JPS61265535A - Apparatus for measuring luminous intensity - Google Patents

Abstract

PURPOSE:To make it possible to uniformly receive incident light at a rectangular opening part, by providing a reflective material having a convex surface shape between the light receiving window comprising the rectangular opening part and a light guide. CONSTITUTION:The illumination light from an exposure illumination apparatus passes through a light receiving window 4 and comes to diffused transmitted light by a diffusion transmission material 25 to reach a reflective material 26 which has a convex surface shape wherein a central part is high and a peripheral part is low. Because of this shape, the diffused transmitted light reaching the reflective material 26 is reflected to the direction of the input terminal of a light guide 19 to be guided to the light receiver provided to the output terminal of said light guide and converted to an electric signal to obtain a manuscript luminous intensity signal. By allowing the reflective material to have the convex surface shape, incident light at a rectangular opening part can be uniformly received. The diffused transmitted light is also incident to a light receiving element 27 for calibrating luminous intensity to be converted to an electric signal which, in turn, comes to a luminous intensity calibrating signal (signal containing no light quantity attenuation at the light guide 19).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an illuminance measuring device for measuring the illuminance of a document surface of an exposure illumination device of an electronic copying machine.

In the exposure system of a conventional electronic copying machine, in order to effectively illuminate the surface of a document, a device comprising a light source and a reflecting mirror is placed at a predetermined position.

To express the illumination characteristics of this exposure illumination device, the method of measuring the illuminance on the document surface (hereinafter referred to as document surface illuminance) has traditionally been often used, and an illuminance measuring device is used for specific measurements. .

A conventional illuminance measuring device will be described below.

Figure 6 shows the configuration of a conventional illuminance measurement device.
1 is a light source for illuminating the original (not shown); 2 is a reflector that partially surrounds the light source 1 and efficiently irradiates the original with illumination light from the light source 1; 3 is the light source 1 and the reflector 2 is an exposure illumination device; 4 is a light-receiving head having a light-receiving window consisting of a circular opening for receiving illumination light from the exposure illumination device 3 at the document position; 6 is a light-receiving head 4;
6 is a light guide made of glass fiber for guiding the incident light from the light receiving head 4 to the light receiver 5; 7 is an area within the area illuminated by the exposure illumination device 3; , the light receiving head moving section 8 moves the light receiving head 4 in the X direction and the Y direction and generates a position signal for the light receiving head 4. The light receiving head moving section 8 receives the document surface illuminance signal from the light receiver 6 and the light receiving head moving section 7. A control section 9 amplifies and processes the light-receiving head position signal, and reference numeral 9 indicates an XY recorder for plotting the distribution of illuminance on the document surface based on the output signal from the control section 8. The light-receiving head moving section 7 is composed of, for example, a servo motor, a servo motor, a feeding mechanism using a wire, and a positioning mechanism using a potentiometer.

This operation will be fully explained below.

The light-receiving head moving unit 7 moves the light-receiving head 4 installed at the illumination position (position where the document is placed) of the exposure illumination device 3 in the X direction (the exposure illumination) in the area illuminated by the exposure illumination device 3. (Long side direction of device 3) and Y direction (Long side direction of exposure illumination device 3)
The illumination light (original surface illuminance) from the exposure illumination device 3 is received by scanning in the direction of the short side of the light, and after passing through the light guide 6, it enters the light receiver 5 for photoelectric conversion. Light receiving S
5 and the light receiving head position signal from the light receiving head shifting section 7.
After amplification and processing via XY recorder 9
is input to plot the distribution of document surface illuminance (document surface illuminance characteristics) as shown in FIG.

Through the above operations, the illumination characteristics of the exposure illumination device 3, that is, the document surface illuminance can be determined.

Normally, since the light receiving head 4 is moved in the X direction and the Y direction, the size and weight of the light receiving head 4 installed in the light receiving head moving section 7 are naturally limited, and it is required to be as small and lightweight as possible.

Furthermore, the area illuminated by the exposure illumination device 3 reaches a considerably high temperature (approximately 60° C. to 60° C.) due to the heat from the light source 1, which adversely affects the light receiving head and the light receiver. Therefore, in the conventional illuminance measuring device, the light receiving head 4 is
By adopting the configuration shown in the figure and arranging the light receiver 5 at a position separated from the exposure illumination device 3, the above-mentioned problems (miniaturization, weight reduction, heat countermeasures) are solved.

To explain the configuration of Fig. 5, numeral 4 is a light receiving head, 10 is a light receiving window consisting of a circular aperture with a diameter of 1, 11 is a diffuse transmission material that diffuses the incident light from the light receiving window 1Q, and 12 is a diffuser. a total reflection mirror (plane mirror) for guiding the transmitted light from the transmission material 11 to a light guide 6 with two diameters (explained in FIG. 6);
Reference numerals 13 indicate presser springs that fix the total reflection mirror.

The operation of the light-receiving head of the conventional illuminance measuring device configured as described above will be described below.

Illumination light from an exposure illumination device (not shown) is transmitted through the light receiving window 10.
After passing through i, the light becomes diffusely transmitted light by the diffusely transmitting material 11 and reaches the total reflection mirror 13 . Here, the diffused transmitted light is the total reflection mirror 1
After being totally reflected in the right angle direction by light guide 6
incident on . The diffused transmitted light that passed through the light guide 6 is
The light enters a light receiver (not shown) provided at the output end of the light guide and is converted into an electrical signal, which ultimately becomes a document surface illuminance signal.

Next, as an example of measuring document surface illuminance characteristics using a conventional illuminance measuring device, X
A case will be described in which the average document surface illuminance distribution in an area of QWm in the direction and W- in the Y direction is determined.

First, the light receiving head 4 is installed at the left end of the exposure illumination device 3. Then, the light receiving head 4 is caused to scan 2rrrIn in the X direction to measure the illuminance distribution on the document surface. Next, the light receiving head 4'
ff: Move by 1N in the Y direction and scan twice in the X direction in the same manner as above to measure the illuminance distribution on the document surface. The above operation was repeated until the iY direction became W, and the average document surface illuminance distribution (FIG. 4) was obtained.

Problems to be Solved by the Invention As can be seen from the above measurement examples, in order to obtain the average document surface illuminance distribution 2 in an area x mm x Wfflm of the illumination area of the exposure illumination device 3, it is necessary to Since the light-receiving head 4, which has a light-receiving window consisting of two parts, has to be moved back and forth several times, it takes time to measure. In addition, one of the drawbacks of the light guide 6 is that it is not easily bent.
As the number of reciprocations of the light-receiving head 4 increases, the light transmittance decreases due to core breakage inside the light guide, resulting in a problem that the reliability of the measured value of document surface illuminance is completely reduced.

For this reason, it is possible to increase the number of reciprocating times of the light receiving nod 4 by km, and one way is to make the opening of the light receiving window of the light receiving head 4 rectangular, for example, in the X direction = 16. It has been proposed to measure the entire average illuminance distribution on the document surface by one scan of the light receiving head 4 at 5 fi in the Y direction.

However, this method also has the problem that if the opening of the light-receiving window is simply made larger, the light-receiving sensitivity differs depending on the position of the light incident on the opening, as shown in FIG.

SUMMARY OF THE INVENTION Therefore, the present invention provides an illuminance measurement device that uniformly receives light incident on a light receiving window having a rectangular opening.

Means for Solving the Problems The present invention provides a light receiving window consisting of a rectangular opening, a diffusely transmitting material that diffuses incident light from the light receiving window, and total reflection of the transmitted light from the diffusely transmitting material, An illuminance measuring device comprising: a reflective material that changes an optical path; a light receiver that receives reflected light from the reflective material; and a light guide that guides the reflected light from the reflective material to the light receiver; By making it convex, it is possible to uniformly receive incident light at the rectangular opening.

For production This technical effect is as follows.

That is, in the present invention, a reflective material whose curvature can be changed, such as an aluminum plate, can be used, and desired characteristics can be obtained by processing this into an arbitrary convex shape. In addition, since it has a built-in light receiving element for illuminance calibration, it is less susceptible to the effects of reduced light guide transmittance and dirt.

Embodiment FIG. 3 shows the configuration of an illuminance measuring device in an embodiment of the present invention. In FIG. 3, 14 is a light source for illuminating the entire document (not shown), 16 is a reflecting mirror that surrounds all of the light source 14 and efficiently irradiates the document with illumination light from the light source 14; An exposure illumination device composed of a light source 14 and a reflecting mirror 16; 17 is an X-direction 1w for receiving all of the illumination light from the exposure illumination device 16 at the position of the document;
n, a light-receiving head with a light-receiving window consisting of a rectangular opening of 6 ran in the Y direction; 18, a light-receiving element having a light-receiving element that receives the incident light from the light-receiving head 1 (visual sensitivity corrected); 19;
20 is a light guide made of glass fiber for guiding the incident light from the light receiving head 17 to the light receiving device 18;
While moving in the X direction and Y direction, the light receiving head 1
A light-receiving head moving unit 7 generates a position signal, and 21 receives an illuminance calibration signal from a light-receiving element (not shown) for illuminance calibration provided inside the light-receiving head 1 and a document surface illuminance signal from a light receiver 18. 22 is a control section that amplifies and processes the illuminance signal from the illuminance calibration section 21 and the light receiving head position signal from the light receiving head moving section 2o; 23 is a control section that uses the output signal from the control section 22 to An XY recorder for plotting the distribution of illuminance on the document surface is shown.

The operation of the illuminance measuring device of this embodiment configured as described above will be explained below. explain.

A light receiving head 17 provided at the illumination position of the exposure illumination device 16? , light-receiving head moving unit 20: From this, the entire area illuminated by the exposure illumination device 16 is scanned in the X direction,
Illumination light from an exposure illumination device 16 is received, passes through a light guide 19, and then enters a light receiver 18 for photoelectric conversion. The document surface illuminance signal from the light receiver 18 and the light receiving head 1
The signal for illuminance calibration from the light receiving element for illuminance calibration provided inside the light receiving element 7 is compared and processed by the total illuminance calibration section 21, and then sent to the control section 22 together with the light receiving head position signal from the light receiving head moving section 2Q for amplification and processing. do. Finally, the data is input to the XY recorder 23 and the entire document surface illuminance characteristic shown in FIG. 4 is plotted.

Through the above operations, the illumination characteristics of the exposure illumination device 16, that is, the document surface illuminance can be determined.

FIG. 1 shows the configuration of a light receiving head 17 in an embodiment of the present invention. 24 is 1wn in the X direction and 6rran in the XY direction.
26 is a diffuse transmitting material that diffuses the incident light from the light receiving window 24, 26 is a convex surface for guiding the transmitted light from the diffuse transmitting material 26 to the light guide 19 with a diameter of 2 mm. 27 is a light-receiving element for illuminance calibration, and 28 is a presser spring for fixing the reflective material 26. Regarding the light-receiving head of this embodiment configured in this way,
The operation will be explained below.

Illumination light from an exposure illumination device (not shown) is transmitted through the light receiving window 24.
After passing through, the light becomes diffusely transmitted light by the diffusely transmitting material 26 and reaches the reflective material 26. The reflective material 26 has a so-called convex shape with a high central portion and low peripheral portions. Therefore, the diffused transmitted light that has reached the reflective material 26 is reflected by the reflective material 26 in the direction of the input end of the light guide 19, and the light receiver (
(not shown) and then converted into an electrical signal to become a document surface illuminance signal. The diffused transmitted light also enters the light-receiving element/element 27 for illuminance calibration and is converted into an electrical signal, which generates a signal for illuminance calibration (a signal that does not include light attenuation in the light guide 19).
becomes. Here, the reflective material 2θ is a total reflection mirror having a convex shape, and its curvature is approximately R=30 rrt
m, the result was obtained that the light-receiving sensitivity of the light-receiving window 24 became almost flat in the 5-width, as shown in FIG.

In FIG. 3, the illuminance calibration signal and the document surface illuminance signal input to the illuminance calibration section 21 are not always compared and processed, but are compared and processed once every 100 times, for example, depending on the number of times the light receiving head 17 is moved. Used when calibrating illuminance based on the ratio of times. Therefore, it is sufficient to normally turn off the optical path or electric circuit for detecting the illuminance calibration signal and turn it on only during calibration.

As described above, according to this embodiment, by providing the reflective material 26 having a convex shape between the light receiving window 24 consisting of a rectangular opening and the light guide 19, the incident light at the rectangular opening is can be uniformly received (light receiving sensitivity is uniform). Furthermore, by providing a light receiving element 27 for illuminance calibration on the convex side (reflection side) of the reflective material 26 and comparing it with the light incident on the light guide 19 as necessary, it is possible to detect a decrease in the light amount due to a break in the light guide. It is possible to perform corrections and calibrate the document surface illuminance.

Note that the size of the light receiving window 24 may be adjusted to the size of the required illumination area of the exposure illumination device 16. In addition, the reflective material 26
The curvature of is also the size of the opening of the light receiving window 24 and the light guide 1.
It may be set arbitrarily depending on the difference in aperture (diameter) of 9.

Further, the cross-sectional shape of the convex surface is not limited to a semicircle, and the same effect can be obtained even if the cross-sectional shape is an ellipse or a parabola.

Effects of the Invention The illuminance measuring device of the present invention makes it possible to make the incident light completely uniform at the rectangular opening by providing a reflective material with a convex shape that completely blinds between the light receiving window and the light guide. When the light can be received, a light receiving element for illuminance calibration that receives part of the reflected light from the reflective material is provided on the convex side (reflection side) of the reflective material, and the amount of light is compared with the amount of light after passing through the entire light guide. By doing so, it is possible to detect and correct a decrease in the amount of light due to the breakage of the light guide, and to calibrate the illuminance on the document surface, which has a great practical effect.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the light receiving head of the illuminance measuring device in an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the light receiving sensitivity of the light receiving window of the same light receiving head, and Fig. 3 is a principle diagram of the illumination measuring device. ,
Figure 4 is a characteristic diagram of the document surface illuminance characteristics (illuminance distribution) obtained from the same device, Figure 6 is a longitudinal cross-sectional view of the light receiving head of the conventional illuminance measuring device, and Figure 6 is a diagram of the principle of the same illumination measuring device. , 7th
The figure is a characteristic diagram showing the light-receiving sensitivity of the light-receiving window of the same light-receiving head. 14...Light source, 16...Reflector, 16.
...Exposure illumination device, 17... Light receiving head,
1B... Light receiver, 19... Light guide, 20... Light receiving head moving unit, 21...
・Illuminance calibration section, 22... Control section, 23...
...XY recorder, 24... Light receiving window, 25...
...Diffuse transmission material, 26...Reflection material, 27
......Light receiving element for illuminance calibration, 28...Press spring. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 3210 f23pn. 3210/23. ,!

Claims (1)

[Claims] A light receiving window consisting of a rectangular opening, a diffusely transmitting material that diffuses incident light from the light receiving window, a reflective material that reflects the transmitted light from the diffusely transmitting material and changes the optical path, and a light receiver that directly receives a portion of the reflected light; a light receiver that receives the reflected light from the reflective material via a light guide; and a light guide that guides the reflected light to the light receiver; An illuminance measuring device in which the surface has a convex shape.