection optical system further includes a DOE 201. The variable focus lens 202 is located between the DOE 201 and the light emitting source. In this embodiment, a variable focus lens 202 that does not move in the optical axis direction is placed between the light emitting element and the DOE 201. In other words, the variable focus lens 202 is fixed in the optical axis direction.

By changing the refractive index of the variable focus lens, it is possible to switch between dot irradiation and surface irradiation. The driving range of the refractive index is such that the laser intensity is 45% or more with respect to the peak intensity.

The light projection device shown in FIG. 2 has the following advantages. In a distance measuring device to which the light projecting device in the embodiment is applied, it is possible to contribute to miniaturization, in particular, by switching between dot irradiation and surface irradiation in the light emitting optical system. As a result, when dot irradiation is performed as irradiation light toward an object as shown in FIG. 3, the density of light can be increased and the measurement distance can be extended. On the other hand, for short distances, in order to improve the distance measurement in areas where the dots are not illuminated, it is necessary to change the refractive index of the variable focus lens and switch to surface illumination, as shown in Figure 4, to measure with high resolution. I can do it.

Conventional methods include using a voice coil motor (VCM) and installing two types of projection optical systems, dot irradiation and surface irradiation, on the ranging module, but there are concerns about increasing the size. Ru. In the above embodiments of the present disclosure, the above merits can be achieved without increasing the size by using a variable focus lens that does not move in the optical axis direction.

In embodiments of the present disclosure, the light projection optical system may further include a DOE and a collimator lens. Here, the collimator lens, the variable focus lens, and the diffractive optical element are installed in order on the optical axis in a direction away from the light emitting source, or , the collimator lens, the diffractive optical element, and the variable focus lens are installed in this order.

For example, if there is sufficient space in the optical axis direction of the projector, the design can be simplified by arranging the variable focus lens 501 closer to the object than the DOE 502 as shown in FIG. Similar to FIG. 2, this embodiment uses a variable focus lens 501 that does not move in the optical axis direction within the projection optical system. The variable focus lens 501 may be positioned on the object side or on the light emitting element side with respect to the DOE.

At this time, as shown in FIG. 6, when employing the dot irradiation method, the diameter of each dot irradiated onto the object is narrowed down using a variable focus lens 501. 7 and 8 are conceptual diagrams of normal dot irradiation and high power dot irradiation with a reduced dot diameter.

The light projection device shown in FIG. 5 has the following advantages. By narrowing down the dot diameter of dot irradiation, it is possible to improve dot resolution and prevent distance measurement errors for objects illuminated far away. However, care must be taken because the distance between the dots increases due to the effect of narrowing down the dot diameter, which increases the area that is not illuminated.

Another embodiment of the present disclosure utilizes the optical power of a variable focus lens to achieve flexible field angle manipulation in dot irradiation. However, if the optical power of the variable focus lens is not sufficient for controlling the angle of view, a plurality of variable focus lenses may be used. That is, in the light projection device according to another embodiment of the present disclosure, there are at least two variable focus lenses.

As shown in FIG. 9, in the light projection device according to another embodiment of the present disclosure, the light projection optical system further includes a DOE 802 and a collimator lens 801, where the light emitting light source ( For example, the collimator lens 801, the DOE 802, and at least two variable focus lenses 803 are installed in order in the direction away from the laser. Optionally, a variable focus lens may be placed between the collimator lens and the DOE. At this time, the collimator lens, at least two variable focus lenses, and a DOE 802 are installed in order on the optical axis in a direction away from the light emitting source.

As a basic operation, the angle of view is adjusted to a wider angle as shown in Fig. 9 for relatively close objects 804, and the angle of view is adjusted as shown in Fig. 10 for distant objects. Squeeze and measure.

The light projecting devices shown in FIGS. 9 and 10 have the following advantages. By narrowing down the angle of view, the distance between dots in dot irradiation can be shortened, and resolution can be improved. It should be noted that the range of dot irradiation within the imaging field of view is narrow. However, when measuring a distance to a distant object, there are many scenes in which the center of the imaging angle of view is measured, so it is beneficial to concentrate dot irradiation only on the center of the imaging angle of view to increase resolution.

Based on the light projecting device provided by the several embodiments described above, the disclosed embodiment further provides a distance measuring device. In addition to including the light projecting devices shown in FIGS. 2, 5, and 9, the device further includes a light receiving device. The light receiving device includes a light receiving element and a light receiving optical system, and FIG. 1 is referred to for the specific structure.

Further, the embodiments of the present disclosure provide an electronic device, such as a smartphone, including the distance measuring device.

Note that the embodiment of the present disclosure takes a projection optical system applied to ToF as an example and proposes the idea of using a variable focus lens; It can be applied not only to systems but also to general light projectors.

Although the embodiments of the present disclosure have been described above based on the drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are illustrative and not restrictive. Many forms that a person skilled in the art can make upon the suggestion of this disclosure without departing from the spirit of this disclosure and the scope of the claims are all included within the protection scope of this disclosure.

Claims (10)

A light projecting device,
The projecting optical system includes a light emitting light source and a variable focus lens arranged on an optical axis, and when the variable focus lens does not move in the optical axis direction, the variable focus lens changes the focal position according to a drive signal. ,
The variable focus lens includes a first driving state and a second driving state, and after the light emitted from the light emitting light source passes through the light projection optical system in the first driving state, it is set to dot irradiation, and the second driving state After the light emitted from the light emitting light source passes through the projection optical system in the state, the light is set to surface illumination,
The light projecting device includes:
The light projecting device further includes a drive module for driving the variable focus lens according to the measured distance to cause the light projecting device to switch to the dot irradiation or the surface irradiation . The light projection device according to claim 1, wherein the variable focus lens is a liquid lens, a thin film lens, or a liquid crystal lens. The light projection device according to claim 1, wherein the variable focus lens is fixed in the optical axis direction. The projection optical system according to any one of claims 1 to 3, wherein the projection optical system further includes a diffractive optical element, and the variable focus lens is located between the diffractive optical element and the light emitting source. light device. The projection optical system further includes a diffractive optical element and a collimator lens,
The collimator lens, the variable focus lens, and the diffractive optical element are installed in order on the optical axis in a direction away from the light emission source;
or
4. The projection according to claim 1, wherein the collimator lens, the diffractive optical element, and the variable focus lens are installed in order on the optical axis in a direction away from the light emitting source. light device. 3. The light projecting device according to claim 1, wherein there are at least two variable focus lenses. The projection optical system further includes a diffractive optical element and a collimator lens,
7. The light projecting device according to claim 6, wherein the collimator lens, the diffractive optical element, and at least two variable focus lenses are installed in order on the optical axis in a direction away from the light emitting source. The projection optical system further includes a diffractive optical element and a collimator lens,
7. The light projecting device according to claim 6, wherein the collimator lens, at least two variable focus lenses, and the diffractive optical element are installed in order on the optical axis in a direction away from the light emitting source. A distance measuring device comprising a light receiving element and a light receiving optical system, and further comprising a light projecting device according to any one of claims 1 to 8. An electronic device comprising the distance measuring device according to claim 9.