JPH0556133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an alignment detection device for an ophthalmological instrument.

(Prior Art) In an ophthalmological instrument, for example, an objective eye refractive power measuring device, a measuring light projection optical system projects a measuring light toward the eye to be examined, and based on the measuring light, the eye refractive power,
Although intraocular pressure and the like are measured, if the measurement light is not properly set for the eye being examined, errors will occur in the measurement. Therefore, ophthalmological instruments have conventionally been provided with an alignment detection device that detects the position of a measurement optical system with respect to the eye to be examined when measuring the eye to be examined.

(Problems to be Solved by the Invention) By the way, this alignment detection device includes an alignment light projection optical system that projects alignment light toward the eye to be examined, and an optical system that receives the alignment light reflected from the eye to be examined. The alignment light reflected from the eye to be examined is detected using a detector of the light receiving optical system, and it is determined whether or not the alignment adjustment is completed. . For example, in an ophthalmological instrument, an alignment light projection optical system and a light reception optical system are incorporated into a measurement optical system, and alignment light is projected toward the eye to be examined through the objective lens of the measurement optical system. The alignment light is imaged at the center of the corneal curvature of the optometrist, and the imaged alignment light is guided through the objective lens to the detector of the light receiving optical system built into the measurement optical system, where it is imaged. Alignment adjustment is performed based on the amount of light detected by the detector, but conventional alignment detection devices for ophthalmic instruments have a complicated configuration and have the disadvantage that it is not possible to visually confirm the completion of alignment.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to provide an ophthalmological instrument that has a simple configuration and can easily visually confirm whether or not alignment has been completed. An object of the present invention is to provide an alignment detection device.

(Means for Solving the Problems) The ophthalmological instrument according to the present invention is characterized by having an alignment light projection optical system that projects alignment light toward the subject's eye, and the alignment light reflected from the subject's eye. observation optics that guides the image to an imaging surface to form a bright spot image, and also forms an anterior segment image of the subject's eye on the imaging surface to display and observe the anterior segment image and the bright spot image. a reference scale image projection optical system that projects reference scale light for alignment discrimination reference onto the imaging surface to form a reference scale image, a video signal corresponding to the reference scale image, and an image corresponding to the bright spot image. Based on the signal and
and a determination processing circuit that determines the relative position of the bright spot image with respect to the reference scale image and determines whether the measurement optical system is aligned with the eye to be examined.

(Function) According to this device, when the alignment light is projected toward the eye to be examined, the alignment light is imaged on the corneal surface as a bright spot image. The alignment light that forms a bright spot image on the corneal surface is guided as reflected light to the imaging surface of the light receiving optical system via the observation optical system again. Since the anterior segment image of the subject's eye is formed on the imaging surface via the observation optical system, the bright spot image and the anterior segment image are displayed by the display means as part of the observation optical system. You can observe them. Further, a reference scale image is projected onto the imaging surface by the reference scale image projection optical system, and a process of determining whether or not alignment is completed is also performed based on the reference scale image and the bright spot image.

(Example) An example in which an alignment detection device for an ophthalmological instrument according to the present invention is applied to an eye refractive power measuring device will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a measurement target image projection optical system of the eye refractive power measurement apparatus, and 2 indicates an objective lens thereof.The measurement target image projection optical system 1 projects a measurement target image as measurement light for measuring the eye to be examined. It has a function of projecting toward the eye 3 to be examined, and the measurement target image is formed on the fundus 5 of the eye 3 to be examined via the half mirror 4, and the measurement target image formed on the fundus 5 is as follows. , is again guided to the target image projection optical system 1 via the half mirror 4, and the eye refractive power measuring device measures the eye refractive power of the eye 3 to be examined based on the measurement target image.The detailed configuration is as follows. Since this is already known, I will omit the explanation.

The half mirror 4 is arranged on the measurement optical axis l of the measurement target image projection optical system 1, and constitutes a part of the observation optical system 6. The observation optical system 6 includes an alignment light projection optical system 7 that projects alignment light, and a light receiving optical system 8 that receives the alignment light reflected from the eye 3 to be examined. The alignment light projection optical system 7 includes a light emitting element 9, a condensing lens 10, and a perforated mirror 11.
, a half mirror 12 , and an imaging lens 13 . The light emitting element 9 generates alignment light, the condenser lens 10 has a function of converting the alignment light into a parallel beam, and the alignment light passes through the hole 11a of the perforated mirror 11 and enters the half mirror 12. The alignment light is focused on the corneal surface 14 of the eye 3 to be examined as a bright spot image.

The light receiving optical system 8 includes an imaging lens 15 and an image pickup tube 1.
6. This image pickup tube 16 receives the anterior segment reflected light from the anterior segment of the subject's eye 3 through the half mirror 4, the imaging lens 13, and the half mirror 1.
2. The alignment light that is guided through the perforated mirror 11 and formed as an anterior segment image and reflected on the corneal surface 14 is directed to the half mirror 4;
The light is guided through an imaging lens 13, a half mirror 12, and a perforated mirror 11, and is formed as a bright spot image. The half mirror 12 constitutes a part of a reference scale image projection optical system 17, and the reference scale projection optical system 17 includes an illumination light source 18,
Condensing lens 19 and reference scale pattern plate 20
and a projection lens 21. A reference pattern 22 is formed on the reference scale pattern plate 20, as shown in FIG. This reference pattern 22 is formed of circular arc-shaped transparent parts 23 and 24 arranged at target positions with the center 0 as a boundary. The image pickup tube 16 includes a reference scale image projection optical system 17.
The reference scale light emitted from the half mirror 1
2. The light is guided through the perforated mirror 11 and the imaging lens 15, and is formed as a reference scale image together with the bright spot image and the anterior segment image.

The observation optical system 6 is for displaying and visually observing the anterior segment image and the bright spot image, and the imaging tube 16 includes:
As shown in FIG. 1, a television monitor 26 as a display means is connected via a video signal extraction circuit 25. Display surface 27 of this television monitor 26
As shown in FIG. 3, an anterior segment image 28, a bright spot image 29, and a reference scale image 30 are displayed. The examiner examines the anterior segment image 28 and the bright spot image 29.
By visually confirming the reference scale image 30 and the reference scale image 30, the target image projection optical system 1 is projected onto the eye 3 to be examined.
This is for coarse alignment adjustment. The video signal extraction circuit 25 has a function of sequentially extracting video signals corresponding to predetermined scanning lines based on the extraction command signal of the extraction command circuit 31, and its output signal is input to the rectangular wave generation circuit 32. ing. The extraction command circuit 31 has a function of outputting extraction command signals corresponding to predetermined scanning lines n ₁ , n ₂ , n ₃ to the video signal extraction circuit 25, as shown in FIG.
The scanning lines n ₁ , n ₂ , n ₃ are within a predetermined range l', and the scanning lines _{n 1} , n ₁ are at symmetrical positions with respect to the scanning line n 2 . These scanning lines n ₁ , n ₂ , n ₃ are bright spot image 2
9 and the reference scale image 30, the waveform of the video signal output from the video signal extraction circuit 25 changes.
_5B shows the video signal corresponding to scanning line n ₁ converted into a rectangular wave, and FIG.
FIG. 5C shows the video signal corresponding to scanning line _n3 converted into a rectangular wave. The judgment as to whether or not the alignment is completed is made based on the rectangular wave signal, and when the horizontal alignment of the eye 3 is completed, the absolute value of the difference between the intervals l ₁ and l ₂ is |l ₁ −l ₂ ｜
Determination is made based on whether <ε ₁ .

This is because if the interval l ₁ and the interval l ₂ are approximately equal, it can be considered that the bright spot image 29 exists at the center in the horizontal direction. Completion of vertical alignment of the eye 3 to be examined is determined based on whether three rectangular waves are detected for all of the scanning lines n ₁ , n ₂ , and n ₃ . This means that the position where each scanning line crosses the reference scale image 30 is determined, and if the position of the bright spot image 29 is shifted from the center of the reference scale image 30, it will correspond to any one of the scanning lines. This is because the number of rectangular waves in the rectangular wave signal is two. Completion of working distance adjustment in the direction of the measurement optical axis is determined based on the size of the bright spot image in the focused state, and here, the distance from the leading edge to the trailing edge of the rectangular wave L is l ₂ < The determination is made based on whether ε ₂ or not. This is because the size of the bright spot image 29 is at its minimum when the bright spot image 29 is in focus.

The output of the rectangular wave generation circuit 32 is input to an arithmetic circuit 33, and the output of this arithmetic circuit 33 is input to a determination circuit 34. The arithmetic circuit 33 has a function of calculating the intervals l ₁ , l ₂ , l ₃ and |l ₁ −l ₂ |, and the determination circuit 34 uses the output from the arithmetic circuit 33. Based _{on the calculated signals calculated by} The alignment state is detected by discrimination. The determination circuit 34 also has a function of determining whether |l ₃ |<ε ₂ and detecting the working distance adjustment state. The output of the determination circuit 34 is output from the output circuit 3
5, and its output is input to a television monitor 26, which displays whether or not the alignment and working distance adjustment have been completed. The rectangular wave generation circuit 32, the calculation circuit 33, and the determination circuit 34 determine the relative position of the bright spot image with respect to the reference scale image and the relative position of the bright spot image with respect to the reference scale image based on the video signal corresponding to the reference scale image and the video signal corresponding to the bright spot image. The focus state of the bright spot image is discriminated and the subject's eye 3
This generally constitutes a determination processing circuit that determines whether or not the alignment and working distance of the measurement optical system have been adjusted.

Although the embodiments have been described above, the completion of the working distance adjustment in the measurement optical axis direction can also be determined based on the output peak value of the rectangular wave corresponding to the light amount of the bright spot image.

Further, in the above embodiment, vertical alignment is completed at each predetermined scanning line n ₁ , n ₂ , n ₃
The judgment is made based on whether three rectangular waves are detected for all of The determination may be made based on whether three rectangular waves are detected.

Regarding horizontal alignment, the horizontal width of the reference scale shown in Figure 4 is set as the alignment allowable width, and only the video signal within a range somewhat larger than the horizontal width of the reference scale is extracted. The determination may be made based on whether or not three rectangular waves are detected.

(Effects of the Invention) As described above, the present invention includes an alignment light projection optical system that projects alignment light toward the eye to be examined, and guides the alignment light reflected from the eye to the imaging surface. an observation optical system that forms a bright spot image and an anterior eye segment image of the subject's eye on the imaging surface to display and observe the anterior eye segment image and the bright spot image; and an alignment determination standard. a reference scale image projection optical system that projects reference scale light for use on the imaging surface to form a reference scale image; and a video signal corresponding to the reference scale image and a video signal corresponding to the bright spot image. ,
Since the configuration includes a determination processing circuit that determines the relative position of the bright spot image with respect to the reference scale image and determines whether or not the measurement optical system is aligned with the eye to be examined, the configuration is simple; In addition, it is possible to easily visually confirm whether or not alignment has been completed.

[Brief explanation of the drawing]

FIG. 1 is an optical system diagram of an embodiment in which the alignment detection device for an ophthalmic instrument according to the present invention is applied to an eye refractive power measurement device, and FIG. 2 is a reference scale pattern plate of the reference scale image projection optical system shown in FIG. FIG. 3 is a plan view showing the anterior segment image, bright spot image, and reference scale image displayed on the display surface of the television monitor shown in FIG. 1, and FIG. 4 is a plan view of the ophthalmological instrument according to the present invention. Explanatory diagrams for explaining the alignment judgment of the alignment adjustment device, Fig. 5 A, Fig. 5 B,
FIG. 5C is a waveform diagram of a rectangular wave output corresponding to each scanning line. DESCRIPTION OF SYMBOLS 1... Measurement target image projection optical system, 3... Eye to be examined, 6... Observation optical system, 7... Light projection optical system for alignment, 8... Light receiving optical system, 16... Image pickup tube, 17...
Reference scale image projection optical system, 26... Television monitor, 27... Display surface, 28... Anterior segment image, 29... Bright spot image, 30... Reference scale image, 31... Extraction command circuit, 32... Rectangular wave generation circuit, 33 ...Arithmetic circuit, 3
4...Judgment circuit.

Claims (1)

[Claims] 1. It has an alignment light projection optical system that projects alignment light toward the eye to be examined, and guides the alignment light reflected from the eye to be imaged to an imaging surface to form a bright spot image, and also directs the alignment light reflected from the eye to be examined to form a bright spot image. an observation optical system that displays and observes the anterior segment image and the bright spot image by forming a partial image on the imaging surface;
a reference scale image projection optical system that projects reference scale light for alignment discrimination reference onto the imaging surface to form a reference scale image; a video signal corresponding to the reference scale image; and a video signal corresponding to the bright spot image; an alignment detection device for an ophthalmological instrument, comprising a discrimination processing circuit that discriminates the relative position of the bright spot image with respect to the reference scale image based on the above, and discriminates whether the measurement optical system is aligned with the eye to be examined. .