Light source and image processor for digestive endoscopy

I. Cold Light Source

The cold light source is the illumination source of the endoscope. According to the bulb type, it can be divided into two types: halogen lamp type and xenon lamp type. Taking the endoscope cold light source produced by Olympus as an example, the CLE-10 type can be used as a representative of the halogen lamp type cold light source, mainly used for fiber endoscope illumination. The xenon lamp type cold light source is the most advanced CLV-U40 type. This type of cold light source is used for electronic endoscopes, but it can also be used for fiber endoscopes. Compared with the former, it has the characteristics of high power, high color temperature, and multiple functions.

(I) Classification of Cold Light Sources

1. Halogen Lamp Type Cold Light Source

(1) Bulb

Generally, it is a low-voltage, high-current bromine tungsten lamp or halogen mercury lamp, with a power of about 150W and a color temperature of 3200K. The emitted light is yellowish and suitable for taking endoscopic photos with light-type film. The bulb price is relatively low.

(2) Heat Dissipation Device

Because the cold light source uses high-power bulbs of more than 100 watts, it generates a lot of heat. To prevent this heat from being radiated to the endoscope, burning the light guide and burning the digestive tract wall, two types of heat dissipation devices are specially designed: one is a spherical reflective cover installed behind the lamp core. The surface of this reflective cover is alternately coated with nearly 20 layers of zinc sulfide and magnesium oxide film, which can filter out the infrared rays that generate heat in the illumination light. In this way, the light radiated by the bulb is free of infrared rays, which becomes cold light; another heat dissipation device in the light source is a cooling fan installed next to the bulb, which fully dissipates the heat generated by the infrared rays filtered by the cold light film.

(3) Air Supply Device

The electromagnetic pump in the cold light source delivers gas under a certain pressure to the endoscope, and the gas flow rate is controlled by the "Air" switch ("HIGH", "MID", "LOW" three levels) on the cold light source panel.

(4) Endoscopic Photography Automatic Control System

The system uses TTL logic circuits to control the opening and closing of the electronic shutter, and automatically adjusts the exposure of endoscopic photography according to the distance between the objective lens and the subject and the amount of reflected light to ensure satisfactory photographic effects.

(5) Panel Structure of Halogen Lamp Type Cold Light Source

It requires a beautiful and simple appearance and easier operation. The devices on the panel include: power switch (POWER), endoscope socket (OUTPUT), manual/automatic exposure selection key, exposure index table, exposure index adjustment knob, illuminance adjustment, illuminance indicator (BRIGHTNESS), air supply intensity indicator (AIR), exposure detection button, backup lamp warning, SC16-10 test switch, air flow adjustment key, exposure index fixed lock, foot switch jack, SC16-10R connector, backup lamp selection button, etc.

2. Xenon Lamp Type Cold Light Source

Compared with the halogen lamp cold light source, the xenon lamp cold light source has basically the same structure, but the brightness of the bulb is increased by 1.5 times, and the color temperature is increased to about 6000K, which can obtain daylight-type illumination effects.

Its panel devices include:

① Power switch (POWER);

② Light guide cable socket (OUTPUT);

③ Endoscope mode series selection key (MODE);

④ Air supply intensity adjustment key (AIR);

⑤ Endoscope photography exposure sensitivity selection key (STILL PHOTO);

⑥ Endoscope brightness control panel (BRIGHTNESS);

⑦ Color filter selection key (FILTER);

⑧ Transillumination switch (TRANS ILLUM). When this key is pressed, the transillumination indicator light can be turned on. At this time, the light emitted from the endoscope is stronger, which can be used for external positioning of gastrostomy tube placement under endoscopy and external positioning of colonoscopy. It will automatically turn off after 7 seconds;

⑨ Bulb life meter (LAMP LIFE), indicating the cumulative working time of the xenon lamp. The indicator mark exceeding the red area indicates that the bulb needs to be replaced;

⑩ Foot switch jack (FOOT SW);

11. Rigid endoscope brightness control line socket;

12. Trigger (IGNITION), which is unique to short-arc xenon lamps. Press this key to light the xenon lamp.

(II) Common Faults and Troubleshooting During Use

1.The cold light source bulb does not light up: After the power is turned on, if the bulb does not light up, there are often three possibilities:

① The bulb has been used for a long time and has been naturally aged and damaged, and needs to be replaced with a new bulb;

② The voltage is too high and the bulb is burned out, and a new bulb needs to be replaced;

③ The halogen bulb pins are oxidized or the socket is loose, resulting in poor contact.

In the first case, take out the bulb, use a small knife or sandpaper to scrape off the rust layer, then wipe off the rust with ether alcohol, and reinstall it; if the lamp socket is loose, you can tighten it with insurance lead wire.

2.Replacement of halogen bulbs and xenon lamps: Turn off the power switch, be sure to remove the cable, and operate according to the instructions.

3.Air pump failure: If the air pump does not inject air or the air volume is insufficient, the possible reasons are: the connection between the infusion bottle connector and the endoscope is not tight, please reinsert it; the rubber ring of the infusion bottle connector is aging, making the infusion bottle not airtight, replace the rubber ring or use latex glove fragments to wrap around the rubber ring, then connect the endoscope interface; the endoscope air injection and water injection button is loose, reinstall the button; air pump mechanical failure, needs to be sent to the repair station for repair.

(III) Maintenance of Endoscope Cold Light Source

1.Handle with care during transportation, and prevent collisions or vibrations. Avoid direct sunlight and moisture during storage.

2.If the supplied power voltage is unstable, a voltage regulator should be added to stabilize the voltage. Xenon lamp cold light sources have a relatively high power consumption; when using a voltage regulator, be sure to select one with a power rating of 2KV or higher.

3 . Note: It is best not to use the cold light source's air injection pump as an endoscope dryer.

II. Endoscope Image Processor

Also known as a converter, this device converts the images acquired by the electronic endoscope into electronic signals and displays them on the monitor. It is a crucial component of the entire electronic endoscope system. The structure of image processors varies among manufacturers, but their main components are largely similar. A brief introduction is provided below:

(1) Front Panel

Its main functions are:

1. Power: Use this key to turn the image processor on or off.

2. Electronic endoscope cable connection jack: The electronic endoscope cable (200, 240, or OES) video converter (OVC-200) connects here.

3. Monitor output indicator (image source, IMAGE SOURCE): Displays the image source on the monitor.

4. Reset key (RESET standard key): Pressing this key restores the image source, [IRIS] (light metering), [ENH] (enhancement), and [COLOR] (hue) to their standard settings.

5. White balance display: This light illuminates during white balance adjustment and turns off once completed.

6. White balance key (WHITE BAL): Press this key to adjust the endoscope's white balance.

7. Light metering mode selection key (IRIS): Press this key to select the light metering mode [PEAK] (peak metering) or [AVE] (average metering).

8. Light metering mode indication: Displays the selected light metering mode, such as PEAK or AVE.

9. Red adjustment key (R): Press this key to adjust the desired red; the hue is displayed on HUE.

10. Hue indication (HUE): Displays the hue level of red or blue.

11. Blue adjustment key (B): Press this key to adjust the desired blue; the hue is displayed on HUE.

12. Select key (SELECT): Press this key to select the monitor output image.

13. Video printer status display: Indicates that the printer is currently working.

14. Video printer key (PRINT): Press this key to send the screen image to the video printer.

15. Structure emphasis selection key (ENH): This key adjusts the level of structure or outline emphasis. You can select whether to emphasize structure or outline in the system's preset selection mode.

16. Structure emphasis indication: Displays the emphasis level of structure or outline, divided into high (HIGH), medium (MED), and low (LOW) levels.

(2) Rear Panel and Connections

The rear panel mainly includes power jacks, light source, monitor, keyboard, and printer input jacks. When purchasing a new machine, the company will send a technician to install it. Medical personnel can also install it according to the operating instructions. This will not be elaborated here.

(3) Keyboard

An endoscope-specific keyboard, used to input various information and select various functions. It is therefore a skill that medical personnel must be familiar with and master.

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