JPH04308975A - Method and device for image recording by camera - Google Patents

Abstract

PURPOSE:To exactly recognize an entire image as a focused image by recording the image by a television camera or the like so as to record one still picture in a photosensitive object while continuously or discontinously overlapping and projecting the image of an object having depth to the photosensitive object. CONSTITUTION:An image formation lens 3 is mounted at a main body 1 of the camera and while relatively displacing a photosensitive object 5 over the range of image formation focus depth L at least by a displacing means 6, the image of an object J having depth is continuously or discontinuously overlapped, projected and recorded as one still picture. The photosensitive object 5 is constituted so as to time sequentially output the amount of electric charges stored in the respective photoelectric converting elements of the photosensitive object 5 as a picture element signal each time the photosensitive object 5 is oscillated by one stroke over the range of the image formation focus depth L at least. Namely, the respective photoelectric converting elements of the photosensitive object 5 store the amount of the electric charges at respectively focused dot image and the amount of electric charge at the image of a scattered circle having a prescribed radius with spreading around the dot image as the charge amount for one picture element.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image recording method and an image recording device for a camera which are particularly useful in, for example, mounting inspection of printed circuit boards and inspection of electronic components in the preceding process. The present invention relates to an image recording method and an image recording device for a camera that can be applied to general cameras.

0002

BACKGROUND OF THE INVENTION For example, as a device for inspecting the mounting of a printed circuit board, the one disclosed in the magazine "Mechatronics" published by Gijutsu Kenkyukai Co., Ltd., April 1991 (VOL. 16) is known. As shown in FIG. 4, it is configured to record an image of a printed circuit board 21 to be inspected using a television camera 22, and to judge the quality of the mounting based on the recorded image. Note that the reference numeral 24 in the figure is an image check device, and the reference numeral 25 is a control circuit. Generally, with this type of television camera 22, only objects with a shallow depth and whose depth of field does not pose a problem are inspected. This is because the depth of focus of the imaging lens is shallow, and the structure is not such that it is possible to simultaneously focus on the front and rear parts of a deep subject.

0003

[Problem to be Solved by the Invention] For this reason, it is necessary to simultaneously record images of character patterns printed on the molded surface of an integrated circuit (IC) and the lead wires of the integrated circuit, where depth of field is a problem. It was not possible to inspect it. When you focus on a character pattern,
This is because the lead wires of the integrated circuit cannot be brought into focus, so accurate image recognition cannot be performed, and conversely, when the lead wires are brought into focus, the character pattern cannot be accurately recognized as an image. For this reason, in the prior art, this type of inspection could only be done manually. The present invention has been made in view of the above circumstances, and it is an object of the present invention to record a single still image that is in focus over the entire depth of field when recording an image of a subject with depth using a television camera or the like. The technical challenge is to be able to perform the above-mentioned mounting inspections and component inspections without human intervention.

0004

[Means for Solving the Problems] The present invention is constructed as follows to solve the above problems. That is, the invention of claim 1 defines the depth distance (K) of the subject (J) in the optical axis (X) direction as the depth of field, and the optical axis (X) of the best imaging position corresponding to the depth of field (K). ) direction depth distance (
L) is defined as the imaging focal depth, and the optical distance between the imaging lens (3) and the photoreceptor (5) is defined as at least the imaging focal depth (
A single still image is created on the photoconductor (5) by continuously or intermittently projecting an image of a subject (J) with depth onto the photoconductor (5) while relatively displacing it over the range of L). This is a camera image recording method characterized by recording.

Further, the invention of claim 2 defines the depth distance (K) of the subject (J) in the optical axis (X) direction as the depth of field, and the optical axis at the best imaging position corresponding to the depth of field (K). (X
) direction is defined as the imaging focal depth, and comprises an imaging lens (3), a photoreceptor (5), and a displacement means (6). is the imaging lens (
3) and the photoreceptor (5) is configured so as to change relatively over at least the range of the imaging focal depth (L), so that an image of a deep subject (J) can be transferred to the photoreceptor (5). (
An image recording device for a camera is characterized in that it is configured to record a single still image on a photoreceptor by continuously or intermittently projecting the image onto the photoreceptor.

[0006]

[Operation] In the present invention, the optical distance between the imaging lens 3 and the photoreceptor 5 is relatively displaced at least within the range of the imaging focal depth L. The photoreceptor 5 has an imaging focal depth L
An image of the subject J with depth is projected continuously or intermittently over the entire range. At this time, as shown in FIG. 2, for example, if we focus on a point Q on the subject J, the projected image (hereinafter referred to as a pixel) of the point Q will have an imaging focal depth L
At a position L0 within the range, a focused point image q is recorded on the photoreceptor, and at other positions, an image spread out into a blurred circle around the point image q is superimposed and recorded. That is, a focused point image q and an image of a circle of confusion r spreading around it are recorded as latent images on the photoreceptor.

By the way, as is clear from FIG. 2, the focused point image q has the highest optical energy density and is more strongly recorded on the photoreceptor than the image of the circle of confusion r, which has a weaker optical energy density. In other words, the image of the expanding circle of confusion r becomes unclear, and the point image q is clearly recorded as a pixel on the photoreceptor. Furthermore, when paying attention to other points of the subject J, the same thing as above can be said. Therefore, when an image of a deep subject J is continuously or intermittently projected over the entire range of the imaging focal depth L, the entire image of the deep subject J is projected onto the photoreceptor 5, with a depth of field K The entire range of the image will be recorded as a still image that is in focus.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram schematically showing an embodiment of the present invention. This embodiment includes a camera body 1 constituting a dark box, an imaging lens 3, a photoreceptor 5 disposed within the camera body 1 so as to be movable within a range of an imaging focal depth L, and a position of the photoreceptor 5 that is It is equipped with a displacement means 6 for displacing in the direction of the axis X, and is configured to continuously project images of a subject J with depth onto the photoreceptor 5 in an overlapping manner and record one still image. There is. Here, the depth distance K of the subject J in the optical axis X direction is defined as the depth of field, and the depth distance L in the optical axis X direction of the best imaging position corresponding to the depth of field K is defined as the imaging focal depth.

The lens barrel 4 of the imaging lens 3 is replaceably mounted on the lens mount 2 of the camera body 1, and its position can be adjusted in the optical axis X direction in accordance with the object distance at which the subject J is placed. is fixed.

The photoreceptor 5 is a CCD (Charge Couple).
It is composed of a two-dimensional image sensor in which photoelectric conversion elements of the PLEDDevice type are arranged two-dimensionally, and the displacement means 6
The coil bobbin 8 is fixed to the front surface of the coil bobbin 8 that constitutes the coil bobbin 8. The amount of charge accumulated in each photoelectric conversion element is outputted in time series in accordance with the light energy of each projected pixel, and the image is displayed on an image display means (not shown).

The displacement means 6 is located on the back wall 1a inside the camera body 1.
A permanent magnet 7A fixed to the permanent magnet 7A, a coil bobbin 8 movably fitted around the permanent magnet 7A and supported by a bellows 9 so as to be freely advanced and retractable, an electromagnetic coil 8a wound around the coil bobbin 8, and a coil bobbin 8 connected to the electromagnetic coil 8a. By controlling the current flowing through the electromagnetic coil 8a with the excitation controller 10, the coil bobbin 8 is moved forward and backward with a required amplitude stroke, and the photoreceptor 5 is moved at least to the imaging focal depth L.
It is configured to vibrate in the optical axis direction over a range of . Incidentally, in this embodiment, as the excitation controller 10, an oscillator that outputs a sinusoidal or triangular waveform pulse current is used, and the scanning speed for extracting pixel signals of the photoreceptor (CCD) 5 is matched with the frequency of the coil bobbin 8. Therefore, the coil bobbin 8 is configured to be adjustable so that its frequency is approximately 30 Hz and its amplitude stroke is within a range of at least the imaging focal depth L (approximately 1 to 2 mm). That is, as shown in FIG. 1, at the position L1 where the photoconductor 5 has advanced the most, the deepest point J1 of the subject J is in focus, and the photoconductor 5
At the position L2 where the subject J is the most retreated, the shallowest point J2 of the subject J is in focus.

On the other hand, each time the photoreceptor 5 is vibrated one stroke over at least the range of the imaging focal depth L, the amount of charge accumulated in each photoelectric conversion element of the photoreceptor 5 during that period is chronologically recorded as a pixel signal. It is configured to output. That is, in each photoelectric conversion element of the photoreceptor 5, the amount of charge of the focused point image q and the amount of charge of the image of the circle of confusion with radius r extending around it are the amount of charge for one pixel. It is accumulated as The focused point image q has the highest optical energy density, and a larger amount of charge is accumulated than the image of the circle of confusion, which has a weaker optical energy density. In other words, only the in-focus point image q is recorded as a pixel in each photoelectric conversion element. Note that the shutter device is not necessarily required in this embodiment. This is because the recorded image data can be saved, erased, and recalled by operating appropriate switches.

FIG. 3 is a longitudinal cross-sectional view of the main parts showing another embodiment of the present invention. In this embodiment, the lens barrel 4 of the imaging lens 3 is vibrated with a required amplitude stroke L instead of vibrating the photoreceptor 5 with a required amplitude stroke in the above embodiment. That is, in this embodiment, the lens barrel 4 itself is constituted by a permanent magnet 7B, and the lens barrel 4 is held within the peripheral wall 1b of the camera body 1 by a bellows 9 so as to be freely advanced and retracted.
An iron core 8A around which an electromagnetic coil 8a is wound is fixed within the peripheral wall 1b of the camera body 1 to ensure sufficient magnetic strength, and the photoreceptor 5
is fixed in the rear wall 1a of the camera body 1 via a fixture 11, and is otherwise constructed in the same manner as in the previous embodiment. 3, an electromagnetic coil 8a is wound around the outer periphery of the lens barrel 4, and the peripheral wall 1 of the camera body 1 is
It is also possible to fix a plurality of permanent magnets 7B inside b and vibrate the lens barrel 4 with a required amplitude stroke L.

[0014] The present invention is not limited to the above embodiments, but
For example, it can be implemented with appropriate changes as shown below. ■
The amount of charge accumulated in each photoelectric conversion element of the photoreceptor 5 is 1
Instead of outputting a pixel signal in time series for each stroke, if the subject is stationary, it is also possible to output a pixel signal for each stroke. (2) The present invention is also applicable to general cameras, and in that case, a general photosensitive film can be used instead of the CCD type photoelectric conversion element for the photoreceptor 5. (2) In this case, a shutter device is used to intermittently project images over a range of the required amplitude stroke (imaging depth of focus L) and record them as one still image. Of course, it is also possible to record one still image by continuously overlapping projections over a range of a required amplitude stroke (imaging depth of focus L) using a shutter device. ■ In the above embodiment, the displacement means 6 directly displaces the photoreceptor and the imaging lens, but it is also possible to interpose a mirror with small inertia on the optical path and displace that mirror, or An imaging lens having a zoom mechanism is configured to be capable of zooming operation,
The optical distance between the imaging lens and the photoreceptor may be changed.

[0015]

As is clear from the above explanation, in the present invention, the optical distance between the imaging lens and the photoreceptor is relatively displaced over at least the range of the imaging focal depth, and images of objects with depth can be obtained. The structure is configured so that the images are continuously or intermittently superimposed on the photoreceptor and a single still image is recorded on the photoreceptor, so the image of the entire subject with depth can be kept in focus over the entire range of the depth of field. As a still image that matches the
Can be recorded on a photoreceptor. As a result, the ripple effects are particularly remarkable, such as being able to accurately recognize the subject with depth, and even inspecting the subject with depth without human intervention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an image recording apparatus showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view of an image recording apparatus showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram of the operation of the present invention.

FIG. 4 is a schematic diagram of a conventional printed circuit board mounting inspection apparatus.

[Explanation of symbols]

J... Subject, K... Subject depth of focus, L... Imaging depth of focus, 1... Camera body, 3... Imaging lens,
5...Photoreceptor, 6...Displacement means.

Claims (2)

[Claims] [Claim 1] The depth distance (K) of the subject (J) in the optical axis (X) direction is defined as the depth of field, and the depth of field (K)
The depth distance (L) in the optical axis (X) direction of the best imaging position corresponding to is defined as the imaging focal depth, and the optical distance between the imaging lens (3) and the photoreceptor (5) is at least An image of a deep object (J) is continuously or intermittently superimposed on the photoreceptor (5) and projected onto the photoreceptor (5) while being relatively displaced over the range of the image focal depth (L). An image recording method for a camera, characterized in that the camera is configured to record a single still image. [Claim 2] The depth distance (K) of the subject (J) in the optical axis (X) direction is defined as the depth of field, and the depth of field (K)
The depth distance (L) in the optical axis (X) direction of the best imaging position corresponding to is defined as the imaging focal depth, and the imaging lens (3),
It comprises a photoreceptor (5) and a displacement means (6), and the displacement means (6) is configured to move the imaging lens (3) and the photoreceptor (5).
is configured so that the optical distance between the two and Alternatively, an image recording device for a camera is characterized in that it is configured to record one still image on a photoreceptor by intermittently overlapping projections.