JPH08304179A - Spectral colorimeter - Google Patents

Abstract

PURPOSE: To save the man power by performing a feedback control, reducing the loss rate of a product being measured, improving the productivity, and reducing the labor required for the measurement. CONSTITUTION: 45 deg. reflection light at a light reception part is received by each lens 6 and each optical fiber 3 and is guided to an interference filter 4 of a light guidance part as it is for spectral analysis. On the other hand, light is transduced into electricity by a number of light reception elements 5 at a photoelectric conversion part and a number of colors are instantly measured without deteriorating measurement accuracy to increase the speed. A capacitor for accumulating electric charge is added to each light reception element 5, electric charge is accumulated simultaneously for each wavelength as soon as the measurement is started, and the accumulated amount is read out speedily after the measurement. By adjusting the capacity of the added capacitor for the sensitivity of a photodiode, the output voltage at each wavelength is made uniform, thus improving the accuracy of a spectral colorimeter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrocolorimeter for measuring the spectral reflectance of an object (eg, printed matter).

[0002]

2. Description of the Related Art FIG. 10 shows a conventional example of a light receiving portion of a spectrocolorimeter for measuring a spectral reflectance from an object (eg, printed matter). This light receiving part is defined by JIS8277, but the structure that can receive light most efficiently is vertical illumination of 45 °. The reason is that, as can be seen from FIG. 11, all the light in the 45 ° direction can be used, and it is described in West German Patent No. 2660604 and JP-A-56-586.
The one described in Japanese Patent No. 40 also uses this method. Then, the light received by the light receiving section is collected by a light receiving device (or an optical fiber) at one place, and is divided again before being dispersed.

In FIG. 11, reference numeral 21 is a light source, 22 is a light projecting lens, 23 is a mirror, 24 is a condenser lens, and 25 is a light receiver (or optical fiber).

[0004]

In the conventional spectral colorimetric device described above, a method of irradiating an object (for example, a printed material) with light at a constant angle and receiving diffused light reflected at a constant angle is described. The details of the processing of light after receiving light are not mentioned in detail. On the other hand, as a practical problem, what is more important is the processing speed of the light after it is received, rather than the processing of the light after it is received.In the color measuring device, the color measurement results are fed back to the machine that is producing at high speed. It is impossible to control the machine. That is, since it takes 2 to 3 seconds to measure one point, it takes 2 seconds × 200 points = 400 seconds to measure a color scale of a printed matter, and the color measuring device is only valuable as an evaluation device. Without it, it is impossible to feed back and control the color measurement results to a machine that is producing at high speed.

The present invention has been proposed in view of the above problems, and the object of the present invention is to perform feedback control, reduce the product loss rate during measurement, improve productivity, and improve measurement efficiency. It is intended to provide a spectrocolorimeter that can significantly reduce the labor and achieve labor saving.

[0006]

In order to achieve the above object, the spectral colorimetric apparatus of the present invention has an image forming lens for vertical irradiation light disposed in the center of a light receiving portion, and A large number of lenses for receiving the 45 ° reflected light are arranged in an annular shape, and an optical fiber is connected to each of the lenses to form a light receiving section (claim 1).

In the spectral colorimetric apparatus according to claim 1, the interference filter and the light receiving element may be connected in this order to the rear end side of each optical fiber to form a light guide section (claim 2). . The spectral colorimetric apparatus according to claim 1,
The photoelectric conversion unit may be configured by connecting two switches in parallel to each of the light receiving elements, connecting one switch to the ground via the charge storage capacitor, and connecting the other switch to the ground. (Claim 3).

In the spectrocolorimetric apparatus according to any one of claims 1 to 3, the optical fiber of the light receiving section and the charge storage capacitor of the photoelectric conversion section may be connected (claim 4). In the spectral colorimetric apparatus according to any one of claims 1 to 3, the charge storage capacitor of the photoelectric conversion unit may be variable (claim 5).

[0009]

The spectral colorimetric apparatus of the present invention is configured as described above, and the vertical irradiation light from the light source is applied to the object (for example, printed matter) through the image forming lens for the vertical irradiation light, and the object is the same. The 45 ° reflected light from is received by a large number of lenses arranged in a ring. At this time, light other than a certain range is not collected due to the image forming performance of each lens. The light collected by each lens is guided to each light guide section by each optical fiber. In the same light guide section, the light is condensed again by the lens, and after passing through the interference filter for separating each wavelength, it is received by the photodiode or the like. The light is received by the element, and the light receiving element
Electric charges are generated in response to light. The accumulation and output of this electric charge are controlled by one and the other switch provided in each light receiving element. That is, one switch (reset switch) is open before the start of measurement, and no charge is accumulated. When the measurement is started, one switch is closed, and at the same time, the other switch (gate switch) is opened, and the charge generated in the light receiving element is stored in the charge storage capacitor. After the measurement is completed (after the accumulation is completed), the other switch is closed so that the charges accumulated in the charge accumulating capacitor are held and sequentially output by the high speed multiplexer. This sequentially output electric charge is once converted into a voltage by a current-voltage conversion element, and then passed through an amplifier, a filter, etc., so that the waveform is shaped and converted into a digital signal by a sample hold and an A / D converter. It Since these timings are controlled by the control conversion circuit, high-speed and accurate processing is performed.

[0010]

EXAMPLE A spectral colorimetric apparatus of the present invention will be described below with reference to an example shown in FIGS. 1 is a perspective view showing the whole of the spectrocolorimetric apparatus, FIG. 2 is a vertical sectional side view showing a light receiving section,
3 is a vertical side view showing the light guide portion, FIG. 4 is a system diagram showing a photoelectric conversion electric circuit, FIG. 5 is a system diagram showing an example of a circuit for simultaneous storage, and FIG. Lens (small lens)
6B is a bottom side view showing an example of the arrangement of the lenses (small lenses) of the light receiving section, and FIG.
FIG. 8A is an explanatory view showing a ray trace of a lens (small lens) of the light receiving portion, FIG. 8A is an operation explanatory view when the light guiding portion does not have a lens (small lens), and FIG. 8B is a light guiding portion. FIG. 9 (a) is an explanatory view of the operation when there is a lens (small lens) in FIG.
Is an operation explanatory view in the case where the photoelectric conversion units are not simultaneously stored,
FIG. 9B is an operation explanatory diagram in the case of simultaneous accumulation in the photoelectric conversion unit.

1 to 9, 1 is a light source,
2 is an imaging lens for vertical irradiation light arranged in the center of the light receiving part, 3 is a large number of optical fibers, 4 is an interference filter, 5
Is a light receiving element, 6 is a large number of lenses (small lenses) for receiving 45 ° reflected light, 7 is a light receiving unit housing, 8 is a charge storage capacitor, 9 is a high-speed multiplexer, 10 is a current-voltage conversion element, 11 is an amplifier, 12 is a filter, 13 is a sample hold, 14 is an A / D converter, 15 is a control arithmetic circuit,
16 is one switch (reset switch) and 17 is the other switch (gate switch).

Next, the operation of the spectral colorimetric apparatus shown in FIGS. 1 to 9 will be specifically described. Vertically radiated light from the light source 1 is radiated to an object (for example, a printed matter) via the vertically radiated light imaging lens 2, and 45 ° reflected light from the object is annularly arranged in a large number of lenses (small lenses). It is received by 6. At this time, diffused light (reflected light) from the object having color information is 45 °, and light other than a certain range is not collected due to the image forming performance of each lens 6 arranged annularly as shown in FIG. .

The light collected by each lens 6 is guided by each optical fiber 3 to the light guide portion shown in FIG. 8B, where it is condensed again by the lens 6 and separated into respective wavelengths. After passing through the interference filter 4, the light is received by the light receiving element 5 such as a photodiode. Here, when the lens 6 is not used as shown in FIG.
Not all the light from the optical fiber 3 is guided to the light receiving element 5.

In the light receiving element 5, charges are generated according to light. The accumulation and output of this electric charge are controlled by one and the other switch provided in each light receiving element 5. That is, before starting the measurement, one switch (reset switch) 16
Is open and no charge is accumulating. When the measurement is started, one switch 16 is closed, and at the same time, the other switch (gate switch) 17 is opened, and the charge generated in the light receiving element 5 is stored in the charge storage capacitor 8.

After the measurement is completed (after the accumulation is completed), the other switch 17 is closed so that the charge accumulated in the charge accumulating capacitor 8 is held and the high speed multiplexer 9
Are sequentially output by. By the simultaneous accumulation, a large number of colors can be measured instantaneously without lowering the measurement accuracy, and the speed can be increased. Since the actual charge is determined by the inter-terminal capacitance of the light receiving element 5 and the capacitance of the charge storage capacitor 8, the capacitance of the charge storage capacitor 8 is changed to
Since the output sensitivity can be controlled, the output of each light receiving element 5 can be adjusted evenly.

The sequentially output charges are once converted into a voltage by the current-voltage conversion element 10, and then the amplifier 1
1, the waveform is shaped by passing through the filter 12 and the like, and converted into a digital signal by the sample hold 13 and the A / D converter 14. These timings are
Since it is controlled by the control conversion circuit 15, processing can be performed accurately at high speed.

In the conventional spectrocolorimeter shown in FIG. 11, the received light is collected by a light receiver (or an optical fiber) at one place and divided before being separated again. In the spectrocolorimeter of the present invention, the 45 ° reflected light of the light receiving section is received by each lens 6 and each optical fiber 3, and is guided to the interference filter 4 of the light guiding section as it is. The light is effectively used by separating the light. In this case, although the loss of the amount of light at the time of splitting is small, the 45 ° reflected light cannot be condensed in the entire circumferential direction. Therefore, as shown in FIG. 2, a large number of lenses 6 are provided on the tip side of each optical fiber 3. It is installed in an annular shape and collects light that is substantially equal to or more than that of the conventional spectral colorimetric device (described in Japanese Patent Application Laid-Open No. 56-58640) to obtain a larger amount of light as a whole. . Further, by providing a large number of lenses 6 in a ring shape as described above, the illumination range is limited as shown in FIG. 7, and the illumination optical system is simplified.

On the other hand, a lens (small lens) 6 is also used in the light guide section as shown in FIG. 3 so that most of the light emitted from the optical fiber 3 can be received. Although it is optically configured as described above, in the photoelectric conversion unit, a large number of colors are instantaneously measured by photoelectrically converting it with a large number of light receiving elements 5 such as photodiodes without lowering measurement accuracy. , Speeding up is possible.

Normally, when photoelectric conversion is carried out by a large number of photodiodes, they are sequentially accumulated as shown in FIG.
Each output is read out, but in this case, it is necessary to store and read out only the number of wavelengths, and it takes a long time to complete the measurement or the storage time must be shortened. Therefore, in the spectrocolorimeter of the present invention, a charge storage capacitor 8 is added to each photodiode as shown in FIG.
(See (b)), and read out at high speed after measurement. By using this means, the accumulation time can be effectively used, and as a result, high speed measurement can be performed.

For a constant charge, the generated voltage is V =
Since it is represented by Q / C, the output voltage can be controlled by the capacitance of the capacitor. By adjusting the capacitance of the added capacitor with respect to the sensitivity of the photodiode, it is possible to make the output voltage at each wavelength uniform and improve the accuracy of the spectrocolorimeter.

[0021]

The spectrocolorimeter of the present invention is constructed as described above and can measure a large number of colors instantly without lowering the measurement accuracy. For example, a measurement that took 400 seconds to measure 200 points can be measured in about 5 seconds. This time is a time during which the feedback control can be sufficiently performed even when the machine is operating, feedback control can be performed, the product loss rate during measurement can be reduced, and productivity can be improved.

Further, by combining the spectral colorimetric apparatus of the present invention with a scanning apparatus, the labor required for measurement can be greatly reduced and labor saving can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an entire embodiment of a spectrocolorimeter of the present invention.

FIG. 2 is a vertical sectional side view showing a light receiving portion of the spectral colorimetric apparatus.

FIG. 3 is a vertical cross-sectional side view showing a light guide section of the spectral colorimetric apparatus.

FIG. 4 is a system diagram showing a photoelectric conversion electric circuit of the spectral colorimetric apparatus.

FIG. 5 is a system diagram showing an example of a circuit for simultaneous storage of the same spectrocolorimeter.

FIG. 6A is a vertical cross-sectional side view showing an arrangement example of lenses (small lenses) of the light receiving section, and FIG. 6B is a bottom view showing an arrangement example of lenses (small lenses) of the light receiving section.

FIG. 7 is an explanatory diagram showing a ray trace of a lens (small lens) of a light receiving unit.

FIG. 8A is an explanatory view of the operation when the light guide unit has no lens (small lens), and FIG. 8B is an explanatory view of the operation when the light guide unit has a lens (small lens).

FIG. 9A is an operation explanatory diagram when the photoelectric conversion units do not simultaneously accumulate, and FIG. 9B is an operation explanatory diagram when the photoelectric conversion units simultaneously accumulate.

FIG. 10A is a view of a light receiving unit of a conventional spectrocolorimeter.
FIG. 5 is an explanatory diagram showing a 5 ° illumination vertical light receiving state, and FIG. 7B is an explanatory diagram showing a vertical illumination 45 ° light receiving state.

FIG. 11 is a vertical cross-sectional side view showing a light receiving portion of a conventional spectrocolorimeter.

[Explanation of symbols]

1 Light source 2 Image forming lens for vertical irradiation light 3 Optical fiber 4 Interference filter 5 Light receiving element 6 45 ° Many lenses (small lenses) that receive reflected light 7 Light receiving unit housing 8 Charge storage capacitor 9 High speed multiplexer 10 Current voltage conversion element 11 Amplifier 12 Filter 13 Sample Hold 14 A / D Converter 15 Control Operation Circuit 16 One Switch (Reset Switch) 17 The Other Switch (Gate Switch)

Claims (5)

[Claims] 1. An image forming lens for vertical irradiation light is arranged in the center of a light receiving portion, and a large number of lenses for receiving 45 ° reflected light of the same vertical irradiation light are arranged in an annular shape. A spectral colorimetric device characterized in that an optical fiber is connected to form a light receiving section. 2. The spectral colorimetric apparatus according to claim 1, wherein an interference filter and a light receiving element are connected in this order to the rear end side of each of the optical fibers to form a light guide section. 3. A photoelectric conversion unit in which two switches are connected in parallel to each of the light receiving elements, one switch is connected to ground via a charge storage capacitor, and the other switch is connected to ground. The spectral colorimetric apparatus according to claim 1, which is configured as follows. 4. The spectrocolorimeter according to claim 1, wherein the optical fiber of the light receiving section and the charge storage capacitor of the photoelectric conversion section are connected. 5. The spectral colorimetric apparatus according to claim 3, wherein the charge storage capacitor of the photoelectric conversion unit is variable.