JPS60192455A - Temperature detector of fluorescent light - Google Patents

Abstract

PURPOSE:To detect the temperature in a fluorescent lamp based on the rate of luminous amount of an infared part and a visual light part by utilizing a phenomenon that a fluorescent lamp irradiates strongly at a low temperature and the irradiation of infrared ray is weaker as the temperature gets higher and the irradiation of visual light by a fluorescent substance is weak at a low temperature and reaches maximum at a prescribed temperature. CONSTITUTION:When the tube temperature of the fluorescent lamp 5 is low, the after glow by the fluorescent substance hardly exists when the lamp 5 is turned off and the output voltage V1 of a photo transistor 6 decreases rapidly. A comparator 12 compares the voltage V1 with a voltage VSLICE, and when the relation of V1<VSLICE exists after 500musec is elapsed from the extinguishment, the fluorescent light 5 flickers at the period of 1sec. When the tube temperature reaches 40 deg.C because of self heating of the lamp 5, the after glow by the fluorescent light when the light 5 is turned off, and the voltage V1 is still high when 500musec is elapsed from a time t0 and the state of V1>VSLICE is kept, the lamp 5 stops flickering and transfers to continuous lighting.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a temperature detection device for a fluorescent lamp that detects the temperature inside the tube of a fluorescent lamp.

When a fluorescent lamp is used as a light source in a document reading device such as a digital facsimile, the fluorescent lamp emits infrared rays at low temperatures, which deteriorates the reading performance of the document being read, especially the red part, and the CCD sensor It is well known that the resolution itself also decreases. It is possible to improve this by using an infrared cut filter, but at low temperatures the amount of light emitted from the visible part of the fluorescent lamp is low, resulting in insufficient light and the S/N ratio of the CCD output becoming worse. It's a great read.

Therefore, in order to solve the above-mentioned problem, it would be sufficient to detect the temperature inside the tube of the fluorescent lamp and scan the document only when the temperature inside the tube is above a predetermined value. Conventionally, there was no means to detect the temperature inside the tube of this fluorescent lamp.

Purpose The present invention has been made in view of the above circumstances, and its purpose is to provide a fluorescent lamp i-opening detection device for detecting the internal temperature of a fluorescent lamp used in a document reading device such as a facsimile machine. be.

Nose - Fluorescent lamps emit strong infrared rays at low temperatures, and as the temperature rises, the infrared rays they emit weakens, and the visible light emitted by phosphors reaches its maximum at low temperatures <40°C. This method is used to detect the temperature inside a fluorescent lamp based on the ratio of the amount of light emitted in the infrared and visible parts.

actual marriage example An embodiment of the present invention will be described below.

FIG. 1 shows the configuration of a reading system of a facsimile to which the present invention is applied, in which a document 2 is driven by a drive source (not shown) on the lower side of the document back plate 1, and the upper side of the base plate 3 is horizontally moved in the figure. A fluorescent lamp 5 projects light onto the moving document 2 through the glass portion 4 of the base plate 3, and the reflected light from the document 2 is transmitted to the mirror 7 and the infrared cut filter 1.
0 and enters the CCD sensor 9 through the lens 8. 6
is a transistor which detects changes in the expansion and constriction of the fluorescent lamp 5. In this embodiment, a fluorescent lamp 5 having a green phosphor is used.

Figure 2 shows the above-mentioned CCl') sensors 9 and 7;
) shows the spectral sensitivity characteristics of Ranjistaro, where the CCD sensor 9 exhibits maximum sensitivity at a wavelength of around 707 nm, as shown by a solid line, and the 7-ototransistor 6 exhibits maximum sensitivity at a wavelength of around 800 nm, as shown by a broken line. FIG. 3 shows the spectral transmission characteristics of the above-mentioned infrared cut filter 10, in which the infrared region with a wavelength of 711 ('1nll1 or more) is cut. It shows the luminescence distribution characteristics near room temperature,
When the wavelength is 65 (') nm or less, the energy emitted by the green phosphor is distributed, and when the wavelength is 700 to 900 nm, the energy emitted by the enclosed gas of argon or krypton is distributed.

FIG. 5 shows the temporal change in the output of the CCD sensor 9 after the fluorescent lamp 5 is turned on when the original 2 is white in the above-mentioned reading system, using temperature as a parameter. Furthermore, FIG. 6 shows the temporal change in the output of the CCD sensor 9 after the fluorescent lamp 5 is turned on for a white original 2 when the infrared cut filter 1 ( ) is not used in the reading optical system described above. is shown using temperature as a parameter.

When the infrared cut filter 10 shown in Fig. 5 is used, the CCD sensor 9 at the outside ambient temperature H1'C and 20C.
The rate of increase in the output of the
This is greater than the rate of increase in the output of the CCD sensor 9 at °C. That is, when the temperature inside the tube of the fluorescent lamp 5 is low, when there is an infrared cut filter 10 on the outside, the output of the CCD sensor 9 changes greatly over time, and when there is no infrared cut filter 10, the output of the CCD sensor 9 changes significantly. The time change in the output is small. This means that when the internal temperature of the fluorescent lamp is low, the fluorescent lamp 5 emits less light in the visible region and more in the infrared region. Furthermore, as the ambient temperature rises by -L, the difference in the output of the CCD sensor 9 with and without the infrared cut filter 10 shown in FIGS. 5 and 6 decreases. ℃, the amount of light emitted from the fluorescent lamp 5 increases in the visible region and decreases in the infrared region. By detecting the ratio of the luminescence amount between the visible part and the infrared part, it is possible to know whether the internal temperature of the fluorescent lamp is at a value JJtL at which the document can be read normally.

Figures 7, 8 and 9 are 7o)) Ranjistaro (
Figure 1) shows the output of
Fluorescent lamps 5 lit at 0℃, 20℃ and 40℃
at time t. This shows the afterglow characteristics of the phosphor when the light is turned off. In FIGS. 7 to 9, the shaded area shows the infrared rays of the fluorescent lamp's output of the output of the 7-ototransistor 6, and the unshaded area shows the visible part of the output from the phosphor. The output of the phototransistor 6 is set to 1 when the fluorescent lamp 5 is turned on at an ambient temperature of 40°C in FIG. 9, and at ambient temperatures of 20°C and 10°C in FIGS.
The output of transistor 6 in each case of 7o)) is 4(
') It is a relative value of the value in the case of °C.

When the ambient temperature is 0'C in FIG. 7, the amount of light emitted in the infrared region is large and the amount of light emitted in the visible region is small. Therefore, time. The amount of afterglow when the light is turned off is also small. On the other hand, as shown in FIGS. 8 and 9, as the ambient temperature increases, the amount of light emitted in the infrared region decreases and the amount of light emitted in the visible region increases. Then, at 40'(:' in Fig. 5), the amount of light emitted in the visible part reaches its maximum.As the amount of light emitted in the visible part reaches its limit, the amount of afterglow becomes the same as when the fluorescent lamp 5 was turned off. In other words, the intensity of the afterglow corresponds to the ratio of luminescence in the infrared and visible regions, and if the magnitude of the afterglow is detected, the ratio of luminescence in the infrared and visible regions can be detected. As a result, the temperature inside the fluorescent lamp can be detected.

FIG. 10 shows the configuration of an apparatus for detecting the temperature inside a fluorescent lamp using the above-described principle.

The collector of the 7-inch transistor 6 that receives the light from the fluorescent lamp 5 is connected to the voltage 11Vcc, and this 7-inch transistor 6
The emitter of is grounded via a resistor R. The emitter of the phototransistor 6 is also connected via a resistor R2 to the input terminal of a voltage 7 lowerer 11 that operates as a buffer, and the connection point between this resistor R2 and the voltage 7 lowerer 11 is grounded via a capacitor C1. . The output terminal of the voltage 7 lowerer 11 is grounded through resistors R3 and R4 in series, and the connection point between the resistors R3 and R4 is connected to one input terminal of the comparator 2.

The emitter of the 7-channel transistor 6 is connected to the input terminal of the comparator 12, and the output terminal of the comparator 12 is connected to the D terminal of the D7 lip 13.

The Q output terminal of this D flip-flop 13 is connected to the RE A l))' terminal of the control circuit 14, and the T terminal of this control circuit 14 is connected to the T terminal of the D flip-flop 13. .

Output terminal TF of control circuit 14 1. , are connected to the input terminal IN of the lighting device 15. The lighting device 15 includes a fluorescent lamp 5
terminals and a power supply (not shown) are connected to the control circuit 14.
The lighting device 15 lights up the fluorescent lamp 5 in response to a signal from the lighting device 15 .

7- When the fluorescent lamp 5 lights up, the light emitted by the fluorescent lamp 5 causes
) Current flows through the transistor. A circuit consisting of a resistor R2 and a capacitor C1 includes a phototransistor 6.
The output voltage v1 of is integrated, and the integrated output \.2 is input to the voltage 7 lower 11. Then, voltage ■2゛, which is the same level as voltage ■2, is voltage 7 or lower 11.
This voltage V21 is divided by resistors R3 and R4, and the obtained voltage \7 is input to one input terminal S1 of the humpator 12, ICE. In this embodiment, the voltage 5LICE is set to 0.7V2''.

The comparator 12 compares the voltage ■1 and the voltage ■5LICE, and if the voltage ■1 is larger than the voltage ■LICE, sets the output terminal 12a to the "High" level.

The D7 lip 70 knob 13 is connected to the comparator 12.
When the output terminal 12a of QAT is at the "1g11" level, when T is input to the latch signal TL from the control circuit 14 to the terminal T, the rising edge of the signal T sets the QAT output terminal to the "High" level. The control circuit 14 outputs a reset signal TLAT8- to the D flip-flop 13, and when it receives a signal at the "Higl+" level from the D7 flip-flop 13 to the READY terminal, it outputs the signal TLAT8- to the terminal TFL.
Outputs a lighting signal to. After that, a constant lighting signal is output, and the fluorescent lamp 5 is lit continuously.

Then, the lighting device 15 connects the terminal TFI No.
``Turn on the fluorescent light 5 outside the level and connect the terminal'' P L
The fluorescent lamp 5 is turned off when it reaches the "Lou+" level.

Figure 11 shows the voltage V+ lV2 +V2'+Vs1, IC
E Finally, the terminals TF, , T, AI of the control circuit 14,
The state of RE AD Y is shown when the temperature is 10°C, and FIG. 12 also shows the state when the temperature is 40°C. Here, the fluorescent lamp 5 is turned on at time t. The afterglow caused by the phosphor starts from the time when the light is turned off at time t. Let Trp be the time until the light emission decreases to 1/10 of the light emission at , and let ΔT be the time from the fall of the signal of the end device of the control circuit 14 to the rise of the signal of the terminal TLAT, then R2・CI>>T
r p, >> ΔT. In this embodiment, the integral constant R2・C,=300 msec, and the afterglow opening “t,
= 30 tnsec, time ΔT = 500 μsec. In addition, the terminal −” PL of the control circuit 14 is 111
-1 pass level time is 2.5 m5pc.

7 The output voltage of the automatic transistor 6 1 corresponds to the sum of the infrared and visible parts of the light emitted by the fluorescent lamp 5 when the fluorescent lamp 5 is on, and corresponds to the sum of the infrared and visible parts of the light emitted by the fluorescent lamp 5 when the fluorescent lamp 5 is turned off. Corresponds to visible afterglow caused by the body.

The output voltage \12 of the integrating circuit consisting of resistor R2 and capacitor C1 and the output voltage \7. +
When the fluorescent lamp 5 is on, the 7-ototransistor 6 corresponds to the sum of the infrared and visible parts of the fluorescent lamp 5's light emission.
When the fluorescent lamp 5 is turned off, it maintains almost the same level as when the fluorescent lamp 5 is turned on. The voltage \'5LICE is obtained by dividing the voltage \12' by the resistors R3 and R, and is at a level of 70% of the voltage 2'. Further, the signal T is transmitted from the control circuit 14 for 1 s
A T is repeatedly output with a period of ec.

The operation will be explained below based on FIGS. 10 to 12.

When the temperature inside the tube of the fluorescent lamp 5 is low, as described above, the visible part of the fluorescent lamp 5's light emission is small, probably due to the proportion of infrared rays. Therefore, as shown in FIG.
When the fluorescent lamp 5 is turned off by setting the terminal TF'I to the 111,0 level at time 1°, there is almost no afterglow due to the fluorescent substance, and the output voltage 1 of the phototransistor 6 suddenly increases. decreases to

And time t. When 5 (1f) μ'Sec has passed since then, V, < V, and the comparator 12L
The output terminal 12a of the ICE is at the ``Loud'' level, and even if the latch signal T is output from the control circuit 14, there is no D flip A.
The Q output terminal of the Tp70 knob 13 holds the level '1.ou+', and the terminal RF of the control circuit 14: A D 'l'
is at the "1., o+u" level. Therefore, the control circuit 14 switches the terminal TF1. is set to the "Hi B l+" level again, and the fluorescent lamp 5 is turned on. Furthermore, the control circuit 14 controls the terminal TF when I sec has elapsed from time 1°.
The fluorescent lamp 5 is turned off by setting L to the ``Loud'' level again for 2.5 m5ec. Comparator 12 is voltage ■1
Compare the voltage ＼・′ with
- \l, the terminal READIICE Y of the control circuit 14 remains at the "Co" level, so the same operation as described above is repeated. Therefore, the fluorescent lamp 5
Flashes at a cycle of c.

Due to the self-heating of the fluorescent lamp 5, the temperature inside the tube rises by 1 and rises to 40'.
When reaching C, - As mentioned above, the amount of light emitted in the infrared region is small and the amount of light emitted in the visible region is large, and when the fluorescent lamp 5 is turned off, the afterglow due to the outside phosphor becomes large. Therefore, as shown in FIG. 12, the control circuit 14 changes at a time of 1°.

When the terminal TFL is set to the "L" level and the fluorescent lamp 5 is turned off, the output voltage (1) of the phototransistor 6 gradually decreases due to afterglow.Then, from time 1° to 50()
When μsec has elapsed, the voltage ■1 is still high and maintains the state of Vl>■, and the comparator 12
The ICE output terminal 12a is at "High+" level, and when the latch signal T is output from the control circuit 1.1, the Q output terminal of the AT D7 lip 70 knob 13 is at "High" level.
become the level. Then, the control circuit 14 connects the terminal RE A
When 2.5 m5ec has elapsed since time 12-1, the terminal ``P'' becomes ``)-1iglI'' level.
Set L to it) (i gl, II level, and from now on,
This terminal "Fl" is held at the II level (il) (ig). Therefore, the fluorescent lamp 5 stops blinking and shifts to continuous lighting.Then, the fluorescent lamp 5 is A signal indicating that the temperature has reached a temperature that allows normal reading of the original is input.The facsimile machine then starts reading the original.

As explained above, in the present invention, a fluorescent lamp emits infrared rays strongly at low temperatures, and the infrared rays emitted weaken as the temperature rises, and the visible light emitted by the phosphor becomes weaker at low temperatures. Utilizing the phenomenon that the temperature reaches a maximum at a predetermined temperature, the temperature inside the tube of a fluorescent lamp can be detected based on the ratio of the amount of light emitted in the infrared and visible regions. Good reading can be performed in a document reading device using a fluorescent lamp.

[Brief explanation of drawings]

Figure 1 is an optical line diagram showing the facsimile reading optical system, Figure 2 is a graph showing the spectral sensitivity characteristics of the CCD sensor and 7-channel transistor, Figure 3 is a graph showing the spectral transmission characteristics of the infrared cut filter, and Figure 3 is a graph showing the spectral transmission characteristics of the infrared cut filter. Figure 1 is a graph showing the luminescence distribution characteristics of a fluorescent lamp, Figures 5 and 6 are graphs showing the temporal change in the output of the CCD sensor, Figures 7 to 9 are graphs showing the output of the 7-ototransistor, FIG. 10 is a block diagram showing one embodiment of the present invention, and FIGS. 11 and 12 are timing charts showing the operating states of the main parts of FIG. 5...Fluorescent lamp, 6...Phototransistor, 11
... Voltage 7 orrower, 12... Comparator,
13...D7 lip flop, 14...control circuit,
15...Lighting device, R,, R2, R3, R4...
Resistor, C1... Capacitor. Patent Applicant Sharp Co., Ltd. Agent Patent Attorney Aobai Ao and two others 15--311! It − = d vertical ku 0! ltsu flea @'z4' Paulownia+Naka★- Fig. 5 30609012o, ec yF, light back face opening Fig. 6 30 60 90 120sec ゑ, light mirror 8! To to +5 to + + to +5 (msec)
〉 〉 ○ 工” 工”〉

Claims (3)

[Claims] (1) A detection means for detecting the ratio of the amount of light emitted by the fluorescent lamp between the infrared and visible parts, and a signal output means for outputting a signal corresponding to the temperature inside the tube of the fluorescent lamp according to the result of this detection. What is claimed is: 1. A temperature detection device for a fluorescent lamp, comprising: detecting the temperature inside the fluorescent lamp based on the ratio of the amount of light emitted in the infrared region and the visible region. (2) According to claim 1, the detection means detects the ratio of the infrared and visible parts of the light emitted by the fluorescent lamp according to the magnitude of afterglow caused by the phosphor when the fluorescent lamp is turned off. The temperature detection device for the fluorescent lamp described. (3) The temperature detection device for a fluorescent lamp according to claim 1, wherein the detection means uses a detector having sensitivity in the visible region and infrared region.