JPS59228108A - Distance sensor - Google Patents

Abstract

PURPOSE:To perform the judgment of a distance simply and stably, by positioning a light receiving element, which is divided into two parts, so that the image of a light spot on a reference surface is formed on a boundary line of light receiving surfaces, and comparing the magnitudes of the voltages from the two light receiving surfaces. CONSTITUTION:A spot light beam is projected on an object surface 12 by a light projecting part 11 comprising a spot light source and a light projecting lens. The image of the light spot is formed on the light receiving surfaces of a photodiode 14, whose light receiving surface is divided into two parts, i.e. the upper and lower parts. Current I1 and I2 are obtained as the outputs of the received light beams at the upper part and the lower part of the boundary line on the light receiving surfaces of the photodiode 14, which is divided into the two parts. The current I1 and I2 are converted into voltage V1 and V2 by photoelectric conversion circuits 15 and 16. The magnitudes of the voltages V1 and V2 are compared and judged by a comparator 17. The judged result is inverted by an inverter 18, and a light emitting diode 19 for display is driven. The result is taken out as the judged output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a distance sensor that compares the distance to a target surface with a predetermined distance by optical triangulation (optical cutting method) to determine the size of the distance.

[Background technology]

Conventionally, as shown in FIG. 1, a distance sensor that measures distance using light cutting emits a spot light onto a target surface 2 through a light projecting unit 1 consisting of a spot light source and a light projecting lens. Light spora due to spot light) [-One-dimensional semiconductor device detector (Sl 352:
(manufactured by Hamamatsu Television Co., Ltd.) 4, and the imaging position of the light spot image is determined by calculation, which determines the reference position 5.
The distance Δl from to the target surface 2 is determined. Specifically, the one-dimensional semiconductor device detector 41 is positioned so that when the surface at the reference position 5 is irradiated with spot light, the imaging position of the light spot image is exactly at the center, and the spot light is placed on the target surface 2. The original spot image when the light is irradiated is formed on the one-dimensional semiconductor device detector 4, and the -
The received light output currents ■□, ■2 from one end and the other end of the dimensional type cow conductor position detector 4 are converted into voltage ■ by the photoelectric conversion circuit 6.7.
□ and ■2, the operational amplifier 8a in the distance calculation circuit 8 calculates the sum voltage V +V, and the operational amplifier 8b calculates the difference voltage V +V, and divider 8c
Normalize by dividing the difference voltage V□-v2 by the sum voltage V□+V - This normalized output vs is calculated from the reference position 5 to the target surface 2.
It is proportional to the distance Δl.

In order to determine the magnitude of the distance Δl from the reference position 5 to the target surface 2 by comparing it with a predetermined distance based on the normalized output ■8, the distance output, that is, the normalized output v8, must be electrically set to a predetermined value. A comparison circuit is required. This circuit is the illustrated high-precision comparison circuit 9.

This high-precision comparison circuit 9 sets a voltage corresponding to a predetermined distance by a potentiometer 9b supplied with power from a constant current power supply 9a, and compares this set voltage vTH with the normalized output VB by a comparator 9C, and compares the set voltage vTH with the normalized output VB. l)
The results of distance comparisons are output.

In addition, in order to compare whether the distance Δl from the reference position 5 to the target surface 2 is within a predetermined eave area range based on the normalized output Vs, the high precision comparison circuit 9 is used. Instead, it is necessary to use a window type high precision comparison circuit 10. This window type high precision comparison circuit 10
As shown in FIG. 2, the upper limit voltage vT corresponding to the upper limit of a predetermined tolerance range is set by the upper limit setting potentiometer 10b supplied with power from the constant current power supply 10a, and the A lower limit voltage VB corresponding to the lower limit value of a predetermined tolerance range is set by the lower limit setting potentiometer 10c, and the upper limit voltage VT, lower limit voltage VB, and normalized output VB are set by the upper limit comparator 1.
0d and a lower limit comparator 10e for comparison.

Now, if the normalized output V8 is larger than the upper limit voltage vT, the upper limit comparator 10d and the lower limit Conhaler/10e
The outputs are H and H, respectively) 10f, lO
g.

If the outputs of 10h become H, L, and L, respectively, and the normalized output ■8 is smaller than the upper limit voltage VT and larger than the lower limit voltage VB, the outputs of the upper limit comparator 10d and the lower limit comparator 1Oe become respectively, and at H, it becomes an AND game) 10
The outputs of f, 10g, and 10h are respectively H.

When the normalized output Vs is smaller than the lower limit voltage VB, the upper limit comparator 10d and the lower limit converter (lator 1
The outputs of 0e and L are respectively F and 10f.

The outputs of 10g and 10h are respectively L and H.

If you put this into a table, it will look like the following table.

That is, when an H output appears from the AND gate 10f, the distance is too large; when an H output appears from the AND gate 10g, it is within the allowable range; and when an H output appears from the AND gate 10h, the distance is too small.

Note that 10i, 10j, and 10 are in/(-even).

However, such conventional distance sensors are difficult to accurately, widely and stably determine whether the distance from the reference position 5 to the target surface 2 is larger or smaller than a predetermined value, or whether it is within an allowable range. , a distance calculation circuit 8, and a high-precision comparison circuit 9 or 10.

[Purpose of the invention]

An object of the present invention is to provide a distance sensor that can perform distance determination with high precision, over a wide range, and stably with a simple circuit configuration.

[Disclosure of the invention]

The distance sensor of the first invention includes a light projecting section that irradiates a spot light onto a target surface, a light receiving lens that converges a light spot on the target surface, and a light receiving surface that is divided into two parts in one direction and the other. a two-part light-receiving element that is positioned so that its boundary line is perpendicular to the deflection direction of the light-receiving axis of the light-receiving lens depending on the distance of the target surface, and forms a light spot image converged by the light-receiving lens on the light-receiving surface; The divided light-receiving element is movable in a direction perpendicular to the boundary line of the light-receiving surface and substantially parallel to the light-receiving surface, and an original spot image of the light spot on the reference plane is formed on the boundary line of the light-receiving surface. a light-receiving element movement/positioning mechanism that positions the two-split light-receiving element, and a first and second light-receiving output current from the light-receiving surfaces of one and the other of the two-split light-receiving elements, respectively. The configuration includes first and second current-voltage conversion circuits that convert the voltage into voltages of The second invention determines whether the distance to the target surface is within a permissible range by providing two sets of a two-split light-receiving element, a light-receiving element movement/positioning mechanism, a current-voltage conversion circuit, and a controller. I try to do that.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

An embodiment of Ml of this invention is shown in FIG. That is, this distance sensor irradiates a target surface 12 with a spot light using a light projecting unit 11 consisting of a spot light source and a light projecting lens,
A light spot image of this spot light is formed through a light receiving lens 13 onto the light receiving surface of a two-part photodiode 14 whose light receiving surface is divided into two parts, upper and lower.
The light receiving output currents 11.12 at the upper and lower parts of the boundary line on the light receiving surface of 4 are converted by photoelectric conversion circuits 15.16 to stain voltages V, 2, respectively, and these voltages V, 2, A comparator 17 compares and determines the magnitude of
It is designed to drive and output as a judgment output.

The two-part photodiode 14 is configured to be movable by the light-receiving element moving/positioning mechanism 20 with its light-receiving surface facing the light-receiving lens 13 . The movement locus of this two-divided photodiode 14 is set so as to meet the Scheimpflug condition. That is, the two-split photodiode 14
The light-receiving surface of the light-receiving surface is moved in the radial direction centered on the light-emitting axis 21 on a plane that intersects the surface containing the light-receiving lens 13 on the light-emitting axis, and the boundary line between the two divided light-receiving surfaces is in the radial direction. It is made to be orthogonal to In this way, by setting the movement locus of the two-split photodiode 14, a reflected light image of the spot light that is always in focus can be obtained on the light receiving surface, and the identification accuracy at the boundary between the divided parts of the light receiving surface can be improved. can be improved.

Therefore, the two-split photodiode 14 is positioned so that the light spot image irradiated onto the reference plane 22 is located on the boundary line of the two-divided light-receiving surface as shown by the dashed line. When the target surface 12 is farther away than the reference surface 22, the light spot image will be located above the boundary line on the two-divided light-receiving surface as shown by the solid line, and the light output of the two-divided photodiode 14 will decrease. Current! , is larger than the optical output current I2, so the voltage V is larger than the voltage v2. As a result, the comparator 17 generates an H output, the inverter 18 generates an L output as a judgment output, and the display light emitting diode 19 is turned on.

On the other hand, if the target surface 12 is located at a far distance from the reference surface 22, the light spot image will be located below the boundary line on the two-divided light-receiving surface, and the light output current I2 of the two-divided photodiode 14 will be becomes larger than the optical output current I. As a result, the comparator 17 generates an L output, the innocent output 18 generates an H output as a determination output, and the display light emitting diode 19 turns off.

As a result of this configuration, there is no need for a distance calculation circuit 8 or a high-precision comparison circuit 9 as in the conventional example, and the comparator 17 that simply compares the size can determine whether the target surface 12 is farther or closer than the reference surface 22. Moreover, since the movement locus of the two-part photodiode 14 is made to match the Scheimpflug condition, the identification accuracy at the boundary of the light-receiving surface of the two-part photodiode 14 is improved, making the judgment highly accurate. It can be done with In addition, the 2-split photodiode 1
4 only needs to be moved by the light-receiving element moving/positioning mechanism 20, stable determination can be made over a wide range.

A second embodiment of the invention is shown in FIG. That is, this distance sensor irradiates a target surface 42 with a spot light using a light projecting section 41 consisting of a spot light source and a light projecting lens,
A light spot image from this spot light is transmitted through a light receiving lens 43 to a two-split photodiode 45 whose light receiving surface is divided into two.
A half mirror 44 is arranged between the light receiving lens and the 2-split photodiode 45, and the reflected light from the half mirror 45 is received by the 2-split photodiode 46 whose light receiving surface is divided into upper and lower halves. The image is formed on a surface. Then, the light receiving output current i
and v2 respectively, and this voltage v1. (2) The upper limit comparator 49 compares and determines the magnitude of 2, and the upper and lower portions 51 of the boundary line on the light-receiving surface of the two-split photodiode 46 convert the voltages V', v, and ', respectively. A lower limit comparator 52 compares and determines the magnitude of 1' and 2'.

The outputs of the upper and lower limit comparators 49 and 52 are input as they are to the Nantes gate 53, and the L output of this Nantes gate 53 is used as an output indicating an excessive distance, and this L output emits light to indicate an excessive distance. The diode 54 is turned on, and the upper limit comparator 4
The output of the lower limit comparator 52 is inverted by the inverter 56 and inputted to the Nant gate 55.
The L output of is used as an output indicating that it is within the permissible range, and the light emitting diode 57 is turned on to indicate that the permissible value is within the permissible range. Invert it and input it to the Nantes gate 60.
The L output of 0 is distance II! In addition to producing an output that indicates an undervalue,
This L output lights up a light emitting diode 61 which indicates that the distance is too short.

'The two-divided photodiodes 45 and 46 are configured to be movable by light-receiving element moving/positioning devices 162 and 63. The locus of movement of this two-part photodiode 45.degree. 46 is set so as to meet the Scheimpflug condition.

That is, the light-receiving surface of the two-split photodiode 46 is moved in the radial direction centered on the light-emitting axis 64 on a plane that intersects the plane containing the light-receiving lens 43 on the light-emitting axis 64, and the light-receiving surface of the two-split photodiode 46 is The boundary fIiJI/'i is perpendicular to the radial direction. Another two-divided photodiode 45 has a moving locus that is divided into two parts with respect to the plane including the half mirror 44.
The photodiode 45 is moved symmetrically with respect to the locus of movement of the divided photodiode 45, and the light-receiving surface is arranged symmetrically with respect to the light-receiving surface of the two-part photodiode 46 and the plane including the half mirror 44. In this way, by setting the movement locus of the two-split photodiode 45.46, the light spot image that is always in focus is created by the two-split photodiode 45.46.
Therefore, the identification accuracy at the boundary between the divided parts of the light receiving surface can be improved.

Then, the two-split photodiode 45 is positioned so that the light spot image irradiated onto the upper limit surface 65 is located on the boundary line of the light-receiving surface of the two-split photodiode 45, as shown by the dashed line, and the light spot image irradiated onto the lower limit surface 66 is positioned. The light spot image is divided into two photodiodes 4 as shown by the two-dot chain line.
The two-split photodiode 46 is positioned so as to be located on the boundary line of the light receiving surface 6.

When the target surface 42 is farther away than the upper limit surface 65, the light spot image is formed below the boundary line on the light-receiving surface of the two-split photodiode 45, and the light-receiving output current i is smaller than the light-receiving output current i2. As the voltage Vl becomes smaller than the voltage v2, the upper limit comparator 49 generates an H output, and the light spot image is formed above the boundary line on the light receiving surface of the two-split photodiode 46, and the light receiving output current increases. 1□(receives light output current, / becomes larger, voltage V' becomes larger than voltage v2', lower limit comparator 52 generates H output, outputs of 53, 55, 60 respectively become H).

When H is selected, only the light emitting diode 54 lights up to indicate an excessive distance.

When the target surface 42 is close to the upper limit surface 65 and far from the lower limit surface 66 and is within the allowable range, the light spot image is located at the boundary on the light-receiving surface of the two-part photodiode 45 as shown by the solid line. The image is formed above the line, and the received light output current I:L
is larger than the received light output voltage if2, and the voltage V is the voltage v2
The upper limit comparator 49 generates an L output due to the larger size, and the light spot image is placed above the boundary line on the light receiving surface of the two-split photodiode 46, as shown by the solid line, so that the light receiving output current i□' The received light output current 12' becomes larger, the voltage V' becomes larger than the voltage v2', the lower limit comparator 52 generates an H output, and the Nant gates 53, 55.
The outputs of 60 become H, L, and H, respectively, and only the light emitting diode 57 lights up, indicating that it is within the permissible range.

When the target surface 42 is closer to the lower limit surface 66, the original spot image is formed above the boundary line on the light-receiving surface of the two-split photodiode 45, and the light-receiving output current i is equal to the light-receiving output current +2. The large force and voltage V□ become larger than the voltage v2, and the upper limit comparator 49 generates an L output, and a light spot image is formed below the boundary line on the light-receiving surface of the two-split photodiode 46, When the light receiving output current 1□' is smaller than the light receiving output current 12', the voltage V' becomes smaller than the voltage v2', and the lower limit comparator 52 generates an L output.
The outputs of Nant gates 53, 55.60 are H and H, respectively.
.

When L is selected, only the light emitting diode 61 lights up to indicate that the distance is too short.

As a result of this configuration, there is no need for the distance calculation circuit 8 and the high precision comparison circuit 10 as in the conventional example, and the upper limit comparator 49 and the lower limit comparator 52 that simply compare the magnitude
and Nant gate 53, 55°60 and inverter 5
6, 58, and 59, it is possible to determine whether the target surface 42 is within the permissible range, and the movement locus of the two-part photodiode 45°46 is made to match the Scheimpflug condition. The discrimination N degree at the boundary of the light-receiving surface of the two-part photodiode 45 and 46 is improved.

Judgments can be made with high precision. In addition, the two-divided photodiode 45 and 46 are moved and positioned by the light-receiving element moving and positioning mechanism 62.
．． 63, it is possible to make a comprehensive determination over a wide range.

A third embodiment of the invention is shown in FIGS. 5 and 6.

That is, this distance sensor is connected to the light receiving lens 43 in FIG.
By using a light-receiving lens 67 in which the plano-convex lens 67a and the cylindrical lens 67b are brought into close contact with each other, the plano-convex lens 67a side faces the object surface 42, and the cylindrical lens 67b side is the 2-split photodiode 45° 46 side. A two-part photodiode 4 arranged in parallel converts the light spot image irradiated onto the photodiode 42 from circular to linear.
The image is formed on both light receiving surfaces of 546. The arrangement of the two-divided photodiodes 45.degree. 46 in the case of the third embodiment is the same as the two-divided photodiodes 46 in FIG.

Note that FIG. 6 is a view of the light receiving lens 67, two-divided photodiode 45, 46, and the light receiving element moving/positioning mechanism 62, 63 viewed in the direction of the arrow in FIG.

Other configurations and effects are similar to those of the second embodiment described above.

〔Effect of the invention〕

According to the distance sensor of the present invention, there is an effect that distance can be determined easily over a wide range with a simple circuit configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional distance sensor, Fig. 2 is a main circuit diagram of another conventional example, Fig. 3 is a block diagram of a first embodiment of the present invention, and the fourth factor is a block diagram of a conventional distance sensor. Configuration diagram of the second embodiment, fifth
The figure is a block diagram of a third embodiment of the present invention, and FIG. 6 is an enlarged view of the main parts thereof. DESCRIPTION OF SYMBOLS 11... Light emitter, J2... Target surface, 13... Light receiving lens, 14... 2-split photodiode, 15.16
... Optical m conversion circuit, 17... Comparator, 18.
...Inverter, 19...Light-emitting diode, 41...
・Light emitter, 42...Target surface, 43...Light receiving lens,
44... Half mirror 145, 46... 2-split photodiode, 47° 48.50.51... Photoelectric conversion circuit, 49... Upper limit comparator, 53, 55.60...
・Cant gate, 56.58.59...Inverter,
54,57.61...Light-emitting diode" Mame Figure 5 3 Figure 6

Claims (3)

[Claims] (1) A light projecting unit that irradiates a spot light onto the target surface, a light receiving lens that converges the light spot on the target surface, and a light receiving surface that is divided into two parts in one direction, one side and the other side, and the boundary line is the light receiving lens. a two-split light-receiving element that is positioned so as to be perpendicular to the deflection direction of the light-receiving axis of the lens due to distance and distance of the object plane, and forms a light spot image converged by the light-receiving lens on the light-receiving surface; The light receiving surface is movable in a direction perpendicular to the boundary line of the light receiving surface and substantially parallel to the light receiving surface so that a light spot image of the light spot on the reference surface is formed on the boundary line of the light receiving surface. a light-receiving element moving/positioning mechanism for positioning the two-split light-receiving element; and converting first and second light-receiving output currents from one and the other light-receiving surfaces of the two-split light-receiving element into first and second voltages, respectively. A distance sensor comprising first and second current-voltage conversion circuits and a comparator that compares the magnitude of the first and @2 voltages. (2) The light-receiving element moving/positioning mechanism moves the light-receiving surface of the two-split light-receiving condenser within a plane that intersects a plane containing the light-receiving lens on the light projection axis. Distance sensor described in (1). (3) A light projecting unit that irradiates a spot light onto a target surface, a light receiving lens that converges a light spot on the target surface, and a light receiving surface that is divided into two in one direction into one and the other, with the boundary line being the light receiving lens. a first and a second second lens for forming a light spot image on the light receiving surface under the same geometrical conditions; a divided light-receiving element, and a first two-divided light-receiving element that is movable in a direction perpendicular to the boundary line of the light-receiving surface and substantially parallel to the light-receiving surface, and a light spot formed by a light spot on the upper limit surface; a first light-receiving element moving/positioning mechanism that positions the #11 two-split light-receiving element so that an image is formed on the boundary line of the light-receiving surface; The second second lens is movable in a direction perpendicular to the line and substantially parallel to the curved light-receiving surface, and is configured such that a light spot image of the light spot on the lower limit surface is formed on the boundary line of the light-receiving surface.
A second light-receiving element moving/positioning mechanism that positions the split light-receiving element and the first and second light-receiving output currents from one and the other light-receiving surface of the two-split light-receiving element of M1 The first and second
a current-voltage conversion circuit; an upper limit comparator for comparing the magnitudes of the first and second voltages; and third and fourth
A distance sensor comprising: third and fourth current-voltage conversion circuits that convert the received light output currents of the output current into third and fourth voltages, respectively; and a lower limit comparator that compares the magnitudes of the third and fourth voltages.