JPS6238081A - Image pickup device - Google Patents

Abstract

PURPOSE:To simplify a correction circuit by designing an image pickup camera and an irradiation device in a specific position relation. CONSTITUTION:In picking up an object on a face to be irradiated by an image pickup camera 9, the scanning direction c-c' of the camera 9 and the A-A' direction in parallel with the tube axis of the discharge lamp on the face to be irradiated are made coincident. When the reflectance of the object is constant, the brightness on the object corresponding to a scanning line in the image pickup camera is made uniform. Thus, in picking up the object, a signal of a constant level is obtained on one scanning line and no correction is required. It is not required to move a light source section 7 from the focus of a condenser lens 13 for making the illuminance distribution on the irradiated plane uniform, the light condensing performance is improved and the utilizing rate of the light is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an imaging device that irradiates light emitted from a light source onto an object on an irradiated surface using a condensing lens and images this object with a scanning camera. Regarding.

2. Prior Art An irradiation device in a conventional imaging device is, for example, disclosed in Japanese Patent Publication No. 69.
As shown in No. 42404, it had a configuration as shown in Figure 3. In FIG. 3, light emitted forward from an incandescent light bulb 1 serving as a light source is condensed by a condensing lens 2 and irradiated onto a surface 3 to be illuminated.

In this case, the intensity of light on the illuminated surface 3 is equal to
This can be changed by changing the irradiation diameter depending on the distance between the lens and the condenser lens 2. The intensity of the light on the irradiated surface 3 is the strongest when the incandescent bulb 1 is on the focal point of the condenser lens 2. At this time, the image of the filament of the incandescent light bulb 1 is projected onto the irradiated surface 3 by the condensing lens 2, so that less light escapes to areas other than the irradiated surface 3, improving efficiency, and the filament has uniform brightness. If it is a surface, the distribution of light on the irradiated surface 3 can be made uniform.

However, the luminous efficiency of incandescent bulbs is generally very poor, and therefore, in recent years, discharge lamps with high luminous efficiency are increasingly being used instead of incandescent bulbs. When a discharge lamp is used as the light source, in order to make the illuminance distribution on the irradiated surface uniform, it is necessary to make the luminance distribution on the surface of the light source that faces the irradiated surface uniform. Therefore, a light source section shown in FIG. 4 has been proposed. In FIG. 4, numerals 4 to 6 indicate linear discharge lamps, and all the discharge lamps are connected in series and are arranged in parallel and close to each other to form one light source section 7 as a whole. As a result, a light emitting surface 8 indicated by a broken line is formed. This light source section 7 is used in place of the incandescent light bulb 10 in FIG. 3, and an image of the light emitting surface 8 is projected onto the irradiated surface.

Problems to be Solved by the Invention When a discharge lamp has a transparent arc tube, the brightness is high near the tube axis, and the brightness decreases as it approaches the end of the tube. The brightness distribution of the light emitting surface 8 of the light source section in Fig. 4 is not uniform, and therefore,
When this light source section 7 was projected onto the irradiated surface 3 using the condenser lens 2, the illuminance distribution on the irradiated surface became non-uniform.

When such an irradiation device is combined with a scanning imaging camera, it is conceivable that an area where the illuminance distribution on the irradiated surface is non-uniform will be scanned on one scanning line. In this case 1. Even if the reflectance of the object on the illuminated surface is constant, the illumination distribution is uneven, so the brightness of the object varies depending on the location, and when the object is imaged with a camera, it may vary depending on the location even on a single scanning line. Signals of different levels are output, and in order to compensate for this, it is necessary to correct the signal levels for all points on the irradiated surface, resulting in a problem that the correction circuit becomes complicated.

Means for Solving the Problems The present invention solves these conventional problems, and includes a scanning imaging camera, a light source section in which a plurality of linear light emitting sections are arranged close to each other in parallel, and the light source. a condenser lens arranged to project an image of the linear light emitting section onto the irradiated surface, and arranged so that the scanning direction of the camera and the central axis direction of the linear light emitting section coincide on the irradiated surface. This is an imaging device characterized by the following.

Effects of the present invention Due to the configuration described in section 2 above, the central axis direction of the linear light emitting section and the scanning direction of the imaging camera are the same on the irradiated surface, so the imaging camera scans a line where the illuminance is uniform. The signal level can be corrected for each scanning line, and as a result, the correction circuit can be simplified.

Embodiment FIG. 1 is a block diagram of an imaging apparatus in an embodiment of the present invention. In FIG. 1, 9 is an imaging camera, 1o is a camera lens, 11 is an imaging surface, 12 is an irradiated surface, and 13 is a condensing lens. Reference numeral 7 denotes a light source section having the same configuration as the light source section shown in FIG. It is located. In FIG. 1, the light source section 7 is arranged on the focal point of the condenser lens 13 and parallel to the condenser lens 13,
The light emitting surface 8 of the light source section 7 is projected onto the irradiated surface 12 by the condensing lens 13. The light emitting surface 8 of the light source section 7 is set to a size such that its image is just irradiated onto the irradiated surface 12 by the condensing lens 13. That is, the distance and thickness between the electrodes of the discharge lamps 4° and 5.6 degrees, and the number of discharge lamps are set according to the irradiated surface 12.

Further, the imaging camera 9 uses a lens 1o to detect the irradiated surface 1.
2 is arranged so as to project the object onto the imaging surface 11 and capture the image.

Furthermore, in FIG. 1, a-a' indicates the direction of the central axis of the discharge lamp 6, b-b' indicates the direction of the medium flame between the electrodes of the discharge lamp 5 and perpendicular to the central axis, and A-A' indicates the direction of the central axis of the discharge lamp 6. a-a'
is projected onto the irradiated surface, B −B' is b −
b' indicates the direction in which the image is projected onto the irradiated surface. In addition, c - c' indicates the scanning line direction on the imaging plane, and d - d
' indicates a direction perpendicular to c-c' on the imaging plane, and the imaging camera 9 is arranged so that c-c' and A-A' are parallel.

The operation of the imaging device configured in this way will be described below. Light from the light emitting surface 8 of the light source section 7 is projected onto the irradiated surface 12 by the condenser lens 13. At this time, the discharge lamp has a uniform brightness distribution in the direction parallel to the tube axis, but the brightness decreases as it approaches the tube end in the direction perpendicular to the tube axis. As shown in Figure 2, the projected illuminance distribution on the irradiated surface is almost uniform in the A-A' force direction parallel to the tube axis of the discharge lamp as shown in (a). -B' The force direction has a distribution with a peak at a position corresponding to the center of the discharge lamp tube, as shown in (b). The object on this irradiated surface is imaged by an imaging camera 9. At this time, A parallel to the scanning direction c-c' of the camera 9 and the tube axis of the discharge lamp on the irradiated surface
-A, ' directions are made to match, so if the reflectance of the object is constant, 1i degrees on the object corresponding to one scanning line in the imaging camera can be made uniform. Therefore, when this is imaged, a signal at a constant level is obtained on one scanning line, and there is no need for correction. Also,
In order to make the illuminance distribution on the irradiated surface uniform, it is no longer necessary to shift the light source section 7 from the focal point of the condensing lens 13, and it is possible to improve the light condensing property and increase the light utilization rate.

In this embodiment, the light source section 7 is installed parallel to the lens 13, but it may be inclined to some extent. In this case, the light emitting surface 8
Even if the brightness distribution is not uniform, it can be corrected because the area of the arc tube relative to the condenser lens 13 is reduced.
The distribution of light on the irradiated surface 12 can be made uniform. Further, although the light source section 7 is arranged on a plane including the focal point of the condenser lens 13, the same effect can be obtained even if it is arranged not on the focal plane but in the vicinity of the focal point. Furthermore, since the image of the light source section 7 is somewhat blurred, the uniformity of the illuminance on the irradiated surface 12 can be improved. Furthermore, although the light source section 7 has the discharge lamps 4, 5.6 electrically connected in series, they may be connected in parallel or in series and parallel as long as the lamps are lit. Discharge lamp 4, 5.6
Each discharge lamp may be powered by a separate power source, as long as they are closely aligned. Moreover, a proximity conductor or a +-V wire may be wound around the discharge lamp. The discharge lamps 4, 5.6 may be discharge lamps such as fluorescent lamps or H-type lamps, flash lamps such as xenon flash lamps, or other lamps having linear light emitting parts. But that's fine. The discharge lamp does not need to emit visible light, and may emit ultraviolet or infrared light. In this case, for example, a condenser lens 1 is used to irradiate the irradiated surface 12 with infrared rays.
Needless to say, a filter may be provided between the light source section 3 and the light source section 7 to block visible light. Alternatively, a reflecting mirror may be installed behind the light source section 7 to reflect the light directed toward the rear toward the lamp and the condenser lens. The image pickup camera may be a scanning type f6, one using an image pickup tube such as a vidicon or one lambicon, or one using a solid-state image pickup device such as a COD image sensor.

Effects of the Invention As described above, the imaging device of the present invention allows the imaging camera to scan a line where the illuminance on the irradiated surface is uniform by setting the imaging camera and the irradiation device in a specific positional relationship. The signal level can be corrected for each scan, and as a result, the correction circuit can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram showing the illuminance distribution on the irradiated surface, Fig. 3 is a block diagram of a conventional irradiation device, and Fig. 4 is a block diagram of a conventional irradiation device. The light source section used is shown. 4.5.6...Discharge lamp, 7...Light source section, 2゜13...Condensing lens, 3,12...
...Irradiated surface, 9...Imaging camera. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure AA' Ba/ Figure 3 Section 4 Section I Light source section πQ Otsufun 7°

Claims (1)

[Claims] A scanning imaging camera, a light source section in which a plurality of linear light emitting sections are arranged close to each other in parallel, and a condensing lens arranged so as to project an image of the light source section onto a surface to be irradiated, An imaging device characterized in that the scanning direction and the central axis direction of the linear light emitting section are arranged so as to coincide on the irradiated surface.